C-NRLF 
 
 SB 
 
Boiler Safe 
 
 T 
 
 ISSUED BY THE 
 
 Industrial Accident ComnM&oft 
 
 of the 
 
 State of California 
 
 SAN FRANCISCO, CALIFORNIA 
 
 CALIFORNIA'S SAFETY ORDER SYSTEM 
 
 BY WILL J. FRENCH. 
 
 THE NEED OF BOILER SAFETY ORDERS. 
 
 BY H. M. WOLFLIN. 
 
 SOME OPINIONS OF THE A.S.M.E. BOILER CODE. 
 
 BY R. L. HEMINGWAY. 
 
 BOILER SAFETY. 
 
 BY R. L. HEMINGWAY. 
 
 HORIZONTAL TUBULAR BOILERS (LETTER AND 
 CIRCULAR). 
 
 BY D. C. HARVEY. 
 
 HOW SAFE IS A USED LAP SEAM BOILER? 
 
 EDITORIAL, JOURNAL OF ELECTRICITY, OCTOBER, 1920. 
 
 BOILER CODE, THE A.S.M.E. 
 
 EDITORIAL, JOURNAL OF ELECTRICITY, OCTOBER, 1920. 
 
 METHODS OF JOINING BOILER SEAMS. 
 
 (INTERNATIONAL STEAM ENGINEER, JANUARY, 1921.) 
 
 APPLICATION OF INSIDE WELT STRAP TO OLD LAP SEAM 
 
 BOILER. 
 
 BY R. L. HEMINGWAY. 
 
 THE SINGLE SHEET LAP SEAM BOILER. 
 
 BY J. P. MORRISON (POWER, APRIL 26, 1921). 
 
 CHANGING OLD LAP SEAM BOILERS TO BUTT SEAM 
 CONSTRUCTION. 
 
 (THE LOCOMOTIVE, APRIL, 1921.) 
 
 LAP SEAM CRACK CAUSES BOILER FAILURE 
 IN PLANING MILL. 
 
 (THE BOILER MAKER, APRIL, 1921.) 
 12180 
 
^sne ^fie/emu andwabuatfy (oom/ianu 
 
 ROBT. J. HILLAS, President 
 
 a 
 
 D. C. HARVEY, 
 
 Superintendent of Inspections 
 
 April 29, 1921. 
 
 ANSWER TO LETTER OF 
 
 Mr. J. H. Petherick, 
 Chief Inspector, 
 Balfour Building, 
 San Francisco, California. 
 
 Dear Sir : 
 
 Re : HORIZONTAL TUBULAR BOILERS- 
 ONE SHEET ON THE BOTTOM 
 TYPE OF CONSTRUCTION. 
 
 Last week a boiler in a Saw Mill at a plant located in the south exploded, killing 
 two people, injuring several others and causing heavy property damage. 
 
 At this writing, complete details are lacking but from what we have received, the 
 boiler, which was of the Horizontal Tubular type, was constructed with one sheet 
 on the bottom and one on the top. The boiler gave way because of a hidden lap 
 seam crack. 
 
 We wish to obtain at once a list of all such boilers and the plants at which they 
 are located. 
 
 Will you go over your records carefully and advise us if you have any such boilers 
 at plants in your territory and if so, the names and locations. In addition we want 
 to be advised of the age of the boilers. 
 
 Read carefully the instructions with regard to this type of boiler in the Book of 
 Inspection Rules and follow them in making your inspections. Further instructions 
 will be issued shortly. 
 
 We will ask you to give us the information asked for promptly. 
 
 Yours truly, 
 
 D. C. HARVEY, Superintendent. 
 
CALIFORNIA'S SAFETY ORDER SYSTEM. 
 By WILL J. FEENCH, Chairman Industrial Accident Commission. 
 
 When the California Workmen's Compensation, Insurance and Safety 
 Act was in course of preparation, a study was made of existing safety 
 laws in different states and countries. The experience of a large group 
 of other jurisdictions was ascertained. Consultation followed with Cali- 
 fornia employers and employees, as well as with citizens in all walks of 
 life. The consensus of opinion favored the plan in operation in Wis- 
 consin, whereby safety standards were issued by the Industrial Commis- 
 sion, and these standards can be changed at any time or exemptions 
 issued to meet unusual conditions. The only other feasible plan was 
 that of having the legislature definitely state in statute how machinery 
 of all kinds should be protected. There could be little or no flexibility 
 under this plan. Its cost to California's employers would have been 
 enormous, because there was no organized safety movement in the state 
 and the field was virgin. 
 
 The legislature of 1913 approved the plan of assigning to the Industrial 
 Accident Commission the work of issuing safety standards for the dif- 
 ferent industries. It is interesting these days to recall the activities of a 
 large group of employers in favor of the plan adopted, because there were 
 pending bills calling for specific safety installations that were drastic in 
 character. 
 
 It is a fair question to ask the experience of the intervening seven and 
 one-half years since January i, 1914. About twenty of the largest indus- 
 tries are governed by safety orders. Other industries will have their 
 standards set just as soon as it is possible for the Safety Department, 
 with its inadequate force and lack of finances, to handle the work. This 
 doesn't mean that general supervision has been impossible. The law 
 requires that all places of employment shall be safe for the employees 
 therein, and employers have cooperated with the Commission in a com- 
 mendable way. 
 
 While the Commission has authority to issue standards of safety of its 
 own preparation, so far as the industries are concerned, that course never 
 has been followed. The law gives authority to appoint "advisers" to 
 assist the Commission. The importance of participation by all interested 
 groups in considering safety standards has always appealed to the Com- 
 mission, and the members of each committee were selected by their 
 respective organizations. In no instance was a committee "hand picked." 
 Letters were invariably mailed to the employers' organization, to the 
 trade union, and to different associations interested in the industry under 
 consideration. Employers and employees predominated on each com- 
 mittee, and the engineers of the Commission's staff only held one or two 
 places. Consequently, tentative safety orders were issued by a group of 
 men with special knowledge of the industry's requirements. They were 
 sent broadcast in printed form for criticism or suggested change. Public 
 hearings were called in San Francisco and Los Angeles. Legal notices 
 appeared as required by law, but, recognizing the fact that but few per- 
 sons see such notices, carefully prepared statements of the contemplated 
 public hearings were sent to all the daily, weekly and monthly publications 
 in California, together with statistical information about deaths and 
 injuries in the industry. 
 
 M92897 
 
4 BOILER SAFETY BULLETIN. 
 
 To each public hearing came the product of the study and planning of 
 the committee in the form of tentative standards. The experiences of 
 other states had been utilized. The widest publicity was given the hear- 
 ing. A member of the Commission presided. No limit was placed on 
 speakers in any way. Each word of criticism or recommendation for 
 change was taken down by a reporter and referred back to the committee 
 that prepared the tentative orders. An invitation was extended to those 
 interested to meet with the committee, in order that there should be com- 
 plete knowledge of the proposed changes. After the fullest deliberation, 
 the committee drafted the safety orders with the experience of the public 
 hearings as a guide, and recommended their approval by the Industrial 
 Accident Commission, to become effective at a date in the future which 
 would give time for compliance. Such extraordinary care was followed 
 in the process of promulgating each set of safety standards that, so far, 
 it has been unnecessary for the Commission to question the advisability 
 of following the committee's recommendations. 
 
 This history is needed. The men on the Industrial Accident Commis- 
 sion and on its staff have had, and still have, for their goal reasonable 
 safety, intelligent administration, the exercise of the power to issue 
 special orders and grant exemptions when justified, and a total avoidance 
 of what might appear to be arbitrary methods. An appeal to the Com- 
 mission is always solicited if an order is considered unreasonable or if 
 there is objection to the ruling of a member of the staff. The use of 
 home-made guards is advocated. The reduction of expense is admittedly 
 important and is aided, provided that safety will not be sacrificed as a 
 result. 
 
 The right hand of fellowship has been given the Commission by a large 
 majority of the employers and the employees in California. It is no idle 
 boast to say that every effort has been put forth to merit the confidence, 
 even though the task has been difficult and the road not always smooth. 
 In spite of these obstacles, it is felt that no small part of this confidence 
 has been earned. While on the one hand the Commission will continue 
 its broadminded policies, on the other hand a continued and increasing 
 measure of cooperation from employers and employees is essential for 
 the benefit of all. 
 
 THE NEED FOR BOILER SAFETY ORDERS. 
 
 By H. M. WOLFLIN, Superintendent of Safety. 
 
 After reading the article on "The Single-Sheet Lap-Seam Boiler," by 
 J. P. Morrison, on page 26 of this bulletin, it may be interesting 
 if a few additional facts are presented concerning the frequency of boiler 
 explosions and the finding of defects that lead to such explosions. 
 
 In a pamphlet entitled "Steam Boiler Explosions," published by the 
 Fidelity and Casualty Company of New York, and delivered at Cornell 
 University in the form of an illustrated lecture, by their Superintendent 
 of the Department of Steam Boiler and Fly Wheel Insurance, Mr. Boehm 
 opens his remarks by quoting the frequency of boiler accidents and 
 "explosions, annually in the United States. 4 He states ^ that there are 
 between 13,000 and 14,000 serious boiler accidents, of which from 300 to 
 
SAFETY BUU^TIN. J 
 
 400 are violent explosions. These mishaps kill between 400 and 500 per- ' 
 sons and injure 700 or 800 more, beside destroying over one-half million 
 dollars worth of property each year. 
 
 Mr. Boehm then gives details of the killed, injured, and property losses 
 occurring in a boiler explosion at the R. B. Grover Shoe Company, at 
 Brockton, Massachusetts, and points out that the explosions of fire-tube 
 boilers are more numerous than those of water-tube boilers. He also 
 indicates that these facts emphasize: (i) The necessity of constructing 
 and installing steam vessels and their appurtenances in as nearly perfect 
 a manner as possible; (2) the importance of preventing carelessness in 
 their operation; (3) the wisdom of having them inspected at regular 
 intervals by disinterested experts; and (4) the desirability of forethought 
 in securing an adequate amount of insurance to pay the loss if an explo- 
 sion occurs. 
 
 He states that it is of the utmost importance that boilers be carefully" 
 designed, that the known stresses to which they are subjected be accu- 
 rately computed, that suitable material be specified, that the material be 
 critically examined for flaws or defects, that specimens of the material be 
 tested to determine its strength, that no abuse of the material be allowed 
 in the process of constructing the boiler and that the completed boiler be 
 subjected to a thorough inspection and a hydrostatic test before being put 
 into service. 
 
 Then follows a dissertation upon the method of determining some of the 
 stresses in the shells of boilers, the bursting pressures, culminating in the 
 statement that "It is usual in boiler practice to fix the allowable working 
 pressure for a new boiler at one-fifth the computed bursting pressure and 
 to decrease the pressure allowance as the age of the boiler increases!' 
 
 Mr. J. H. Petherick, chief inspector of the Fidelity and Casualty 
 Company of New York, has called attention to a letter which he has just 
 received from Mr. D. C. Harvey, superintendent of inspections, concern- 
 ing a recent explosion of a lap-seam boiler located in a sawmill in the 
 South. This is another instance of a lap-seam disaster which may be 
 added to the long list of boiler accidents resulting from this method of 
 construction. The letter is dated May 6, 1921, and reads in part as 
 follows : 
 
 "The boiler was of the Horizontal Tubular type, 66 inches in diameter and 16 
 feet long. The age of the boiler has not been determined but it was at least 13 
 years old and was constructed with one sheet on the bottom and one sheet on the 
 top, with lap longitudinal seams extending from head to^head. The seams were 
 inaccessible for inspection on account of the tubes on the inside and the brickwork 
 on the outside. The boiler exploded violently, killing two men, injuring several 
 others and causing heavy property damage. The explosion occurred in the early 
 morning between five and six and just as the plant was being gotten ready for the 
 day's run, and our advices are that the steam pressure on the boiler was about 80 
 pounds. 
 
 "The explosion was due to a hidden lap-joint crack developing about 18 inches 
 from the front head on the left side of the boiler. The crack was about 2 feet long. 
 The initial rupture took place at this crack and extended for 6 feet through the 
 net section of the seam, then for another 6 feet through the solid plate to rear head. 
 
 "The boiler opened up flat, shearing the rivets in rear head seam and breaking 
 the front head into three places, also breaking the cast iron manhole frame in 
 several places. 
 
 "The six other boilers adjacent to the one that exploded were knocked off the 
 settings and the building was entirely demolished. 
 
 "The explosion of this boiler is another striking instance of the unreliability of 
 the lap-seam type of construction." 
 212180 
 
6 BOMR SAFETY BULLETIN. 
 
 Referring once more to Mr. Boehm's address, I quote from page nine : 
 
 "Besides our ignorance of the dependable strength in all parts of the plate, there 
 is also our ignorance of the character of the workmanship in the boiler. We can 
 not be certain that all rivet holes come fair, or that incipient cracks have not been 
 set up by an abuse of the material during the process of construction. 
 
 "It is seen therefore, that factors of safety are really made up of two parts one 
 part a true factor of safety, the other a pure factor of ignorance. // this matter 
 were better understood, boiler owners would themselves insist upon a computed 
 factor of safety ^ of not less than -five and they would not be> so persistent, as many 
 are, in demanding that their boiler insurance company grant an unwise increase of 
 pressure." 
 
 The remainder of the address is devoted to an explanation of some of 
 the causes of boiler explosions, the time required to attain pressure suf- 
 ficient to rupture, and an explanation of the energy stored in the hot 
 water in boilers. 
 
 There follows an interesting quotation from a book entitled "A Manual 
 of Steam Boilers, their Design, Construction and Operation," by Pro- 
 fessor R. H. Thurston, who was in his day one of the foremost authorities 
 on this subject. On page 645, Professor Thurston says: 
 
 "The experience of the steam-boiler inspection and insurance companies indicates 
 that, in the United States, not less than a half, often two-thirds, of the boilers 
 inspected may be expected to be found more or less defective and perhaps ten per 
 cent in a dangerous condition. Of the boilers which are not subject to constant 
 supervision and frequent inspection nearly all may be assumed to be defective, and 
 a large percentage dangerously so." 
 L 
 
 As tending to substantiate the claim of Professor Thurston, I quote 
 statistics of the Hartford Steam Boiler Inspection and Insurance Com- 
 pany, published in their quarterly magazine The Locomotive : In the year 
 1920 this company made complete internal inspections of 393,900 boilers, 
 they found 1139 of them uninsurable, and the inspectors discovered 
 212,739 defects, of which 23,063 were rated as dangerous. To show that 
 these statistics for one year are not abnormal, but represent a fair average 
 over a number of years, I also quote the complete figures of the Hartford 
 Company since the year 1866 up to December, 1920. In the 54 years 
 included, this company made 3,832,669 complete internal inspections, 
 condemned 29,978 boilers and discovered 5,492,424 defects, of which 
 603,683 were considered dangerous. These figures may be substantiated 
 by referring to page 184 of the April, 1921, issue of The Locomotive. 
 
 From the foregoing the need of careful boiler inspection is apparent. 
 Unless standards are developed for these inspections there will be a wide 
 variation between the findings of individual inspectors. The possibilities 
 of these variations have become increasingly evident, as shown by the 
 records of the Department of Safety which is responsible for the inspec- 
 tion of some 3,500 uninsured boilers each year. If it is difficult to secure 
 uniformity among relatively few men inspecting boilers, where they are 
 working under the immediate supervision of one man, certainly there will 
 be greater difficulty in securing uniform practices in inspection, operation 
 or construction of boilers where the work is performed under the super- 
 vision of many different individuals. To assist in securing this uniform- 
 ity and thus increase the safety of employees, with a minimum of hardship 
 on employers, a practical, workable set of safety orders covering these 
 points was prepared and made effective in California, some four and one- 
 
BOILER SAFETY BULLETIN. 7 
 
 half years ago. Each year since that time some 20,000 boilers have been 
 inspected under the provisions of these standards. Not only has this 
 experience shown beyond question the need for the Boiler Safety Orders, 
 from the standpoint of safety, but it also has indicated the desirability of 
 making a few minor changes in their provisions. These changes are 
 under way. 
 
 SOME OPINIONS OF THE A.S.M.E. BOILER CODE. 
 
 By R. L. HEMINGWAY, Chief Boiler Inspector. 
 
 Another article in this bulletin gives a brief history of how the 
 A.S.M.E. Boiler Code came to be drafted. It may be of interest to many 
 of our readers to learn how this code is regarded, not only by those who 
 drafted it, but by others who are concerned in its application, and still 
 others whose opinions of a technical engineering specification of this 
 kind, if the opinion of experts is to carry any weight, must convince even 
 the most skeptical of the absence of selfish motives in the preparation of 
 the code. 
 
 Hitherto, in dealing with scientific subjects, it has been common 
 practice for individuals to record the results of their observations, experi- 
 ments, experiences and knowledge gained through years of research, in 
 the form of individual books. Such books, while of immense value to 
 those interested in the subject covered, seldom carried the weight that 
 does the A.S.M.E. Boiler Code. This code is not an expression of 
 opinion of one man, resulting from individual effort, but represents the 
 combined views of many of the recognized highest authorities in the 
 United States. It goes even further, since the committee that drafted 
 this code was not content to accept the views of Americans and American 
 practice alone, but sent one of their members to Europe where an exhaus- 
 tive investigation of the government rules of European countries was 
 made, in order that this American Society of Mechanical Engineers' 
 Boiler Code might not fall short of the high aim that the individuals on 
 the committee desired to attain when they undertook this work of 
 universal value. 
 
 The society in the past has given to the engineering profession a great 
 deal of information that has been of immense value, and all of it is dis- 
 seminated broadly among its 14,000 members without extra charge. It 
 is doubtful, however, if. any work that the society has ever undertaken is 
 of more value or of greater importance than this boiler code, representing 
 as it does the last word in steam boiler specifications and assuring to the 
 United States that freedom from preventable boiler explosions which 
 European countries have long since attained. There can be few, if any, 
 who will deny that the record of boiler explosions, with the accompanying 
 loss of life and property in the United States, is a strong indictment 
 against this country for its lack of progress and its failure to keep abreast 
 of the times. 
 
 One of the keynotes of modern progress is conservation, whether it be 
 of natural resources or, equally as important, human life. Next in 
 importance, probably, comes property. The possibility of immense loss 
 to both human life and property that may occur from the sudden release 
 of the pent up forces contained in the modern steam boiler are hardly ever 
 
8 BOILER SAFETY BUIXETIN. 
 
 realized by the layman, and it is difficult to bring home to the non- 
 technical mind any idea of the immensity of these forces. 
 
 The boiler code of the American Society of Mechanical Engineers is 
 designed to safely control these forces and if it did nothing more, it has 
 performed a service that commands the gratitude and respect of the entire 
 nation. 
 
 In the face of the facts given above, and they are incontrovertible, it is 
 surprising to find that efforts have been made to combat the continuance 
 in force of this code in California. As soon as the Industrial Accident 
 Commission understood that this attack was to be made, a number of 
 letters were written asking for opinions of the A.S.M.E. Boiler Code. 
 Excerpts from some of these opinions will be found appended. It is inter- 
 esting to note that none of those who answered the letters condemned or 
 criticized the A.S.M.E. code. The specious argument adduced by local 
 opponents of the code, to the effect that its adoption in California would 
 act in favor of eastern boiler manufacturers and react detrimentally to 
 the industry in California, will not stand even the most elementary 
 analysis. 
 
 Regardless of what code California puts into effect, eastern manu- 
 facturers will build in competition with local builders. If California 
 should draw a special code of its own, eastern competition will continue, 
 but the boiler users of California will pay more for the special specifica- 
 tions. On the other hand, if California should take the unthinkably retro- 
 grade step and revert to the conditions of placing the boiler users and the 
 employees of the state at the tender mercy of eastern manufacturers, 
 with no restrictions, then the local manufacturers will indeed have cause 
 for complaint, because the reputation that the latter have earned for 
 constructing good boilers of sound material and workmanship must be 
 sacrificed if they compete with the unrestricted efforts of eastern 
 manufacturers. 
 
 It is desirable, in a controversy of this kind, to limit the discussion to 
 the engineering standpoint and to keep out all commercial aspects, as far 
 as possible. Unfortunately, this desirable condition is not always attain- 
 able, and arguments of a commercial nature are introduced to prove that 
 the code has been beneficial to California. 
 
 The largest manufacturer of boilers in the state, and the one having 
 the most modern and up-to-date shop, attributes the success of his boiler 
 manufacturing business almost entirely to the adoption of this code. It 
 is an undeniable fact that more boilers have been built in California in 
 the last three years than were built in a period of over ten years immedi- 
 ately preceding. 
 
 Accurately speaking, the boiler code of the American Society of 
 Mechanical Engineers is nothing more nor less than an engineering 
 specification, stipulating the quality of materials to be used in boiler con- 
 struction, the broad general principles to be followed in construction and 
 vSetting forth in simple language the mathematics that enter into the cal- 
 culations necessary to the proper design of any type of boiler. If these 
 facts are thoroughly understood, it is felt that the objections to the code 
 will be entirely removed. 
 
BOILER SAFETY BULLETIN. 9 
 
 OPINIONS OF THE A.S.M.E. CODE. 
 United States Bureau of Standards. 
 
 "The Bureau regards the Boiler Code of the American Society of 
 Mechanical Engineers as the most authoritative publication on the sub- 
 ject of safety in the construction and operation of steam boilers, that is 
 available. 
 
 "The Bureau of Standards is very glad to endorse the work of the 
 American Society of Mechanical Engineers in this field and we hope 
 that these standards will become national throughout the country." 
 
 W. W. Hanscom, Chairman, San Francisco Section, A.S.M.E.'. 
 
 "It has long been recognized that standardization in manufacturing is 
 a most important factor, especially where the products are to be of 
 national use and are liable from the nature of their application to be 
 dangerous to life and property if neglected or improperly handled. I 
 know of no product to which this statement will apply with more force 
 than in the case of steam boilers, for in their use forces are constantly at 
 work to decrease the original strength and factor of safety. In the 
 manufacture of boilers, like every other product, there are some who 
 take advantage of every opportunity to reduce cost, not always with the 
 idea of maintaining safety in use, but generally with the idea of increas- 
 ing profit at the expense of the purchaser. 
 
 "In summing up what has been previously written, it would be evident 
 that there is sufficient and immediate demand for standard rules regulat- 
 ing the construction, installation and operation of steam boilers. That 
 these rules should be nationally adopted and enforced so that conditions 
 will be uniform throughout the country ; that proper provision should be 
 made for the depreciation and deterioration continually taking place in 
 the boiler and on it, to allow for the misuse and the invisible and visible 
 changes taking place in the materials of the boilers and also for the utter 
 impossibility of ever reaching 100% efficiency in the manufacture of 
 materials, the working of them into commercial shape, or in the use of 
 the finished product in the service of man. 
 
 "As the fundamental basis upon which the Code has been formulated is 
 safety, one of the principal, if not the principal, factors is undoubtedly 
 that which determines the allowable pressure at which a boiler should 
 be operated." 
 
 Charles Edward Lucke, Professor of Mechanical Engineering, 
 Columbia University: 
 
 "You may, therefore, assure" everybody that no better basis exists, nor 
 is there any prospect of securing a better basis for a safe procedure 
 regarding boiler construction and maintenance than is now available in 
 the A.S.M.E. Boiler Code. * * * Just how to make a boiler safe 
 and how to prescribe rules insuring its safety, the Code sets forth that it 
 was framed by people who knew, and it would be difficult and very likely 
 impossible to find any group of people better able to do what has been 
 done." 
 
 S. F. Jeter, Chief Engineer, 
 
 Hartford Steam Boiler Inspection and Insurance Company: 
 "As an engineer who is interested first, last and always in the steam 
 users' viewpoint relating to questions regarding rules and regulations to 
 
10 BOILER SAFETY BULLETIN. 
 
 govern boiler operation, I can not see how any organization is better fitted 
 to draft safety rules than the American Society of Mechanical Engineers. 
 
 "The rules were adopted only after the utmost publicity and an 
 invitation to every one interested to criticise the proposed rules before 
 they were actually made a part of the Code. 
 
 "As a final check against the adoption of any rule that might react 
 against the steam user or was not consistent with good practice, and as an 
 aid in securing uniformity, a Conference Committee to the Code Com- 
 mittee was appointed by the Society, this Conference Committee being 
 composed of the chief inspectors of all the states having adopted the 
 Code." 
 
 F. R. Low, Editor, "Power": 
 
 "The specifications are no more exigeant than is necessary to insure 
 safety, and any boiler shop can build to conform to them. The conten- 
 tion on the part of those who would prefer to take a chance upon a 
 boiler that was not so safe, that the Code has been formulated by the big 
 boiler builders so as to put the small builders at a disadvantage, is natural 
 but cheap and fatuous." 
 
 John A. Stevens, Chairman, Boiler Code Committee, A.S.M.E.: 
 
 "The A.S.M.E. Code is and was certainly at the time of the convention 
 the most complete code in existence for the safe and commercial con- 
 struction of boilers in the United States of America, as evidenced by the 
 number of states and municipalities which have since made this Code a 
 law on their statute books." 
 
 S. J. Williams, Secretary-Chief Engineer, National Safety Council: 
 
 "I have no hesitation in saying that the A.S.M.E. Boiler Code is by 
 far the best code in existence and is so recognized by a great majority of 
 boiler owners and users, government authorities, and engineers. This 
 Code was formulated by a joint committee under the auspices of the 
 American Society of Mechanical Engineers. This society is entirely free 
 from any selfish interest in the matter, its only desire being to standardize 
 boilers in the interest of safety, and, secondarily, of economy." 
 
 H. W. Mowery, President, American Society of Safety Engineers: 
 
 "The A.S.M.E. Code is a Safety Code. In the original statement of 
 the Committee to the Council of the A.S.M.E., it stated: 'The primary 
 hope of these rules is to secure safe boilers/ 5: 
 
 W. F. Durand, Stanford University: 
 
 "Prom such contact as I have had with the Code, I have been impressed 
 with the fact that it seemed designed throughout to promote safety in 
 industrial establishments, and to hold up to boiler makers and users a 
 high standard of construction and installation. 
 
 "The ideal before the Society (A.S.M.E) in promulgating this Code 
 was to place before the builders and users of boilers a standard code, 
 reasonable in its requirements, undeniably safe and which might ulti- 
 mately become the universally recognized standard throughout the 
 country." 
 
SAFETY BULLETIN. II 
 
 J. C. McCabe, Chief Inspector, State of Michigan: 
 
 ''The essential feature in the adoption of the A.S.M.E. Boiler Code is 
 that under a code of recognized standing, having the authority of the 
 greatest engineering society in the world as its sponsor, it removes any 
 reasonable doubt as to the safety of a boiler built under its rules. 
 
 "I have been in constant touch with the development of the A.S.M.E. 
 Boiler Code, and the only criticism which I can make against the Boiler 
 Code Committee is that they are endeavoring to make the provisions of 
 the Code as reasonable as possible, and occasionally they overstep what 
 would be considered, in my opinion at least, good engineering practice, all 
 with the best intent of making the Code workable, popular and effective. 
 
 "It would certainly be a step in the wrong direction if the authorities 
 recede from their endorsement and use of the A.S.M.E. Code in the State 
 of California." 
 
 Chas. T. Main, Engineer, Boston: 
 
 "When the Boiler Code Committee of the American Society of 
 Mechanical Engineers was set up, the members were very carefully 
 selected to represent equally the manufacturers, users, and designers, and 
 that proportion of members has been carefully maintained since that time, 
 so that no one interest has ever dominated the committee in the past, nor 
 does in the present." 
 
 BOILER SAFETY. 
 
 By R. L. HEMINGWAY, Chief Boiler Inspector. 
 
 The Workmen's Compensation, Insurance and Safety Act, effective 
 January I, 1914, gives to the Industrial Accident Commission authority 
 to inspect all places of employment, to require reasonable safety in such 
 places of employment, and for the purpose of determining what consti- 
 tutes reasonable safety, the act specifically gives the Commission power 
 to set safety standards and to establish such rules and regulations as may 
 be deemed necessary to furnish this modicum of reasonable safety. 
 These powers are very clearly set forth in sections 51 to 72 of the above- 
 mentioned act. 
 
 Since the statute imposes these responsibilities upon the Commission, 
 it naturally proceeded to establish safety standards and regulations to 
 to meet the requirements of the various industries. It will be very 
 generally admitted that no set of safety standards could be complete 
 unless it contained rules and regulations governing the operation of 
 steam boilers, for the very obvious reason that a boiler, even though 
 operating at low pressure, contains all the potentialities of a catastrophe, 
 unless the pressure it carries is regulated to within safe limits and 
 unless the appliances for controlling that pressure are maintained in 
 proper working order, under the supervision and care of men intelligent 
 enough to realize the responsibility that they assume when taking charge 
 of a steam boiler. 
 
 In the natural sequence of events, the drafting of safety orders to 
 cover boilers that were already installed in the state was first undertaken 
 and this led to the adoption of rules governing the construction and 
 installation of new boilers in the future. 
 
12 BOMR SAFETY BULLETIN. 
 
 The formulation of any one set of safety orders is a matter involving 
 views of widely separated interests and in consequence of this the Com- 
 mission decided to adopt the plan of appointing committees who would 
 represent these numerous interests, and thus a set of safety orders would 
 be formulated which would obtain the maximum of safety with the least 
 hardship to all parties concerned. Thus, when it came to drafting Boiler 
 Safety Orders, interests were invited to send representatives who would 
 sit on the committee and have a voice in all its deliberations. To further 
 widen the scope of the work, two such representative committees were 
 convened, one in San Francisco and the other in Los Angeles, and in this 
 manner those having the greatest interests at stake, including employers 
 and employees, were fully represented. These committees met over a 
 period of many months during 1915 and 1916 and, as a result of their 
 labors, the Boiler Safety Orders comprising rules for existing installations 
 and a code for the construction and installation of new boilers were 
 presented at public hearings in the fall of 1916. As is now well known, 
 the committee decided to adopt the boiler code of the American Society 
 of Mechanical Engineers, which code was published in the year 1914, 
 after several years of earnest work on the part of some of the foremost 
 engineers in America. Two of these public hearings were held, one in 
 San Francisco and one in Los Angeles. Both meetings were largely 
 attended and many points were freely discussed although it was remark- 
 able that but few changes were even requested when explanation was 
 given of the why or wherefore in each case. In no case was the change 
 or amendment of more than minor import. 
 
 The need of such a standard code was becoming more and more 
 obvious, as individual states in their desire for progress saw the necessity 
 of having some regulation governing the construction of new boilers. 
 Massachusetts, the pioneer state in this respect, had a code of its own and 
 when Ohio, two or three years later, decided to adopt a code, It was 
 found that there were some features in the Massachusetts code that did 
 not appeal to the engineers in Ohio. When Michigan followed, a dif- 
 ference of opinion arose between the Michigan engineers and those in 
 Ohio and Massachusetts, and so it went all down the line, until the boiler 
 manufacturer was almost at his wits' end to know how to comply with 
 the various state codes, which, owing to their strict enforcement, would 
 not permit an Ohio standard boiler to go into Massachusetts or a Michi- 
 gan standard boiler to go into Ohio. 
 
 It is easy to see what tremendous financial hardship this lack of 
 uniformity was imposing on the industries of the country, and also since 
 every boiler, practically, that was built in the shops required a special 
 specification, the cost to the user was always higher than it need be. 
 Conditions were rapidly leading to confusion when about 1907 or 1908, 
 the president of the American Society of Mechanical Engineers appointed 
 a boiler code committee whose special object was to draft a uniform 
 code for the construction and installation of stationary boilers. The 
 original committee consisted of eight members and they in turn appointed 
 an advisory committee to assist them in the draft of the code. The 
 advisory committee represented consulting engineers, manufacturers of 
 various types of boilers and boiler materials, boiler insurance companies, 
 agricultural boiler manufacturers, boiler users and the American Society 
 of Mechanical Engineers. 
 
BOILER SAFETY BUU^TIN. 13 
 
 This code was finally approved by the Council of the American Society 
 of Mechanical Engineers in February, 1915, and is known as the 1914 
 edition of the A.S.M.E. code. The committee in submitting it recom- 
 mended that a permanent revision committee be appointed to undertake 
 such modification or revision as might be necessary, as the state of the 
 art of boiler construction advanced, and that such committee should hold 
 meetings at least once in two years, at which time all interested parties 
 might be heard. This, then, is the code which the Boiler Safety Orders 
 committee of California approved and recommended to the Industrial 
 Accident Commission for adoption. There was no objection raised to 
 the adoption of this code at either public hearing on Boiler Safety Orders 
 in the fall of 1916. The Commission approved this recommendation and 
 the code became effective on January i, 1917, together with the Boiler 
 Safety Orders relating to existing installation, which the committee 
 appointed by the Commission had drafted. 
 
 During 1919 it was deemed advisable to undertake a revision of the 
 Boiler Safety Orders, less with the idea of changing the requirements in 
 any respect than with the idea of introducing certain minor matters 
 which the previous two years' experience had shown would increase 
 boiler safety by making certain orders more specific and incidentally 
 would be advantageous and more convenient for inspectors who had to 
 apply these rules. The only serious change contemplated related to the 
 rules governing second-hand boilers of lap-seam construction, and also 
 the adoption of the 1918 edition of the A.S.M.E. code, as revised by the 
 code committee in lieu of the 1914 code. In this manner it was thought 
 that the Boiler Safety Orders relating to both existing installations and 
 new installations would be brought up to date. Certain interests in the 
 state raised objections to some of the features contained in the Boiler 
 Safety Orders, principally with reference to the factors of safety for lap- 
 seam boilers of existing installations and the factors of safety for second- 
 hand lap-seam boilers. 
 
 In prosecuting their case, these objectors brought in representatives of 
 labor who, unfortunately, formed an entirely erroneous impression of 
 what the A.S.M.E. code is or what it purports to do, the controversy cul- 
 minating in a bill being introduced into the legislature, known as 
 Assembly Bill 1300, which bill was designed to repeal the Boiler Inspec- 
 tion Act, known as chapter 202 of the laws of 1917 and thus take from 
 the Industrial Accident Commission the authority to require permits for 
 boiler operation, to charge inspection fees and to require that all boiler 
 inspectors hold certificates of competency before being allowed to inspect 
 boilers. Some of the proponents of the repealing measure had a mis- 
 taken impression that the A.S.M.E. code would be eliminated in Cali- 
 fornia by the enactment of Assembly Bill 1300. The fact is that only by 
 either revising the Boiler Safety Orders or amending the Workmen's 
 Compensation, Insurance and Safety Act would it be possible to eliminate 
 the A.S.M.E. code. 
 
 In protesting against the adoption of the A.S.M.E. code in California, 
 the claim was frequently made that this code would militate against local 
 builders and would favor Eastern manufacturers, though in what way 
 was never made even approximately clear. An illustrating incident 
 tending to controvert this argument occurred in May, 1921, when a state 
 boiler inspector found a code boiler that had been built in California on a 
 
 312180 
 
14 BOILER SAFETY 
 
 Brown hoist. The owners are a concern representing Eastern manu- 
 facturers among other lines, and on asking why an Eastern built boiler 
 had not been used to replace the old boiler (also built in the East), the 
 inspector was told the California built boiler cost thirty per cent less than 
 the price quoted by the original manufacturer. The records in the offices 
 of the Industrial Accident Commission show conclusively that more 
 boilers have been constructed in California in the past three years than 
 were manufactured in the state in the ten years immediately preceding 
 1918. This does not take into account boilers built for marine service. 
 In all, approximately 400 California standard boilers have been built in 
 California since January i, 1918. 
 
 As a matter of fact, the A.S.M.E. code was designed and formulated 
 with a threefold object, viz: (i) Primarily to secure safe boilers; (2) 
 to safeguard the interests of all concerned, especially manufacturers of 
 boilers, whether in California or elsewhere, by making requirements 
 which were such that they would not entail undue hardship by departing 
 too widely from present practice; (3) the furnishing of a uniform code 
 with which any manufacturer, whether east, west, north or south, could 
 readily comply. 
 
 The thought in the minds of those who objected to the code seemed to 
 be that California should draft a code of her own, which would incorpo- 
 rate certain features and rules that would favor local manufacturers and 
 enable them more readily to compete with Eastern manufacturers. It is 
 self-evident that these men failed to realize the enormous amount of 
 labor and money required before such a code could be prepared. 
 Furthermore, it is very unlikely that such a local code would be as good 
 as the A.S.M.E. code, for the reason that there would not be available 
 the engineering talent that was available for the latter. 
 
 Mr. S. F. Jeter, Chief Engineer of the Hartford Steam Boiler Inspec- 
 tion and Insurance Company, writing on this subject, in the July, 1916, 
 issue of The Locomotive says * 
 
 "If the need for adopting the same set of rules in each state where laws are 
 proposed to govern the construction of boilers is considered advisable and it does 
 not seem possible that the least thought on the subject can lead to any other con- 
 clusion from the steam users' standpoint then the American Society of Mechanical 
 Engineers' Boiler Code is practically the only set of rules available for such use. 
 All disputed points in connection with these rules have been fought out with the 
 parties interested and a conclusion reached ; and any attempt at selecting a different 
 set of rules would mean that the same ground would have to be fought over again. 
 It is more than likely that in the end practically the same conclusions would be 
 reached, if a like amount of care was used, as in the preparation of the Boiler 
 Code." 
 
 There can be no question of the wisdom in California adopting this 
 code when one considers the fact that nineteen states and twenty- four 
 municipalities have already adopted it, and it has been added to the text- 
 books in many of our most prominent engineering colleges and schools. 
 Once more quoting Mr. Jeter, from the same source: 
 
 "It would, therefore, appear that the American Society of Mechanical Engineers' 
 Boiler Code should be superior to any set of rules that has been put out or may be 
 put out by a State Board delegated to perform a similar duty." 
 
 In his conclusion, Mr. Jeter says : 
 
 "Since the steam user is the one who ultimately will derive the greatest benefit 
 by the attainment of the desired end, in that he will secure the greatest return for 
 
15 
 
 his investment, in boiler equipment, it would seem only right that, as the project 
 has been so auspiciously launched, the steam users should lend their full coopera- 
 tion in carrying the work to a complete and successful finish." 
 
 Reverting to the statement already made, that the only change of note 
 in the revised Boiler Safety Orders, as they relate to existing installa- 
 tions, was in connection with the factor of safety for second-hand boilers 
 of lap-seam construction the charge was frequently made that the revision 
 of the Orders was along,lines that would call for drastic reduction in work- 
 ing pressures on lap-searn boilers and even the proposed new rules would 
 condemn all lap-seam boilers in California. No statement could possibly 
 have been more remote from the actual facts, since the revision committee 
 has never even contemplated changing the factors of safety on any 
 boilers except the second-hand lap-seam boilers, either by upward or 
 downward revision. 
 
 Since the Boiler Safety Orders went into effect on January I, 1917, 
 the Boiler Division of the Department of Safety has inspected approxi- 
 mately 4,049 boilers, of which number the records show only 46 were 
 actually condemned as being unfit for further service. Many of these 
 might still have been of some use as heating boilers, had there been any 
 call for them. At prevailing junk prices, however, they were worth 
 more to their owners as scrap. There were, of course, numerous cases, 
 where pressures were reduced to comply with the rules, but these were in 
 no way to be regarded as condemnations, because under the Boiler Safety 
 Orders the boilers could still be operated under a factor of safety of 5^ 
 as second-hand boilers after proper inspection. 
 
 The claim was frequently made that these factors of safety for lap-seam 
 boilers of existing installation were unreasonable and that they inflicted 
 serious hardships on the owners of boilers of that type. It is, however, 
 extremely difficult for the initiated, or indeed for any one accepting 
 the logic of engineering, to see how such a claim could be made, when it 
 is considered that the least factor of safety that may be used on a brand 
 new code boiler is 5, and the Boiler Safety Orders do not call for any 
 higher minimum factor of safety than 5 on a boiler of lap-seam con- 
 struction, existing installation, regardless of age or service, provided in 
 the opinion of an inspector its condition warrants continuing this factor 
 of safety. 
 
 One can hardly believe that the proponents of lower factors of safety 
 would claim that a boiler is less safe in Massachusetts or Ohio than in 
 California, since in those two states operators of boilers are required to 
 have licensed engineers and firemen in charge, and yet the factors of 
 safety in Massachusetts vary from 5 as a minimum up to ten years of age, 
 5*/2 up to fifteen years of age, and 5^4 up to twenty years of age, with 6 
 for boilers over twenty years of age, there being no exceptions and no 
 provisions. In other words, if a lap seam boiler in Massachusetts has 
 passed its twentieth anniversary and the pressure given by a factor of 
 safety of 6 will not perform the work required of it, that boiler must 
 automatically be thrown out, regardless of its condition, no provision 
 even being made to allow for part time use. The following table illus- 
 trates the factors of safety on boilers of longitudinal lap seam construc- 
 tion in some of the states that have boiler rules in effect. 
 
i6 
 
 - B01U& SAFETY BULLETIN. 
 
 FACTORS OF SAFETY. 
 
 
 Existing installation 
 
 New installation 
 
 Longitudinal lap seam 
 
 Butt strap 
 construe. ion_, 
 
 Second hand 
 longit. lap 
 
 f 
 
 j 
 
 f 
 
 
 
 f 
 
 ! 
 
 M o 
 
 ** 
 \ 
 
 ..0 
 
 r 
 
 1. 1917 California* 1 
 
 11 
 
 41 
 41 
 41 
 41 
 41 
 5 
 5 
 6 
 
 41 
 41 
 4| 
 41 
 41 
 41 
 41 
 5 
 5 
 6 
 
 tf 
 
 4 
 
 41 
 
 43 
 41 
 41 
 
 51 
 51 
 6 
 
 5 
 41 
 
 41 
 5 
 5 
 4| 
 51 
 
 ? 
 
 5| 
 4| 
 41J 
 
 Si" 
 5i 
 41 
 6 
 6 
 6 
 
 4 h 
 8 g 
 41 
 41 
 4 J 
 4 i 
 41 
 41 
 41 
 
 51 
 
 41 
 
 51 
 
 51 
 
 8 8 
 
 8' 
 6.3 
 
 A.S M E Code 5 
 
 2. 1916 Ohio ce 
 
 A S M E Code 5 
 
 3. 1919 Missouri 
 
 A S M E Code - 5 
 
 4. 1916 Pennsylvania 
 
 A.S.M.E. Code 5 
 
 5. 1920 New York" 
 
 A.S.M.E. Code 5 
 
 6. 1918 New Jersey be 
 
 A.S.M.E. Code 5 
 
 7. 1920 Wisconsin 
 
 A.S M.E Code __ 5 
 
 8. 1910 City of Detroit*... 
 9. 1919 Massachusetts 8 
 10. 1913 British Columbia- 
 
 A.S M E Code - 5 
 
 Mass. Boiler Rules 5 
 Provincial Law... __ k 
 
 a Factor of safety of 5 allowed if conditions warrant. 
 
 b Riveted joints to be uncovered for hydrostatic test if factor of safety 5 is continued over 20 
 
 years of age. 
 
 c Factor of safety shall be increased if the conditions and safety of the boiler demand it. 
 d Allowance in age made for part time use. 
 e No allowance in age made for part time use. 
 'Pressure cut to 50 Ibs. except that factor of safety 4J may be continued to 25 years if condition 
 
 of boiler warrants it. 
 
 eFor shells over 36 inches diameter factor of safety 6 if 36 inches or less in diameter. 
 h After Jan. 1, 1922, the minimum factor of safety is 4J. 
 'Over 20 years of age the minimum factor of safety is 41. 
 JOver 10 years of age the minimum factor of safety is 4jfe. 
 k The basic factor of safety is 4, to which are added penalties for conditions and bad practices 
 
 during construction. 
 
 In the face of the foregoing, it is difficult to understand the reasoning 
 that actuates men in asking for a reduction in the factors of safety that 
 are stipulated in the Boiler Safety Orders of January I, 1917. 
 
 The question may be asked, "Why is it necessary to discuss at such 
 length the factors of safety on lap seam boilers?" The answer is found 
 in the pages of engineering magazines, such as Pozver and The Boiler- 
 maker, which report boiler explosions, together with the details of the 
 causes that have been determined upon investigation. 
 
 History has shown that the boiler with longitudinal lap seams has a 
 disagreeable propensity for developing a hidden crack which seldom 
 gives warning of its presence. Furthermore, when the failure occurs, it- 
 comes with a suddenness and violence that results in havoc and destruc- 
 tion all around. Such a case occurred in the Grover Shoe Company, at 
 Brockton, Massachusetts, when 58 lives were lost and 117 people were 
 injured, the property loss amounting to over $250,000. In another part 
 of this bulletin will be found descriptions of a more recent boiler explosion 
 that was caused by a lap-seam crack. 
 
BOILER SAFETY BULLETIN. 17 
 
 j / j 
 
 aetefu ana 
 
 ROBT. J. HILLAS, President 
 
 - 1, 
 
 of <yVe 
 
 D. C. HARVEY, / x 
 
 Superintendent of Inspections <sVec 
 
 May 31, 1921. 
 DCH.MAW 
 
 CIRCULAR LETTER NO. 151. 
 
 ANSWER TO LETTER OF 
 TO ALL BOILER AND FLY-WHEEL INSPECTORS : 
 
 HORIZONTAL TUBULAR BOILERS. 
 LAP SEAM TYPE OF CONSTRUCTION. 
 
 HORIZONTAL TUBULAR BOILERS 
 CONSTRUCTED WITH LONGITUDINAL LAP SEAMS 
 
 EXTENDING FROM HEAD TO HEAD 
 
 AS IN CASE OF ONE SHEET ON THE BOTTOM 
 
 AND ONE SHEET ON THE TOP BOILERS. 
 
 In making inspections of Horizontal Tubular boilers of the lap seam type of 
 construction twenty years or more old, each inspection report, other than data 
 report, should have written on it by the inspector the following statement: THIS 
 
 BOILER IS OF THE LAP SEAM TYPE AND IS YEARS OLD. 
 
 The object of this is so that in s-ending out the report, attention may be called to 
 the age and construction of the boiler. It does not necessarily follow it is con- 
 sidered the pressure should be reduced or the boiler replaced by one of modern 
 design. The result of the inspection will show what is required in this respect. 
 
 It is important the assured should be advis-ed of the situation and the reasons for 
 discarding boilers of this type so that when the proper time arrives to reduce the 
 pressure or call for the boiler to be replaced, they can not say the matter has not 
 been brought to their attention before we advised taking action. 
 
 Explain to the assured the weakness of the construction and point out disastrous 
 explosions have resulted from the continued operation of such boilers. Explain to 
 them how a piece of metal will, after repeated bending, eventually break. How a 
 similar action takes place at the lap longitudinal seams due to the distortion from 
 the true circle. 
 
 It is important you see the above is done. 
 
1 8 BOILER SAFETY BUU/ETIN. 
 
 HYDROSTATIC TESTS : In the case of boilers of the lap seam type of construction 
 that have reached the age of 20 years, arrangements should be made for applying a 
 hydrostatic test at the time of the internal inspections. In case there are no facilities 
 at the plant for applying such a test, then draw attention to this fact on the 
 inspection report. 
 
 HORIZONTAL TUBULAR BOILERS CONSTRUCTED WITH LONGITUDINAL LAP SEAMS EXTEND- 
 ING FROM HEAD TO HEAD: All boilers of this type are of obsolete construction and 
 should be looked on with suspicion and the inspections should be most rigid. When 
 boilers of this typ'e have reached the age of twenty (20) years, they should be 
 replaced and under no circumstances should they be continued in service unless 
 subjected to a hydrostatic test of 50 per cent in excess of the pressure at which they 
 are to be operated, with the brickwork removed to expose the longitudinal seams. 
 
 In making inspections of this type of boiler, arrangements should be made with 
 the assured to apply the hydrostatic test and to uncover the longitudinal seams 
 when this is done. If the test and inspection show there is no evidence of lap seam 
 cracks or other weakness, the boiler may be continued in service for a limited 
 period, in ord'er to give the assured an opportunity to procure a new one. The 
 matter should be followed up closely until the boiler has been replaced. 
 
 The following factors of safety should be us'ed in determining the allowable 
 pressures : 
 
 10 to 15 years factor 5 
 
 15 to 20 years factor 6 
 
 20 years and over factor 8 
 
 In making your inspections if you find the factors of safety as given above will 
 reduce the pressure to a point that would make the boiler useless, then explain to 
 the assured, providing the age and condition of the boiler in your opinion warrants, 
 thai at your next inspection, it will be necessary to reduce the pressure to correspond 
 with the factors of safety, as stated and in this manner give them ample warning 
 in advance of what will be done and so they may have time in which to make 
 change that may be required to meet the conditions. 
 
 It is important you explain to the assured the weakness of the construction of 
 the boilers, pointing out the longitudinal seams are continuous and are not broken as 
 in the case of boilers built in ring courses and that the absence of girth seams 
 tends to further weaken the structure. 
 
 The instructions, as outlined above, must be rigidly adhered to and we hold the 
 inspector responsible for seeing this is done. 
 
 Please acknowledge receipt of this letter. 
 
 Yours truly, 
 
 D. C. HARVEY, Superintendent. 
 
BOMR SAFETY BULLETIN. IQ 
 
 HOW SAFE IS A USED LAP-SEAM BOILER?* 
 
 The question of the factor of safety to be used in determining safe 
 working pressures for boilers other than those built to comply with the 
 A.S.M.E. code and which have been for some years in operation, has 
 been one fraught with considerable discussion in recent weeks in the 
 West. It seems that the boiler revision committee of the Industrial Acci- 
 dent Commission of California, holding hearings in San Francisco, pro- 
 poses a factor of safety increasing with the actual use of the boiler. 
 Some serious objections have been made to these factors by users of 
 boilers and by second-hand dealers. It would appear evident that an 
 increasing factor should be applied from year to year in proportion to the 
 length of service of the boiler, and it is to be hoped that the objections 
 will be cleared away in a friendly manner and the entire code put into 
 operation at the earliest date possible, in order that this commonwealth 
 may stand in its usual position, that of front rank in matters of progress 
 towards safety and accident prevention. 
 
 Lap-seam construction has come in for the greatest amount of dis- 
 cussion. The attitude of the committee appears to be fair to the owners 
 of lap-seam boilers within the state of California in that it proposes no 
 change in safety factors on existing installations from those in force 
 since January I, 1917. These boilers were purchased and installed in 
 good faith, under the conditions of safety then generally known. But 
 the committee seems to be unwilling to permit a prospective purchaser to 
 buy and change the location of a lap-seam boiler which has already been 
 in use, without applying a factor of safety which it believes reasonably 
 safe for this type of construction. Eventually, the committee feels, the 
 lap-seam construction must be displaced by a design that is free from the 
 inherent defect known to boiler experts as "the typical lap-seam crack." 
 
 "Second-hand stationary boilers within the state of California on 
 October I, 1920, by which is meant boilers where both ownership and 
 location are changed, shall, if of lap-seam construction, have a factor of 
 safety of at least six," says Sec. 381, (a) of the proposed revision. 
 Virtually identical installations in other communities show that the states 
 of New York, New Jersey, and Pennsylvania require the same factor of 
 at least six, while Ohio, Massachusetts and the city of Detroit will permit 
 nothing under eight, except for boilers thirty-six inches in diameter or 
 under, when the factor of safety is at least six. It would seem then that 
 a factor of six could well stand, and that the objections urged against its 
 adoption as being too high and as leading to prohibitive boiler practice 
 should be overruled. 
 
 BOILER CODE THE A.S.M.E.* 
 
 Unquestionably one of the most constructive pieces of engineering 
 work ever undertaken by an engineering society is that of the boiler code 
 of the American Society of Mechanical Engineers. This code goes into 
 great detail as to how boilers should be properly constructed, the factors 
 of safety involved in designing the boiler and many other helpful and 
 valuable rules for proper design and installation. Since the code was 
 first promulgated in 1914, seventeen states and several cities, including 
 
 *E)ditorial, Journal of Electricity, October 1, 1920. 
 
20 BOILER SAFETY BULLETIN. 
 
 Philadelphia, Detroit and Seattle, have adopted it as the official legal 
 document for state inspection work. California has adopted the 
 A.S.M.K. 1914 code as from January I, 1917, and the revised boiler safety 
 orders propose to adopt the 1918 code. The California Industrial Acci- 
 dent Commission is to be congratulated on this forward step toward 
 boiler safety. 
 
 METHODS OF JOINING BOILER SEAMS.* 
 
 The boiler is unquestionably the most prolific source of danger and 
 disaster in steam plant operation. The history of steam generation for 
 power purposes furnishes ample demonstration of what this magazine of 
 stored-up energy can accomplish, in the way of general destructiveness, 
 when once it breaks out of bounds. An almost interminable list of dis- 
 astrous experiences with defective and neglected boilers has made us 
 thoroughly alive to the potentiality of this detail of power plant equip- 
 ment as the instrument of devastation and ruin; and as a result, the 
 boiler has always been the theme of a vast amount of discussion and 
 agitation, looking to general improvement along the lines of safe design, 
 construction and operation. Indeed, it is the case in many localities and 
 states that legislative enactment is resorted to in the endeavor to safe- 
 guard life and property from the menace of dangerous boiler plants, by 
 compelling vigilant care in the selection of correct designs and the best 
 obtainable materials, as well as in the items of good workmanship and 
 intelligent operating conditions. 
 
 The Lap-Seam Boiler. 
 
 The type of boiler that has furnished by far the greatest number oi 
 explosions during recent years, is the horizontal tubular boiler, with 
 boiler-riveted lap-joints, longitudinal seams and as a general rule, it has 
 been found that when one of these boilers explodes the initial rupture 
 occurs in one of the aforesaid seams. 
 
 While there is a constantly growing sentiment among practical 
 engineers antagonistic to the lap-riveted longitudinal seam and notwith- 
 standing likewise that boilers with this type of seam are being gradually 
 legislated out of existence in some states, in favor of boilers having the 
 mechanically correct butt-and-strap joined seams, still the manufacture 
 and use of boilers of this type continues to go on unrestricted in most 
 parts of the United States, and it appears highly probable from present 
 indications that we will not see the end of this mechanical monstrosity for 
 some years to come. It is, therefore, appropriate that in this discussion 
 of boiler seams, we should give priority of attention to this oldest and 
 generally most prevalent, as well as most reprehensible form of joint. 
 
 The Lap-Riveted Longitudinal Seam Inherently Defective. 
 
 To begin, let us first investigate the lap joint as used in longitudinal 
 seams, with a view of finding out wherein it is really deficient, for a 
 superficial glance at the proposition would indicate that so far as the 
 ordinary stresses of operation are concerned, this type of joint should 
 be just as safe and reliable as any other ; and such is the case, for by 
 correctly proportioning the diameter and pitch of the rivets and the 
 
 *Reprinted from the January, 1921, issue of International Steam Engineer. 
 
BOILER SAFETY BULLETIN. 
 
 21 
 
 thickness of the plate, to the tensile, shearing and compressive stresses 
 involved, a joint of this kind may be designed which will give a percent- 
 age of the strength of the solid plate ample for all ordinary purposes. 
 
 The objection to the lap-joint construction is not based, however, upon 
 any deficiency of strength when new, but upon the deterioration that 
 immediately sets in, the very moment the boiler first goes into service, by 
 reason of the bending stress in the net section of plate between the rivets 
 in the outer row. 
 
 To make this point clear, let us refer to Figure One, which represents a 
 cross-section through a shell made of boiler plate one-half inch thick, and 
 rolled to a nominal internal radius of ten inches. 
 
 Now if this shell plate, when flattened out, had been sheared to the 
 exact width necessary to form the envelope of a cylinder twenty inches 
 in diameter, and had then been rolled to conform to a 2O-inch circle, it 
 would have met or butted edge to edge, and the internal radius would 
 have been exactly ten inches, no matter in what direction it might have 
 been measured from the axis of the shell. 
 
22 BOILER SAFETY 
 
 But in order to make a lap joint for a shell of ten inches radius, as 
 shown in the illustration, it is necessary to cut the sheet wider than the 
 length of the circumference of a 2O-inch circle, and so, when the plate 
 is rolled to a lo-inch radius and the edges slipped by each other to 
 form the joint, any radius in the segments A, B, C will be ten inches, or 
 an extremely close approximation thereto ; but at the same time the radii 
 in the lower half of segment D will gradually increase toward the joint, 
 while the radii in the upper half will decrease as they approach the 
 joint, the net result being that a radial line measured to a point directly 
 beneath the joint will approximate very close to ten and one-fourth 
 inches, while the corresponding radial line above the joint will be nine 
 and three-fourths inches or thereabouts, the resilience of the plate being 
 assumed as uniform throughout. 
 
 Now we know that the energy of an internal pressure against the wall 
 of a cylindrical vessel is manifested in the effort to maintain the true cir- 
 cular form and round out any indentations or irregularities tending to 
 impair the cylindrical contour of the vessel. Consequently, if a liquid or 
 fluid pressure were applied to the inner surface of our shell in Figure One, 
 through the agency of water, air, steam or otherwise, its energy would 
 immediately be exerted in an effort to make all points in the surface of the 
 shell conform to the same distance from the axis, and the direct effect of 
 this straining after perfect symmetry, would be to induce a flexure in the 
 seam by the lengthening of the radii above the joint and the shortening 
 of those below. This bending stress would obviously expend itself in 
 straining the inner lap through the section of metal between the rivet 
 holes in the upper row, and the outer lap through the section of metal 
 between the rivet holes in the lower row. 
 
 It might reasonably appear from cursory and superficial study of the 
 phenomenon that the strain involved, being of such inconsiderable mag- 
 nitude, could really have no deleterious effect on boiler plate possessing- 
 the highly malleable and ductile properties required of first-class 
 material ; and such would undoubtedly be the case, if the bending of the 
 plate in the places indicated would occur only at comparatively long 
 intervals in the life of the boiler, as for instance, at the beginning and 
 close of a period of actual service. 
 
 This advantageous condition, however, can not possibly be realized in 
 boiler practice, for the maintenance of a constant steam pressure is some- 
 thing highly impracticable, if not to say impossible of accomplishment 
 with ordinary method of operation, and the aforesaid flexure occurs with 
 every change of pressure, howsoever slight. The very moment a diminu- 
 tion of pressure occurs, the resilience or springiness of the material 
 instantly responds in an effort to restore the shell to its original shape, 
 as shown in the illustration.;, but when the pressure again augments, no 
 matter how trivial the increase, the edges of the plate again attempt to 
 get into the line of strain ; the pulsation being continuous, though 
 insidious and never discernible to the eye. The alternate movement here 
 described is frequently referred to as the "breathing" action of the 
 boiler, since it is quite analogous to the regular expansion and contrac- 
 tion of the human torso under the stimulus of the respiratory nerves. 
 
 It is inevitable, therefore, that this constant bending to and fro should 
 eventually cause a series of cracks to appear along the line of the rivets 
 
BOILER SAFETY BUUvE/TlN. 23 
 
 in either row, which are evidently the lines of least resistance, and that 
 these cracks should go deeper at every flexure until the strength of the 
 plate is finally reduced to the point of rupture. It is one of the mysteries 
 of the phenomenon that these cracks invariably manifest themselves first 
 in the inner surface of the outer lap, and never in the outer surface of the 
 inner lap. 
 
 Thus it appears that opposition to the lap-seam boiler construction, 
 springs not from any contention that such seams are unsafe for constant 
 pressure, but from the evident impossibility of maintaining absolute 
 uniformity of pressure in operation, and the consequent localization at 
 the joint of the breathing movement which such lack of uniformity 
 entails, as well as from the fact that the resultant deterioration, being 
 hidden between the lapped ends of the sheet, precludes all possibility of 
 adequately estimating its extent without actually drawing out the rivets 
 and taking the joint apart. 
 
 One peculiar fact which stands out quite prominently in connection 
 with the lap seam failures of the past is that wrought iron boilers seem 
 to be practically immune from rupture of this kind. The theory has 
 been advanced to account for this apparent anomaly for anomalous it 
 seems, since it is the popular idea that the use of steel as a boiler 
 material reduces the liability to disaster from any inherent cause 
 is that the laminated structure of wrought iron, which, on general 
 principles, is rather an objectionable feature than otherwise, acts as an 
 obstacle to the progress of the deterioration, inasmuch as a crack starting 
 in the outer stratum of metal will expend itself in getting through that 
 stratum, so that an entirely new crack must be started in the next layer, 
 and thus the impairment of the joint is arrested and delayed from time to 
 time, but is never entirely overcome. Steel, on account of its homo- 
 geneous texture, is deprived of this advantage. 
 
 However, it may be accepted as a foregone conclusion deducible from 
 the essential character of this latent imperfection in longitudinal lap 
 seams, that any boiler having such seams, whether it be built of wrought 
 iron or of steel, if continued in service long enough, and spared the 
 ravages of corrosion and other sources of wear and tear, will eventually 
 go to pieces by rupture of those seams as herein described. 
 
 APPLICATION OF INSIDE WELT STRAP TO OLD LAP-SEAM 
 
 BOILERS. 
 
 By R. L. HEMINGWAY, Chief Boiler Inspector. 
 
 There is probably not one of us that has not had carefully instilled into 
 him the value of economy in all things, and while it is perfectly true 
 that economy is the foundation of all business, it does seem that this 
 trait can be overdone, at least in so far as it applies to the use of steam 
 boilers. Apparently, too strict economy was the object of many con- 
 cerns that put boilers in California in years gone by, for they demanded 
 and obtained cheap boilers. 
 
 In order to obtain a cheap boiler, one of the first economies that the 
 manufacturer makes is in the thickness of plate used in its construction, 
 at the expense of the factor of safety. Another saving is accomplished 
 
24 BOILER SAFETY BULLETIN. 
 
 by adopting the lap-seam construction for the longitudinal joints of the 
 boilers. 
 
 When the Boiler Safety Orders became effective in California on 
 January I, 1917, there were a few instances in which the pressures on 
 boilers had to be reduced, owing to the factor of safety that had to be 
 applied, on account of the age of the boilers. This condition will recur 
 year after year as age accumulates on these lap-seam boilers. Some 
 owners, rather than discard their old equipment, on which the rules 
 correctly require the working pressures to be reduced on account of age, 
 have endeavored to find some means of extending the useful life of their 
 old boilers, which still bear the earmarks of being good, at least on the 
 surface. In doing this they have hit upon the old expedient of 
 strengthening ordinary double-riveted lap-seam joints by the application 
 of what is sometimes called the inside welt-strap joint, or the locomotive 
 joint. The latter name conies from the not infrequent use of this type 
 of joint in locomotive boilers. The joint itself consists of an ordinary 
 double-riveted lap-joint, provided with an inside cover-plate, which is 
 jogged so that it conforms to the curvature of the shell on both sides of 
 the lap-joint. In addition to the rivets in the double-riveted lap-joint, 
 there is also an outer row provided on each side, having twice the pitch 
 of the rivets in the inner rows. This will be more readily understood 
 by reference to figure one. 
 
 Fig.L 
 
 Sectional and plan view of lap joint with inside strap applied. 
 
 There is nothing new about this type of joint, as it has been known 
 and used for many years, although it has never come into great popularity, 
 owing to the fact that it is a mere subterfuge. In other words, while the 
 application of an inside welt may increase the efficiency of the joint, the 
 joint itself still remains a lap-joint, and as such it may be regarded as 
 still subject to the development of the hidden cracks and to fatigue of 
 
SA^TY BUL^TIN. 25 
 
 the metal through constant flexure, owing to the breathing action of the 
 boiler shell. 
 
 About 1887 some very exhaustive tests were made on this welt-strap 
 type of joint at the Watertown Arsenal in New York, in order to deter- 
 mine if possible just what increase in efficiency this type of joint would 
 furnish. The Government engineers, in preparing for the test, chose the 
 very best possible material available at that time, the utmost care being 
 taken in the preparation of the joints for the test. In addition to careful 
 selection of material, the workmanship in the riveting was performed 
 under the very best possible conditions. Notwithstanding these facts, 
 the record of these tests shows that the average increase in efficiency did 
 not amount to more than seven and one-half per cent above the efficiency 
 of the ordinary double-riveted lap-joint to which no cover plate was 
 applied. 
 
 This, then, is the expedient to which quite a number of California 
 boiler owners and operators have recently resorted in order to restore 
 the working pressures to or maintain working pressures at a point where 
 they can still continue to operate their plants. The probabilities are that 
 if this type of joint were used in the original construction of the boiler, 
 there would be considerably less objection to it than now arises in apply- 
 ing it to boilers that have already seen some years of service. 
 
 It will be readily understood that one can not remove the rivets from 
 a longitudinal lap-seam without seriously affecting the strength of the 
 joint when other rivets are driven. Then, again, it is entirely problem- 
 atical whether even the closest examination of the insides of a lap-joint 
 would reveal the infinitesimally fine cracks which may be present in the 
 material and which, although so fine, are still a pregnant source of 
 danger. 
 
 To summarize, the locomotive, or inside welt-strap joint is no better 
 than a lap-seam, beyond the fact that it is capable of a theoretically 
 higher efficiency than is the ordinary double-riveted lap-joint. It is 
 extremely doubtful whether this increase in efficiency does not constitute 
 an increase in the hazard by reason of the fact that higher pressures are 
 obtained through its use. 
 
 So far as known there is no law in any state which prohibits the use 
 of this type of joint and probably there is no state in which its use has 
 attained anything like the prevalence that it now seems to be gaining in 
 California. 
 
 Lacking precedent for prohibition of its use, this type of joint will be 
 accepted on conditions to be determined by the Industrial Accident Com- 
 mission after the Boiler Safety Orders revisions committee shall have 
 submitted its recommendations to the Commission. Under no consider- 
 ation can the welt-strap type joint be recommended from an engineering 
 standpoint, from the sandpoint of safety, or yet from the standpoint of 
 economy. It may be trite to add at this time, but it is no less true, that 
 safety and economy are inseparable in the long run. 
 
26 BOII^R SAFETY BUU,TIN. 
 
 THE SINGLE-SHEET LAP-SEAM BOILER. 
 
 By J. P. MORRISON, Chief Inspector, Hartford Steam Boiler Insurance and Inspection 
 
 Company. 
 
 [Reprinted, by permission, from April 26, 1921, issue of Power*.] 
 
 The single-sheet lap-seam boiler, so destructive of life and 
 property, must go. An analysis of its weaknesses is evidenced 
 by numerous explosions. It does not possess a sufficient mar- 
 gin of safety, is made of questionable material, is subject to 
 injuries during the process of fabrication, is impossible of 
 thorough inspection, and in operation is stressed beyond the 
 safe limit by temperature difference, by lack of girth-seam 
 support and by the unequal distribution of the weight of the 
 boiler, contents and connections. 
 
 It is probable that no question of machine design has received more 
 careful and intelligent consideration than has the design of the shell 
 seams of steam boilers. Fairbairn's tests were conducted in 1838. W. 
 Bertram conducted tests at the Woolwich Dock Yards in 1860. D. K. 
 Clark discussed riveted seams in 1877. A lap-seam crack was reported 
 in The Locomotive, issued in April, 1880, while that publication dealt at 
 considerable length with the stresses occurring in lap seams. On April 
 17, 1891, J. M. Allen, who was then president of the Hartford Steam 
 Boiler Inspection and Insurance Company, delivered a lecture at Sibley 
 College, in which he gave a complete diagnosis of the various joints then 
 in use, having particular reference to the triple-riveted butt-strap joint. 
 This lecture was published and widely distributed, and the principles set 
 forth are those upon which the calculations of riveted joints, encountered 
 in modern practice, are based. In the early days of steel-plate manu- 
 facture the product was confined to sheets of small dimensions. As a 
 consequence the boilers built in those days were composed of a number 
 of courses, and each course, if the boiler was unusually large, would be 
 made up of several sheets. It was not uncommon to encounter a boiler 
 14 feet in length and 48 inches in diameter made up of seven courses 
 formed of four sheets each. But as the steel makers became able to 
 produce larger plates, boilers were constructed of a lesser number of 
 courses, each composed of fewer sheets. This appeared to be of con- 
 siderable advantage in many ways, and when it became possible to 
 produce plates of such size that only two were needed to form the shell 
 plates of a boiler, they found a ready market. With the development in 
 steel manufacturing the importance of the physical and chemical 
 properties of the boiler plates was recognized, particular emphasis being- 
 placed on the advantages of great ductility even when obtained at a loss 
 in ultimate tensile strength. Laminations found in steel plate had elicited 
 some criticism, and there was a loud protest at the practice of some steel 
 makers of shipping unbranded plates, for the boilermakers were begin- 
 ning to realize the necessity of having the steel maker's brand appear on 
 each sheet of the finished boiler. Boiler plates manufactured by both 
 the open-hearth and Bessemer processes were used, and it was under- 
 stood that the quality of the boiler plate depended more upon the grade 
 of raw materials than upon the particular process. 
 
 *Cuts to illustrate this reprint were loaned by the editor of Power, 10th Avenue at 36th St., 
 New York. 
 
SAFETY BULLETIN. 27 
 
 Difficulty that had been experienced by reason of girth-seam leakage, 
 fire cracks and mud burns, all attributed to the sediment within the 
 boiler accumulating against the girth-seam laps, gave added attraction 
 to the idea of rolling one sheet- to form the bottom half of the boiler. 
 The upper half continued in some cases to be constructed of two or three 
 plates, while in other cases one large plate only was used. This form' of 
 construction necessitated the use of a longitudinal seam on each side 
 of the boiler extending from head to head, and, was confined to shops 
 having plate-bending rolls of sufficient length to pass a i6-ft. or i8-ft. 
 sheet between housings. 
 
 It is worthy of note that this construction was criticised twenty-five 
 or more years ago, and subsequent developments have proved the cor- 
 rectness of those who, while without sufficient facts at hand to justify 
 outright condemnation of the single-sheet boiler, brought its weaknesses 
 to public attention and withheld approval, citing the explosion of one 
 boiler due to the single bottom sheet construction, and which resulted in 
 the loss of two lives and an estimated property damage of $5,000. Those 
 unacquainted with shop practice of the older days will hardly realize the 
 possible damage done to a sheet during the process of fabrication of the 
 boiler. The rivet holes were punched full size, except where special 
 requirements were to be met, so the mill cracks started by the punching 
 process were not removed. Few of the shops were equipped with a 
 press to shape the ends of the sheet to the proper curvature. The work 
 was done by placing the sheet over a rail or one of the bending rolls and 
 sledging the edges, often stressing the questionable material beyond its 
 elastic limit along the line of rivet holes in the second row, where the 
 sheet had already been weakened by the reduction of the metal and by 
 mill cracks, due to punching the rivet holes. To this were added the 
 stresses set up when the poorly fitting joint was bolted up and later 
 riveted. Usually, the joint was then sledged into shape for calking. 
 
 Fig. i indicates the change in shape of the ends of a plate when 
 being formed over the roll by the use of the sledge. Fig. 2 illustrates 
 the condition of the ends of the plate, after the rest of the plate has been 
 rolled to the proper curvature. The ends, having been shaped by blows 
 of the sledge, do not conform to the true curvature. That was also the 
 era of the drift pin, when an unfair hole could be made fair, adding more 
 stresses to the sheet along the line of rivet holes. 
 
 Even then the trend of the times was toward boilers of larger 
 diameter. Since the size of the plates obtainable would not permit locat- 
 ing the head-to-head seams above the horizontal diameter, the seams of 
 such a boiler were exposed to furnace temperatures, in addition to the 
 stresses due to difference in temperature of the upper and the lower 
 section of the boiler, the former being exposed to the atmosphere, while 
 the latter was subjected to furnace heat as indicated in Fig. 4. The 
 intensity of these stresses would vary considerably, but one authority has 
 reported them as amounting to approximately 6,000 Ib. per square inch. 
 
28 BOILER SAFETY BULLETIN. 
 
 The never-ending effort of the contained pressure to perform the 
 impossible feat of rounding out the irregular surface existing at the lap 
 seams produces the lap-seam crack, for which this joint is notorious. In 
 Fig. 3, x and z indicate the development of such a crack, while Fig. 5 
 
 FI63 
 
 Fig. 1. Forming end of plate over roll. 
 
 Fig. 2. Ends of plate to be sledged to shape. 
 
 Fig. 3. Lap seam stressed to failure. 
 
 shows a crack that developed in a plate in service. Furthermore, this 
 lack of symmetry renders the plate along the line of greatest stresses 
 susceptible to corrosive action, which would be intensified where there 
 were three pairs of supporting brackets, as was the case with large 
 boilers; and the settling of the furnace walls at the front or rear trans- 
 ferred the load, amounting to one-half the weight of the boiler and 
 contents, onto the center bracket. 
 
 The strengthening effect of the girth seam has been the subject of 
 considerable discussion. It is in principle quite the same as applying a 
 hoop to the circumference of the boiler. This is evidenced in a number 
 of instances when, upon the vessel being stressed beyond the elastic limit, 
 the increase in circumference did not even extend to the girth seam, 
 owing to the hoop effect of the seam. The fact that the explosion of a 
 two- or three-course boiler, due to lap-seam failure, rarely results in a 
 rupture extending across a girth seam should leave no need of further 
 argument in favor of a construction embodying girth seams. 
 
 Before the double-strapped butt joint was universally adopted, a large 
 number of lap-seam boilers, many of them of the single-sheet variety, 
 were placed in operation. The majority of these boilers were intended 
 for loo Ib. pressure, using a factor of safety of 4. This factor has 
 been generally recognized as inadequate even for boilers of superior 
 construction, and could not be expected to be continued as satisfactory 
 for lap-seam boilers after a few years of service and abuse. ( Italics ours.) 
 
 After considering the various factors having a direct influence on the 
 safety of single-sheet boilers, it does not appear strange there have been 
 so many violent explosions, with the loss of numerous lives and property 
 damage approximating a million dollars in value. The facilities for 
 
BOILER SAFETY 
 
 -^ 
 
 investigating boiler explosions were probably not in keeping with the 
 general industrial activities, but in the early days, when 80 to 100 Ib. 
 pressure was considered high, each explosion was more or less shrouded 
 in mystery, and the theories advanced as to the cause were about as 
 intricate and vague as could be imagined. The presence of a super-gas, 
 the spheroidal state of the water, the geyser action of the water, super- 
 heated water, low water or no water, inflammable steam and the presence 
 of a vacuum were theories, each of which had its following. The cause 
 of the difficulty, the single-sheet lap-seam crack, was generally over- 
 looked by investigators seeking to establish the correctness of their pet 
 theory as to the force, or phenomena causing the destruction. A few 
 engineers realized the influence of manufacture on boiler safety. Zera 
 Colburn is quoted as stating in 1880, "All our knowledge of boiler 
 explosions goes to show that in the majority of cases the actual explosion 
 results from some defect, either original or produced, and either visible 
 or concealed, in the material, workmanship or construction of the boiler." 
 There is no complete list of explosions of single-sheet boilers nor of 
 the number that have been found to be unsafe and discarded from service, 
 but the record available is sufficient to indicate clearly the unusual hazard 
 attending the operation of boilers of that description. The condemnation 
 of a boiler having a seam crack 14 feet in length was recorded in 1894, 
 
 Fig. 4. Seams of single-sheet boiler inaccessible and exposed to furnace heat. 
 
3O BOILER SAFETY BULLETIN. 
 
 and on February i, 1895, a boiler 66 inches in diameter by 16 feet long, 
 containing 54 four-inch tubes, and constructed of steel plates % inches 
 thick, forming a single course of the bottom of the boiler and three 
 courses of the top, exploded in an electric light plant with disastrous 
 results. One man is reported to have been killed, three others seriously 
 injured, and the power plant totally wrecked. The line of failure fol- 
 lowed the seam from the head two-thirds of the length of the boiler, 
 from which point separation occurred, the girth seam being followed 
 across the top of the boiler by one branch of the crack, and the other 
 extending through the solid plate downward toward the rear. The 
 boiler had three pairs of supporting lugs, and conditions indicated that 
 the initial failure occurred under the middle lug. 
 
 The Rochester, N. Y., Brewery explosion followed in 1889, and 
 caused the death of one man, as well as property damage estimated at 
 $25,000. On November 26, 1901, a disastrous explosion of a 66-inch by 
 
 Fig. 5. A lap-joint crack. 
 
 1 6-foot boiler at the plant of the Penberthy Injector Works, Detroit, 
 Mich., demolished a three-story brick building and cost the lives of 
 thirty and seriously injured thirty-five others. The total property 
 damage was estimated at $100,000. This boiler had seen but six or seven 
 years of service and was understood to be in good condition. The line of 
 failure followed the longitudinal seam on one side of the shell, sub- 
 stantially in a straight line from one head to the other. 
 
 Of a single-sheet boiler the next violent explosion of which record is 
 available, occurred at the plant of the American Tin Plate Company, 
 Canton, Ohio, on May n, 1910, and was reviewed in the issue of Power 
 of May 31, of that year. Then followed the Midvale, Ohio, explosion 
 and the Shelton, Conn., explosion in 1911; the Pleasant Valley, Conn., 
 explosion in 1915 ; the Athol, Md., explosion in 1916, and the Cross Run, 
 Pa., explosion in 1917; all bearing the earmarks of lap-seam defects and 
 occurring to single-sheet boilers, taking the usual toll in life and damaged 
 property. 
 
 While the Fargo, Tex., explosion, occurring on October i, 1914, was 
 caused by a lap-joint failure of a single-sheet boiler, it differed materially 
 from some of those previously mentioned, inasmuch as the boiler had 
 been carefully examined by an expert inspector and pronounced unsafe 
 
SAFETY 
 
 to operate, his opinion being based on the corrosion which had attacked 
 the longitudinal seam. These seams were not visible on account of 
 their location below the upper tubes, but after cleaning those parts as 
 thoroughly as possible, the inspector determined by his finger tips that 
 there had been so much reduction in thickness that there was not suf- 
 ficient strength to withstand the pressure. However, the owner placed 
 the boiler in operation, and the second day thereafter it exploded, killing 
 two men, injuring two others and wrecking the plant. Investigation 
 developed the fact that the rupture had occurred in the outer sheet of 
 the lap, that sheet forming the bottom half of the boiler, as is common 
 with single-sheet construction, and followed a line parallel to the edge 
 of the inner lap, extending from head to head through metal which, 
 owing to corrosion, did not average % inch in thickness. 
 
 The accompanying photographs, Figs. 6 to 8, illustrate the damage 
 done by the explosion of a single-sheet boiler, which resulted in the 
 death of two workmen, and serious injury of two others, and the total 
 
 Fig. 6. Result from the explosion of a single-sheet boiler. 
 
 destruction of the plant. Fig. 6 gives a good idea of the general 
 damage to the plant, and Fig. 7 is a close-up view of the boiler tubes 
 and head. The boiler was said to have been about 24 years old, and 
 its builder was unknown, as it had been used elsewhere and had changed 
 owners a number of times. So far as couM be learned, the boiler 
 never had been subjected to an examination by "anyone qualified to pass 
 judgment in such matters. The double-riveted lap seams extended from 
 the front head to the rear head on each side of the boiler. The means of 
 support consisted of three pairs of castiron brackets resting on the 
 furnace walls, one being between the dome and longitudinal seams, on 
 either side of the boiler. The pressure carried at the time of the explo- 
 sion was loo lb., and it was probable the builder sold the boiler when new 
 with the customary guarantee of that pressure, which would be permitted 
 by a factor of safety of 4. 
 
 Some time previous to the accident leakage was observed at the 
 longitudinal seam under one of the center support brackets. A boiler- 
 maker of questionable ability and experience patched the seam as 
 
32 BOILER SAFETY BULLETIN. 
 
 indicated by the arrow in Fig. 8, apparently without giving thought to 
 the cause of the difficulty, but riveting the patch at the boiler seam, and 
 using patch bolts for securing the new seam. The boiler was continued 
 in operation without further trouble until about a week before the 
 explosion, when seam leakage was again observed. The mill superin- 
 tendent and an employee are said to have drilled and threaded for 
 "54-inch capscrews, four holes along the seam where leakage had 
 appeared. A soft patch consisting of a sheet of plow steel and a thin 
 sheet of lead was secured to the boiler by means of capscrews and nuts, 
 and the boiler was again placed in service. 
 
 The failure occurred in the sheet forming the lower part of the boiler, 
 on a line coinciding with the edge of the inner lap, just about the same 
 location as in the failure of the Fargo, Tex., boiler, and did not follow 
 nor enter the rivet holes. It extended the entire length of the seam, as is 
 customary with violent failure of this kind. The rivets in the head 
 
 Fig. 7. Close-up view of boiler tubes and head. 
 
 seams either sheared at the junction of the plates or the rivet heads 
 pulled off, as none of the rivet holes were destroyed, although some of 
 them were found to be considerably elongated. 
 
 After an accident, where there are so many possible causes, it is difficult 
 to define responsibility. In this case the center bracket above the point 
 where the initial leakage and crack developed, most likely supported the 
 entire weight of that side of the boiler, which, as has been outlined, 
 would follow from the settling of the furnace at the front or back 
 bracket, and would clearly justify the modern requirements which pro- 
 vide for four-point suspension only. The factor of safety was not 
 one-half as great as considered necessary by good authorities for boilers 
 of such great age and design, and had a proper factor of safety been 
 maintained, the explosion would not have occurred, as the pressure per- 
 mitted then would not have been sufficient to operate the plant, and the 
 boiler would have been scrapped. 
 
 Had the service of the boiler been limited to ten years, as has been 
 advocated for the lap-seam boiler, its use would have been abandoned 
 
33 
 
 years before. The owner no doubt would have experienced some financial 
 loss, but nothing compared to the loss resulting from the explosion. Had 
 the boilermaker who patched the boiler been acquainted with develop- 
 ments of recent years, so far as boiler design and safety are concerned, 
 and the rules which prohibit repairing a boiler in which a lap-seam 
 crack has developed, or had the mill superintendent realized the clear dan- 
 ger warnings and discontinued the boiler from service until the advice of 
 competent persons could be obtained, there would have been no explosion. 
 This accident emphasizes the difficulty of obtaining proper coopera- 
 tion of boiler owners in enforcing reasonable rules and regulations, as 
 the boiler was being operated without a certificate from the state 
 authorities, who had no knowledge of its existence, and it is doubtful if 
 the owner and those in charge of its operation knew that the boiler dif- 
 fered in any material way from new boilers of modern design. 
 
 Fortunately, the installation of new boilers of this description is 
 prohibited in many states and cities, so its manufacture practically has 
 been abandoned, but there are a great number in operation, and the next 
 few years may witness an increasing number of failures, as the defects, 
 undoubtedly existing, develop until rupture takes place. An increase in 
 the factor of safety will result in a reduction of pressure ; this may cause 
 the removal of the boiler from its present place of operation, to be dis- 
 posed of, if there are no restrictions, through dealers in second-hand 
 boilers, only to be placed again in service, to the jeopardy of someone's 
 life and property. 
 
 In discussing the Cross Run, Pa., explosion, The Locomotive, in the 
 July, 1917, issue, asserts: "The lap-seam boiler has been a fruitful 
 
 Fig. 8. Shell plates blown free of the ends and tubes. 
 
 source of steam-boiler accidents in this country, and of lap-seam boilers 
 perhaps no class has been more subject to disaster than those made in a 
 single course with two sheets, one above and one below." It is evident 
 that the single-sheet boiler "has been weighed in the balance and found 
 wanting." It has sustained injuries during the. process of fabrication, 
 is impossible of thorough inspection, has been stressed beyond its safe 
 limit by temperature difference, by continual flexure due to nonconformity 
 to a true circle, by lack of girth-seam support, and by the unequal dis- 
 tribution of the weight of the boiler, contents and connections. 
 
34 BOIIvER SAFETY BULLETIN. 
 
 Shall those boilers now in use be continued in service, to change 
 owners and operating conditions at will, until each gives positive and 
 direct evidence of its worthlessness by exploding, with the aggregate loss 
 of another hundred of lives, and of another million-dollar property 
 damage? Or shall the rule against habitual criminals be invoked, and 
 each boiler of that type sentenced permanently to the scrap yard, where 
 it will have no further opportunity to destroy, just as the police character, 
 in whom the bad outweighs the good, is given an indeterminate prison 
 sentence, so he can do no more injury to society? If those financially 
 responsible for the continued operation of single-sheet boilers could be 
 made to realize that immediately preceding each lap-seam boiler accident 
 the owner considered his boiler perfectly safe to operate ; or appreciated 
 the fact that under certain circumstances any person might be the victim, 
 as our sidewalk basement boiler rooms, hotel power plants and depart- 
 ment store power plants, if they do not contain unquestionably safe 
 equipment, place the lives of all in jeopardy; or realized that defective 
 boilers endanger the lives of the employees to whom the employer owes 
 the moral responsibility of furnishing safe tools then there is no ques- 
 tion that the verdict would be, "The single-sheet boiler must go." 
 
 CHANGING OLD LAP SEAM BOILERS TO BUTT SEAM 
 CONSTRUCTION.* 
 
 Not long after the steam boiler came into general use in America 
 .considerable discussion was aroused with respect to the question of 
 limiting the life of a boiler. Numerous instances of serious accident, 
 which it seemed impossible to account for, had impressed many with the 
 
 Fig. 1. When plates are rolled to a cylindrical form there is a tendency for 
 plate edges to remain flat as in this case. 
 
 idea that a boiler, like any other piece of apparatus, was subject to 
 deterioration from constant use and that therefore it would be best to 
 take a boiler out of service after a certain period. In fact, a number of 
 concerns followed this practice. The majority of boiler users and 
 
 *From The Locomotive, Hartford Steam Boiler Inspection and Insurance Company, Hartford, 
 Conn. Cuts to illustrate this reprint were loaned by The Boiler Maker, 6 Fast 39th St., New 
 York. 
 
BOILER SAFETY BULLETIN. 35 
 
 engineers, however, felt then, as they do now, that rigid inspection 
 would safeguard their boiler plants and would furthermore be of greater 
 service in the interest of economy, for it was admitted that many boilers 
 had served for twice the life that, by some, had been allowed for safety. 
 
 The plan of relying on inspection for a forewarning was adopted and 
 served well, but there were a number of unaccountable explosions in 
 boilers of relatively short life. At the time, the majority of boilers in 
 use were constructed with a longitudinal lap joint. A series of investi- 
 gations was conducted to study the stress conditions in this type of joint, 
 and it was found that the construction, both from its fundamental shape 
 and the conditions of manufacture, presented a most dangerous condition. 
 
 In The Locomotive for April, 1905, there appeared an account of the 
 disastrous boiler explosion at Brockton, Mass., on March 20, 1905, and 
 also an article on the "Lap-joint Crack," to which type of defect the 
 explosion was said to be due. For the sake of clearness we shall 
 present here some of the more important points which were brought 
 out in the last-named article. 
 
 When a boiler plate is rolled to a cylindrical form the edges of the 
 plate, in passing through the rolls, are not gripped as effectively as is 
 the middle of the plate, so that the ends are left somewhat flat. The 
 condition produced is illustrated in Fig. I. This necessitates the plates 
 being forced together at the edges, and this produces an added stress 
 that persists unless relieved by annealing. In addition to this, the plates, 
 if bent after punching, will bend along a line of rivet holes as shown in 
 Fig. 2 in somewhat exaggerated form. 
 
 The elementary lap joint is illustrated in Fig. 3. If tension is applied 
 as indicated in Fig. 4, the plates, in an attempt to aline themselves 
 with the load, will bend along a line running under the outer edge of 
 the rivet heads. 
 
 The combined effect of all these conditions, together with the constant 
 bending of these joints by changes of pressure when in use, is to impose 
 excessive stresses in the surface of the boiler plate along the line just 
 mentioned. This has produced, in many boilers, a crack which starts 
 always from the inside or covered surface of the inside or the outside 
 plate of the joint as indicated at A and B in Fig. 4. This crack may 
 eventually work its way through the plate until it shows itself by leakage. 
 But in many cases it may develop for some distance along the joint and 
 yet remain absolutely invisible. Eventually the weakness may develop 
 to the point of complete failure and a disastrous explosion. 
 
 Inspection is generally accepted as being safe for the determination of 
 the fitness of a boiler for use. The lap seam crack, however, is invisible 
 to all methods of inspection, except cutting out the rivets and separating 
 the plates. Recognizing the insidious danger presented in the lap joint 
 for longitudinal seams in boilers, the Boiler Code Committee of the 
 American Society of Mechanical Engineers formulated the following 
 regulation (par. 380, A.S.M.E. Boiler Code, edition 1918) : 
 
 "The age limit of a horizontal return tubular boiler having a 
 longitudinal lap joint and carrying over 50 pounds pressure shall be 20 
 years, except that no lap joint boiler shall be discontinued from service 
 solely on account of age until 5 years after these rules become effective." 
 
 Some boiler owners may be of the opinion that the longitudinal lap 
 seams of boilers of this type can be changed to butt strap construction 
 
BOILER SAFETY BULLETIN. 
 
 and the boilers kept in service after the time limit. This change of 
 design and construction is not approved, however, by those thoroughly 
 familiar with steam boilers, for, although butt straps and more rivets 
 may be added, the material along the line of the joint, which was abused 
 and tortured by the forming of the lap joint and fatigued by the years of 
 service which subjected it to the expansion and contraction brought 
 about by the many changes of temperature and pressure, would be further 
 abused on the portion of the original construction left after cutting off 
 one side of the lap joint and forcing the edges of the plate into line to 
 form a butt joint. 
 
 Assuming that a double riveted lap joint has been changed to a triple 
 riveted butt construction, the joint, after placing the butt straps and 
 riveting, would appear as shown in Fig. 5 with the rivet holes of the 
 original lap joint at B and the new holes at C. If a defect existed in the 
 
 Fig. 2. If bent after punching, plates will bend along a line of rivet holes. 
 
 plate as shown at A the joint would be very faulty. Assuming the 
 original joint as having the rivet holes spaced 3^ inches and the 
 additional holes spaced 6y 2 inches, if the plate material were defective 
 or contained a lap crack as shown, the failure of the joint would require 
 only the shearing of the rivets in long pitch, or 6^/2 inches, and the 
 failure of the defective plate. 
 
 Fig. 3. Elementary lap joint. 
 
 Fig. 4. Effect of tension on joint. 
 
 It might be argued that the exposure of the inside of the lap seam, 
 when the change to a butt seam is made, would reveal the presence of a 
 lap-seam crack. A crack of this nature is, however, often present in a 
 boiler of this construction after years of service, although it may not 
 be visible to the naked eye. But even though no crack exists it must be 
 remembered that boiler plate, like any other material, becomes fatigued 
 after long years of service, and for this reason, after it has been under 
 stress for many years, it should not be subjected to a change of shape and 
 torture of the material in an endeavor to keep the boiler in service, 
 especially when there is evidence that the altered structure is defective. 
 
 The age limit of twenty years is none too exacting, as will be evidenced 
 by an explosion resulting from a lap seam crack of a boiler at the 
 Tallahoma Lumber Company at Mossville, Miss., on October 21, 1920. 
 
BOILER SAFETY BULLETIN. 
 
 37 
 
 This boiler was less than five years old. The explosion completely 
 wrecked the plant, killed three men and injured four others. There was 
 no negligence on the part of the operators and there was ample proof 
 that the accident did not result from low water or overheating. On the 
 other hand, the lap seam cracks could be clearly seen in the boiler plates 
 after the disaster. 
 
 Regulations such as we have quoted are not intended to be arbitrary. 
 Railroad companies determine the safe load capacity for each of their 
 freight cars, and if they discover an overloaded car they refuse to trans- 
 
 Fig. 5. Double riveted lap joint changed to triple riveted butt strap type. 
 
 port it. This is done not only to avoid the possibility of straining and 
 breaking the overloaded car, but also to prevent a possible wreck which 
 might result in loss of life, property damage and delay. In a like man- 
 ner the Boiler Code Committee requests that steam boilers and pressure 
 vessels be designed and constructed for a safe working pressure and 
 that they be not subjected to overloads. The rule quoted above is sane 
 and economic because it is intended for the protection of life, limb and 
 property. So also should be regarded the action of the boiler inspector 
 condemning any construction regarded as unsafe. 
 
3<5 BOILER SAFETY BULLETIN. 
 
 LAP SEAM CRACK CAUSES BOILER FAILURE IN PLANING MILL.* 
 
 [Reprinted, by permission, from April, 1921, issue of The Boiler Maker.] 
 
 Many of the details of boiler making, and in that term we, of course, 
 include boiler repairing, have found no place in written language but 
 may be said to be traditional, being handed down from the journeyman 
 to the apprentice, by word of mouth. Other details may be said to be 
 proprietary, that is, some workman experiments with new processes, 
 until he becomes acquainted with some formerly unknown fact, applicable 
 to the trade, of which he immediately takes advantage, with satisfactory 
 personal results, and with some permanent benefit to the trade in general, 
 when the detail becomes more widely known. 
 
 The good workman is proud of the results of his efforts, and when 
 trade-pride ceases to exist, whether he be manufacturer or workman, he 
 may no longer be depended upon, and sooner or later his work will 
 become outclassed. In order to obtain satisfactory results, a complete 
 understanding of the trade is essential. The boiler maker doing repair 
 work is thrown more upon his own resources than is the workman 
 engaged in routine shop work. When on new construction, the foreman 
 and other journeymen are usually near at hand for advice when neces- 
 sary. It may be said, however, that friendly counsel and conferences of 
 a trade nature are far too uncommon. 
 
 EXPERIENCE REQUIRED IN REPAIR WORK. 
 
 At any rate, when a call for outside repair work is received, one of the 
 most capable and experienced men in that class of work is, or should be, 
 sent to the job, for it is impossible to determine the far reaching effects 
 
 Fig. 1. Result of boiler explosion in planing mill, Antlers, Okla. 
 
 of a lapse in judgment, when outlining the repairs to be made, and the 
 manner of making them. The owner of a boiler is anxious to obtain 
 the greatest possible term of service, consistent with safety, and is often 
 
 *Cuts to illustrate this reprint were loaned by the publishers of The Boiler Maker, 6 East 
 39th St., New York. 
 
BOILER SAFETY BULLETIN. 
 
 39 
 
 willing to spend more for patches, new tubes, or resetting, than the value 
 of the boiler warrants. Of course, if permanent, safe and satisfactory 
 repairs are possible, no one should object to a patch of proper dimensions, 
 properly applied, but the boiler maker should have sufficient judgment 
 to determine ,and sufficient confidence to refuse, if repairs should not be 
 made, for otherwise lives and property are placed in danger. 
 
 LAP SEAM CRACK IN BOILER CAUSES EXPLOSION. 
 
 At 7:30 a.m., September 20, 1920, the town of Antlers, Okla., was 
 shocked by the explosion of a boiler located in a planing mill at that 
 place. The plant was totally wrecked, and two men were killed, while 
 two others were seriously injured. The head of one of the men who 
 were killed was completely severed from the body. 
 
 The immediate cause of the explosion was a lap seam crack, which 
 extended from the front head to the rear head of the boiler, along the 
 
 Fig. 2. View of shell plates, showing patch and extent of crack. 
 
 longitudinal seam, and which no doubt had been years in fully develop- 
 ing. The complete history of the boiler was unknown, but it was said to 
 have been purchased second hand, provided with usual safety appliances, 
 and placed in operation at 100 pounds pressure, which was continued 
 until leakage was observed at the longitudinal seam on the right hand 
 side, when facing the front. 
 
 The home made brand of calking, provided by those in charge, was 
 not sufficient to stop the leakage, so a boiler maker was sent for, and 
 patching was determined upon. The patch can be seen plainly in Fig. 2, 
 which also shows the extent of the seam failure, and the shell plate 
 detached from the heads and tubes, resting where it landed, about 300 
 feet from its original position. 
 
 Fig. 3 gives a close-up view of the patch, and crack which extended 
 through the threaded holes, used in securing a soft patch, which had been 
 applied by those in charge of the plant. 
 
4O BOILER SAFETY BULLETIN. 
 
 It is possible that the boiler maker who made the riveted patch repair 
 looked with pride upon his work, for the patch was tight, and while its 
 shape could have been improved upon, its workmanship was above the 
 average. It is further probable he had never heard of a lap seam crack. 
 This is a defect thousands of men are seeking daily, in order to prevent 
 just what took place at Antlers, and if this mechanic had been thoroughly 
 posted upon the developments which have taken place in his trade in 
 recent years, the designs which have proven faulty, and the many failures 
 of lap joints, due to the lap joint cracking, he could have prevented the 
 disaster, by refusing to make repairs. 
 
 Many of the states have adopted laws regulating the material, design, 
 construction and operation of steam boilers, but few of them have dealt 
 
 Fig. 3. Close-up view of patch and crack. 
 
 extensively with rules controlling boiler repairs. However, there is one 
 requirement which has been almost universally adopted, which prohibits 
 the repairing of a sheet in which a lap seam crack has developed. 
 
 The A.S.M.E. Boiler Code limits the pressure on lap seam boilers to 
 50 pounds after 20 years of service, and likewise prohibits repairing 
 the sheet of a boiler in which a lap seam crack has been discovered. 
 The loss of life and damage to property at the Antlers planing mill 
 alone, to say nothing of the great number of similar explosions which 
 have occurred elsewhere, clearly justifies the Code requirements, and 
 every boiler maker called upon to tighten by calking, or repair by patch- 
 ing the longitudinal seam of a lap seam boiler, should refuse to make 
 repairs until it is clearly demonstrated that a lap seam crack does not 
 exist. J. P. MORRISON. 
 
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