The Birth of a Code: ASME Boiler and Pressure Vessel Code

“The Boiler and Pressure Vessel Code establishes rules of safety governing the design, fabrication, and inspection of boilers and pressure vessels, and nuclear power plant components during construction. The objective of the rules is to assure reasonably certain protection of life and property and to provide a margin for deterioration in service. Advancements in design and material and the evidence of experience are constantly being added by Addenda.”

The above briefly explains what the Boiler and Pressure Vessel Code is in a booklet by the American Society of Mechanical Engineers (ASME).

As far back as the Middle Ages, engineers were consumed with the challenges of developing non-human forms of power that would ease the burdens of workers while at the same time making available more comforts and conveniences for a greater number of people. The major sources of such power were animals, wind, water, and other natural forces, harnessed to drive an increasing variety of devices and inventions, many of them remarkably ingenious and efficient.

In 1800, Richard Trevithick, an Englishman who was a self-taught engineer, designed an engine that operated at a pressure of 65 psi. The boiler and engine were mounted together.

In 1825, an American engineer, John Stevens, had constructed a boiler with multiple tubes.

It was not until three decades later that Stephen Wilcox perfected what was later considered a “real breakthrough” in water-tube boilers. He designed inclined water tubes that connected water spaces at the front and rear, with a chamber above. This permitted much better circulation of the water, provided more heating surface, and reduced the risk of explosion that was one of the banes of the early water-tube design.

On March 2, 1854, at 2.10 pm., while a mechanic and the operating engineer of Gray Car Works were in conversation in the engine room, the boiler exploded, completely destroying the boiler room and the adjoining blacksmith shop, and badly shattering the main building. Nine persons were killed outright, twelve died later, and more than fifty others were seriously injured.

The investigation that followed the tragedy revealed only that the explosion should never have taken place. The boiler was a new one, having been in use for barely one month. It had been manufactured at the boiler works of Woodruff and Beach, one of Connecticut’s most reputable industrial concerns and well experienced in the design and production of commercial boilers.

In the end, a coroner’s jury concluded that the basic cause of the disaster was an “excessive accumulation of steam” and that “said excessiveness of steam in said boiler was owing to the carelessness and inattention of the engineer.”

The jury went on to suggest proposals and recommendations which in the following years, many of them were adopted. Among the proposals were the following:

How long the boiler problem might have remained in limbo is a moot question, but the next episode in boiler code history rested with a steamboat name the Sultana. She was a typical Mississippi side-wheeler with two tall stacks. On April 27, 1865, steaming along the river above Memphis, she met a catastrophic end when three of her four boilers exploded for reasons never determined. Ironically, instead of her usual complement of 375 passengers, she was jammed from stem to stern with 2,200 people, most of them Union soldiers who had just been released from Confederate prisons. Within 15 minutes, she had burned to the waterline, with a death toll that varied in later reports from 1,200 to more than 1,500, thus providing a given statistic in the record books as the nation’s worst marine disaster in history, past or present.

Despite the steadily spreading work and influence of the Hartford Steam Boiler Company, progress toward codes and standards was painfully slow. When research projects were undertaken to provide guidance, they were often inconclusive or short-lived.

In 1883, the Committee on Standard and Gauges of ASME considered the determination of a standard for rating steam-boiler capability. As one member observed then, “It is part of our duty, no doubt, to establish gauges and standards.” In this new spirit of coordination, the Society took a giant step forward when in 1884, it formulated a code entitled Standard Method for Steam Boiler Trials. One year later, it established a Standard Committee on Pipe and Pipe Threads, thus characterizing the nature of its future work and policies that would be so influential in the late program to develop boiler codes and standards.

William Kent, chairman of the first committee to compile a set of rules for boiler testing, pointed out how difficult a job it was going to be to keep such documents current and updated. The 30 or 40 committee members involved with the original code had increased several times over and Kent summarized quite accurately that it would be “a difficult matter to bring them together.”

Shortly after the founding of ASME (1880), other societies and associations came into being that were to make a marked impact on the evolution of boiler codes and standards. One of these was the American Boiler Manufacturers’ Association (ABMA), which was chartered in 1889. Its stated objective was to raise the standards of boiler design and manufacture, and prevent the production and sale of boilers unfit for safe operation. Initially committees were formed on materials, recommended tests and inspections, riveting, tubes, the attachment of valves and fittings, and setting. Three years later, ABMA appointed its first committee on uniform specification laws.

By the turn of the century, the Association was heavily involved in detail work and the presentation of papers on such subjects as riveting, factors of safety, caulking, dished heads, flanging, tubes, bending and forming, stay bolts, braces, drums, and hydrostatic-pressure tests.

Colonel Edward D. Meier, who was to figure prominently in the birth of  the ASME Boiler Code was quoted in his position as chairman of the ABMA Uniform Specification Committee as being dissatisfied with one direction that committee work was taking. Too many members were looking at specifications in light of bidding for boilers and components and not toward the adoption of standard and codes by states and municipalities. This outlook, he felt, was way off balance. The concepts he adhered to during this period in his career reflect the ideas he would later bring to the creation and development of the first ASME Code.

However, despite all the efforts, there was still no legal code for safe stationary boilers in any of the states of the Union. Massachusetts had considered the enactment of laws and regulations because of the prevalence of steam boilers in hundreds of factories and mills throughout this increasingly industrialized state, but legislators had become complacent for two reasons. The first was the positive influence of Hartford Steam Boiler Inspection and Insurance Company throughout New England, whose agents had done an excellent job of policing equipment which the firm insured. The second was that between 1898 and 1902, there had been no serious boiler explosions reported in any of the industrial regions of the state, a dramatic contrast to the nation’s total of more than 1,600 during the same period. This was attributed in part to the fact that Massachusetts had passed a law in 1850 requiring fusible plugs on all stationary high-pressure boilers.

This complacency was shattered quite abruptly on March 10, 1905, when a fire-tube boiler in Brockton, Massachusetts, shoe factory exploded. The toll was 58 dead, 117 injured, and damages of one quarter of a million dollars. Since the factory boilers were not insured and the cause was never officially determined, it was evident that the state laws were not as effective as had been claimed.

On December 6, 1906, another serious explosion took place at a shoe factory, this time in Lynn. Although only one person was reported killed, this incident motivated the Governor of Massachusetts to include in his inaugural address a month later a demand for prompt action.

The wheels were set in motion, a 5-man Board of Boiler Rules was authorized that spring, and by late summer of 1907, the first Massachusetts Rules were approved. The document was short and simple, containing only 3 pages. The first was devoted to a facsimile of the standard format of the certificate of insurance. The second page covered fusible plugs and their performance characteristics, based on the earlier state requirements for these safety devices. The third page provided specific rules, which included, among others, limiting cast-iron boilers to a pressure of 25 psi, limiting boiler with cast-iron headers to 160 psi, and data governing the shearing strength of rivets.

There were objections, coming mostly from manufacturers who viewed these regulations as a prime example of needless government intervention. Some denounced the state for imposing commercial hardships that would put small boiler makers out of business. The hue and cry, along with legislative lobbying, forced a public hearing in 1909 to listen to complaints and recommendations for revisions. Attending this hearing was Dr. David S Jacobus, who had arrived from New York representing the Babcock & Wilcox Company. Dr Jacobus was later recognized for his fine work on the ASME Boiler Code, but in this instance he was branded an “outsider” and criticized for coming all the way to make proposals that would be injurious to the welfare of manufacturers in Massachusetts. Jacobus responded by stating that it was his personal policy, as well as that of his company “to act in the broadest way possible to endorse a movement for the protection of human life and property.” Following his statement and leadership, others at the hearing spoke out in favor of the Rules.

The result was that “An Act Relating to the Operation and Inspection of Steam Boilers” was passed in 1909. The rules were divided into 3 parts. The first applied to boilers installed prior to January 1, 1909, fixing the maximum allowable pressures for boilers composed of steel and wrought iron. It also specified the sizes of the non-spring-loaded safety valves and bottom blow-off valves. Part two referred to boilers installed “now and in the future,” defining maximum pressures for cast-iron boilers, for boilers with cast- or malleable-iron headers or with cast-iron mud drums. Part three covered boilers of the future, anticipating requirements of materials to be employed in the fabrication of various components. It also described the procedures for stamping boilers that met the requirements of the rules and provided guidelines for every kind of component, as well as non-standard boilers and portable boilers. The document concluded with an appendix devoted to structural recommendations and the care and operation of boilers in service.

The success of the Massachusetts law, along with public pressure to do something about continuing boiler explosions, motivated another state, Ohio, to take similar action. In October 1911, the Governor approved the Rules that had been formulated during the previous five months by the Ohio Board of Boiler Rules, which had been appointed for that purpose. The Ohio Board adopted with few modifications the Rules of the Massachusetts Board in most cases, changing only the dates to refer to boilers constructed prior to, and after, the passage of the bill.

One of those appointed in 1911 to compose the initial draft of the Boiler Code was Colonel Edward Daniel Meier, who had studied in Germany where he graduated from the Royal Polytechnic College in Hanover before returning to the United States. After his distinguished service with the Army of the Potomac during the Civil War, and a rise in the ranks to the position Colonel, he designed machinery for compressing cotton and in 1884 was one of the founders, and later president of Heine Safety Boiler Company. He designed and installed boilers in New York City’s new Grand Central Station and was the first to introduce the Diesel engine to the United States, after it was patented in1892.

At the time of the formation of the new Boiler Code Committee, he was president of ASME and also the American Boiler Manufacturers’ Association.

As early as 1898, he was president over a committee whose objective was to standardize specifications for the construction of boilers. He was ably qualified for that assignment, having already made an exhaustive study of European Standards and surveyed the practices and policies of major American boiler manufacturers.

Meier’s first step was to request that the ASME Council appoint a Committee to formulate standard specifications for the construction of steam boilers and other pressure vessels and their components. Ironically, while in the midst of trying to achieve his goal of industry-wide standardization, the Colonel became ill and barely survived long enough to see the final version of the Code approved for publication.

Fortunately, there was a fellow engineer who was an equally strong influence in creating the Code: John A Steven, of Massachusetts, a consultant whose career had been devoted largely to power generation. He had already amassed a wealth of experience in the area of Codes and Standards, having served on the Massachusetts Board of Boiler Rules, which as early as 1907 had established the first state law to regulate the construction, installation, and operation of steam boilers. Significantly, the Board was not simply a state regulatory body, but was composed of individuals representing boiler manufacturers, operators, inspectors, and owners. This varied structure tied in with a basic objective of the first ASME Code: to assure complete and well-balanced representation on the part of those who were concerned with consistency, efficiency, and safety.

When the ASME Council appointed Steven chairman of the Boiler Code Committee in September, 1911, it was virtually assured that his kind of balance would be established and maintained.

The Boiler Code Committee, as approved by the ASME Council, was listed in the minutes of the meeting of September 15, 1911 as follows:

“Voted to confirm the appointment of a committee to formulate standard specification for the construction of steam boilers and other pressure vessels for the care of same in service to consist of John A Stevens, chairman; E F Miller, C L Huston, H C Meinholz, Richard Hammond, R C Carpenter, and W H Boehm.”

Another key advisor was William Kent, with long and varied experience as a mechanical engineer including positions as editor of Iron World and American Manufacturer, manager of the Pittsburgh office of Babcock & Wilcox, and president of the American Society of Heating and Ventilating Engineers. Greatly concerned about the diversity of standards and the absence of coordination in testing of the steam boilers, he set up demonstrations, however, each person viewing the demonstration was probably using methods that differed from those applied by others in the audience. The point was well taken, particularly when another engineer, Henry T Towne, complained to all who would listen that there was not even a common language with which engineers could communicate many of the differences.

The first two years of the Code Committee were devoted to organizational work and two meetings, the first in New York City, the second in Ithaca, New York. Then, in 1913, following procedures that were already well established in ASME, C S Obert, the Secretary typed up the Preliminary Report of the Committee and sent some 2,000 copies to the Society’s list of interested professionals. The report was essentially the Code itself, requiring 230 pages and including charts, tables, laws, rules, and appendixes.

Following the receipt of suggestions that were triggered by this mailing, the Committee eventually completed revisions for a second printing, dated February 18, 1914. Comparison of the two editions shows relatively few changes of significance, which would seem to indicate that few of the recipients had been dissatisfied with the initial effort. As in previous case, copies of the new printing were then mailed to the ASME list, now increased to some 2,500.

Unlike the first mailing, the second one brought what was termed “a storm of protests.” Although dissension had not really surfaced until now, it was apparent that there had long been dissatisfaction among members of ASME who were opposed to rules and restrictions governing their businesses. In the proposed Boiler Code, they had seen a threat to their economy and even to the whole free enterprise system. There was a movement underfoot to scuttle the issuance of the Code by planting seeds of doubt in the mind of the Council members themselves so that the publication would be voted down, or at least postponed.

Why had not the first mailing stirred up this hornet’s nest, and why was it only at this later hour that opposition was mounting? As one opponent admitted, “I guess we all thought that if we ignored the Code, it would simply go away.” A more logical conclusion is that many who opposed the Code did so because they felt that the Committee was too heavy-handed, if not autocratic.

In the end, both sides won, Hess and the others who had expressed strong opposition backed off and agreed that the Committee should be allowed to continue its works. For its part, the members of the Committee conceded that they would make every effort to review the proposed Code with representatives of all factions involved and make suitable revisions before publishing the official First Edition. To that end, a Society resolution was passed, calling for a public hearing to be held on September 15, 1914, at which time a review would be made of all suggestions, criticisms, and reports submitted in writing on or before August 15.


The public hearings were held at the Engineering Societies Building at 29 West 39th Street in New York City on September 15, as scheduled. The 150 individuals who attended represented every facet of the industry, from consulting engineers, educators, and editors, to manufacturers, insurers, inspectors, government officials, agriculturists, railroaders, designers, heating and energy specialists, and researchers. The list of associations present read like a blue book of the industry.

At the conference, after preliminary discussions, the nature and wording of the Code were discussed item by item so that everyone attending could express opinions whenever changes had to be undertaken. The accomplishments were notable. It was noted for example, that “for the first time in their history” all of the makers of the safety valves agreed upon a uniform specification for their products. And representatives of the railroad industry presented “a most splendid criticism of the Preliminary Report which helped greatly in bringing about the actual success of the hearing.”

The official transcript of the hearings led immediately to preparations for what was actually the third draft of the Code, though still refer to as the “Preliminary Report.” Incorporating the critiques compiled during the hearings and working around the clock, the Committee managed to have the draft ready to send out to its mailing list by November 5, a gargantuan accomplishment in the light of the amount of detail that had to incorporate changes requested on the third printing and be ready for presentation to the ASME Council for its Annual Meeting on December 1.

It would seem from all outward appearances that a spirit of cooperation had replaced the notes of dissension that previously delayed the acceptance of the new Code. But at the meetings held during the first week of December 1914, there was a new campaign on the part of the opposition to defeat the approval of the Code, or at least to postpone the action. However, the supporters now greatly outnumbered the dissenters and had so firmly entrenched themselves that the Committee was able to proceed on the final draft of the Code. According to the records of the Secretary, C S Obert, the seven-member Committee and the 18-member advisory committee labored 13 hours a day, six days a week, for seven weeks to incorporate the changes and additions that had been presented to them. The galley proofs for the Code were presented to the Council at its regular meeting on February 5, 1915. In its published form, including a detailed 30-page index, the Code was 148 pages long. By the time of the next Council meeting, on March 12, 1915, the Code had become an official, approved document of the American Society of Mechanical Engineers. Despite being actually published in 1915, the first Code went on record as the 1914 Edition, which thus became the official birth-date of the Code. The format was a hardcover book 6” x 9” in size, and bound in olive drab cloth. Entitled REPORT OF THE BOILER CODE COMMITTEE OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS, it was published at the expense of Babcock & Wilcox.

This first Code book was divided into two parts, PART I on new installations and PART II on existing installations. The Committee devoted 80 pages to new installations and only 5 to those already existing. The remainder of the First Edition was allocated to an Appendix, with suitable diagrams, formulae, and charts, and a detailed Index. Power boilers and heating boilers were both covered in the main body of the text, with particular attention given to such topics as the selection of materials, manufacture, the thicknesses of the components, workmanship, inspection and testing, safety valves, water and steam gauges, fittings and appliances, and official ASME Stamps for uniform standards.

It was cited the first Code formula as:

                                                       P = Ts  x  t  x  E
                                                                 R  x  Fs
P stood for the maximum allowable working pressure in pounds per square inch; Ts the ultimate tensile strength in pounds per square inch; t the minimum thickness of shell plate; E the efficiency of longitudinal joints or ligaments between tube holes; R the inside radius; and Fs the factor of safety.

At the start of the 1920s, it was discovered that “a great need existed for a code for air tanks and pressure vessels, as some manufacturers had been attempting to apply the power-boiler rules to the design of their vessels, but with only minimal success. Within the next three years, the Code Committee had appointed a subcommittee on the subject, drafted preliminary rules, held two public hearings, and decided that the need for the code was “urgent.”

In January 1922, the Committee voted that “all matters pertaining to the proposed Unfired Vessel Code be turned over to the Subcommittee on Welding, which shall be requested to revise it so as to present a Welding Code to the Boiler Code Committee and to confer as it sees fit with the Executive Committee.” It was to be three years, however, before these vessels would receive due recognition, following additional hearings, many more “preliminary” drafts, and continuing suggestions from manufacturers and interested parties of all kinds, including the American Welding Society.

The sixth, and final, draft of the new Code for Unfired Pressure Vessels was adopted by the ASME Council on January 15, 1925, as Section VIII of the Code.

Since its first edition in 1925, the ASME Unfired Pressure Vessel Code has been an important reference for designers and fabricators of pressure vessels. Its specifications now govern all unfired pressure vessels used in most states and all Canadian provinces.

By the start of the 1930s, the Code had grown to eight sections:


Leong Yee Hong
Pressure Systems Interest Group (PSIG)
American Society of Mechanical Engineers
Singapore Section.

Acknowledgement with thanks – THE CODE, An Authorized History of the ASME Boiler And Pressure Vessel Code by Wilbur Cross.

© Pressure Systems Interest Group 2010