Most of us in the valve industry take for granted the interchangeability and standardization of the valves produced today. Yet it wasn’t that long ago that valves were individually produced in accordance with the standards of each manufacturer.
Things like end-to-end dimensions, flange sizes and bolt circles, and even pressure ratings, were left up to the engineering and production departments of each company. Such factors were addressed in due time; however, as with many drivers in the manufacturing world, the first valve standard to be drafted covered something much more important—life and death.
Back in the latter half of the 19th century, boiler explosions were occurring at an alarming frequency, and public outcry was heard throughout the land—it appeared that the steam-fired industrial revolution was threatening to literally blow itself up.
In 1880, the American Society of Mechanical Engineers (ASME) was formed and over the next few decades this group of engineers created the first iteration of the Boiler and Pressure Vessel Code (B&PVC). The problem of inconsistent boiler integrity was high on the group’s list of topics to be addressed. While the code initially dealt with a number of issues concerning materials and construction, it wasn’t until the 1914 edition of the B&PVC that safety valves were covered. It would be the first time in history that makers of safety valves had agreed to common standards for their products.
These groundbreaking safety valve rules and regulations would be honed over the years and are still actively supported today by a group in ASME called the National Board of Boiler and Pressure Vessel Inspectors.
A PUSH FORWARD
The industrial growth during the first years of the 20th century highlighted the need for valve and piping standardization throughout the world of manufacturing. The Henry Ford automobile assembly line techniques were adopted by many industries, including valve and fitting manufacturers. While products were flying off the assembly lines at record rates, there was no interchangeability between manufacturers’ products. You only have to look at catalogs of the day—product images show valves with blank flanges, devoid of bolt holes—to see that something was missing. The something was flange standards. Back then, it was up to the purchaser to provide the bolt-hole drilling information.
This lack of interchangeability resulted in a Committee of Manufacturers on Standardization of Pipe Fittings and Valves, which was formed in 1912. The group would later become the Manufacturers Standardization Society (MSS); it published its first pamphlet on pipe schedules of flanges and flanged fittings in October of 1912 and additional flange standards over the next few years. The official creation of MSS in 1924 opened the door for many valve standards over the next nine decades. During that time, numerous standards originally developed by MSS would be adopted by other organizations, such as ASME and the American Petroleum Institute (API).
The American Standards Association committee B16, Sectional Committee on the Standardization of Pipe Flanges & Fittings, was created in 1921. It would later spawn other B16 committees of great importance to the valve industry. For example, one of the issues tackled by this B16 group was the lack of valve end-to-end standards. A 1927 charter to create common end-to-end standards was beset by many difficulties, not the least of which was the economic downturn of the 1930s. In 1937, the group finally adopted a proposal MSS originally put forth in 1931. This document would later become ASME/ANSI B16.10, Face-to-Face and End-to-End Dimensions of Valves.
In 1936 API, in response to the huge growth in the oil and gas business, published 5-G-1, Pipeline Valves. Following the turmoil of World War II, API 5-G-1 would be expanded into the first edition of API 6D, at the time titled Iron and Steel Flanged Gate, Plug and Check Valves for Pipeline Service.
Probably the most familiar standard in the industrial valve business today is API 600, which covers steel valves for refinery service. When first published in 1939, the document was titled API Standard on Flanged Steel, Outside Screw and Yoke, Wedge Gate Valves. The API 600 document exists today as Steel Gate Valves, Flanged and Butt-welding Ends, Bolted Bonnets.
Until the late 1950s and early 1960s, valve pressure/temperature ratings were based on flange ratings (i.e., ASME B16.5), but the limitations of American Standard B16.5 and its predecessor B16e, along with the popularity of the butt-welding end pressure seal bonnet valve, warranted a new method of rating valves. MSS created SP-66, Pressure Temperature Ratings for Steel Butt-welding End Valves in 1964 to address the limitations. The standard used the mechanical properties of the different body materials to determine the minimum wall thicknesses and ratings of the valves under its scope. The SP-66 document would later be expanded and form the basis of ASME/ANSI B16.34 in 1974. B16.34, Valves—Flanged, Threaded and Welding End, is the most referenced valve design standard in the world.
Flanges and bolt patterns have been standardized since the mid-20th century; however, there were two different flange standards, MSS SP-44 and API 605 for valves over 24 inches in size. Even though the flange designs and bolt patterns are totally different, the difference has never been successfully addressed and continues to plague manufacturers, distributors and end-users.
TESTING AND MORE RECENT STANDARDS
Valve testing standards are a relatively new creation. When the API 600 document was first published (before World War II), testing criteria was simple—valves couldn’t leak during testing. Try selling that concept today! In response to the lack of realistic testing standards, MSS created, SP-61, “Pressure Testing of Valves” in 1961. It has been supplanted substantially by the most widely used testing standard in the U.S. today, API 598, “Valve Inspection and Test,” which was first published in 1968.
During the 1960s through the 1980s, many new valve standards were developed by API, MSS and ASME. These new standards covered a variety of valve types, including check, butterfly, ball and others. Although most of the valve standards emerged from API, MSS and ASME, other standards organizations were also developing valve standards. Across the pond, for example, was the British Standards Institute, which created several standards used in the U.S. for many years. Also, the International Organization for Standardization (ISO), which published its first standard in 1947, has been very active in valve standards creation during the past 25 years. Some of the ISO standards are used regularly in the U.S.
For the water and wastewater industry, the American Water Works Association has created general standards, while the International Society of Automation is the creator and custodian of control valve specifications.
The history of valve standards is a still being written: Old standards are revised and new ones created. In API, for example, standards created during the past 20 years have covered valve repair, valve qualification, fugitive emissions testing and fire testing of valves, to name a few.
When we look at the rich past of the valve industry, we find that valve standardization runs both a parallel and an intertwined path dotted with stories of famous companies as well as great achievements in valve design.