Having these valve standards in the reference library can be handy in a pinch.
by Greg Johnson
September 26, 2019

The valve industry has many standards. It is difficult to keep up with all of them, but having access to, and a working understanding of, key valve standards can make the job easier. Although knowledge of every valve standard is overkill, and probably impossible, unless you are Sheldon Cooper of “The Big Bang Theory,” there are some key valve standards that end users should be familiar with and add to their reference library.

Valve standards are produced by many standards development organizations (SDOs). The primary SDOs that create valve standards in the United States are: the American Petroleum Institute (API), American Society of Mechanical Engineers (ASME), American Water Works Association (AWWA), and the Manufacturers Standardization Society of the Valve & Fittings Industry (MSS). The primary SDO outside the U.S. for valve standards development is the International Organization for Standardization (ISO).

The kind of valuable information contained in these standards includes materials of construction, dimensions, application data, pressure and temperature ratings, testing requirements and design criteria.

Water & Wastewater Standards

AWWA’s 26 valve-related standards are where the water valve information can be found for users involved with clean water or wastewater piping systems. Several stand out due to product usage and installed base and should be at the top of the water valve reference list. Key AWWA valve standards:

  • AWWA C-500 “Metal Seated Gate Valves for Water Supply Service”
  • AWWA C-504, “Rubber-Seated Butterfly Valves, 3 in. through 72 in.”
  • AWWA C-507, “Ball Valves, 6 in. through 60 in.”
  • AWWA C-508, “Swing-Check Valves for Waterworks Service, 2 in. through 24 in.”
  • AWWA C-509, “Resilient-Seated Gate Valves for Water Supply Service”

Pressure Ratings & ASME B16.34

The most important data in a valve standard concerns the working pressure and temperature (P-T rating) of the valve. These ratings are presented in two ways: a “WOG” rating or a class-rating. WOG (water, oil and gas) ratings are based on two points—the pressure rating at ambient temperature and the pressure rating at the maximum-rated temperature for the valve. WOG valves will have a marking such as “250 WOG” on the body. This means that the valve is good for 250 pounds per square inch (psi) at ambient temperature. Many waterworks valves will be similarly marked with the working water pressure, for example, “250W.”

Class-rated valves are based on a dimensionless number, such as class 150 or class 600, indirectly related to the pressure-retaining ability of the component at various temperatures. The document that details these pressure and temperature ratings is ASME B16.34, “Valves-Flanged, Threaded, and Welding End.” B16.34 is probably the most important valve standard and should be in the library of anyone working with class-rated piping and valves.

In addition to the P-T ratings, the document also contains many general design considerations that are referenced in a host of other product specifications. B16.34 also contains several appendices of nondestructive evaluation procedures and acceptance criteria. The power industry relies heavily on valves designed only in accordance with ASME B16.34. Most of the document’s 150-plus pages lists working pressures for valves based on material, temperature and class rating. Page 48 shows a reproduction of the table for group 1.1 materials, in this case, ASTM A216, grade WCB and carbon steel valves.

API Standards: Not Just for Oil & Gas

API valve standards are not only used in the oil and gas industry, but also are applied to valves in chemical and petrochemical service. In addition to standards covering all the popular valve types, API publishes valve standards for pressure testing, fire testing, valve repair and other valve-related processes. All API valve standards reference ASME B16.34 for their basic design requirements.

Group 1.1 materialsImage 1. Group 1.1 materials, which include ASTM A216, grade WCB and carbon steel valves (Image courtesy of United Valve)

Key API valve standards:

  • API 594, “Check Valves: Flanged, Lug, Wafer, and Butt-Welding”
  • API 598, “Valve Inspection and Testing”
  • API 599, “Metal Plug Valves-Flanged, Threaded and Welding Ends”
  • API 600, “Steel Gate Valves-Flanged and Butt-Welding Ends, Bolted Bonnets”
  • API 602, “Gate, Globe and Check Valves for Sizes DN 100 (NPS 4) and Smaller for the Petroleum and Natural Gas Industries”
  • Others include API 608, 609 and 623

API also publishes a unique “recommended practice” (RP) that is useful to piping professionals in all industries, although the primary focus is for refinery valves. The document is Recommended Practice RP 615, “Valve Selection Guide.” RP615 contains excellent information for choosing the right valve. It also includes generic cutaway drawings of all the key valve types.

MSS Valve Standards

MSS has been creating valve standards for nearly 100 years. Many of its original standards were later adopted by other organizations such as ASME and API. MSS has a host of valve standards that are generic in nature and are applicable to many industry sectors.

Additionally, the organization has published standards for a host of valve- and piping-related process activities, such as oxygen cleaning and positive material identification. Some key MSS valve standards:

  • SP-45, “Bypass and Drain Connections”
  • SP-61, “Pressure Testing of Valves”
  • SP-67, “Butterfly Valves”
  • SP-70, “Gray Iron Gate Valves”
  • SP-71, “Gray Iron Swing Check Valves, Flanged and Threaded”
  • SP-80, “Bronze Gate, Globe, Angle & Check Valves”
  • SP-81, “Stainless Steel or Stainless Steel Lined Bonnetless Knife Gate Valves with Flanged Ends”
  • SP-88, “Diaphragm Valves”
  • SP-92, “MSS Valve User Guide”
  • SP-96, “Terminology for Valves, Fittings and Their Related Components”
  • SP-99, “Instrument Valves”
  • SP-122, “Plastic Industrial Ball Valves”
  • SP-126, “In-Line, Spring Assisted, Center-Guided Check Valves”
  • SP-134, “Valves for Cryogenic Service, Including Requirements for Body/Bonnet Extensions”
  • SP-135, “High-Pressure Knife Gate Valves”

In addition to the seminal B16.34 standard discussed previously, ASME has another standard that provides vital information to piping professionals—B16.10, “Face-to-Face and End-to-End Dimensions of Valves.” The information in this standard is crucial to ensure installation interchangeability for valves of a given material, type, size, rating class and end connection.