What is the ASME standard for valve testing?

Main Valve Test Standards

API 598 Valve Inspection and Test

The most widely used test specification in the world. The standard covers all types of valves (soft & metal seated) in sizes up to 600NB (NPS 24). It also includes leakage rates and testing criteria for metal-seated and resilient seated valves.

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API6D Pipeline Valves Test Standard

Used for API6D ball valves, plug valves and API6D design pipeline check/gate valves (also now adopted as part of ISO ).

ISO Valve Test Standard

Incorporates an adoption of API6D test standard. Leakage rate A is specified for soft seated valves and plug valves (zero leakage*). Also includes standards for gate, globe and check valves (EN -).

BS Valve Test Standard

Previously used by some European Manufacturers, now superseded by ISO (EN -1) standard. It includes leakage rates and testing criteria for metal and resilient seated valves.

ASME B16.34 Valves &#; Flanged, Threaded and Welding End

The primary valve design standard, it also contains pressure/temperature charts for determining the working pressures of valves to be used in conjunction with other test standards, such as API 598.

ASME PTC 25 Pressure Relief Devices

The main reference document for the testing of pressure relief valves, PTC 25 contains detailed procedures for testing relief valves with air or steam.

API 527 Seat Tightness of Pressure Relief Valves

This covers the seat tightness of pressure relief valves. It also includes allowable leakage rates for testing with steam, water and air.

FCI 70-2* Control Valve Seat Leakage

This document contains detailed test procedures and leakage rate classes for control valves. The leakage classes are also occasionally referenced by other documents and used as acceptance criteria. Supersedes ANSI B16.104. Class VI is the highest shut off class*.

ISA S75 Hydrostatic Testing of Control Valves

This standard provides a procedure for the hydrostatic shell testing of control valves. Seat testing and acceptance criteria are out of the scope of this document and usually are covered by referencing FCI 70-2.

ISO Industrial Valves, Pressure Testing of Valves

ISO&#;s primary testing standard, this document covers all types of valves and has four levels of allowable closure test leakage rates.

MSS SP70 Cast Iron Gate Valves, Flanged and Threaded Ends

The primary design standard for cast iron gate valves, it also contains testing procedures and acceptance criteria.

MSS SP71 Iron Swing Check Valves, Flanged and Threaded Ends

The primary design standard for cast iron check valves also contains testing procedures and acceptance criteria.

MSS SP61* Hydrostatic Testing of Steel Valves

Similar to API 598 (in the case of soft seated valves) this document has some minor variations in test holding times and leakage rates. Metal seated valves the leakage can be a little higher than API598.

MSS SP78 Cast Iron Plug Valves, Flanged and Threaded Ends

The primary design standard for cast iron plug valves also contains testing procedures and acceptance criteria.

MSS SP80, Bronze Gate, Globe, Angle and Check Valves

The primary design standard for commodity bronze valves also contains testing procedures and acceptance criteria.

MSS SP85, Cast Iron Globe & Angle Valves

The primary design standard for cast iron globe valves also contains testing procedures and acceptance criteria.

EXPLANATION OF ZERO AND LOW LEAKAGE TEST STANDARDS

In general, specification such as API598 or MSS SP-61 that govern leakage for soft seated valves call for &#;0&#; bubbles of air or &#;0&#; drops of water under the specified test conditions over the minimum test time period. These valves are therefore sometimes referred to as &#;zero leakage&#; valves. In reality, there really is no such thing as &#;zero leakage&#;, since microscopic amounts of material may indeed cross the seat or packing boundaries, especially if helium or hydrogen or other small molecule gases are used. Another common term for soft seated valves is &#;bubble tight&#;.

Less frequently, the leakage performance for soft seated valves is referred to as Class VI, which is the tightest leakage under FCI 70-2, and generally applies to resilient seated control valves (as opposed to metal seated control valves or soft seated shut off valves). In fact, FCI 70-2 Class VI (formerly ANSI B16.104) allows a small number of bubbles per minute, increasing with valve size, during the test, whereas API598 and MSS SP-61 do not (for soft seat, but does for metal seat). FCI 70-2 Class VI is for soft seated control valves but is frequently used as a leakage acceptance test criteria for metal seated isolation valves such as ball and butterfly valves. FCI 70-2 only requires a low pressure test, consequently closure and seat tests should also be done per API 598 or MSS SP-61.

In actual fact even for metal seat valves the API 598 leak acceptance criteria for metal seated valves allows less leakage than FCI 70-2 Class VI above 150NB (6&#;) and 50NB (2&#;) and under. For zero leakage metal seated valves API 6D or API 598 soft seated zero leakage criteria can be specified (such as triple offset metal seated butterfly valves and some metal seated ball valves). Special provisions for zero leakage gate valves can also be specified to BS and ISO under special zero leakage classes. Metal seated valves, on the other hand, usually (not always, triple offset butterfly and ball valves for instance are available bubble tight) have some level of acceptable leakage when tested, defined first as some acceptable amount of liquid, under test conditions and over the time period of the test.

ISO (EN -1) supersedes BS -1 and specifies acceptable leakage rates such as &#;Rate A&#; and &#;Rate B&#;. Rate A allows &#;no visible leakage&#;, similar to API 598 for resilient seated valves. Rate B is used for gate valves.

Links

For cross reference tables and charts of ASTM/ANSI specifications covering equivalent materials used for valves, flanges & fittings click here.

For other ANSI, ASME, ISO, API, valve related technical cross references relating to pressure, temperature, application, suitability, equivalents, valve body & trim materials, valve manufacturing & test standards, etc., go to the technical section of our website.

If we don&#;t have the valve in stock we can source it from our overseas network of stockists and very short lead time specialty manufacturers. We can even supply exotic grades like Nickel, Super Duplex F55 and Monel (ASTM A494-M35-1) Cd4M-Cu, Hastealloy C (ASTM A494 CW12MW), 317 (C8G8M) in short lead-time.

For technical references and cross reference information on stainless, duplex, chrome-moly and Alloy steel used in valves and piping systems in the petrochemical and refining industry go to the technical section of our website.

We stock valves in A105, LF2, 304, 304L, 316, 316L, F51, CF8, CF3, F82, WC5, WC6, WC9, F11, F5, Bronze, Iron, etc. Ball, Butterfly, Check, Control, Gate, Globe, Needle, Parallel slide, Plug, etc. Valves are manufactured to API 600, API 602, API 603, API 6D, BS and numerous other standards.

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Pressure relief valves must be tested based on a regular schedule and according to a strict set of requirements. Those requirements and schedules can vary based on industry, but they can also vary depending on which organization governs the safety regulations within that industry. 

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The ASME (American Society of Mechanical Engineers) sets one of the most well-known pressure relief valve testing standards across the United States. 

What is the ASME?

The ASME or American Society of Mechanical Engineers is a not-for-profit organization of professionals that is dedicated to promoting the vital role of the engineer in society. 

As a third-party not-for-profit organization, the ASME develops safe, unbiased codes and standards that work to create safer engineering environments for all. The ASME has safety standards and codes for various industries, but the one we will focus on in this article relates specifically to pressure relief valve testing standards. 

What are ASME Pressure Relief Valve Testing Standards?

ASME pressure relief valve testing standards are a set of standards, requirements, and procedures that must be met when testing an ASME-certified pressure relief valve. These standards are primarily located in Section 1 and Section VIII of the ASME Boiler & Pressure Vessel Code. 

Section I of the ASME Boiler & Pressure Vessel Code

Section I provides guidance and standards for pressure applications for boiler applications. A valve conforming to the requirements of Section I is identified by a National Board &#;V&#; stamp, and usually features two blowdown rings. 

Section VIII of the ASME Boiler & Pressure Vessel Code

This code specifically refers to vessels that operate at pressures above 15 psig. Safety relief valves that conform to Section VII standards are identified by a National Board &#;UV&#; Stamp. 

What Does Does the ASME Boiler & Pressure Vessel Code Recommend for Safety Valves?

To get the full, detailed instructions from ASME, you&#;ll need to be trained and certified on the Boiler and Pressure Vessel Code (BPVC), specifically Sections I and VIII. Specific training requirements can vary depending on the industry, the type of pressure relief valve being tested, and the valve&#;s location. That said, there are usually three categories of requirements for all ASME pressure relief valve standards. 

Periodic Valve Testing

Every pressure relief valve must be tested at some interval of regularity. Testing ensures valves function normally, from opening at the appropriate pressure to releasing fully when they are actuated. 

You&#;ll need to refer to the code directly to determine the best frequency for the type of valve being tested, but typical testing frequencies are:

• Annual

• Every three years

• Every five years

• And per inspection history

The frequency of the testing required will depend on the importance of that pressure relief valve. 

For example, valves that are in high-risk areas typically need to be tested more often, while those that can cause minimal damage or do not have a significantly negative impact may be tested less often. 

ASME-Approved Valve Size

In addition to regular testing, ASME-certified valves must also be sized appropriately for the system they are installed in. In general, the valve&#;s outlet piping should be at least as large in diameter as the valve&#;s outlet, but again, specific requirements depend on the application. Refer to ASME&#;s testing standards for more details. 

Appropriate Operating Pressure

ASME standards also call for the appropriate tank operating pressure for the pressure valve. As a rule, the operating pressure should be at least 10% below the set pressure of the valve for valves conforming to Section VIII standards, and at least 3% below the set pressure of the valve for those conforming to Section I standards. This is specific to ASME relief valves though, and again, it&#;s up to the valve technician to ensure that proper protocol is followed. 

Ensure Your Valve Technicians Have the Appropriate Equipment to Meet Required Valve Testing Standards

In the end, regardless of what exact ASME pressure relief valve testing standards a valve must meet, it is up to the valve technician to ensure that the valve is in compliance. This means they are also responsible for sourcing the appropriate equipment and ensuring that valve tests are completed properly and according to those ASME standards. 

If you&#;re looking for high-quality valve testing equipment that supports your valve technicians in the field, AccuTEST&#;s sophisticated inline pressure relief valve testing equipment delivers. Get in touch with our team to learn more about AccuTEST Systems. 

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