Standard

Piping Codes and Valve Standards: As with every intended use for valves, piping carries its own set of standards that valve companies and users need to understand. This article provides an overview of the codes (it does not necessarily cover detailed requirements for specific services).

1. Most codes covering piping in non-water service have tables that list valves covered by the code. Non-listed valves need case-by-case analysis.

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THE CODES

The typical piping codes used in the valve industry (excluding the water industry) are ASME B31.1 for Power Piping 2014, ASME B31.3 for Process Piping 2014, ASME B31.4 for Pipeline Transportation Systems for Liquids and Slurries 2012, and ASME B31.8 for Gas Transmission and Distribution Piping Systems 2014.

In each of these codes, valves are listed in tables. When that’s the case, no additional requirements are generally placed on the valve manufacturer and supplier besides the valve product standards (e.g., API 6D, ASME B16.34, etc.). Although special cases exist, such as class M in B31.3, they are not discussed in this general overview.

The question also arises about what happens in situations that call for non-listed valves. These situations vary from piping code to code so they should be examined on a case-by-case basis.

ASME B31.1

The ASME B31.1 code lists three valves standards, excluding cast iron and bronze valves. The standards are: 1) ASME B16.34, Valves–Flanged, Threaded, and Weld End; 2) MSS SP67–Butterfly Valves; and 3) MSS SP68–High Pressure Butterfly Valves with Offset Design. As stated in B31.1, para 107.1, “Valves not complying with above [the list] shall be of a design, or equal to the design, that the manufacturer recommends for the service as stipulated in para. 102.2.2. Such valves shall be pressure tested in accordance with MSS SP-61.”

This puts the responsibility on the valve manufacturer to recommend the design for the service and compounds the issue when valves are supplied through distribution. Rarely will the valve manufacturer know the actual service, since that manufacturer is not responsible for the piping system. Therefore, it is essential that the designer of the piping system clearly understands what is offered when the valve is unlisted. This is especially important with respect to pressure/ temperature ratings. The piping designer should always check the suitability of the valve for the service.

ASME B31.3

The ASME B31.3 code lists four valve standards, again excluding cast iron and bronze valves. The standards are: 1) ASME B16.34, Valves–Flanged, Threaded and Welding End; 2) MSS SP72–Ball Valves with Flanged or Butt-Welding Ends for General Service; 3) API 608–Metal Ball Valves with Flanged, Threaded and Welding Ends; and 4) API 6D–Specification for Pipeline and Piping Valves.

The API 6D standard was added in the 2014 edition of this code with a caveat that the design of valves comply with ASME B16.34. (Therefore, it does not really add anything to the 2012 edition list).

In the 2014 edition of ASME B31.3, the designer has to be satisfied that composition, mechanical properties, method of manufacture and design are suitable for the intended service. The pressure/temperature ratings should be established in accordance with rules in paragraph 304. The change from the 2012 edition to the 2014 edition caused the onus to fall on designers. This is because the 2012 edition states that pressure design shall be verified in accordance with paragraph 304 of the code; however, the latest edition states the designer has to be satisfied the design is suitable for the intended service. The situation is similar to what happens with B31.1 since the manufacturer rarely knows the service.

ASME B31.4

ASME B31.4 lists eight valve standards, once again excluding cast iron and bronze valves.

These valve standards, which are more comprehensive than the previous codes, are:

• ASME B16.34, Valves–Flanged, Threaded, and Welding End

• MSS SP68–High Pressure Butterfly Valves with Offset Design

• MSS SP72–Ball Valves with Flanged or Butt-Welding Ends for General Service

• API 600–Steel Gate Valves-Flanged and Butt-Welding Ends, Bolted Bonnets, Twelfth Edition

• API 602–Steel Gate, Globe and Check Valves for Sizes DN 100 and Smaller for the Petroleum and Natural Gas Industries

• API 603–Corrosion-resistant, Bolted Bonnet Gate Valves-Flanged and Butt-Welding Ends

• API 6D–Specification for Pipeline and Piping Valves

• API 6A–Specification for Wellhead and Christmas Tree Equipment

In this code, special valves not on the list are permitted, provided the valve design is of at least equal strength and tightness, the valves are capable of withstanding the same test requirements as covered in the above standards, and the valve’s structural features satisfy the material specification and test procedures of the valves in similar service set forth in the standards. These requirements are stricter than previous codes, requiring the designer to make the valve with equal strength and tightness.

ASME B31.8

The ASME B31.8 code lists five valve standards, excluding cast iron and thermoplastic valves. These standards are: 1) ASME B16.33–Manually Operated Metallic Gas Valves for Use in Gas Piping Systems up to 175 psi (Sizes NPS1/2 Through NPS 2); 2) ASME B16.34 Valves–Flanged, Threaded and Welding End; 3) ASME B16.38–Large Metallic Valves for Gas Distribution: Manually Operated, NPS 21 .2 (DN 65) to NPS 12 (DN 300), 125 psig (8.6 bar) Maximum; 4) API 6D–Specification for Pipeline and Piping Valves; and 5) API 6A–Specification for Wellhead and Christmas Tree Equipment.

ASME B31.8 does not have criteria for unlisted valves. It states that “Valves shall conform to standards and specifications referenced in this Code and shall be used only in accordance with the service recommendations of the manufacturer.” This means that with the 31.8 code, one must only use valves that are listed.

CONCLUSION

The common standard for valves is ASME B16.34. While this standard has several aspects that are positive, it is not really a design code like ASME BPVC section VIII, where material strength, corrosion allowance and formula for irregular shapes are taken into account. For this reason, designs should be cross checked against a pressure vessel code.

While compliance with the piping codes is necessary in almost all cases, compliance with national laws is obligatory.

Highlights of the Valves

Specification

 API 6D, API 600, API 599, API 598, API 608, API 602, BS 1873 ASME B16.10, ASME B16.5, ASME B16.47 (Serie A and Serie B) and MSS SP44 are the key specifications covering the dimensions and the manufacturing tolerances of valves.

• ASTM A105, A182, A216, A217, A351, A352, A494 are the common materials related to valves.

• MSS SP25 covers the marking system.

• ASTM A 703 /A 703M IS Speciﬁcation for Steel Castings, General Requirements, for Pressure-Containing Parts

• ASTM A 487 /A 487M is Speciﬁcation for Steel Castings Suitable for Pressure Service

• ASTM A 985 /A 985M is Speciﬁcation for Steel Investment Castings General Requirements, for Pressure-Containing Parts.

• API 6F is About recommended practice for fire test for valves.

Pressure Test

• Normally, valves are pressure tested by the factory to check for leaks before they’re shipped. The type and method of testing conforms to one or more of many different standards. The purpose of these tests and the expected results are often misunderstood and misapplied, resulting in unnecessary delays and unanticipated costs. The most common standard for pressure test is API D and API 598.

Disadvantage

• Valves are the most sensitive item comparing with other piping material so should be chosen carefully, for every services the engineering team should chose right type and right material in order to avoiding any failure.

• For flange end valves, Each flange connection can leak (some people claim that a flange connection is never 100 percent leak proof).

Cost

• Comparing with other piping components (flange, fittings and pipe), valve is the most expensive one because of internal parts and different manufacturing process.

Size

• FROM 0.5'' TO 72'‘

• conformity with the customers drawing

Other Properties

• Valves vary widely in form and application. Sizes typically range from 0.1 mm to 60 cm. Special valves can have a diameter exceeding 5 meters.

• Valve costs range from simple inexpensive disposable valves to specialized valves which cost thousands of US dollars per inch of the diameter of the valve.

• Disposable valves may be found in common household items including mini-pump dispensers and aerosol cans.

• A common use of the term valve refers to the poppet valves found in the vast majority of modern internal combustion engines such as those in most fossil fuel powered vehicles which are used to control the intake of the fuel-air mixture and allow exhaust gas venting.

Standard

API 6D, API 600, API 599, API 598, API 608, API 602, ASME B16.10, ASME B16.5, ASME B16.47 (Serie A and Serie B) and MSS SP44 are the key specifications covering the dimensions and the manufacturing tolerances of valves.

API 6D

Specification for Pipeline Valves. API Specification 6D is an adoption of ISO 14313: 1999, Petroleum and Natural Gas Industries-Pipeline Transportation Systems-Pipeline Valves. This International Standard specifies requirements and gives recommendations for the design, manufacturing, testing and documentation of ball, check, gate and plug valves for application in pipeline systems.

API 600

Bolted Bonnet Steel Gate Valves for Petroleum and Natural Gas Industries - Modified National Adoption of ISO 10434:1998.

API 599

Metal Plug Valves - Flanged, Threaded and Welding Ends. A purchase specification that covers requirements for metal plug valves with flanged or butt-welding ends, and ductile iron plug valves with flanged ends, in sizes NPS 1 through NPS 24, which correspond to nominal pipe sizes in ASME B36.10M. Valve bodies conforming to ASME B16.34 may have flanged end and one butt-welding end. It also covers both lubricated and no lubricated valves that have two-way coaxial ports, and includes requirements for valves fitted with internal body, plug, or port linings or applied hard facings on the body, body ports, plug, or plug port.

API 598

The API STANDARD 598: VALVE INSPECTION AND TESTING, covers the testing and inspection requirements for gate, globe, check, ball, plug & butterfly valves. It has acceptable leakage rates for liquid as well as gas testing. All valves built to the various API standards are required to meet API-598 leakage criteria prior to shipment from the manufacturer or supplier.

API 608

Metal Ball Valves - Flanged and Butt-Welding Ends. The standard covers Class 150 and Class 300 metal ball valves that have either butt-welding or flanged ends and are for use in on-off service.

API 602

Compact Steel Gate Valves - Flanged, Threaded, Welding, and Extended-Body Ends. The standard covers threaded-end, socket-welding-end, butt-welding-end, and flanged-end compact carbon steel gate valves in sizes NPS4 and smaller.

BS 1873

British Standard Institute: Specification for steel globe and globe stop and check valves (flanged and butt-welding ends) for the petroleum, petrochemical and allied industries.

ASME B16.10

Face to Face & End to End Dimensions of Valves.

ASME B16.5

ASME B16.5 Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Included are: flanges with rating class designations 150, 300, 400, 600, 900, and 1500 in sizes NPS 1/2 through NPS 24 and flanges with rating class designation 2500 in sizes NPS 1/2 through NPS 12.

ASME B16.47 (Serie A and Serie B), MSS-SP44

Large Diameter Steel Flanges, NPS 26 through NPS 60 Metric/Inch Standard, Weld Neck, Slip-On, Blind. Class 150 to Class 900.

ASTM A703/ A703M

This specification covers steel castings, general requirements, for pressure-containing parts. The steel shall be made by open-hearth or electric-furnace process, with or without separate refining such as argon-oxygen-decarburization (AOD), unless otherwise designated by the individual specification. Ferritic and martensitic steel shall be cooled after pouring to provide substantially complete transformation of austenite prior to heat treatment to enhance mechanical properties. The material shall conform to the specified chemical composition requirements. An analysis of each heat shall be made by the manufacturer to determine the percentages of the elements specified. The mechanical test methods and definitions are presented in details. One tension test shall be made from each heat, and shall conform to the tensile requirements specified. Test coupons shall be cast from the same heat as the castings represented, except that for investment castings, the test coupons shall be cast in the same type of mold as the castings. After machining, each casting shall be tested under specified hydrostatic shell test pressures in the applicable steel rating for which the casting is designed.

ASTM A487/ A703M

This specification covers low-alloy steel and martensitic stainless steels in the normalized and tempered, or quenched and tempered conditions, suitable for pressure-containing parts. All castings shall receive the specified heat treatment requirement: austenitizing temperature, medium, quenching cool, and tempering temperature. Preliminary heat treatment and multiple tempering are permitted. Recording-type pyrometers shall be used to control the furnace temperature. The steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, vanadium, boron, and copper. Residual elements include: copper, nickel, chromium, tungsten, molybdenum, and vanadium. Tensile properties of the steel shall conform to the requirements for tensile strength, yield strength, elongation, reduction of area, hardness, and maximum thickness. Product analysis tolerance is specified. Repair by welding may be done.

ASTM A985/ A985M

This specification covers a group of common requirements that are mandatory for steel castings produced by the investment casting process for pressure-containing parts. Master heats shall be made by the electric furnace process with or without separate refining such as argon-oxygen-decarburization (AOD), vacuum-oxygen degassing (VOD), vacuum-induction-melting (VIM). Ferritic and martensitic steel shall be cooled after pouring to provide complete transformation of austenite prior to heat treatment to enhance mechanical properties. Chemical, heat, and product analyses shall be performed and the chemical composition thus determined shall conform to the prescribed values in carbon, manganese, silicon, phosphorus, sulfur, nickel, chromium, molybdenum, vanadium, tungsten, copper, and aluminum. Tensile testing shall be done on the castings and shall meet the required yield and tensile strength, elongation, and reduction of area. Each casting shall also be tested after machining to hydrostatic shell pressure test and shall not show any leaks.

API 6F

API 6F is About recommended practice for fire test for valves.

NACE

NACE International is a not-for-profit professional organization for the corrosion control industry whose mission is to "[equip] society to protect people, assets and the environment from the adverse effects of corrosion."

NACE was established in 1943 as the National Association of Corrosion Engineers. It is headquartered in Houston, Texas and offices in San Diego, California, Kuala Lumpur, Malaysia, Shanghai, China, São Paulo, Brazil, and Khobar, Saudi Arabia.

NACE publishes the magazine Materials Performance and the journal CORROSION. NACE also publishes standard practice, test method, and material requirements standards for use by industry and other corrosion societies. Standing committees periodically review and update the standards every five years. The association hosts an annual conference and several regional meetings and conferences around the world.

NACE MR0175 /ISO 15156 gives requirements and recommendations for the selection and qualification of carbon and low-alloy steels, corrosion-resistant alloys, and other alloys for service in equipment used in oil and natural gas production and natural gas treatment plants in H2S-containing environments, whose failure could pose a risk to the health and safety of the public and personnel or to the equipment itself.

Forged carbon Steel valves: ASTM A105/ A105M, This specification covers standards for forged carbon steel piping components, that is, flanges, fittings, valves, and similar parts, for use in pressure systems at ambient and higher-temperature service conditions. Materials shall be subjected to heat treatment (annealing, normalizing, tempering, or quenching). Material shall conform to carbon, manganese, phosphorus, sulfur, silicon, copper, nickel, chromium, molybdenum and vanadium contents. The forgings shall be subjected to tension, hardness and hydrostatic tests, with the latter applicable when required. Material shall adhere to tensile strength, yield strength, elongation, reduction of area, and hardness requirements. Guidelines for retreatment, repair by welding, and product marking are given.

Forged carbon Steel valves For low Temprature Service: ASTM A350/ A350M (LF1, LF2, LF3, LF5, LF6, LF9, LF 787), This specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and valves for low-temperature service. The steel specimens shall be melt processed using open-hearth, basic oxygen, electric furnace or vacuum-induction melting. A sufficient discard shall be made to secure freedom from injurious piping and undue segregation. The materials shall be forged and shall undergo heat treatment such as normalizing, tempering, quenching and precipitation heat treatment. Heat analysis and product analysis shall be performed wherein the steel materials shall conform to the required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, columbium, vanadium, and nitrogen. The materials shall also undergo tension tests and shall conform to the required values of tensile strength, yield strength and elongation. Impact tests shall also be performed and the steel materials shall conform to the required values of minimum impact energy, temperature, and minimum equivalent absorbed energy. Hardness and hydrostatic tests shall also be performed.

Forged Alloy Steel and Stainless Steel valves For High Temprature Service: ASTM A182/ A182 M-98ª(F 304, F 304H, F 304L, F 304N, F304 LN, F 309H, F310, F 310H, F 310 MoLN, F 316, F 316H, F 316L, F 316N, F 316LN, F 317, F 317L, F 347, F 347 H, F 348, F 348 H, F 321, F321 H), This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service. After hot working, forgings shall be cooled to a specific temperature prior to heat treatment, which shall be performed in accordance with certain requirements such as heat treatment type, austenitizing/solution temperature, cooling media, and quenching. The materials shall conform to the required chemical composition for carbon, manganese, phosphorus, silicon, nickel, chromium, molybdenum, columbium, titanium. The material shall conform to the requirements as to mechanical properties for the grade ordered such as tensile strength, yield strength, elongation, Brinell hardness. All H grades and grade F 63 shall be tested for average grain size.

Forged Duplex Steel valve: ASTM A182 (F 50, F 51, F 52, F 53M F 54, F 55, F 57, F 59, F 60, F 61, F 904L)

ASTM A352/ A352M (LCA, LCB, LCC, LC1, LC2, LC2-1, LC3,LC4, LC9(J31300), CA6NM), This specification covers steel castings for valves, flanges, fittings, and other pressure-containing parts intended primarily for low-temperature service. Several grades of ferritic steels and one grade of martensitic steel are covered. All castings shall receive a heat treatment proper to their design and chemical composition. It should be recognized that liquid quenching of the ferritic grades is normally required to meet the mechanical properties of heavier sections. The steel shall conform to the requirements as to chemical composition specified. Tensile test and impact test shall be made to conform to the requirements specified.

ASTM A351/ A351 M (CF8(F304), CF3(F304L), CF3M(F316L), CF8M(F316)), This specification covers austenitic steel castings for valves, flanges, fittings, and other pressure-containing parts. The steel shall be made by the electric furnace process with or without separate refining such as argon-oxygen decarburization. All castings shall receive heat treatment followed by quench in water or rapid cool by other means as noted. The steel shall conform to both chemical composition and tensile property requirements.

ASTM A217/ A217 M-98a( WC1, WC4, WC5, WC6, WC9, WC11, C5, C12, C12A), standard specification for steel casting, martensitic stainless and alloy, for pressure-containing parts, sutable for high-temprature service.

ASTM A351/ A351 M (CN7M, CD4MCu, CG8M, CK3MCuN), This specification covers austenitic steel castings for valves, flanges, fittings, and other pressure-containing parts. The steel shall be made by the electric furnace process with or without separate refining such as argon-oxygen decarburization. All castings shall receive heat treatment followed by quench in water or rapid cool by other means as noted. The steel shall conform to both chemical composition and tensile property requirements.

ASTM A890/ A890 M, This specification covers castings, iron-chromium-nickel-molybdenum corrosion-resistant, duplex(austenitic/ferritic) for general application. Castings shall be heat treated in accordance with the required procedure and heat-treat temperature. Proper heat treatment of these alloys is usually necessary to enhance corrosion resistance and in some cases to meet mechanical properties. Minimum heat-treat temperatures are specified; however, it is sometimes necessary to heat-treat at higher temperatures, hold for some minimum time at temperature and then rapidly cool the castings in order to enhance the corrosion resistance and meet the required mechanical properties. The steel shall conform to the required chemical composition for carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, molybdenum, copper, tungsten, and nitrogen. Castings shall be marked for material identification with the specification designation and grade.

SA-494/ SA-494 M(UNS N02100, UNS N24135, UNS N04020, UNS N24030, UNS N24025, UNS N24130, UNS N30012, UNS N30007, UNS N30003, UNS N06040, UNS N30002, UNS N30107, UNS N26455, UNS N26625, UNS N26055, UNS N30003, UNS N26022, UNS N08826, UNS N26059), This specification covers nickel, nickel-copper, nickel-copper-silicon, nickel-molybdenum, nickel-chromium, and nickel-molybdenum-chromium alloy castings for corrosion resistant service. The castings shall be heat treated. When Class 1 is specified, grades CY40 and M25S shall be supplied in the as-cast condition. When Class 2 is specified, grades CY40 and M25S shall be supplied in the solution treated condition. When Class 3 is specified, grade M25S shall be supplied in the age-hardened condition. The chemical composition requirements of the alloys are presented. The tensile property requirements including the heat treatment procedure for the castings are presented in detail. It is required that one tension test shall be made from each master heat except for grades M25S and CY5SnBiM when the master heat is used to pour the castings. One tension test shall be made from each melt except for grades M25S and CY5SnBiM. Test results shall conform to the specified tensile requirements.