GB/T 12224-2015General requirements for industrial steel valves (English PDF)

3.1 General

3.1.1 Pressure-temperature rated values

For Class series valves, the pressure-temperature rated values of standard pressure level shall comply with the requirements of Table 2-1A ~ Table 2-28A, and the pressure-temperature rated values of special pressure level shall comply with the requirements of Table 2-1B ~ Table 2-28B.

For PN series valves, the pressure-temperature rated values of standard pressure level shall comply with the requirements of Table 2-29A ~ Table 2-71A, and the pressure-temperature rated values of special pressure level shall comply with the requirements of Table 2-29B ~ Table 2-71B. The pressuretemperature rated values of standard pressure level that are not specified in Table 2-29A ~ Table 2-71A may be in accordance with the requirements of GB/T 9124-2010.

The pressure-temperature rated values of defined pressure level valves do not exceed the value calculated according to Annex A.

3.1.2 Standard pressure level valves

Valves that meet the requirements of this Standard, except those that meet the requirements of Clause 8 for special pressure level valves and requirements of Annex A for defined pressure level valves, are designated as standard pressure level valves, of which the pressure-temperature rated values comply with the requirements of 3.1.1.

3.1.3 Special pressure level valves

Valves that meet the requirements of 3.1. […]

3.1.5 Intermediate rated value valves

Class series welded or threaded valves, standard pressure level Class400 flanged valves, which can be linearly interpolated to determine the intermediate rated values between the rated temperature or the rated pressure listed in the table as specified in 6.1.5. However, for flanged valves of other pressure levels, linear interpolation is not allowed to be used to determine the nominal pressure level.

3.1.6 Assembled-and-welded members

Valves assembled-and-welded in whole or in part with castings, forgings, bars, plates or tubes shall meet the following requirements:

such as welding of seat blocks, seat rings, lifting lugs and auxiliary joints.

3.3 Temperature effects

3.5 Deviation

5.1 General

of the valve body shall be determined according to the applicable pressuretemperature rated values. The material of the bonnet or cover plate shall be adapted to the pressure-temperature rated values of the valve body. Valve stems, discs, and other parts, such as medium flange gaskets and bolts that are subjected to pressure or other loads, shall be adapted to the pressuretemperature rated values of the valve. 5.1.3 For valves of which the valve body, bonnet or cover plate is carbon steel, the nominal pressure is not greater than PN40 and Class300, under the use condition that the temperature is not greater than 200 °C, the medium flange connection bolt is allowed to adopt the carbon steel of which the yield strength is not lower than Class B in ASTM A307-2004, such as 25and 35-steel in GB/T 699, and marked on the nameplate as specified in Clause 4. 5.1.4 For valves with a nominal size not greater than DN100 and a nominal pressure not greater than PN100 or not greater than Class600, the valve body and bonnet or cover plate shall be in accordance with the standard requirements referenced in Table 1A or Table 1B when investment castings are used. However, tensile specimens of Ф5 × 25 mm (No. R7 specimen specified in GB/T 228.1-2010) taken from the same standard melting furnace are allowed to replace the standard tensile specimens to determine mechanical and chemical properties. The metal from the standard melting furnace is the metal that has been previously refurbished separately. The tensile specimen shall be cast in the same refractory mold as the casting and shall be heat treated the same as the casting. […]

5.2 Material selection

6.1 Valve body design

6.1.1 Nominal size and nominal pressure

The nominal size of PN series valves is in accordance with GB/T 1047, and the nominal pressures are PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN250, PN320, PN400, and shall comply with the requirements of GB/T 1048.

The nominal size of Class series valves is in accordance with ASME B16.34- 2013, and the nominal pressures are Class150, Class300, Class600, Class900, Class1500, Class2500, Class4500, and shall comply with the requirements of ASME B16.34-2013.

The nominal size DN and the digital followed of PN series valves, and the nominal size NPS and the digital followed of Class series valves are used to identify the connection marking at the end of the pipe or valve, not necessarily the same as the inside diameter of the valve.

6.1.2 Wall thickness

The wall thickness tm of the valve body shall not be less than those specified in Table 3A or Table 3B or the minimum value tm calculated according to Annex B, except as indicated in 6.1.4 ~ 6.1.8, 6.2 and 6.7. When using the values listed or calculated in Table 3A or Table 3B, the minimum wall thickness value among the values may be obtained by linear interpolation method. The minimum wall thickness of the valve body is required to be measured from the inner surface of the contact fluid. The minimum wall thickness does not include the thickness of the lining or bushing.

6.1.3 Inner diameter

The relationship between the basic inner diameter of the valve body end and the nominal size of the pipe is given in Annex C. To determine the wall thickness tm, the inner diameter d in Tables 3A, 3B and B shall meet the following requirements: minimum diameter is not less than 90 % of the basic inner diameter of the valve end. […]

6.2 End dimensions

6.3 Auxiliary connector

6.5 Stem

6.6 Installation restrictions

7.1 Housing test

7.1.1 Housing test pressure

Each valve shall be subjected to the housing test with a test pressure not less than 1.5 times the 38 °C pressure rated value, which is rounded to 0.1 MPa. […]

7.1.3 Determination of housing test results

It is determined unqualified when there is visible leakage through the pressurereceiving wall. The pressure-receiving wall includes all the pressure-receiving members such as valve body, bonnet or cover plate, and middle flange gasket. Leakage through the stem seal shall not be a cause of qualification. However, the stem seal shall be able to maintain at least 38 °C pressure rated value without significant visible leakage.

7.2 Seal test

7.2.1 Seal test pressure

After the housing test, each shut-off valve and check valve shall be subjected to the seal test. The test medium shall be as specified in 7.1.1. The test pressure shall be 1.1 times the 38 °C pressure rated value. When the gas is used for the seal test, the seal test shall be carried out right after the housing test. But for valves of which the specification is less than NPS4 and the pressure level is less than Class1500, the seal test may be carried out before the housing test; for other valves, the seal test shall be carried out after the housing test. If selected by the user, for valves with the specification and pressure rated values listed in Table 12, the seal test may be carried out with a gas of not less than 0.55 MPa.

7.2.2 Seal test duration

The minimum duration of the seal test is as specified in Table 13. The test duration is the inspection duration in the test pressure state after the valve test pressure has fully reached the required value.

8.2 General

After heat treatment according to the requirements for the technical conditions of materials, the casting, forging, rolling member, rolling or welding materials are tested, and it is determined by the manufacturer whether to carry out before or after machining. The surface of the test piece shall be clean and must not conceal unacceptable surface defects. The inspection surface (see 8.3.1.2 and 8.3.2.2) does not include threads, drilled holes or threaded holes, such as surfaces for bolted connections, sealing members, stems or auxiliary connection holes.

8.3 Required testing

8.3.1 Castings

8.3.1.1 Radiographic testing

8.3.1.1.1 The part of the valve body, bonnet or cover plate required for radiographic testing is as shown in Figure 9 ~ Figure 19. The section A shown in the diagram is the required radiographic coverage, expressed in multiples of tm, tm is the minimum wall thickness required value determined by 6.1. The length of section A is specified as 3tm or 70 mm, whichever is greater. However, in some cases, the specified A value will exceed the radiographic coverage required by Figure 9 ~ Figure 19. For example, the radiographic coverage of the valve body neck or channel of Figure 14 may not accommodate the specified overall A value. In this case, the requirements can be expressed by providing a realistic radiographic coverage diagram. If the specified total cover width A causes the actual radiographic coverage to extend to the adjacent edge and mouth, the A value can be reduced to the actual maximum value, and a small amount of coverage reduction is allowed. The radiographic testing procedures and acceptance criteria used shall be in accordance with JB/T 6440. 8.3.1.1.2 Valve body testing is as follows: of 3tm or 70 mm from the valve body end, whichever is larger. […]

8.3.2 Forgings, bars, plates and tubes

8.4 Defect removal and repair

A.2 Pressure-temperature rated values

The pressure-temperature rated values of defined pressure level valves are as specified in this annex. The pressure-temperature rated values are applicable to the threaded valves not greater than Class2500 and the socket welded valves not greater Class4500.