GB/T 12235-2007Steel globe valves and lift check valve for petroleum, petrochemical and allied industries [including MODIFICATION 1] (English PDF)

4.11 Handwheel and operation

4.11.1 Unless otherwise specified in the order contract, the globe valve and globe stop valve shall be supplied with a direct operated handwheel that opens the valve when turned in a counter-clockwise direction.

4.11.2 The handwheel operating globe valve shall be a spoke-rim type with a maximum of six spokes. Unless otherwise specified in the order contract, the handwheel shall be a one-piece carbon steel cast or forging, malleable cast iron, or spheroidal graphite iron casting’s structure or a multi-piece carbon steel fabrication that includes other carbon steel product forms. Fabricated handwheels shall have strength and toughness characteristics comparable to that of one-piece handwheels.

4.11.3 Unless the handwheel is too small, the handwheel shall be marked with the word

“OPEN” and an arrow pointing in the rotation direction.

4.14 Non-destructive testing

4.14.1 Welding position at welded end

4.14.1.1 As for all the valves at the welded ends, liquid penetrant testing must be carried out at the welding ends to be free from injurious defects.

4.14.1.2 As for the welding ends with the following junction conditions, radiographic

testing shall be carried out in accordance with JB/T 6440 and the results shall conform to the requirements of JB/T 6440 or the order contract.

a) Carbon steel connecting pipeline that the outside diameter is greater than 273mm and wall thickness is greater than 19mm; alloy steel pipeline that the outside diameter is greater than

410 mm and wall thickness is greater than 19mm;

b) Other than a), carbon steel pipeline that the wall thickness is greater than 29mm; alloy steel pipeline that the wall thickness is greater than 41mm.

4.14.1.3 As for the valves at special pressure levels as specified in GB/T 12224, radiographic testing shall be carried out in accordance with JB/T 6440 and the results shall conform to the requirements of JB/T 6440 or the order contract.

4.14.2 Pressure-bearing parts of body and bonnet

As for the alloy steel cast valves that the nominal pressure is greater than or equal to PN 250 and those at special pressure levels as specified in GB/T 12224, radiographic testing shall be carried out for the bodies and bonnets of the first five valves of new models one by one in accordance with GB/T 12224 and the results shall conform to the requirements of JB/T 6440 or the order contract; then at least one valve shall be taken from every five (or less than five) valves for the radiographic testing in accordance with GB/T 12224 and the results shall conform to the requirements of JB/T 6440 or the order contract; if the inspection results are unqualified, the rest 4 valves shall be inspected again and the results shall conform to the requirements of JB/T 6440 or the order contract.

4.15 Pressure test

4.15.1 The shell test, tightness test and backseat tightness test for each valve shall meet the requirements of JB/T 9092.

4.15.2 During the tightness test and backseat tightness test for each valve with electric, hydraulic, pneumatic or other actuator type, the actuator equipped shall be used to open/close the operating valve for inspecting the tightness test.

4.15.3 Over the duration of the shell test, there shall be no visually detectable leakage on each part of the valve after the shortest duration of test pressure, and the packing shall be adjusted so as to maintain the test pressure.

4.15.4 Over the duration of the tightness test, the maximum permitted leakage rate past the seating surface shall be in accordance with JB/T 9092. There shall be no visible evidence of leakage from behind the installed seat rings.

4.15.5 Over the duration of the backseat tightness test, there shall be no visually detectable leakage after the shortest duration of test pressure.

5.1 Body and bonnet

5.1.1 Unless there are special requirements in the order contract, the metallic materials of valve shell shall meet the requirements of GB/T 12224.

5.1.2 If the valves have sulfur resisting requirements, the materials sensitive to sulfide stress corrosion cracking such as valve pressure shell shall be treated by the heat treatment mode, so as to improve their sulfur resisting performance. Heat treatment methods of the materials shall be in accordance with the relevant standards or processes. The corrosion resistance of split seat materials shall not be lower than that of body materials, and other alloy materials shall be weld-deposited on the sealing surface as required. The supplier shall provide the material quality documents, e.g. chemical composition, mechanical property and heat treatment reports.

5.1.3 The carbon content in the body of valve at the welding end shall also meet the following requirements:

a) For carbon steel or carbon manganese steel, the maximum carbon content is 0.25 %;

b) For Cr5Mo alloy steel, the maximum carbon content is 0.15 %.

5.2 Seat

Seats shall adopt the materials that the corrosion resistance is not lower than the body performance, and other alloy materials shall be weld-deposited on the sealing surface as required.

5.3 Disc

Discs shall adopt the materials that the corrosion resistance is not lower than the body performance, and other alloy materials shall be weld-deposited on the sealing surface as required. The seal ring materials for the soft seal structures shall meet the requirements of service operating conditions as a minimum and the bolts or nuts for fixing shall adopt austenitic stainless steel materials.

5.4 Weld-deposited facing of seating surface

Gland follower shall adopt chromium stainless steel or chromium - nickel stainless steel;

gland flange shall adopt carbon steel or stainless steel.

5.13 Packing

Flexible graphite packing and flexible graphite braided packing containing metallic corrosion inhibitor that apply at -29°C~538°C in such media as steam and petroleum products

5.14 Stem nut

Stem nut shall adopt Ni hard or copper alloy that has enough bearing capacity, at the melting point above 955 °C.

5.15 Bypass piping and valve

Bypass piping and valve shall adopt the material of the same corrosion resistance with the body material as a minimum.

5.16 Handwheel

Handwheel shall adopt carbon steel cast, carbon steel forging, spheroidal graphite cast iron or malleable cast iron.

5.17 Handwheel retaining nut

Handwheel retaining nut may adopt carbon steel, stainless steel, malleable cast iron or spheroidal graphite cast iron. In the case of carbon steel being adopted, anticorrosive treatment measures shall be taken to the surface.

6.1 General Provisions

The extent of the purchaser’s inspection shall be limited to the following, unless other additional inspection requirements are specified in the order contract:

a) Inspection of the valve by the non-destructive inspection method during the assembling process;

b) Examination of "Processing records", and "heat treatment records", etc.;

c) Examination of "non-destructive testing records" in accordance with 4.14 of this standard or the order contract;

d) Pressure test.

6.2 Test methods

6.2.1 Pressure test

Valve pressure tests shall be in accordance with JB/T 9092.

6.2.2 Body wall thickness measurement

The wall thickness of body run, central cavity and bonnet shall be measured with a thickness tester or special caliper.

6.2.3 Stem diameter measurement

Diameter of stem and outside diameter of trapezoidal screw thread of stem in the contact zone between stem and packing shall be measured with a vernier caliper.

6.2.4 Sealing surface hardness measurement

Three points in the central zone of disc sealing surface shall be measured with a hardness tester to obtain the average value.

6.2.5 Stem hardness measurement

Three points on the polish rod of stem shall be measured with a hardness tester to obtain the average value.

6.2.6 Material composition analysis

Sampling shall be conducted from the materials of body, bonnet and disc. Drilling and sampling shall be conducted 6.5 mm below the surface.

6.2.7 Mechanical properties of body materials

They shall be tested with the coupon of the same furnace number and heat treatment batch as the body in accordance with the methods specified in GB/T 228.

6.2.8 Potential pressure life test

6.2.8.1 Life test shall be carried out for the globe valve of metallic seals in accordance with

JB/T 8859.

6.2.8.2 Life test shall be carried out for the globe valve of soft seal with dry air at the rated differential pressure or maximum allowable service differential pressure in accordance with

JB/T 8859.

6.2.9 Body marking inspection

Bodies shall be visually inspected for the casting or franking contents on the surfaces.

6.2.10 Identification plate content inspection

7.2.1 The bodies must be marked permanently as follows:

-- Manufacturer's name or trademark;

-- Body material or code;

-- Nominal pressure or pressure grade;

-- Nominal dimension or nominal diameter of pipeline;

-- Medium flow direction marking;

-- Hearth number or forging batch number;

-- Product production serial number.

7.2.2 The bonnets must be marked permanently as follows:

-- Body material;

-- Nominal pressure;

-- Nominal dimension;

-- Hearth number or forging batch number.

7.3 Marking on the identification plate

The following contents shall be marked on the identification plate:

-- Manufacturer's name;

-- Nominal pressure or pressure grade;

-- Nominal dimension or nominal diameter of pipeline;

-- Product model;

-- Maximum allowable service pressure at 38°C;

-- Maximum allowable service pressure corresponding to the maximum allowable service temperature;

-- Material (body, stem, and seal, seals, etc.);

-- Product standard number.

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