Some standard content:
Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Cryogenic Valves
1 Subject Content and Scope of Application
JB/T 7749...95
This standard specifies the structural type, technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of cryogenic gate valves, stop valves, check valves, ball valves and butterfly valves.
This standard applies to cryogenic gate valves, stop valves, check valves, ball valves and butterfly valves with nominal pressure PN16~10.MPa, nominal diameter DN15~350mm, temperature -1(0~196°C) and welded connections. Other cryogenic valves may also be used for reference. Reference Standard
GB12220
GB 12221
GB12225
GB12230
GB12231
GB12234
GB12235
GB12236
GB12237
GB12238
General valve mark
Structural length of flange-connected metal valves
General valves
General valves
General valves
Technical conditions for copper alloy castings
Technical conditions for austenitic steel castings
Appearance quality requirements for valve steel castings
General valves
General valves
General valves
General valves
General valves
GB/T 12252
Flanged and butt-welded steel gate valves
Flanged steel stop valves and lift check valvesSteel swing check valves
Flanged and butt-welded steel ball valves
Flanged and wafer-connected butterfly valves
Supply requirements
Tongli valves
G13/T 15188.1
Valve structure lengthButt-welded valves
Magnetic particle inspection of pressure vessel forgings
J34248
Technical requirements for plasma arc cladding of valve sealing surfacesJB/T 6438
113/T6439
JB/T 6440
J3/T 6902
JB/T 7248
JB/1 7748
ZBJ04 005
ZBJ16 006
3 Language
3.1 Cryogenic treatment
Magnetic particle flaw detection inspection of pressure castings of valves
Radiographic inspection of pressure castings of valves
Liquid penetrant inspection method of valve castings
Technical conditions for low-temperature steel castings for valves
Cleanliness and determination method of valves
Pentnetrant flaw detection method
Testing and inspection of valves
A treatment method that immerses parts in a low-temperature liquid nitrogen box for insulation and regular maintenance to reduce deformation caused by temperature difference and change of metallographic structure, thereby improving the sealing performance of valves at low temperatures. Approved by the Ministry of Machinery Industry of the People's Republic of China on 1995-06-20, 1996.0101 implementation
4 Product type and structure
J13/T 7749-95
The basic structure of cryogenic valve is shown in Figures 1 to 5. a
1 Valve body: 2--Wine seat; 3-Gate: 1 Tie rod 5 Gasket: 6-Valve cover: 7··Stud: 8 Nut, 9 Upper sealing seat: 1·Support auxiliary Oh; 11-Packing pad: 12-Packing; 13 Swivel bolt; 14-Packing gland: 15 Packing cap: 16-Bracket; 17·Valve stem screw; 18 Oil cup 19. Gland: 2 Handwheel: 21 Nut: 22 Screw Figure 1 Cryogenic gate valve
JB/T7749-95
Valve body; 2··Valve seat 3-Valve disc; -Valve disc clamp. Valve cup; - gasket, · valve plate · 8 · stud; 9 nut: 1 sealing rate 11 · support bearing; 12 - packing pad: 13 - packing; 11 packing gland: 15 live bolt; 1G packing gland: 17. Anti-rotation device · 18. Bracket; 19--Oil cup; 20-Stem nut; 21 Cover, 22 Wheel: 23 Nut; 24·-Screw Figure 2 Low temperature stop valve
JB/T7749--95
1 Valve body? 2 Valve seat; 3·-Valve disc; 4~Nut; 5--Heat; 6 Rocker arm; 7--Bracket 8-Bolt; 9--Washer; 10 Valve cover: 11--Screw: 12 Gasket: 13--Stud: 11-Nut Figure 3 Low temperature check valve
JB/T7749--95
Valve body 2--Ball: 3--Seal Figure 4 Valve cup·-Packing gland Figure 4 Low temperature ball valve
JB/T 7749--. 95
1 Valve body: 2 Wide body sealing ring (valve seat); 3 Butterfly plate sealing ring: 4 Sealing ring pressure plate: 5 Butterfly plate: Valve stem: 7 Row grid digging system Lifting valve: Stage drive installation: 9. - Secondary drive device: 1·Handwheel: 11 Power switch: 12 Torque control; Motor 6
Figure 5 Low temperature electric butterfly valve
5 Technical requirements
General requirements
In addition to complying with the provisions of this standard, low temperature valves shall also comply with the provisions of (GB312234, GB1223 (132236, (H131\23:12238 and other applicable valve product standards) 5.2 Valve body
JB/T7749-95
5.2.1 The structural length of the low temperature valve connected by welding shall comply with the provisions of GB12221, and the structural length of the low temperature valve connected by welding shall comply with the provisions of GB/T15188.1.bzxz.net
5.2.2 The valve body shall be subjected to the temperature change stress caused by repeated changes in the medium temperature for a long time. It should be able to maintain sufficient strength under the total load of the additional stress caused by the force and the connecting pipes.
5.2.3 For valves with flow direction requirements, the valve body or the nameplate fixed to the valve body should be marked with a sign indicating the flow direction of the medium. 5.3 Valve cover
5.3.1 The valve cover of low-temperature gate valves, stop valves, ball valves, and butterfly valves should be designed as a long-necked valve blue structure that is easy to keep cold according to different operating temperature requirements to ensure that the temperature at the bottom of the packing remains above 0C. 5.3.2 The long neck part of the valve can be welded to the valve cover and stuffing box with a seamless steel pipe of the same material as the body. Heat treatment should be performed after welding to eliminate stress. The gap between the valve stem and the long neck part should be designed to minimize the convective heat loss: the long neck part should have sufficient wall thickness: 5.3.3 For gate valves, stop valves, etc. with upper sealing Cryogenic valves with sealing requirements should be equipped with upper seals. The upper sealing seat should be welded with hard alloy or welded with an old bushing on the threshold cover. The upper sealing surface of the austenitic stainless steel valve cover can also be directly processed. 5.3.4 The valve body and valve cover should be connected by bolts, welding or pipe joints. The valve cover connected by pipe joints is only suitable for cryogenic valves with a nominal diameter of 10 or less than 50mm. The pipe joint screws should be locked with the valve body, and threaded connections are not allowed. 5.4 Valve disc and valve seat
5.4.1 Valve disc and valve seat sealing structure
5.4.1.1 For cryogenic valves that can seal on both the inlet and outlet sides, measures should be taken to prevent abnormal pressure increase in the middle cavity of the valve body. Pressure reducing holes, pressure reducing channels or other pressure relief methods can be set. The pressure reducing holes should be set at the inlet end. If the user has no special requirements, the pressure relief method is determined by the manufacturer. 5.4.1.2 The valve disc of the stop valve should adopt a conical or spherical sealing structure. 5.4.1.3 The sealing pair of the cryogenic valve should be designed as metal to metal or metal to soft sealing surface. If a soft sealing surface is used, it is supported by a metal valve seat to avoid cold flow deformation of the soft sealing valve seat. 5.4.2 The hard alloy surfacing on the sealing surface of the valve disc and the valve body should comply with the provisions of JIB/T6438. When the operating temperature is lower than: 100), deep cryogenic treatment should be carried out after surfacing, that is, before grinding, it should be immersed in liquid nitrogen at 196°C for 2 to 6 hours, then taken out for natural treatment, and then ground and assembled. 5.5 Stuffing box
5.5.1 The stuffing box should adopt a double packing structure with an intermediate metal isolation bad, and can also adopt a general valve stuffing box structure or a double packing structure with self-tightening valve stem.
5.5.2 For low-temperature valves used for flammable media, it is advisable to use a combination packing between the packing gland and the valve stem and between the packing gland and the inner wall of the stuffing box.
5.6 Valves used for flammable media should be designed with an anti-static structure to ensure that the valve components can conduct electricity. 5.7 Materials
5.7.1. The materials for cryogenic valves shall be selected according to the working temperature and material properties, and shall meet the following requirements: a. At the working temperature, the material shall not produce low-temperature brittle failure; h. At the working temperature, the material structure shall be stable to prevent the material phase change from causing volume change. For cryogenic valves below 100℃, the valve body, valve cover, valve disc, valve seat, valve stem and other parts should be cryogenically treated before finishing, that is, the parts are immersed in liquid nitrogen box for cooling. When the temperature of the parts reaches -196℃, they are kept warm for 1-2h, then taken out of the box and naturally treated to room temperature, and the cycle is repeated for 2 hours;
c. When using welding structure, the welding performance of the material and the reliability of the weld at low temperature must be considered; d. For cryogenic valves that are frequently operated under low temperature conditions, the internal materials should be able to avoid blocking, biting and scratching. 5.7.2 The recommended materials for the main parts of low overflow valves are shown in Table 1. Wet
Valve body, valve cover, valve stem, valve seat
Sealing surface
Middle flange gasket
Middle flange bolt
Middle flange nut
JB/T 7749---95
ICr17Ni2
ZG00r18N9
ZGiCri8Nig
ZGHCr1SNOH
ZGIGr18Ni9T:
00r18Ni2M32r1
ICrlSNi9
oCr19Ni9||t t||Ir8N9Ti
F2201F(JBF22-15, SH.F221)
(SJ-o42.Co12.F221)
F2202F(F22 12,(n-1)
F2203F(F222.SH)(F222.F2217)
F2204F(StelliteN06)
F2205F(StelliteNe12)
PTFE
Sang Xing Stone Snail
PTFE White Cotton Rope
Wax Impregnated Asbestos Rubber Sheet
Polychlorotrifluoroethylene
Stainless steel spiral wound gasket
ZG0Cr18Ni9
ZG1Cr18Ni9
ZGoCr18Ni91i
ZG1Cr18Ni91i
CCr18Ni12M02Ti
5.7.3 Low temperature steel castings shall be in accordance with JB/T7284 Provisions; copper-containing gold castings shall comply with the provisions of GB12225: the chemical composition and mechanical properties of austenitic stainless steel castings shall comply with the provisions of GB12230. The impact test results shall comply with the provisions of Table 2; the appearance quality of castings shall comply with the provisions of (B12231.
Test temperature
5.8 Non-destructive testing
5.8.1 Radiographic inspection
Minimum value of ... samples among three samples
Minimum half mean of three samples
21:~27
5.8.1.1 For each new design of casting, the first two castings shall be fully inspected by radiographic inspection, and the inspection results must be qualified. For the castings cast under the same casting conditions, each of the remaining five or less than five pieces shall be inspected. If the sampling inspection fails, the remaining pieces in the group shall be inspected. 5.8.1.2 Parts and locations to be inspected
JB/T 7749---95
Cast valve body, the root of the valve cover, the location of the valve seat welded on the valve body; the butt-welded bevel gate;
The cut part of the valve cap;
The location for repair welding,
The radiographic inspection method shall be in accordance with the provisions of JB/16440. The inspection result shall not exceed the provisions of Level 2 (including Level 2) in JB/T6440. Magnetic particle inspection and liquid penetrant inspection
5.8.2.1
A casting or forging shall be subjected to magnetic particle inspection or liquid penetrant inspection: Parts and locations to be inspected
Raw roots of cast valve bodies and valve covers: butt welds and welded parts;
Raw joints of forged valve bodies;
Metal alloy sealing surfaces.
5.8.2.3 Magnetic particle inspection
5.8.2.3.1 Valve bodies, valve covers and other parts made of ferrous materials shall be inspected by magnetic particle inspection. 5.8.2.3.2 Magnetic particle inspection of steel castings shall be carried out in accordance with the provisions of JB/T6439. The magnetic particle inspection method of forgings shall be carried out in accordance with the provisions of J131218. 5.8.2.3.3 The defects of the surface of steel parts inspected by magnetic particle inspection shall not be lower than the provisions of J13/16439412 (including 2 levels). The parts inspected by magnetic particle inspection shall be free of cracks and linear defects. 5.8. 2.4 Liquid Penetrant Inspection
5.8.2.4.1 Valve bodies, valve covers and other parts made of ferromagnetic materials and hard alloy sealing surface cladding layers shall be inspected by penetration inspection: 5.8.2.4.2 The liquid penetration inspection method for castings shall be in accordance with the provisions of JL/T6902. The liquid penetration inspection method for forgings shall be in accordance with the provisions of Z13101003.
5.8.2.4.3 The inspection of hard spraying surface cladding layers and welding slopes shall be carried out before finishing. 5.8.2.4.4 The hard alloy sealing surface cladding layers and welding slopes shall be free of defects by penetration inspection. 5.8.2.4.5 The defects of the parts of castings inspected by liquid penetration inspection shall not be lower than the provisions of JL/T69024 Grade 2 (including Grade 2). The defects of the parts of forgings inspected by liquid penetration inspection shall not be lower than Grade 2 (including Grade 2) specified in 213304005. 5.8.2.4.6 The repaired welded parts shall be inspected according to the above requirements after repair welding. 5.9 The cleanliness of cryogenic valves shall comply with the provisions of J13/T7718. 6 Test methods
6.1 Normal temperature test
The normal temperature test shall comply with the provisions of 213J16006. 6.2 Low temperature test
The low temperature test of low-temperature valves shall be carried out after the normal temperature test is passed. 6.2.1 Test conditions
Before the test, remove the moisture and grease of the valve and tighten the bolts to the predetermined torque or tension, record its value, connect the valve with a thermocouple that meets the test requirements, and avoid measuring the temperature of the valve body and valve cover during the test. The cooling medium of the low temperature test is a mixture of liquid nitrogen and alcohol or liquid atmosphere, and the test medium is nitrogen gas.
6.2.2 Test steps
6.2.2.1 See Figure 6 for the test device of cryogenic valves. As shown in the figure, install the valve in the test container and connect all joints to ensure that it is sealed! The material is in the upper part of the container. The temperature is kept above 0.0The impact test results shall comply with the provisions of Table 2; the appearance quality of the castings shall comply with the provisions of (B12231.
Test temperature
5.8 Nondestructive testing
5.8.1 Radiographic inspection
Minimum value of ... samples among three samples
Minimum half mean of three samples
21:~27
5.8.1.1 For each new design of casting, the first two castings shall be fully radiographically inspected, and the inspection results must be qualified. For the castings cast under the same casting conditions, each of the remaining five or less than five pieces shall be inspected. If the sampling inspection fails, the remaining pieces in the group shall be inspected. 5.8.1.2 Parts and parts to be inspected
JB/T 7749---95
The root of the cast valve body and valve cover, the welded valve seat on the valve body; the butt-welded bevel;
The cut of the second cap:
The repair welding part,
The radiographic flaw detection method shall be in accordance with the provisions of JB/16440. The flaw detection result shall not exceed the provisions of Level 2 (including Level 2) in JB/T6440. Magnetic particle inspection and liquid penetrant inspection
5. 8. 2. 1
Magnetic particle inspection or penetration testing of all castings or forgings: Parts and parts to be inspected
Casting valve body, valve cover, butt weld and welded part;
Forged valve body joint;
Metal alloy sealing surface.
5.8.2.3Magnetic particle inspection
5.8.2.3.1Magnetic particle inspection of valve body, valve cover and other parts made of ferrous materials. 5.8.2.3. 2. The magnetic particle inspection method for steel castings shall be in accordance with the provisions of JB/T6439. The magnetic particle inspection method for forgings shall be in accordance with the provisions of J131218. 5.8.2.3.3 The defects of the surface of steel parts inspected by magnetic particle inspection shall not be lower than the provisions of J13/16439412 (including 2 levels). The parts inspected by magnetic particle inspection shall be free of cracks and linear defects. 5.8.2.4 Liquid penetrant inspection
5.8.2.4.1 The valve body, valve cover and other parts made of ferromagnetic materials and hard Alloy sealing surface cladding layer should be inspected by penetration test: 5.8.2.4.2 Liquid penetration test method for castings shall be in accordance with the provisions of 1L/T6902. Liquid penetration test method for castings shall be in accordance with the provisions of Z13101003. 5.8.2.4.3 Inspection of hard alloy sealing surface cladding layer and welding slope surface shall be carried out before finishing. 5.8.2.4.4 Penetrant flaw detection of hard alloy sealing surface cladding layer and welding slope surface shall be free of defects. 5.8.2.4.5 Liquid penetration test of castings shall be carried out after finishing. The defect should not be lower than the provisions of JL/T690242 (including level 2). The defect level of the liquid rolling inspection area of the forging should not be lower than the level 2 (including level 2) specified in 213304005. 5.8.2.4.6 The area to be repaired should be inspected according to the above requirements after repairing. 5.9 The cleanliness of low-temperature valves should comply with the provisions of J13/T7718. 6 Test method
6.1 Normal temperature test
The normal temperature test should comply with the provisions of 213J16006. 6.2 Low temperature test
Low temperature test of low-temperature valves should be carried out after the normal temperature test is passed. 6.2.1 Test conditions
Before the test, remove the moisture and grease of the valve and tighten the bolts to the predetermined torque or tension, record the value, connect the valve with a thermocouple that meets the test requirements, and avoid measuring the temperature of the valve body and valve cover during the test. The cooling medium for low temperature test is a mixture of liquid nitrogen and alcohol or liquid atmosphere, and the test medium is nitrogen vapor.
6.2.2 Test steps
6.2.2.1 Low temperature valve test device See Figure 6. Install the valve in the test container as shown in the figure, open and connect all joints to ensure that the material is in the upper part of the container. The temperature is kept above 0 (0.0The impact test results shall comply with the provisions of Table 2; the appearance quality of the castings shall comply with the provisions of (B12231.
Test temperature
5.8 Nondestructive testing
5.8.1 Radiographic inspection
Minimum value of ... samples among three samples
Minimum half mean of three samples
21:~27
5.8.1.1 For each new design of casting, the first two castings shall be fully radiographically inspected, and the inspection results must be qualified. For the castings cast under the same casting conditions, each of the remaining five or less than five pieces shall be inspected. If the sampling inspection fails, the remaining pieces in the group shall be inspected. 5.8.1.2 Parts and parts to be inspected
JB/T 7749---95
The root of the cast valve body and valve cover, the welded valve seat on the valve body; the butt-welded bevel;
The cut of the second cap:
The repair welding part,
The radiographic flaw detection method shall be in accordance with the provisions of JB/16440. The flaw detection result shall not exceed the provisions of Level 2 (including Level 2) in JB/T6440. Magnetic particle inspection and liquid penetrant inspection
5. 8. 2. 1
Magnetic particle inspection or penetration testing of all castings or forgings: Parts and parts to be inspected
Casting valve body, valve cover, butt weld and welded part;
Forged valve body joint;
Metal alloy sealing surface.
5.8.2.3Magnetic particle inspection
5.8.2.3.1Magnetic particle inspection of valve body, valve cover and other parts made of ferrous materials. 5.8.2.3. 2. The magnetic particle inspection method for steel castings shall be in accordance with the provisions of JB/T6439. The magnetic particle inspection method for forgings shall be in accordance with the provisions of J131218. 5.8.2.3.3 The defects of the surface of steel parts inspected by magnetic particle inspection shall not be lower than the provisions of J13/16439412 (including 2 levels). The parts inspected by magnetic particle inspection shall be free of cracks and linear defects. 5.8.2.4 Liquid penetrant inspection
5.8.2.4.1 The valve body, valve cover and other parts made of ferromagnetic materials and hard The cladding layer of the alloy sealing surface should be inspected by penetration test: 5.8.2.4.2 The liquid penetration test method for castings shall be in accordance with the provisions of 1L/T6902. The liquid penetration test method for castings shall be in accordance with the provisions of Z13101003. 5.8.2.4.3 The inspection of the cladding layer and the welding slope of the hard alloy sealing surface shall be carried out before finishing. 5.8.2.4.4 The cladding layer and the welding slope of the cemented carbide sealing surface shall be free of defects by penetration test. 5.8.2.4.5 The liquid penetration test of castings shall be carried out after finishing. The defect should not be lower than the provisions of JL/T690242 (including level 2). The defect level of the liquid rolling inspection area of the forging should not be lower than the level 2 (including level 2) specified in 213304005. 5.8.2.4.6 The area to be repaired should be inspected according to the above requirements after repairing. 5.9 The cleanliness of low-temperature valves should comply with the provisions of J13/T7718. 6 Test method
6.1 Normal temperature test
The normal temperature test should comply with the provisions of 213J16006. 6.2 Low temperature test
Low temperature test of low-temperature valves should be carried out after the normal temperature test is passed. 6.2.1 Test conditions
Before the test, remove the moisture and grease of the valve and tighten the bolts to the predetermined torque or tension, record the value, connect the valve with a thermocouple that meets the test requirements, and avoid measuring the temperature of the valve body and valve cover during the test. The cooling medium for low temperature test is a mixture of liquid nitrogen and alcohol or liquid atmosphere, and the test medium is nitrogen vapor.
6.2.2 Test steps
6.2.2.1 Low temperature valve test device See Figure 6. Install the valve in the test container as shown in the figure, open and connect all joints to ensure that the material is in the upper part of the container. The temperature is kept above 0 (0.0
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