JB/T 8691-1998 This standard specifies the definition, classification, requirements, test methods, inspection rules, marking, packaging, transportation, storage and quality assurance of wafer-type knife gate valves. This standard is applicable to wafer-type knife gate valves with nominal pressure PN≤2.5MPa, DN50~70mm, and working medium containing solid particles. JB/T 8691-1998 Wafer-type knife gate valve JB/T8691-1998 Standard download decompression password: www.bzxz.net

JB/T8691—1998
This standard is proposed and managed by the National Technical Committee for Valve Standardization.
The responsible drafting unit of this standard: Hefei General Machinery Research Institute of the Ministry of Machinery Industry. The participating drafting units of this standard: Shijiazhuang Valve Factory No. 1 Co., Ltd., Fuzhou Valve General Factory. The main drafters of this standard: Yuan Tongzhen, Chi Xiangfen, Xia Fumin1Scope
Machinery Industry Standards of the People's Republic of China
Wafer Knife Gate Valve
Wafer Knife Gate Valve
JB/T 8691
This standard specifies the definition, classification, requirements, test methods, inspection rules, marking, packaging, transportation, storage and quality assurance of wafer knife gate valves.
This standard is applicable to knife gate valves with a nominal pressure PV not greater than 2.5MPa, a nominal diameter DN50700mm, and a medium containing solid particles.
2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision. Parties using this standard should explore the feasibility of using the latest versions of the following standards: GB699---88 Technical conditions for high-quality carbon structural steel GB70088 Carbon structural steel
GB711--88 Hot-rolled thick steel plates and wide steel strips for high-quality carbon structural steel GB/T104795 Nominal diameter of pipeline components G131048---90 Nominal pressure of pipeline components GB/T11841996 Tolerances of shape and position without tolerance value GB 1220-92
Stainless steel bars
GB 4216.2~4216.584
Size of flanges for grey cast iron pipes
GB423792
Hot-rolled stainless steel plates
GB 5796. 1~-5796.4---86
Trapezoidal thread
GB 9113--- 88
GB 9131—88
GB 9440----88
GB 12220-89
Integral steel pipe flange
Steel pipe flange
Forgeable iron castings
Pressure-temperature grade
General valve mark
G 12222—89
GB12225
GB 12226---89
GB 12227—89
GB 12229—89
GRB 12230---89
Connection of multi-turn valve drive
General valves
Technical conditions for copper alloy castings
General valves
Technical conditions for gray cast iron parts
Technical conditions for ductile iron parts
General valves
Technical conditions for carbon steel castings
General valves
Technical conditions for austenitic steel castings for general valves GB12380.112380.4-90 Raised integral ductile iron pipe flanges GB12386---90 Ductile iron pipe flanges Pressure-temperature grades Approved by the Ministry of Machinery Industry of the People's Republic of China on March 19, 1998 534
Implemented on July 1, 1998
JB/T 8691
GB/T 1392792
General valve pressure test
GB/T15188.2-·94 Structural length of valve: Wafer-connected valve
IB106--78 Valve marking and identification paint
J330875 Valve model compilation method
J13/T7748-95 Valve cleanliness and determination method General valve supply requirements
JB/T 7928-95
JB/Z 243-85
Gate valve static pressure life test regulations
HG 2-234-78
3 Definitions
Polytetrafluoroethylene
This standard adopts the following definitions.
Wafer knife gate valve
waferknifegale valves
The valve is connected by long screw gun clamp in pipeline or equipment, and its opening and closing parts are a kind of knife-shaped intermediate valve 4 classification
4.1 Model
The model representation method of wafer knife gate valve is in accordance with the provisions of JB308. If the valve body channel is angular or pentagonal, it should be marked with "3" or 5" in the unit representing "structural type" in the form of footmarks to distinguish the circular channel. Take the manual, wafer connection, pentagonal valve body channel, alloy steel seat sealing surface material, nominal pressure 1.6MPa, and carbon steel body material parallel single gate knife gate valve as an example: Z 73, H-- 166
4.2 Basic parameters
4.2.1 The nominal diameter of knife gate valves shall comply with the provisions of GB/T1047. 4.2.2 The nominal pressure of knife gate valves shall comply with the provisions of GB31048. 4.3 Structural type
The structural type of knife gate valves is shown in Figures 1 to 4 (taking manual as an example). Other structural types are allowed under the condition of meeting the technical requirements of this standard.
JB/T 8691
Valve body; 2 sealing strip 3 gate: 4 bracket; 5 valve stem; 6 valve stem nut; 7 handwheel Figure 1
JB/T86911998
1 valve body. Sealing ring; 3 gate packing gland; 5 valve stem 6--Ligui; 7 valve stem nut; 8 bearing seat; 9 end cover; 10 handwheel Figure 2
JB/18691--1998||tt ||1 Valve body; 2 Sealing ring: 3--gate; 4---packing gland; 5. Support plate; 6 Valve stem; 7 Seat: 8 Bevel gear reducer Figure 3
5 Requirements
5.1 Pressure-temperature grade
JB/T8691
1 Valve body 2 Wedge block 3- Sealing ring--gate; -Padding; 6--Padding gland; 7 Bracket; 8 Valve stem 9 Valve stem nut; 10 Seat: 11 Handwheel Figure 4
5.1.1 The pressure-temperature rating of the gray cast iron shell material shall be in accordance with the provisions of (B4216.1. 5.1.2 The pressure-temperature rating of the ductile iron shell material shall be in accordance with the provisions of GB12386. 5.1.3 The pressure-temperature rating of the steel shell material shall be in accordance with the provisions of (GB9131. 5.2 Valve body
5.2.1 The valve body can be designed as a split type or an integral type. 5.2.2
The minimum wall thickness of the valve body shall be in accordance with the provisions of Table 1.
Valve body material
Nominal pressure PN
Nominal diameter I)N
Ductile iron
Minimum wall thickness of the valve body
Valve body material
Nominal pressure PV
Nominal diameter IN
JB/T 8691--- 1998
Table 1 (end)
5.2.3 The structural length and limit deviation of the valve body shall comply with the provisions of Table 6 and Table 7 in B/T15188.2-Nodular Cast Iron
Que Body Minimum Wall Thickness
94
5.2.4 The flange connection dimensions and sealing surface types shall comply with the provisions of GB4216.1~~4216.5, GB12380.1~~12380.4 or (B9113. Special requirements shall be stated in the contract. 5.2.5 The displacement tolerance of the axis of the connecting flange screw hole relative to the locating circle shall not exceed 1/4 of the gap between the bolt and the bolt hole. The coaxiality tolerance of the two bolt holes at the same position on the flange surfaces on both sides shall be in accordance with the provisions of Table 2. Table 2
Nominal diameter DN
Tolerance value
150-500
600~-700
5.2.6 The seal on the valve body can be designed to embed an elastic sealing strip on the upper part of the valve body as shown in Figure 5, or it can be designed as a stuffing box as shown in Figure 6. These two methods should obtain the lowest opening and closing torque under the premise of ensuring sealing. Pressing method
Pressing method—
/Rubber strip sealing strip Gate
Nuts and bolts
5.3 Valve body sealing ring or sealing strip
Stuffing cover
JB/T 8691 --
Adjustment direction
The valve body seal ring or seal strip embedded in the valve should be firm and reliable, and should not fall off during use. 5.4 Gate, valve seat, valve stem, valve stem nut 5.4.1
The flatness of both sides of the gate shall not be lower than the 12th grade accuracy specified in GB/T1184--1996, and the parallelism of the valve seat shall not be lower than the 11th grade accuracy specified in GB/T1184--1996. 5.4.2 The connection between the gate and the valve stem should be firm and reliable, and should not fall off during use. 5.4.3
When the valve is fully open, the gate should not block the passage. 5.4.4 The valve seat of the metal-sealed knife-type gate valve can be a separate part connected to the valve body, or it can be welded on the valve body. The thickness of the welded layer is not less than 2mm; for austenitic stainless steel valves, L can also be directly added to the valve body. 5.4.5
The minimum diameter of the valve stem shall be in accordance with the provisions of Table 3
Nominal diameter DN
Note: The minimum diameter of the valve stem refers to the nominal diameter of the thread or the diameter of the smooth stem of the valve stem. Stem
Small diameter
JB/T 8691 -1998
5.4.6 The threads of the valve stem and the valve stem nut adopt trapezoidal threads, and their basic dimensions and tolerances shall be in accordance with the provisions of GB5796.1~5796.4. If there are special requirements, they can be indicated in the order contract.
5.4.7 The screwing length of the valve stem and the valve stem nut shall not be less than 1.4 times the diameter of the valve stem thread. 5.5 Bracket
The bracket can be designed as integral casting, four-legged, support plate and other types. The connection size of the bracket and the drive device shall comply with the provisions of (1312222 5.6 Packing gland
The packing gland adopts an integral type.
5.7 Driving mode
The driving modes of knife-type gate valves are manual, electric, pneumatic, hydraulic and sprocket drive. 5.7.1 Manual
5.7.1.1 Manual can be operated directly by handwheel or assisted by gearbox. For knife-type gate valves directly operated by handwheel, the handwheel is fixed to the valve stem nut by locking nut or other means. The rim of the handwheel should have obvious arrows and The direction of rotation of the wheel is clockwise to close and counterclockwise to open. 5.7.1.2 When 1V400mm or the nominal pressure is high, in order to reduce the operating torque on the handwheel, the use of a gearbox to assist in operation should be considered. If the user requires a gearbox to assist in operation when DN<.400mm, it should be noted in the order contract. 5.7.2 Pneumatic and hydraulic
The knife-type gate valve driven by pneumatic or hydraulic devices. Its working gas sign or hydraulic cylinder should have a buffer structure to prevent the gate from impacting the bottom of the valve body at an excessively fast speed at the moment of closing, causing deformation or damage to certain parts. 5.8 Materials
The materials of the main parts of the knife-type gate valve are selected according to the structure and medium properties according to Table 4. When the properties meet the requirements, Other materials can be selected under the condition of energy requirements.
Parts name
Packing gland
Stem nut
Upper seal or
Material name
Gray cast iron
Ductile cast iron
Carbon steel
Austenitic stainless steel
Austenitic stainless steel
Stainless steel bar
Gray cast iron
Carbon steel
Austenitic stainless steel
Copper alloy
Free-cutting stainless steel
Polytetrafluoroethylene
Graphite asbestos rope
Material brand
HT250, HT300| |tt||QT400-15,QT450-10
ZG1Cr18Ni9Ti,CF8
Standard grades listed
1Cr13,2Cr13,304,316.0Cr18Ni9Ti,1Cr18Ni9TiHT250HT300
Q235-A
ZG1Cr18Ni9,ZGJCr18Ni9Ti.CF81Cr18Ni9Ti
ZCuZn38Mn2Pb2.ZCuSn5Pb5Zns
Y1Cr13
Standard number
GB 12226 | | tt | 3 700
GB12230
GH 4237
GB12225
GB1220
Parts name
Sealing ring or
Sealing strip
Material name
Polyvinyl fluoride
Mallet cast iron
Ductile cast iron
JB/T86911998
Table 4 (end)
Material brand
Nitrile rubber, fluororubber, EPDM rubber KTI1330 08.KTH350-10
QT400-15.QT450-10
Standard number
HG2-234
GB9140
GB 12227
5.9 The assembled knife gate valve should be firmly connected, flexible to open and close, and without obstruction. For the knife gate valve driven by the drive device, the travel switch and the over-torque protection mechanism should operate reliably and accurately.
5.10 Shell test and seal test
5.10.1 The shell test and seal test medium of the knife gate valve are water (containing preservatives), kerosene or other suitable liquids with low viscosity and water sticking. 5.10.2 For knife gate valves with non-metallic seals, the shell test and seal test shall be in accordance with the provisions of GB/T13927. 5.10.3 For knife gate valves with metal seals, if there are requirements for sealing performance, the leakage of the sealing test shall be calculated as 1XDNmm/, and if there are no requirements for sealing performance, this test shall not be performed. Shell test and other requirements shall still be in accordance with the provisions of GB/T13927 5.10.4 For knife gate valves driven by electric, hydraulic or pneumatic devices, after the closing position is adjusted, close 3 times and conduct shell and seal tests in accordance with 5.10.1 to 5.10.3.
5.11 The cleanliness requirements of knife gate valves shall be in accordance with the provisions of JB/T7748. 5.12 Static pressure life test
The number of static pressure life tests of knife gate valves shall be in accordance with the provisions of Table 5, and other technical requirements shall be in accordance with the provisions of JB/Z234. Table 5
DV≤150 mm
Metal seal
Static pressure life
Test times
Non-metal seal
1 Metal seal refers to the sealing material of metal-metal. IDN=200~400 mm
DV450 mm
DN≤150 mm
DN 200~400 mn
DN450 mm
2 Non-metallic seal refers to the sealing material is metal-non-metal or non-metal·non-metal 5.13 Painting
1200 times
1000 times
800 times
1400 times
1200 times
1000 times
5.13.1 Except for austenitic stainless steel knife gate valves, the non-machined surfaces of other metal knife gate valves should be painted. The paint layer should use durable paint, and the coating at the marking should ensure that the marking is clear. The color of the paint shall be in accordance with the provisions of JB106. Special requirements shall be indicated in the order contract. 5.13.2 The non-painted or non-rust-proof surface must be coated with an easily removable anti-rust agent. The inner cavity and parts of the valve shall not be painted and shall be free of dirt and rust.
6 Test methods
6.1 The shell test and seal test methods of knife-type gate valves shall comply with the provisions of GB/T13927. 6.2 The cleanliness determination method of moon-shaped gate valves shall comply with the provisions of JB/T7748. 6.3 The static pressure life test method of knife-shaped gate valves shall comply with the provisions of JB/Z243. 7 Inspection rules
Departure inspection
JB/T 8691
Each knife-type gate valve must undergo a departure inspection and can only be shipped after all inspection items are qualified. The departure inspection items, technical requirements, tests and inspection methods shall comply with the provisions of Table 6. 7.1.2
Inspection items
Shell test
Seal test
Cleanliness
Static pressure life test
Note: "\" is an inspection item.
7.2 Type inspection
Inspection type
Factory inspection
Type inspection
7.2.1 In any of the following situations, type inspection should generally be carried out: a) Trial production and identification of new products or old products transferred to the factory for production; Technical requirements
According to 5.10.1~3.10.4
According to 5.10.15.10.4www.bzxz.net
According to 5.13.15.13.2
According to 8.18.2
b) During formal production, regular inspections should be carried out periodically or after a certain amount of production has been accumulated; c) After normal production, when there are major changes in structure, materials, and processes that may affect product performance; d) When the product is resumed after a long period of suspension; e) When the inspection results are significantly different from the last type inspection; ") When the national quality supervision agency proposes a requirement for type inspection. 7.2.2 Sampling method
Test and inspection method
GB.T 13927
GR/T 13927
JB/T 7748
J13/7 213
7.2.2.1 Sampling can be randomly selected from the qualified products at the end of the production line, or randomly selected from the finished product warehouse, or randomly selected from the products that have been supplied to users but have not been used and remain in the factory state. The minimum batch and sampling quantity for each specification shall be in accordance with the provisions of Table 7. When sampling by users, the minimum batch for sampling is not limited by Table 7, and the sampling quantity shall still be in accordance with the provisions of Table 7. When assessing the quality of the entire series of products, 2 to 3 typical specifications shall be inspected according to the size of the series. The minimum batch and sampling quantity for each specification shall still be in accordance with the provisions of Table 7,
Nominal diameter DN
7.2.2.2 Determination of cleanliness: single sampling of one group of samples. Minimum batch ink
7.2.2.3 For the static pressure life test, select any one of the sampled products. 7.2.3 Type inspection items, technical requirements, tests and inspection methods shall be in accordance with the provisions of Table 6. Sampling quantity
7.2.4 During the type inspection, the shell test, liquid seal test and static pressure life test results of each knife gate valve must comply with the corresponding technical requirements in Table 6: For the remaining inspection items! If one of the knife gate valves does not meet the technical requirements in Table 6, it is allowed to draw a specified number of samples from the force gate valves for sampling. When re-inspecting, the results of all inspection items must meet the technical requirements in Table 6, otherwise it will be judged as a defective product.
8 Marking
8.1 The marking of knife gate valves shall be in accordance with the provisions of GB12220341
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