Sorting out the US manufacturing standards for knife gate valves
The US manufacturing standards for knife gate valves mainly involve design, materials, inspection and other aspects. The core specifications are as follows:
1. Design and manufacturing standards
API 600
General specifications for steel gate valves, covering material selection, structural strength and other requirements, suitable for the basic design of industrial gate valves (including knife gate valves) with rigid structures;
Clearly specify key parameters such as valve channel size and valve body thickness to ensure that the flow performance matches the pressure bearing capacity.
API 6D
Special standards for pipeline valves, standardizing the interface size, pressure level and sealing performance requirements of knife gate valves in long-distance pipelines such as oil and natural gas;
Mandatory requirements for floating gate design to meet bidirectional sealing tests (such as API 598 verification).
2. Structural dimensions and connection standards
ASME B16.10
Define the valve structure length (end face spacing) to ensure the compatibility of knife gate valves and pipeline flanges;
For compact knife gate valve wafer structures, specify bolt hole spacing and valve body thickness limits.
ASME B16.5
Flange connection dimension standard, covering the flange specifications of knife gate valves with pressure levels from Class 150 to Class 2500;
Specify the adaptation requirements of flange sealing surface types (such as raised face RF, ring connection face RTJ).
ASME B16.25
Specify the groove processing dimensions of butt-weld end valves (such as high-pressure knife gate valves) to ensure welding process compatibility.
3. Material and inspection standards
ASTM material specifications
Common materials for valve bodies include ASTM A216 WCB (carbon steel), ASTM A351 CF8M (stainless steel), etc., which must meet the temperature and pressure resistance requirements of API 600;
If the sealing material contains rubber or polyurethane, it must pass the NACE MR0175 corrosion resistance certification (such as acidic medium scenarios).
API 598
Valve sealing test standard requires knife gate valves to maintain zero leakage (soft seal) or allow trace leakage (metal seal) at 1.1 times the nominal pressure;
Includes specific processes such as high and low pressure gas sealing test and life test.
4. Pressure-temperature grade
Following ANSI B16.34, determine the maximum allowable working pressure of knife gate valves at different temperatures according to material type (such as WCB, 316SS) (such as Class 150 valves with a pressure resistance of 20 bar at 38°C).
Typical application scenarios
Pipeline containing particle media: API 6D-compliant knife gate valves are used for mud cutoff in oil and gas transportation;
Sewage treatment system: Class 150 soft seal knife gate valves are suitable for corrosive liquid control (ASTM material certification required).
Selection recommendations
High-pressure pipelines: API 6D certified metal-sealed knife gate valves are preferred, with ASME B16.25 butt-weld end design;
Corrosive environments: ASTM A351 CF8M material + fluororubber seals are selected to meet NACE MR0175 requirements.
