What is the difference between API 624 and API 641?
API 641 and API 624 are both standards for valves developed by the American Petroleum Institute (API), but they differ significantly in their scope, testing requirements, and focus. A detailed comparison is as follows:
Scope of Application
API 641:
Applicable to metal-seated soft-seal (elastic seal) valves, such as those using soft-seal materials like polytetrafluoroethylene (PTFE).
Primarily targets small valves (typically DN100/4" or less, but specific dimensions may vary depending on the standard version), which are widely used in the oil, gas, and chemical industries.
API 624:
Applicable to metal-seated (hard seal) valves, such as gate valves, ball valves, plug valves, and check valves.
Testing Requirements
API 641:
The test medium is nitrogen (N₂).
The test pressure is 1.1 times the maximum differential pressure or the valve's rated pressure (whichever is less).
The test duration is 60 minutes, and the leakage rate requirement is ≤ 100 cm³/min/inch (or may vary depending on the specific standard version).
The test includes leakage rate verification after multiple on/off operations to assess valve durability.
API 624:
The test medium is also nitrogen (N₂).
The test pressure is the valve's maximum rated pressure.
The test time is divided into multiple stages, including pressurization, holding, and depressurization, and the total time may be longer.
The leakage rate requirement is ≤ 0.1 sccm (standard cubic centimeters per minute) per inch of seal diameter, which is a relatively low leakage rate standard.
The test also focuses on the leakage rate of the stuffing gland and allows for adjustment during the test.
Standard Focus and Scope
API 641:
Focuses on evaluating the sealing performance and durability of soft-seal valves.
Suitable for applications requiring high valve leakage rates but not extremely low leakage rates.
API 624:
Focuses on evaluating the low-leakage performance of hard-seal valves.
Suitable for applications requiring extremely high valve sealing performance, such as pipelines transporting flammable, explosive, toxic, or hazardous media.
API 641 and API 624 Valve in stock
