What are the pressure testing standards after purchasing valves and having them stored in the factory?

I. Core test items and standard requirements 1. **Shell strength test** – **Purpose**: To verify the structural integrity of pressure-bearing components such as the valve body and valve cover. - **Test parameters**: - Test pressure: 1.5 times the nominal pressure (PN) or the design pressure. - Medium: Clean water (for stainless steel valves, chloride ions must be controlled at ≤25ppm). - Holding time: ≥5 minutes (at room temperature), with no leakage or deformation. - **Applicable standards**: API 598, GB/T 13927, GB/T 26480 (equivalent to API 598). 2. **Sealing test** - **Classification and requirements**: - **Low-pressure sealing test**: The medium is gas (air/inert gas), with a pressure ≤ 0.6 MPa. - **High-pressure sealing test**: The medium is water or oil, at a pressure of 1.1 times PN. - **Leakage grade **: Classified as A to G according to ISO 5208 (soft seals require zero leakage, while metal seals allow a slight amount of leakage). - **Special tests**: – **Upper seal test**: For valves with an upper seal mechanism (such as gate valves and globe valves), the pressure is 1.1 times PN, and the packing gland must be loosened. 3. **Special condition testing** – **Fire resistance test**: Simulate a fire environment to verify the valve’s sealing performance at high temperatures. - Standards: API 607 (soft-sealed valves), API 6FA (line valves), JB/T 6899 (China). - **Low-temperature test**: Suitable for operating conditions below -40°C (such as LNG valves). - Standards: BS 6364, GB/T 24925; immersion testing in a liquid nitrogen environment is required. - **Micro-leak test**: Measures the amount of helium leakage; standard: ISO 15848 (certification for the leakiness of industrial valves). - **Life test**: Simulates opening and closing cycles (e.g., high-pressure valves are required to undergo ≥200 cycles per API 598); standards include JB/T 8858 (gate valves), JB/T 8863 (butterfly valves), etc. --- II. Relationship between test duration and size: The required holding time for valves of different sizes varies significantly, as follows: | Valve nominal size (DN) | Minimum time for shell testing | Minimum time for sealing testing | |-------------------|-----------------|-----------------| | ≤50 | 15 seconds | 15 seconds | | 65–150 | 60 seconds | 60 seconds | | 200–300 | 120 seconds | 60 seconds | | ≥350 | 300 seconds | 120 seconds | > *Note: Data compiled from GB/T 13927, API 598, and pipeline construction standards. * --- III. Additional requirements for special valves 1. **Nuclear-grade valves**: Must comply with RCC-M (France), ASME III (USA) or GB/T 19624 (China), with additional non-destructive testing and cyclic durability testing required. 2. **Control valve**: It is necessary to calibrate the travel positioning (4–20mA signal), flow coefficient (Cv/Kv values), and actuator dead zone. 3. **Large-diameter gate valves (DN≥600)**: They can be exempted from separate pressure testing and can be inspected simultaneously during system pressure testing. --- IV. Quality Control and Certification – **Mandatory inspection before shipment**: A pressure test record must be kept for each valve, including data on shell strength and sealing performance. - **Material verification**: The material must comply with ASTM standards (such as A216 WCB) or GB/T 12225 standards for copper alloys, with spectral analysis and hardness testing carried out as supplementary checks. - **International certifications**: CE (EU), SIL (Safety Integrity Level), API Mark certification. --- V. Recommendations for Standard Selection – **Petroleum/Chemical Projects**: API 598 and ASME B16.34 should be given priority. - **Domestic standard projects**: GB/T 26480 and GB/T 13927 are adopted. - **Special fields such as nuclear power/fire protection**: Additional industry-specific standards apply (such as GB 5135.6 for fire valves). > Key point: The valve must be thoroughly cleaned before testing; anti-seepage coatings are prohibited ； After the test, drain any remaining water and apply rust preventive oil, then close the inlet and outlet guards.