Why Pressure Testing Matters for Sanitary Valves
Every valve we ship from our facility in Wenzhou, China goes through a pressure test before it leaves the production line. We do this because a valve that passes at 1.5x rated pressure will hold at operating pressure. We have tested over 6,000 valves across butterfly, diaphragm, ball, and check valve lines in the past 12 months. The data from those tests feeds back into our production process — if we see a pattern of failures on a specific size or seal type, we adjust the QC procedure.
The Standards We Test To
Three standards cover the pressure testing we do:
ISO 5208: Covers pressure testing of metallic valves. We follow Rate B (0.5x allowed leakage for liquid tests). For sanitary valves, we test at 1.5x the rated pressure on the shell and 1.1x on the seat.
ASME B16.34: Defines pressure-temperature ratings for valve bodies. We use this as the reference for our shell test pressures. A DN50 clamp-end valve rated at 10 bar (145 psi) gets shell-tested at 15 bar.
API 598: While this standard is written for industrial valves, we adapt its test durations and acceptance criteria for our sanitary valve line.
For customers who specify ASME BPE compliance, we follow Section SD-4 of the standard, which requires hydrostatic testing at 1.5x the design pressure for not less than 15 minutes.
What We Test On Every Valve
Shell test: The valve body is pressurized with the valve in the partially open position. Both ends sealed. We hold at 1.5x rated pressure for 60 seconds minimum. Any visible leakage through the body wall or end connections is a fail.
Seat test: The valve is closed at the specified torque. One side is pressurized to 1.1x rated pressure. The opposite side is monitored for leakage. Acceptance: zero visible leakage for resilient-seated valves (our standard for sanitary butterfly and diaphragm valves).
Seal test (for automated valves): The valve is cycled 5 times at rated pressure, then the seat test is repeated. This catches seal displacement issues that a single seat test would miss.
(Source: OMSS QC procedure manual, Pressure Test section, revision Q1-2025.)
What Our Test Data Shows
In our 2025 annual batch test, we pressure-tested 512 valves across four types — butterfly, diaphragm, ball, and check. Results:
Butterfly valves (clamp-end, DN25-DN100): 186 tested. Two failed the shell test at 1.5x. Both failures traced to a single subcontractor gasket batch. We replaced the entire batch and requalified the supplier.
Diaphragm valves (DN15-DN80): 134 tested. Zero failures on shell and seat tests.
Ball valves (DN15-DN50): 108 tested. One failure on the seat test at 1.1x — the PTFE seat showed minor deformation under test pressure. Root cause: seat thickness below spec. Adjusted machining tolerance.
Check valves (DN15-DN100): 84 tested. Zero failures.
Overall first-pass rate: 99.4%. All failed units were reworked and passed retest.
(Source: OMSS test batch QA-PT-2025, all valve types.)
Equipment We Use
We use a hydrostatic test pump with digital pressure transducer (accuracy ±0.5% of full scale). Test pressure is recorded on a chart recorder — we keep the paper records for 5 years. For pneumatic tests (low-pressure air testing on request), we use a regulated air supply with a calibrated pressure gauge.
Test medium: Clean water with corrosion inhibitor for standard tests. Deionized water for pharmaceutical-grade valves. For valves destined for oxygen service, we test with deionized water and document residual chloride levels.
Documentation We Provide
Every valve order ships with: EN 10204 3.1 material certificates, FDA 177.2600 compliance letter, surface finish report, and pressure test certificate (upon request). The test certificate lists: valve type and size, test pressure, test duration, test medium, and the inspector’s stamp.
Questions We Get Asked
Q: Do you test every single valve or just batch samples?
A: Every valve. Shell test is 100% on all valves we ship. Seat test is 100% on butterfly, diaphragm, and ball valves. Check valves get a uni-directional seat test.
Q: What pressure do you test at for a 150 psi rated valve?
A: Shell test at 225 psi (1.5x). Seat test at 165 psi (1.1x). Test duration: 60 seconds for shell, 30 seconds for seat. These are our standard parameters for all sanitary valves up to DN100.
Q: Can you test at higher pressures if our system requires it?
A: Yes. We have tested valves up to 3x rated pressure for specific projects. Lead time depends on the valve size and type. Contact onemo@onemoss.com with your parameters.
Q: Do you include the test certificate with the shipment?
A: Included by default for pharma and biotech orders. Available on request for food and beverage orders. No additional charge.
Technical Review
Zhang Wei, Senior Valve Engineer — 15 years in sanitary valve manufacturing. Oversees the pressure test program and equipment calibration.
Li Ming, Quality Manager — ISO 9001 Lead Auditor. Manages test record keeping and supplier qualification.
onemo@onemoss.com
Data Sources
• OMSS pressure test batch QA-PT-2025 (512 valves tested across 4 types)
• ISO 5208: Metallic valves pressure testing
• ASME B16.34: Valve pressure-temperature ratings
• ASME BPE-2022 Section SD-4: Hydrostatic testing
• OMSS QC procedure manual, revision Q1-2025
