1. General Requirements
Safety valves are important safety accessories for supercritical equipment and are generally key items in annual equipment inspections, export acceptance, and factory safety checks. In practice, the calibration interval should be determined not only by equipment type but also by the medium, pressure rating, local regulations, manufacturer requirements, and customer technical agreements. The intervals below are common practices in projects and are provided for reference.
2. Common Calibration Intervals
Continuous industrial production equipment: safety valves are usually calibrated once every 6 months.
Pilot-scale equipment and intermittently used laboratory equipment: professional calibration should be carried out at least once a year.
Export projects and GMP workshop projects: customer specifications are often stricter, and many projects require quarterly calibration. The specific interval should be governed by the contract and technical agreement.
Regardless of the interval, calibration should be performed by a qualified third-party organization. Calibration certificates should be archived and kept available for retrieval during acceptance.
3. Conditions Requiring Replacement
A safety valve should not remain in service and should be replaced promptly if any of the following conditions occur:
Obvious pressure deviation, unstable opening, or slow pressure-relief response;
Valve body corrosion, sealing surface wear, medium leakage, or spring aging.
If the equipment has experienced a high-pressure relief protection event, the safety valve should generally not be reused and should be replaced or scrapped in accordance with manufacturer requirements and project specifications. Some project specifications also use two years of service as a uniform replacement point. If the contract or customer specification has explicit requirements, those requirements should be followed.
4. Daily Operation and Record Management
During daily production, safety valves must not be adjusted, plugged, or dismantled without authorization. The exterior of the valve body should be kept clean, and oil contamination and debris accumulation should be avoided. After major equipment overhaul or pressure testing, it is recommended to recheck the sensitivity of the safety valve and update the calibration and replacement records. Keeping these records well organized in advance can reduce the need for explanations during export acceptance and factory inspections and can also help mitigate high-pressure overpressure hazards.