3 steps to determine whether re-calibration is needed after the safety valve operates!

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Let’s discuss whether it is necessary to recalibrate the safety valve after it trips. The first view is that a safety valve is an important component for protecting the safety of pressure vessels and pipelines; once it activates, it returns to its original position once the pressure drops. However, there may be issues with incomplete return to that position, and this is the cause of internal leakage in the safety valve. If leakage occurs after the safety valve is reset, it is likely that there are impurities in the medium; in such a case, the safety valve needs to be removed for repair. If the valve operates normally during activation, and no leakage occurs after it returns to its seated position, then the safety valve is still reliable and does not need to be removed for recalibration. After the safety valve opens as intended when it reaches the set pressure value, the exterior of the valve body, including all its components, remains unchanged; however, the internal spring expands and contracts, and at this point a sound indicating pressure release can be heard from the outlet ； After the pressure is released after a while, the spring returns to its original position; the collision between the spring and the valve seat produces a knocking sound. All of this takes place inside the valve body, with no changes occurring outside the valve. (The same applies to safety valves with a handle; the handle is an emergency-use component. When the spring inside the safety valve becomes stuck, the valve can be manually opened using the handle in an emergency. In such cases, the handle will not be pulled up due to the automatic activation of the safety valve.) The lead seal also remains unchanged. Therefore, after the safety valve has normally relieved pressure and returned to its seated position, there is no need to immediately verify its set pressure; it can be checked at the next scheduled inspection date. However, when the pulsating load on the system is high, or when the spring stiffness of the safety valve is insufficient, the safety valve may chatter frequently. Damage to the valve seat sealing surface and the presence of impurities between the valve disc and the valve seat have resulted in media leakage. At this time, the safety valve is in a faulty state and cannot function properly; it needs to be recalibrated. 【Since a slight internal leakage in the safety valve has little impact on pressure, it is not easy to detect. To determine whether there is an internal leak, it is necessary to measure the temperatures of the safety valve and the pipeline downstream of the valve. If the temperature of the pipeline downstream of the valve is roughly the same as that of the pipeline upstream of the valve, it indicates that there is an internal leak in the safety valve. The safety valve needs to be replaced, and the one that is leaking internally must be sent for calibration.] Second opinion: As a precaution, once a safety valve activates, it cannot be used again after being reset; it must be taken to a qualified calibration facility for re-calibration before it can be used. There are no regulations, technical specifications, or sources for standards – safety first! It seems rather inappropriate to require a re-calibration simply because of the compression and expansion of the spring after takeoff. Because when it is sent for testing and verification, it also launches under a set pressure. If a normal takeoff occurs, send it for testing again. Repeating verification over and over will inevitably lead to spring fatigue failure. For special locations, special media, and similar situations, it is recommended to reschedule the calibration. After all, the safety valve can’t trip frequently either! Frequent starting and stopping – aside from the problems related to the safety valves themselves – warrants consideration from a process manufacturing perspective regarding the issue of operating under excessive pressure. Frequent overpressure conditions represent a very serious violation of regulations! u Flammable and explosive media: Used in systems where flammable or explosive materials may be generated, such as in the petroleum, chemical, and coal mining industries. u Toxic media: Systems used for handling or storing toxic substances, such as chemicals and pesticides. u High-temperature and high-pressure systems: Systems that operate under high temperature or high pressure conditions, such as power plant boilers and supercritical equipment. u Crowded areas: In areas where many people work or live, such as office buildings, shopping malls, residential communities, etc. u Protection of critical equipment: For safety valves that ensure the proper operation of critical equipment, such as large industrial machines. u Special process requirements: Certain manufacturing processes may require that safety valves be calibrated immediately after they activate, in order to ensure the continuity of the process and the consistency of the products. u Historical accidents: Areas where accidents have occurred or were close to occurring require special attention. So, after the safety valve trips, is it necessary to recalibrate it? ! The regulations and standards do not specify it; the freedom is left to the using entity! No one has the power to enforce anything. For reference only: 1. Under abnormal operating conditions, the safety valve operates properly at its set pressure, and it confirms that it has returned to its normal position. 2. No leaks. 3. Not in special locations or with special media. In cases other than the above, it is recommended to arrange for re-calibration! If jumping still occurs frequently, investigate the reasons from a manufacturing perspective; meanwhile, consider improving the setting pressure of the safety valve in light of the design.