Inspection cycle for safety accessories

(Published on June 25, 1999, by the Quality and Technical Supervision Bureau under Document No. Ji Ji Jian Guo Fa (1999)154) Regulations on Safety Technical Inspection of Pressure Vessels, Article 154: Safety accessories shall be subject to a regular inspection system. The regular inspection of safety accessories is carried out in accordance with the provisions of the \"Inspection Regulations for Pressure Vessels in Use\". Where the Provisions for Inspection of In-service Pressure Vessels do not provide specific guidelines, the inspection agency shall prepare an inspection plan and submit it to the provincial safety supervision authority for approval. Safety valves should generally be calibrated at least once a year; when it is difficult to remove them for calibration, on-site calibration (in-line calibration) should be used. The rupture disc devices should be replaced regularly; those that have exceeded the maximum design rupture pressure without bursting must be replaced immediately ； Blowout valve devices used under harsh conditions should be replaced annually ； Generally, blast disc assemblies should be replaced within 2–3 years (except where the manufacturer specifies that the service life can be extended). Pressure gauges and temperature measuring instruments shall be calibrated within the period specified by the user entity.

According to Article 3, Annual Inspection, of the Rules for Periodic Inspection of Pressure Vessels – TSG R7001-2004, an annual inspection refers to an on-line inspection carried out during operation in order to ensure the safety of the pressure vessel throughout its inspection period, and it shall be conducted at least once a year. Article 16: The inspection of safety accessories includes the examination and calibration of pressure gauges, level gauges, temperature measuring instruments, rupture disc devices, and safety valves. (1) Pressure Gauges 1. The annual inspection of pressure gauges shall include at least the following items: (1) Selection of the pressure gauge ； (2) Regular inspection and maintenance system for pressure gauges, calibration validity period, and seals ； (3) Appearance, accuracy class, range, and dial diameter of the pressure gauge ； (4) Location, opening marks, and locking device for installing a three-way stopcock or needle valve between the pressure gauge and the pressure vessel ； (5) Whether the readings of the pressure gauges on the same system are consistent. 2. During the annual inspection, if any of the following situations is detected, the user is required to make corrections within a specified time frame and to take effective measures to ensure safety during that period of correction; if no corrections are made by the deadline, the use of such pressure vessel shall be suspended: (1) Incorrect selection ； (2) The glass covering the dial is cracked or the dial markings are blurred ； (3) The seal is damaged or the inspection validity period has expired ； (4) Leakage in the gauge spring tube or loose gauge pointer ； (5) The pointer is twisted and broken, or the casing is severely corroded ； (6) The opening mark on the through-stopcock or needle valve is unclear, or the locking device is damaged. (II) Level gauges 1. The annual inspection of level gauges shall include at least the following: (1) A regular maintenance system for the level gauges ； (2) Appearance of the level gauge and accessories ； (3) Selection of level gauges for outdoor use in cold regions or those used to contain media at temperatures below 0°C ； (4) Leak prevention protection device for the level gauge when used in liquefied gas pressure vessels containing flammable media with an extremely high degree of toxicity and high hazard. 2. During inspections, if any of the following conditions is found, the user is required to make corrections within a specified time frame and take effective measures to ensure safety during that period of correction; if no corrections are made by the deadline, the use of such pressure vessel shall be suspended: (1) Exceeding the prescribed maintenance deadline ； (2) The glass plate (tube) has cracks or is broken ； (3) Valve components stuck ； (4) False level appears ； (5) The level gauge gives an unclear reading ； (6) Incorrect model selection ； (7) Prevent damage to the protection devices against leakage. (III) Temperature measuring instruments 1. The annual inspection of temperature measuring instruments shall include at least the following: (1) A system for regular calibration and maintenance of these instruments ； (2) The suitability of the temperature measuring instrument’s range to the temperature range it is designed to measure ； (3) The appearance of the temperature measuring instrument and its secondary instruments. 2. During the annual inspection, if any of the following conditions is found, the user is required to make corrections within a specified time frame and take effective measures to ensure safety during that period of correction; if the corrections are not made by the deadline, the pressure vessel shall be suspended from use: (1) Exceeding the specified periods for inspection and maintenance ； (2) Damage to instruments and their protective devices ； (3) Incorrect selection of instrument range ； (IV) Pressure relief device 1. The annual inspection of the pressure relief device shall include at least the following: (1) Checking whether the pressure relief disc has exceeded the service life specified in the product manual ； (2) Check whether the installation direction of the blast disc is correct, and verify that the burst pressure and temperature indicated on the nameplate meet the operational requirements ； (3) When the rupture disc is used as a pressure relief device alone (Figure 1), check whether the shut-off valve between the rupture disc and the container is in the fully open position, and whether the lead seal is intact ； (4) When a burst disc and a safety valve are used in series, if the burst disc is installed on the inlet side of the safety valve (Figure 2), it is necessary to check whether the pressure gauge installed between the burst disc and the safety valve shows any pressure; also, open the stop valve to verify whether gas is being discharged ； (5) When a burst disc and a safety valve are used in series, if the burst disc is installed on the outlet side of the safety valve (Figure 3), it is necessary to check whether the pressure gauge installed between the burst disc and the safety valve shows any pressure. If pressure is indicated, the shut-off valve should be opened to verify whether water and air can be drained smoothly ； (6) When a burst disc and a safety valve are used in parallel (Figure 4), check whether the shut-off valve installed between the burst disc and the container is in the fully open position and whether the lead seal is intact. 2. During the annual inspection, if any of the following conditions is detected, the user is required to replace the burst disc device within a specified time frame and to take effective measures to ensure safety during that replacement period; if the replacement is not carried out by the deadline, the pressure vessel shall be suspended from use: (1) The burst disc has exceeded its specified service life ； (2) The rupture disc is installed in the wrong direction ； (3) The burst pressure, temperature, and operating requirements specified for the rupture disc device do not match ； (4) Those that exceed the calibrated blasting pressure during use but do not explode ； (5) When the burst disc is installed on the inlet side of the safety valve and used in series with it, there should be a pressure indication on the pressure gauge between the burst disc and the safety valve, or gas should leak out when the stop valve is opened ； (6) Leakage from the rupture disc device. 3. During the annual inspection of pressure vessels in which the rupture disc is used as a pressure relief device alone or in parallel with a safety valve, if it is found that the shut-off valve between the rupture disc and the vessel is not fully open or that the seal is damaged, the user is required to make corrections within a specified time frame and to take effective measures to ensure safety during that period; if the corrections are not made by the deadline, the use of such pressure vessel shall be suspended. (5) Safety valves 1. The annual inspection of safety valves shall include at least the following items: (1) Whether the selection of the safety valve is appropriate ； (2) Check whether the validity period has expired ； (3) For lever-type safety valves, check whether the devices preventing the weight from moving freely and the lever from extending beyond its limits are in good condition; for spring-type safety valves, check whether the sealing device on the adjustment screw is intact ； Check the weight-type safety valve to ensure that the device preventing the weight pieces from falling off is in good condition ； (4) If a stop valve is installed between the safety valve and the discharge port, check whether the stop valve is in the fully open position and whether the seal is intact ； (5) Whether the safety valve is leaking. 2. During the annual inspection, if any of the following conditions is found, the user is required to make corrections within a specified time frame and take effective measures to ensure safety during that period of correction; if the corrections are not made by the deadline, the pressure vessel shall be suspended from use: (1) Incorrect selection ； (2) Exceeded the verification validity period ； (3) Damaged seal ； (4) Safety valve leakage. Article 17: Safety valves shall generally be calibrated at least once a year. For spring-loaded direct-load safety valves, when the conditions specified in this clause are met, the calibration interval may be appropriately extended with the approval of the technical supervisor of the user unit. (1) For directly-loaded safety valves that meet all of the following conditions, their calibration interval can be extended up to 3 years: 1. The safety valve manufacturer has obtained a manufacturing license issued by the **quality inspection department ； 2. Safety valve manufacturers shall be able to provide proof that the springs they use have been subjected to stress treatment or heat-treated stress treatment in accordance with the GB/T 12243-1989 standard for \"Spring-loaded direct-action safety valves\". For springs of the same specification taken from the same heat treatment furnace, 10% (but not less than 2) of them shall be tested for their deformation or stiffness under specified loads, and the deviation in their deformation or stiffness shall not exceed 15% ； 3. The material of the safety valve components is resistant to media corrosion ； 4. The safety valve has not opened during use ； (No further delays allowed) 5. The pressure vessels and safety valve bodies show no obvious rustation when in use ； 6. The pressure vessel contains non-sticky media with a moderate or lower level of toxicity. 7. During two consecutive operational inspections, no issues listed in Article 16(5)2 were found with the safety valves used ； 8. The user unit has established a safety valve calibration station that meets the requirements of Annex III, and carries out safety valve calibration on its own ； (3) The user unit is equipped with reliable pressure control and regulation devices or overpressure alarm devices. (II) For spring-loaded safety valves that meet the requirements specified in items 1, 3, 4, 5 of paragraph (I) and paragraph (II) of this article, their calibration interval may be extended to a maximum of 5 years provided that the following conditions are also satisfied: 1. The safety valve manufacturer can provide proof that the springs used have been subjected to high-pressure treatment or heat-treated under high pressure in accordance with the standard GB/T 12243-1989 \"Spring-Loaded Safety Valves\"; furthermore, 20% of the springs of the same specification from the same heat treatment furnace (but not less than 4 springs) shall be tested for deformation and stiffness under the specified load, with the deviation in deformation or stiffness being no more than 10% ； 2. The pressure vessel contains gas media with a low degree of toxicity or even lower, and the operating temperature does not exceed 200°C.

What was said upstairs was quite clear; it’s just that I wonder whether the inspection of pressure gauges is still divided into three categories, whether the calibration intervals for these three types of gauges differ, and how to calibrate safety valves that cannot be removed.

Safety valves can be inspected without having to be removed; those in our factory haven’t been removed, yet they have still been inspected. The safety valves on boilers are inspected every six months

All the pressure gauges in our company have a validity period of 6 months, and the reports are issued by the quality supervision agency, including those for negative pressure! :victory:

The regular inspection of safety accessories is carried out in accordance with the provisions of the \"Inspection Regulations for Pressure Vessels in Use\". Where the Provisions for Inspection of In-service Pressure Vessels do not provide specific guidelines, the inspection agency shall prepare an inspection plan and submit it to the provincial safety supervision authority for approval. Safety valves should generally be calibrated at least once a year; when it is difficult to remove them for calibration, on-site calibration (in-line calibration) should be used. The rupture disc devices should be replaced regularly; those that have exceeded the maximum design rupture pressure without bursting must be replaced immediately ； Blowout valve devices used under harsh conditions should be replaced annually ； Generally, blast disc assemblies should be replaced within 2–3 years (except where the manufacturer specifies that the service life can be extended). Pressure gauges and temperature measuring instruments shall be calibrated within the period specified by the user entity.

The answer on the 2nd floor was very detailed; I learned a lot from it