The General Administration’s responses to eleven issues, including “the use of pressure vessels beyond their designed service life”

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Question 1: Questions regarding temperature measuring instruments/temperature measurement devices? According to relevant requirements, Article 9.2.3 of the “Safety Technical Inspection Regulations for Stationary Pressure Vessels” (TSG21-2016) stipulates that temperature measuring instruments shall be calibrated regularly ； Clause A3.5.7 of the \"Rules for Periodic Inspection of Pressure Pipelines – Industrial Pipelines\" (TSG D7005-2018) stipulates: Inspection items for temperature measuring instruments (1) Whether the regular calibration and maintenance of temperature measuring instruments meet the requirements ； Clause 3.5.3.4(2) of the \"Rules for Periodic Inspection of Boilers\" (TSG G7002-2015) stipulates that it is necessary to examine the calibration or verification records and reports of temperature measurement devices to ensure that they meet relevant requirements and are within their valid period. ”Temperature measuring instruments/devices used for special equipment need to be calibrated regularly; however, no relevant standards have been found that specify the calibration cycle, calibration agencies, and items to be calibrated. May I ask: 1) What is the calibration cycle for the temperature measuring instruments/devices installed on special equipment, and which are the calibration institutions? 2) Which temperature measuring instruments/temperature detection devices within the boiler area need to be calibrated, and which do not? 3) If it is found on-site that the temperature measuring instrument/device has not been calibrated or its calibration period has expired, does this affect the inspection conclusion/inspection rating? Reply 1: For questions regarding the verification and calibration of temperature measuring instruments/devices, please consult the relevant metrology department. Question 2: Certification for personnel responsible for the inspection and maintenance of fixed pressure vessels and pressure pipelines? Appendix 2 to Document No. 3 of 2019 states that there is no corresponding fixed-pressure vessel category among the certification requirements for special equipment operations; instead, it refers to pressure vessels with quick-opening doors ； In addition, there is no pressure pipeline inspection and maintenance. Since the pressure vessels used in our facility are all fixed-type pressure vessels, does this standard imply that it is permissible for personnel responsible for the inspection and maintenance of fixed-type pressure vessels and pressure pipelines to work without holding relevant certificates? Please provide a response to facilitate the management of special equipment operators. Reply 2: After the implementation of the “Announcement No. 3, 2019 by the State Administration for Market Regulation”, among the qualifications required for operators of pressure vessels, only three types of operations—operation of quick-opening pressure vessels, operation of mobile pressure vessels, and maintenance of oxygen chambers—mandate that operators must hold relevant certificates. For all other personnel, enterprises may conduct training as deemed appropriate based on their specific circumstances. Question 3: Cryogenic pressure vessels? The vacuum-insulated cryogenic vessel designed and manufactured by our company in November 2016 has a volume of 50 m3, a design pressure of 3.0 MPa, and uses liquid nitrogen as the working medium. It adopts a vertical structure and consists of an inner container, an outer tank, and an insulation layer. The diameter of the storage tank is D=3200 mm, the height of the tank is H=12908 mm, and the height-to-diameter ratio is H/D=4.034. The bottom of the container has multiple pipes and valves. It represents the typical structure of cryogenic containers in our country. The containers are designed and manufactured in accordance with GB150 and GB/T18442, and are subject to supervision under TSG21-2016; they have obtained a Special Equipment Manufacturing Supervision and Inspection Certificate issued by the supervision and inspection authority in the place of manufacture. To facilitate the operation of the bottom valves, drawing on our many years of industry design experience, the vessel is equipped with support saddles (three saddles installed on the outer tank) to ensure safe operation of the valves. In the calculation for checking the supports, considering that NB/T 47041-2014 “Tower-type vessels” is not applicable to jacketed tower-type vessels, the supports were calculated and checked in accordance with SH 3048-1999 “Code for seismic design of petrochemical steel equipment” (which was the valid version as of November 2016, the date of vessel design). The calculation results meet the requirements. After the product is installed, experts from the geological inspection department have suggested that, in accordance with Articles 8, 19, and 27 of the Special Equipment Safety Law, it is necessary to meet the requirements of safety technical specifications and relevant standards. The term \"relevant standards\" covers a wide range of regulations; therefore, this equipment should use skirt-type supports as specified in Article 12.4 of HG/T20583-2011 \"Specifications for the Structural Design of Steel Chemical Storage Vessels\", rather than support-type supports. Out of an abundance of caution, I would like to consult with your bureau regarding whether the aforementioned container and the relevant standards mentioned above can be regarded as being in compliance with Article 2 of the General Provisions of the Standards Act (amended in 2007), which stipulates that “mandatory standards must be implemented.” **\"The adoption of recommended standards is encouraged.\" The requirement in HG/T20583-2011 or NB/T47041-2011 to use skirt-type supports is regarded as a recommended practice; it is still possible to adopt a supported structure for the design of such supports Since this container meets the requirements of GB/T150, GB/T18442, and the \"Regulations on Fixed Pressure Vessels\", is it acceptable to use a design with 3 legs for the bottom support based on empirical considerations? Does it still need to meet the requirements of standards HG/T20583-2011 or NB/T47041-2014? Reply 3: The said container should generally use skirt-type supports; specific details can be discussed with industry experts. Question 4: Domestic pressure relief valves are manufactured with left-handed connections in accordance with national standards. There are security risks associated with this interface; the problems include: 1. Most of the handwheels on pressure relief valves are made of aluminum, which can oxidize, preventing them from being tightened properly and leading to air leaks ； 2. The left-handed thread itself has over 30 turns, and some cylinder valves have tolerances such that the elderly and women are unable to tighten the handwheel. Air leakage occurs. 3. A loose, damaged, or deformed sealing ring at the front end of the pressure relief valve can cause air leakage. Account for over 50% of accidents. 4. Pressure relief valve threads (especially those made of aluminum): When changing the bottle, the threads of the pressure relief valve can be easily damaged, making it difficult to turn them. It causes air leakage. 5. Damage to the valve stem and valve core leads to air leakage; fixed valves cannot be repaired on-site, are prone to explosion, and thus are not suitable for widespread use. 6. Liquid-phase valves and gas-phase valves must not be used interchangeably. It has already caused multiple serious accidents. Using new type of plug-in angle valves can prevent gas explosions. A public account on gas explosions reported that in 2018, 80 people died and 928 were injured as a result of such explosions. Regarding the national standard GB/T 7512-2017, 3.1 Non-detachable valves: There is only one sealing ring on the valve stem of the gas cylinder. It must withstand frictional forces from vertical and rotational movements; any cuts or irregularities inside the valve body can cause damage to the sealing ring, leading to air leaks. The valve core is also a wear part that needs to be replaced frequently. Air leakage occurs very easily. Safety is not guaranteed. Reply 4: The cylinder valve shall meet the requirements of **standards and safety technical specifications. For questions related to standards, please contact the relevant standard management department. Question 5: Is a pressure gauge a safety accessory? Is a pressure gauge considered a safety accessory? (Neither the Catalog of Special Equipment nor the relevant safety technical regulations explicitly classify pressure gauges as safety accessories.) If the calibration period has expired, should it be dealt with in accordance with Article 83 of the Special Equipment Safety Law? Reply 5: A pressure gauge is not considered a safety accessory. Meters and other devices that require mandatory metrological verification must be inspected by the metrology authorities in accordance with the requirements of relevant metrological laws and regulations. Question 6: Questions about the “equipment system”? 　 1) What exactly are the “equipment systems” referred to in Quality Inspection Special Letter [2016] No. 46? 　　 2) Do the pressure vessels used in complete sets of equipment (such as oil separators and evaporators in central air conditioning systems, and liquid storage tanks in the cold chain systems of supermarkets and shopping malls) fall under the category of “equipment systems”? “For pressure vessels in the “equipment system,” there is no need to submit notifications regarding their installation or to have their installation supervised. What are the specific requirements regarding the installation quality certification documents issued by the installation company when such vessels go through registration for use? Reply 6: 1). Pressure pipelines, pressure vessels are installed and connected to devices and structures such as movable skids or mechanical equipment to form systems with certain functions, thereby creating skid-mounted pressure equipment systems or mechanical equipment systems; for specific details, consult relevant technical institutions ； 2). The said device system can be registered directly. Question 7: Inquiry regarding inlet coils for pressure vessels. Our company needs to manufacture Class D1 pressure vessels equipped with internal heating coils made of pipes with a diameter of DN30–60. The material to be used is austenitic stainless steel; the total length of these coils is approximately 100 meters. The pressure inside the pipes is 290 bar, and the medium involved is beverage/milk or water. The operating temperature is 135 degrees Celsius. These coils need to be imported rather than manufactured locally, and they will then be welded to the vessel’s cylinder. During the inspection of this pressure vessel, is it necessary for this coil component to be subject to inspection and supervision as a part of the pressure vessel? What are the requirements regarding the qualifications of the manufacturing unit for this coil imported from abroad? Reply 7: It can be handled in accordance with the requirements for multi-chamber pressure vessels stipulated in Article A1.3.2 of the “Regulations on Pressure Vessels”. The coil in question does not qualify as a pressure vessel; thus, there are no qualification requirements for its manufacturing unit, and no manufacturing supervision and inspection is necessary. Question 8: Tubular container? Please advise on how regular inspections are carried out in the case where a tubular container is not moved and is used only within the site What testing qualifications are required? Should it be inspected and managed for use under the category of fixed pressure vessels, stationary gas cylinder bundles, or tube trailers? What inspection qualifications are required? Thank you. Please specify what exactly is used as a reference for the inspection, and what qualifications are required for inspection agencies? Reply: Tube bundles containers are classified as mobile pressure vessels. Their use and management, as well as periodic inspections, must be carried out in accordance with the “Regulations on Mobile Pressure Vessels”. Inspection agencies must possess the qualification to inspect RD8 long tube trailers (including tube bundle containers). Question 9: Exceeding the designed service life of pressure vessels? The \"Periodic Inspection Report for Fixed Pressure Vessels\" submitted by a certain company to our organization indicates that the inspection date was May 2017, with the next inspection scheduled for May 2021 ； The date of manufacture is September 1987, and the date of use is July 1989. This container has exceeded its designed service life of 10 years based on the date of use, but no registration change for its use has been carried out. According to Article 2.14 of the Rules for the Use and Management of Special Equipment, 1) may our bureau decide not to accept it? ； 2) Is the extended service life calculated based on the date of manufacture or the date of use? Thank you! Reply 9: 1) Pressure vessels that have reached their designed service life and are to be used further must be handled in accordance with the requirements of Article 7.1.7 of the Regulations on Fixed Pressure Vessels, as well as Articles 2.14 and 3.8 of the Rules for the Use and Management of Special Equipment. Only after obtaining a revised registration certificate for use can they continue to be utilized; 2) The calculation is based on the actual date of commissioning. Question 10: Manholes for pressure vessels? Our company often provides manholes for use with pressure vessels to our customers; some of these manholes are even imported from abroad. Regarding this, we have the following questions: 1). Is it necessary to conduct supervision and inspection on the manholes of pressure vessels? If supervision and inspection are required, which procedure should be followed? 2). If it is a foreign company, is it necessary to obtain a special equipment manufacturing license in our country? Reply 10: 1). There are no supervision and inspection requirements for the manhole manufacturing process ； 2). Manhole manufacturing companies are not required to have a manufacturing license. Question 11: Issues regarding local inspection of accumulators? According to Article 1.4 of the Fixed Capacity Regulations, accumulators only need to meet the requirements regarding general provisions, design, and manufacturing; they do not require local inspection or registration. Is that the case? Reply 11: Accumulators do not require registration for use, nor do they need to undergo regular inspections during their designed service life. Source: Special Equipment Safety Supervision Bureau