【Weekly Topic】The topic on whether pressure relief valves need to be calibrated (second week of August)
Thread Content
This week’s topic will be one of the suggested topics; everyone is welcome to participate in the discussion! The oxygen and acetylene cylinders used in the factory are rented from qualified professional manufacturers; during external audits, questions are asked as to whether the pressure regulators on these cylinders have been calibrated Later, after checking relevant information, it was stated that pressure regulators do not need to be calibrated. I asked the local special equipment inspection agency and the Quality and Technical Supervision Bureau, and both said that pressure regulators do not require calibration. However, the Quality and Technical Supervision Bureau mentioned that the pressure gauge attached to the pressure regulator does need to be calibrated. But since the pressure in the gas cylinder keeps decreasing, and although it is a pressure vessel, it is in a process of pressure release – is it really necessary to calibrate it? Feel free to share your opinions. [Collection of Essential Knowledge from the Mechanical Forum] http://bbs.hcbbs.com/thread-1389197-1-1.html Topics for each week and daily questions (prizes for participation) http://bbs.hcbbs.com/thread-1373282-1-1.html Summary thread of weekly topics: http://bbs.hcbbs.com/thread-1404940-1-1.html
According to the Quality Supervision Bureau, an appraisal is required. Pressure gauges used on-site, and since they involve potential hazards, they definitely need to be calibrated. If the pressure gauge fails, it can also pose safety hazards during use. From an official perspective, that’s what it means.
In accordance with China’s Metrology Law and related regulations, measuring instruments are classified into those that require mandatory verification and those that do not. Instruments subject to mandatory verification must be sent to qualified metrology verification institutions for periodic checks, while for other instruments, enterprises may choose to carry out internal verification/calibration or entrust external agencies to do so, depending on their actual circumstances; the interval between such verifications can be longer or shorter than what is specified in the relevant regulations. Meters and instruments subject to mandatory inspection for use in work include those used in safety protection, environmental monitoring, healthcare, and trade settlement, and which are listed in the **Catalogue of Meters and Instruments Subject to Mandatory Inspection**. The use of an oxygen cylinder involves a pressure relief process. The pressure gauge on the pressure regulator serves to monitor pressure; this regulator is installed on the oxygen cylinder only during use and removed after it is no longer in use. Therefore, the pressure gauge on it is not considered a device for safety measurement, and it is not subject to mandatory calibration. Nevertheless, calibration is still necessary, though it can be carried out more flexibly, with the frequency of inspections possibly being increased. Additionally, it is the pressure gauge used at gas stations for filling oxygen and acetylene cylinders that serves safety purposes, and it is a measuring instrument subject to mandatory inspection.
Refer to JJF 1328-2011 \"Calibration Specification for Gas Pressure Reducers with Bourdon Tube Pressure Gauges\"
Pressure gauges and gas cylinders themselves must undergo regular mandatory inspections, and pressure regulators should also be checked; however, they are not considered items subject to mandatory inspection
The corner valve on the gas cylinder should not be used as a pressure regulator; it is intended to serve as the root valve of the cylinder, with a separate pressure regulator being installed
Check the provisions of Articles 9 and 11 of the Gas Cylinders Safety Inspection Regulations.
Pressure gauges, as safety accessories, must be inspected; pressure relief valves seem to be included in the inspection of gas cylinders.
The pressure gauge needs to be inspected; if the supplier provides only the gas cylinder without a pressure regulator, then the pressure regulator also needs to be inspected. Additionally, the gas cylinder must have a gas purity certificate.