Requirements for pressure gauges used in pressure testing of pressure equipment

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Pressure testing is an important step in the manufacturing process of pressure-bearing equipment; it is also a process for inspection and verification. It includes hydraulic testing and pneumatic testing, with hydraulic testing being the method commonly used. A pressure gauge is required during the testing process, and this article outlines the requirements for pressure gauges used in testing as specified in the main pressure vessel standards. The domestic technical regulation TSG 21-2016 requires the following: 1. At least two pressure gauges with the same calibrated range ； 2. Place it in a visible position at the top ； 3. Precision grade requirements. The domestic technical standard GB/T150-2011 further specifies the requirements for the range (1.5 to 3 times the test pressure, with 2 times the test pressure being preferred), and it also stipulates that the diameter of the dial must be at least 100 mm. No requirements are specified for the verification time interval, nor is the use of digital pressure gauges clarified. Let’s take a look at the requirements of ASME VIII-1 (2021 edition), which are commonly used in the industry: 1. The pressure gauge must be connected directly to the vessel (without any valves) ； 2. For large pressure vessels, one record-type and one indicator-type are recommended ； 3. The range is recommended to be 1.5 to 4 times the test pressure, with 2 times being preferred ； 4. Verification is required; there is no specified interval for verification (this needs to be defined in the quality manual). 5. A digital pressure gauge can be used, requiring accuracy comparable to that of an analog gauge. ASME VIII-2 specifies a inspection interval of 6 months based on VIII-1. Let’s now take a look at the requirements of the EU carbon pressure vessel standard EN13445 (version 2021), which is being used more and more often: The requirements for pressure gauges used in testing under EN13445 are essentially the same as those specified in ASME VIII-2, with a calibration interval of 1 year. There are no clear requirements regarding the use of digital pressure gauges. Suggestion: As digital pressure gauges are becoming increasingly widely used, it is recommended that domestic technical specifications and standards include requirements for their use.