A safety valve is not required during the airtightness test; there is no need to adjust the setting pressure of the safety valve, and the maximum allowable operating pressure does not need to be specified
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This post was last edited by *AOL_1 on 2018-2-8 at 13:05. According to the requirements of TSG R0004-2009, when conducting a airtightness test, the safety accessories should generally be installed in their complete form. According to the requirements of TG21-2016, when conducting a airtightness test, it is generally necessary to have all safety accessories installed. Therefore, the requirement that safety accessories be fully installed during airtightness testing is more reasonable in the 2016 version of the regulations, as it sets a lower standard compared to the 2009 version. TG21-2016’s tolerance specifications do not provide an explanation for this in the revision notes. According to the interpretation in TSG R0004-2009, when conducting a airtightness test, the maximum allowable operating pressure of the container can be used as the maximum value for the operating pressure of the safety valve. However, this definition also specifies the key points as follows (for the details, see the original text): For pressure vessels manufactured by factories, a gas-tightness test can be conducted at the factory without safety accessories; whereas during operational tests at the site of use, the sealing performance of their connections can be checked ； The manufacturer can conduct a gas-tightness test with the safety accessories in place; if the test is successful, even if those accessories are removed and reinstalled on site, it is still necessary to check the sealing performance of their connections during operational testing on site. The pressure used for running tests is generally the operating pressure, which is lower than the design pressure. When performing a gas-tightness test on equipment manufactured on-site and equipped with safety accessories, if leakage occurs at the connection points of these safety accessories, the possible problem is leakage at the sealing surface of the container flange ； Leakage at the sealing surface of the safety valve ； Installation issues caused the leakage ； Or various combinations of the above 3 situations may occur, and each of these reasons needs to be investigated individually. However, if the device is subjected to a gas-tightness test without safety accessories and leakage occurs at its connections, it must be resolved by the container manufacturer. It can be concluded that pressure vessels manufactured by factories can undergo airtightness testing without safety accessories ； For pressure vessels manufactured on-site, in accordance with the TG21-2016 pressure vessel standards, a gas-tightness test can also be conducted without safety accessories. However, in both of the above cases, pressure vessels require that their sealing performance at the connections to safety accessories be checked during on-site operation tests. Since the pressure used for conducting the tests is generally the operating pressure, which is lower than the design pressure, it is not necessary to adjust the setting pressure of the safety valve in order to carry out the tests. Since pressure vessels can undergo airtightness testing without safety accessories under any circumstances, and this still meets the requirements of the vessel regulations, there is no need to specify the maximum allowable operating pressure for such vessels.
The calibration of safety valves allows for checking the airtightness of the valves themselves. When a pressure vessel is airtight, it is sufficient to check only the airtightness at the outlet of the safety valve. The requirement in relevant regulations that safety accessories must be fully installed when airtightness is to be verified is intended merely to check the tightness of the connections between the safety valve and the equipment; in my opinion, this is unnecessary and adds to the design calculations without providing much practical benefit.
I have read the following posts: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1473786 https://bbs.hcbbs.com/thread-1282611-2-1.html https://bbs.hcbbs.com/thread-731290-1-1.html https://bbs.hcbbs.com/thread-1022360-1-1.html My opinion: 1. It is not very useful for containers for which air-tightness testing is required by regulatory standards to have the “maximum allowable operating pressure” marked; moreover, there are many factors involved in the design calculations, so this value may not be accurate. 2. The opening pressure of the safety valve does not need to be diversified.
On the third-to-last line, are you sure the test pressure is lower than the design pressure? ?
For pressure vessels, the operating pressure is definitely lower than the design pressure.
It’s chaotic; the regulations are a bit confusing already, and your explanation makes things even more chaotic.
According to regulatory standards, airtightness tests generally require the use of safety accessories; one of the purposes of this is to check the sealing performance of the flange connections, but it is primarily done for safety reasons. After all, gases are compressible substances – unlike liquids. If a leak occurs during pressure testing of equipment, the pressure drops when liquid leaks out, but gases can cause greater damage. That’s what is said, but there is currently no uniform approach regarding whether safety accessories are actually provided for the airtightness tests; all there are are unrealistic responses from the authorities. Some time ago, my colleague gave a defense presentation to present the relevant evidence; in order to ensure the proper conduct of the airtightness tests, the drawings specified the maximum allowable operating pressure, with the setting pressure of the safety valve being higher than the design pressure. Experts say this is a technical error that does not meet the standard requirements. Is it like a mute person forced to eat bitter herbs?
Our colleagues also have varying opinions on this, so I’m posting it here to gather more ideas, in the hope of arriving at a clearer conclusion.
The operating pressure of a pressure vessel can be equal to the design pressure; where the maximum allowable operating pressure is indicated in the diagram, the operating pressure may temporarily (ideally) exceed the design pressure.