Regarding the operating pressure and maximum allowable working pressure of the overpressure relief devices in the Fixed Pressure Vessels Code
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This post was last edited by flasho2 on 2010-3-10 at 10:51. It is known that a container is to undergo a airtightness test; the operating pressure is 0.78 MPa, while the design pressure is 0.88 MPa. The container is equipped with overpressure relief devices such as safety valves and burst discs. Question: According to the requirements for leakage tests in Section 3.24 of the “Fixed Pressure Vessels Code,” “for pressure vessels equipped with overpressure relief devices such as safety valves and burst discs, if an airtightness test is required during design, the designer shall specify the maximum allowable operating pressure for that pressure vessel.” ” Definition in “Fixed Pressure Vessels”, page P92: “A pressure higher than the design pressure is used as the operating pressure for the overpressure relief device, in order to prevent the activation of this device during testing and ensure the smooth progress of the tests.” This can resolve the conflict between installing safety accessories and the test pressure during the airtightness test. The maximum allowable operating pressure I calculated is 0.882 MPa, which is only 0.002 MPa higher than the design pressure. For vessels with a lower design pressure, the maximum allowable operating pressure is of little significance. Question: For a container in the situation described above, must the maximum allowable operating pressure be indicated on the general diagram or nameplate? Addition: 1. Paragraph (2) of Article 4.8.3 in the Manufacturing section of the ‘Fixed Pressure Vessels Regulations’: ‘When conducting a airtightness test, the safety accessories should generally be fully installed.’ ”In other words, it is not mandatory to have all accessories installed; if a gas-tightness test is conducted without these accessories, then there is no issue related to the activation of safety accessories. For containers that undergo a gas-tightness test, is it then not necessary to specify the maximum allowable operating pressure?
1. Refer to clause 4.1.5 of the capacity regulations; the maximum allowable operating pressure is not required to be specified； Once the maximum operating pressure is specified, the operating pressure for the overpressure relief equipment can be set at this value. 2. As can be seen from 3.24, if the container does not have overpressure relief devices such as safety valves when tested for airtightness, it is not necessary to specify a maximum allowable operating pressure. In fact, the explanation already makes it clear: for pressure vessels equipped with relief devices, it is necessary to specify the maximum allowable operating pressure; this allows the operating pressure at which the overpressure relief device activates to be set higher, thereby preventing it from activating unnecessarily during testing
Article 4.8.3, Paragraph (2) of the Manufacturing Section of the New Regulations: “When conducting a airtightness test, the safety accessories should generally be fully installed.” ” Generally, according to the definition here, it means that installation is necessary. The specification states that if selected by the user, a blind flange can be used as a substitute, but this must be indicated in the quality certification documents, and re-testing on site is required; safety accessories must be installed at that time.
This post was last edited by flasho2 on 2010-3-9 at 17:58. In other words, when conducting a leak test, it is necessary to have all the safety accessories in place. The pressure used for the leak test differs from the pressure at which the safety valve activates by only 0.002 MPa – can a pressure gauge detect such a small difference? The discrepancy between the activation pressure of the overpressure relief device and the pressure used in the leak test is a long-standing issue...
Is the starting pressure of the spring the same as the set pressure of the safety valve?
I think the key to this issue lies in whether a safety relief device is installed during the airtightness testing of the equipment. If such a device is used, the triggering pressure should be set at the maximum allowable operating pressure; the designer must provide this value, otherwise it is not possible to ensure proper airtightness. If it’s not installed, that’s best; the starting pressure should be set, in accordance with the established standards, to a value that is higher than the operating pressure but not greater than the design pressure. As far as I know, the safety accessories for containers are purchased by the owner themselves; the manufacturer is not responsible for providing them. The water pressure and airtightness I’ve checked show that no safety accessories are installed on them
It’s better not to conduct pressure testing with safety attachments – it’s impossible to attach a burst disc in any case. Moreover, it is problematic to equip this device with both a safety valve and a burst disc; it is difficult to determine the appropriate burst pressure for the burst disc, and it is very likely that this pressure will exceed the maximum allowable operating pressure. Even manufacturing tolerances cannot meet the requirement of 0.002 MPa, so installing a burst disc is pointless.
I understand that “if a requirement for a gas-tightness test is specified during the design phase, the designer should provide the maximum allowable operating pressure for that pressure vessel”. The maximum allowable operating pressure must be indicated on the general diagram or nameplate.
This post was last edited by flasho2 on 2010-3-10 21:41. 2. Question: Regarding the requirements for leakage tests on March 24th: “For pressure vessels equipped with overpressure relief devices such as safety valves and burst discs, if a gas-tightness test is required as part of the design, the designer shall specify the maximum allowable operating pressure for that pressure vessel.” ”How should it be understood? According to the definition, the maximum allowable operating pressure should be specified in order to ensure that safety accessories do not activate during airtightness tests; it is not mandatory for pressure vessels equipped with safety valves or rupture disks to have their maximum allowable operating pressure indicated on the design drawings and nameplates. If, during the airtightness test, the airtightness of the container is tested first and then the pressure is reduced to the setting pressure of the safety valve, the safety valve will not activate at that point, thereby achieving the purpose of the airtightness test. I’m not sure if my understanding is correct? The location in the \"Fixed Pressure Vessel Regulations\" where the maximum operating pressure is specified: a, 3.9.2 Pressure at which the overpressure relief device operates: \"For pressure vessels for which the maximum allowable operating pressure is indicated in the design drawings, the pressure at which the overpressure relief device may operate shall not be higher than that maximum allowable operating pressure.\" ” Purpose: Specifying the maximum allowable operating pressure is to increase the activation pressure of the overpressure relief device, thereby preventing it from activating frequently while still ensuring safety. b. 3.24 Leak test: \"For pressure vessels equipped with overpressure relief devices such as safety valves and rupture discs, if a gas-tightness test is required in the design, the designer shall specify the maximum allowable operating pressure for that pressure vessel.\" Purpose: To address the issue of difficulty in completing airtightness tests when the overpressure release device activates during the installation of safety accessories for such tests. c, 4.1.5 Product nameplate: \"(8) Design pressure, maximum allowable operating pressure (if necessary)\\" Purpose: To provide operational data for 3.9.2 and 3.24. d. 8.3.2 Setting pressure of the safety valve: \"The setting pressure of the safety valve is generally not greater than the design pressure of the pressure vessel.\" If the design drawings or nameplate indicate the maximum allowable operating pressure, this value can also be used to determine the setting pressure of the safety valve. Purpose: Same as clause 3.9.2. e: 8.3.3 Burst pressure of rupture discs – When a rupture disc device is installed on a pressure vessel, the designed burst pressure of the rupture disc shall not be greater than the designed pressure of that vessel, and the minimum designed burst pressure of the rupture disc shall not be less than the operating pressure of the vessel. When the maximum allowable operating pressure is specified on the design drawings or nameplate, the designed burst pressure of the rupture disc shall not be greater than the maximum allowable operating pressure of the pressure vessel. Purpose: Same as clause 3.9.2. Personal understanding: The ‘Fixed Pressure Rating Standards’ use terms such as ‘allowed’, ‘permissible’, ‘when necessary’, etc., and there is no requirement to specify the maximum allowable operating pressure on the design drawings or nameplates. If the maximum allowable operating pressure is specified on the design drawings or nameplate, the setting pressure of the safety accessories can be adjusted according to this maximum allowable operating pressure. Markings are provided to supply data for setting the pressure of safety accessories. I hope everyone will come and discuss it.
I implore you: Container weight: 710 Kg; 3. Volume: 1.5 m3; 4. Design pressure: 0.88 MPa; 5. Maximum operating pressure: 0.8 MPa; 6. Pressure test pressure: 11 MPa; 7. Design temperature: 100°C. What is the model?
If you conduct a airtightness test without using all the attachments, how can you be sure that there will be no leaks at those connections? The airtightness test loses its meaning then.