For steel atmospheric pressure vessels where the medium is extremely hazardous, are there any requirements regarding the pressure rating of manholes?
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For steel atmospheric-pressure vessels operating at atmospheric pressure, when the medium is extremely hazardous, the pipe flanges are required to meet the specifications specified in HG/T20583, with a pressure rating of 2.0 MPa, and they must be neck-welded flanges. However, there are no detailed regulations regarding manholes. I would like to ask experts: Are there any requirements regarding the pressure rating and sealing surface for this DN500 manhole?
At least it’s the same as taking over; it’s possible that a higher level will also be required.
Which standard specifies this?
In which standard is this specified?
I*usually classify manholes as vessel flanges; according to the regulations, vessel flanges need to have a pressure rating of 1.0 MPa or higher
It is specified in Article 4.1.6 of HG/T20583.
The manhole does not have an external flange; the requirements regarding pipe flanges do not apply, and 1.6WN is sufficient
This post was last edited by Suspected law-abiding citizen on 2023-2-20 at 15:20. Personally, I think of the equipment as a single unit, and the manhole should have the same pressure rating as the equipment’s flanges. I couldn’t find any specific specifications, but the logic is as follows. 1. The manhole flange seat is directly attached to the equipment body and shall meet the relevant requirements regarding flange pressure stipulated for the equipment body. 2. Even if the nominal diameter is the same, flanges of different pressure grades differ in terms of bolt hole spacing and diameter; therefore, the flange cover corresponding to the manhole door must also match the specifications of the flange in order to ensure proper installation. 3. In summary, once the two main components of the manhole are determined, the manhole itself is also defined; its pressure rating should be consistent with the requirements of the equipment flanges. Additionally: For the answer to this question, people sitting in different positions tend to give different answers. As a designer, I tend to be conservative and cautious, and of course I want to meet all the requirements specified in the standards that are available. The client hopes to cut costs wherever possible. If you are a designer or a technical staff member responsible for operation, it is recommended to adhere to higher standards, as you will indeed be held accountable if there are problems with the equipment. As long as the design is in line with the specifications, the designer is not at fault. Don’t be too fussy over such minor costs; after all, the savings go to the boss, not you, while you have to bear the risks yourself.
When the medium is extremely highly hazardous, atmospheric-pressure vessels must be designed in accordance with pressure vessel standards.
It is specified in Article 4.1.6 of HG/T20583.