Selection of manhole flanges
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Today I saw a discussion in the group regarding manhole flanges. The medium in question is highly hazardous, with a design pressure of 0.8 MPa. According to HG/T 20583-2011, the nominal pressure class of pipe flanges used for highly hazardous media should be no less than 2.0 MPa. Additionally, TSG21 requires the use of long-neck weld-on flanges. Thus, the problem arises: the WN manhole flange with PN25 rating weighs only 59 kg, while the WN pipe flange with PN25 rating weighs 96 kg. In order to save money, the manager wants to replace the manhole flanges with equipment flanges. :L 1. Is it possible to use a PN16 pressure rating? (The reason is that the flange is lightweight, which helps reduce costs.) 2. Is it possible to use the equipment’s long-neck flange? (The reason is that the flange on the equipment is lightweight, which helps reduce costs…) Come on, let’s discuss your thoughts. Given a difference of several dozen kilograms in the material weight, between using a standard manhole and creating a design for a custom manhole, which option would you choose? I truly don’t know what changes the reforms will bring to the market. With the elimination of the requirement for qualifications to approve pressure vessels, I wonder how much this will allow small factories to act recklessly, and whether there will be a costly price to pay for it…
. . . Why isn’t anyone discussing it? This is really a great topic! ! ! I think it’s better to follow the standards; otherwise, what’s the point of having standards? . .
It might be a small business! I want to avoid violating standards and regulations while also reducing costs. But thinking about it the other way around, the flanges differ by just a few dozen kilograms; this reduces the material cost. However, the need to create custom designs increases labor costs. Moreover, since these are custom parts that require machining, the processing costs also rise. Overall, it’s not necessarily a saving. Right?
This should be a corporate action; it’s something separate from the revocation of an approver’s qualifications...
Well, yes, the approver has nothing to do with the content of this post. I’m just expressing my thoughts – since the rule stating that no approval credentials are required for auditing was introduced, and the thresholds for signing off on audits were lowered, it’s inevitable that people with insufficient skills end up taking on these roles.
This post was last edited by SDHZZXM on 2017-10-24 at 17:26. Supervision needs to be strengthened, and the skills of inspection personnel need to be improved...
However, the entities responsible are the companies and their executives; you can use it if you think it’s appropriate, but it’s clear that the companies are accountable for quality and safety. Haha
Just choose according to the standards for manholes; is it necessary to design them from scratch? There’s no need. Besides, changing the manhole flange doesn’t save much money either, and it causes problems when issues arise.
This should be the normal way for most people to act while they’re alive, but in order to cut costs, all sorts of things happen; well, that’s just how it is!
It can be designed this way; neither the fixed-volume specification nor GB150 requires that pipe flanges must be used. If it is not designed in accordance with manhole standards, there is of course no need to comply with them. We have designed flat-weld flange manholes with a pressure rating of PN10. The key is to comply with the pressure vessel regulations and adhere to GB150. Other standards can be used first, or they can also be omitted. It is not necessary to design in accordance with HG/T 20583-2011, nor is it required to comply with it. Of course, it is best to design in accordance with HG/T 20583-2011.
The company is not responsible; only the designer is