What are the structural types for pipe flanges used with explosive media?
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This post was last edited by shinaijian on 2020-7-14 at 12:53. I happened to take a look at TSG R0004-2009 – why does it stipulate that for pipe flanges used with flammable and explosive media, wafer-type butt-welded flanges should be used? How do you usually use it?
Choose according to the standard – go for the higher one, not the lower!
The welds of butt-welded flanges are subjected to better stress conditions; local stresses do not experience sudden changes due to the presence of fillet welds, which reduces stress concentration. This is beneficial for the stiffness of the flange, as it prevents the flange from becoming unstable under structural stress, thereby lowering the risk of seal failure. My personal understanding is that, in simple terms, this architecture makes it difficult for leaks to occur at the flange locations, thus making the equipment safer.
Following the highest standards, we use WN for 0.4 MPa steam pipelines here as well
The definition of explosive is quite broad; in fact, most flammable substances can be classified as explosives. In the design of conventional pressure vessels on site, it is no longer necessary to indicate whether a substance is flammable or not. The selection of flanges for flammable and explosive media is based solely on sealing performance, with no regard for stress or pressure resistance. For flammable and explosive media, necked butt weld flanges can definitely be used; plate butt weld flanges should not be used in such cases. GB150 only mandates that flanges with necks be used for highly hazardous media.
When designing systems involving explosive materials, we have chosen flat-welded flanges with a neck; such flanges provide sufficient stiffness. Wrapped gaskets can also be used – so what’s the problem? Flanged butt-welded pipes with necks are required only under condition 3.2.5(2) of TSG21-2016. The answers to your questions don’t include the correct sources: lol
Under normal circumstances, if the medium is only explosive and the pressure meets the requirements of the temperature rating, necked butt-weld flanges of PN16 are commonly used.
Please pay attention to the word “wait” and consider the stress distribution model of the flange with a neck for butt welding.
Our quality inspection department says it’s an explanation, not a standard, and this explanation doesn’t match the standard.