Can loose-flange welded rings (PJ/SE) replace welded flanges with necks (WN)?
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This post was last edited by Yu Qing on 2021-3-19 at 15:01. For pipelines using high-temperature process gases (around 350°C), wafer-type butt weld flanges were previously used; these pipelines were connected to multiple storage tanks. Due to manufacturing and installation errors, the flanges connecting the tanks were out of alignment, making it impossible to fasten them together with bolts. Is it possible to use loose-flange butt weld fittings (PJ/SE) as a substitute for wafer-type butt weld flanges (WN), so that the flanges can be rotated during connection to align the openings? Is there any standard that addresses this issue? The tables in chemical pipeline design manuals provide information on flange selection; they mention PJ/SE but only state that it is suitable for stainless steel pipes. Moreover, the wall thickness of the part of such flanges that is welded to the pipe is quite thin (the wall thickness of a DN100 flange is 3.6 mm). Could using PJ/SE instead of WN have any adverse effects?
You can consider using a metal hose with a necked butt-weld flange as a substitute； It’s necessary to use it according to the standards; there’s no way around it!
Okay, are there any standard specifications stating that the medium in metal hoses can be flammable, explosive, high-temperature gases containing oil and gas?
Metal flexible connectors are often used for the interfaces of forced circulation pumps! The liquid is a flammable and explosive organic solvent!
Personally, I think this is a way to save alloy steel materials