Issues regarding flange connections, flange selection, as well as the connection and welding processes
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What are the requirements for selecting flanges during the connection process? The types of flanges include: slip flanges, socket weld flanges with necks, butt weld flanges with necks, socket weld flanges, threaded flanges, loose sleeve flanges, flange covers, and welded flanges
Regarding the flange gaskets, the selection specifications and format details can be found in the standard HG/T20592-20635-2009 \"Steel Pipe Flange Gaskets and Fasteners\"; please refer to this standard for relevant information.
It’s included in the standards. Generally, flat welding and butt welding with a neck are used most often; one is applied in medium and low pressure applications, while the other is used in high pressure applications.
Could you please explain it to me more clearly?
This post was last edited by Refiner on 2015-12-6 08:53. General principles for selecting flange types: The pressure ratings must be consistent; different flange types are suitable for different pressures – flat flanges, raised face flanges, and grooved face flanges. The properties of the medium flowing through the pipeline also play a role; for example, in low-pressure pipelines carrying industrial water, flat welding flanges are used, while for pipelines carrying flammable substances, raised face welding flanges are required. Working conditions also influence the choice of flange type – for instance, slip-on flanges are used in locations where frequent disassembly is necessary
It depends on your process requirements; for water pipelines with low pressure, it is advisable to use inexpensive butt-welded flanges
Butt welding and socket welding flanges are generally used more frequently; butt welding is applied to sizes above DN50, while socket welding is used for sizes below DN50. Flat welding flanges are generally used for ordinary water pipelines. Loose-flange connections can be used for corrosive media and are relatively economical.
It is recommended to read more standard books on flanges. Threads and socket types have limitations: they offer a narrow range of specifications and few pressure grades. Flat welding flanges are widely used, but their pressure range is limited; they come in a full range of sizes including large ones, and belong to the low-pressure category. Necked flat welding flanges fall into the medium-pressure category, situated between flat welding and butt welding flanges. Necked butt welding flanges belong to the high-pressure category, with the lowest pressure level being 10 bar. There are many types of sealing faces, such as FF, RF, M, FM, T, G, RJ, etc. Flange covers are the easiest to understand – they are used in conjunction with flanges for sealing, functioning similarly to plug nuts and pipe caps, only with bolt connections