Editing Flange (section)

== Pipe flanges ==
Piping components can be bolted together between flanges. Flanges are used to connect pipes with each other, to valves, to fittings, and to specialty items such as strainers and pressure vessels. A cover plate can be connected to create a "blind flange".<ref>{{Cite web|url=https://www.piping-world.com/piping-flanges-types-of-flanges-in-piping-systems|title=Piping Flanges – Types of Flanges in Piping Systems|website=www.piping-world.com|date=31 May 2023 }}</ref> Flanges are joined by bolting, and sealing is often completed with the use of gaskets or other methods. Mechanical means to mitigate effects of leaks, like spray guards or specific spray flanges, may be included. Industries where flammable, volatile, toxic or corrosive substances are being processed have greater need of special protection at flanged connections.
Flange guards can provide that added level of protection to ensure safety.<ref>{{Cite web|url=https://www.indanasteel.com/p-guards.php|title=Flange Guards Safety Spray Shields For Pipe &#124; Valve Cover & Guard |website=Indana Steel}}</ref>

There are many different flange standards to be found worldwide. To allow easy functionality and interchangeability, these are designed to have standardised dimensions. Common world standards include ASA/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean). In the USA, the standard is ASME B16.5 (ANSI stopped publishing B16.5 in 1996). ASME B16.5 covers flanges up to 24 inches size and up to pressure rating of Class 2500. Flanges larger than 24 inches are covered in ASME B16.47.

In most cases, standards are interchangeable, as most local standards have been aligned to ISO standards; however, some local standards still differ. For example, an ASME flange will not mate against an ISO flange.{{Citation needed|date=May 2021}} Further, many of the flanges in each standard are divided into "pressure classes", allowing flanges to be capable of taking different pressure ratings. Again these are not generally interchangeable (e.g. an ASME 150 will not mate with an ASME 300).<ref name=B165>ASME B16.5</ref>

These pressure classes also have differing [[pressure]] and [[temperature]] ratings for different materials. Unique pressure classes for piping can also be developed for a process plant or power generating station; these may be specific to the corporation, engineering procurement and construction (EPC) contractor, or the process plant owner. The ASME pressure classes for flat-face flanges are Class 125 and Class 250. The classes for ring-joint, tongue and groove, and raised-face flanges are Class 150, Class 300, Class 400 (unusual), Class 600, Class 900, Class 1500, and Class 2500.<ref name=B165 />

The flange faces are also made to standardized dimensions and are typically "flat face", "raised face", "[[Groove (machining)|tongue and groove]]", or "[[Gland (engineering)|ring joint]]" styles, although other obscure styles are possible.

Flange designs are available as "[[Weld neck flange|weld neck]]", "slip-on", "lap joint", "socket weld", "[[Threaded pipe|threaded]]", and also "blind".<ref name=B165 />