An Overview of ANSI Flange Dimensions and Pressure Classes

2015 May25

An Overview of ANSI Flange Dimensions and Pressure Classes

An external or internal ridge, or rim is known as a flange. The main uses for flanges are for strength, for connecting to another object, and in keeping rail wheels from derailing. The flange of an iron beam is an example of use for strength; the flange on the end of a pipe is an example of use for connecting.

Flanges Provide Easy Assembly and Disassembly of Pipes

Flanges help with the easy assembly and disassembly of pipes. Flanges are welded or screwed most of the time. When fastened to a pipe, a flange can be a plate or ring that forms a rim at the end of the pipe, like a closet flange for example. A plate for sealing the end of a pipe is called a blind flange. A connection of pipes that are bolted together by the flanges of the connecting parts, is known as a flange joint.

Pipe Flange Dimensions – ANSI & ASME

Pipe flanges are made with standard dimensions so that they can be easily utilized and interchanged. The ASA/ANSI/ASME standards are followed in the USA, while other countries follow different standards. The PN/DIN standard is followed in Europe, while the BS10 standard is followed in Britain, and the JIS standard is followed in Japan. Generally, flanges confirming that conform to different standards are not interchangeable. Even within the same standard, flanges from different pressure classes are not interchangeable. For example, an ANSI flange rated 150 will not work with an ANSI flange rated 300.

Different Pressure Classes for Flanges

These pressure classes also have differing pressure and temperature ratings for different materials. Flange faces are, typically, of the following types: “flat face”, “raised face”, “tongue and groove”, or “ring joint”. Flange designs have names such as “weld neck”, “slip-on”, “lap joint”, “socket weld”, “threaded”, and “blind”.

Pipe flanges have machined surfaces and are made of different materials like cast iron, stainless steel, plastic, bronze and aluminum. Usually, flange material is of the same material as the pipe.

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