When building a pipeline, the length of the pipes used are not always known. By manufacturing the pipe separate from the plate flange, the welders can cut the pipe to length and weld a plate flange in place to join the pipes at any needed length. The plates can also be welded to the pipe on a slight bias, allowing two pipes to be joined that may not be precisely lined up.
 
plate flange designs are uniform in any given size regardless of materials used to create them. This allows a 6-inch (15 cm) black pipe flange to mate perfectly with a 6-inch stainless steel flange. The plate flanges will have a serrated finish on the inside mating surface, which allows the plate to seat into the gasket material. This ensures a perfect seal between two joining pipes.

For applications with no/low pressure at ambient temperatures, plate flanges are often a cost effective solution when raised faces and hubs are not necessary.

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