The Butt Welding Ring Loose Flange, also known as a Lap Joint Flange, is a two-piece flange system consisting of a backing flange and a butt welding stub end (ring). 

The stub end is welded to the pipe, while the loose flange slides over the pipe and rotates freely around the stub end.

This design allows easy alignment of bolt holes during installation and reduces flange material costs. 

Butt welding ring loose flanges are widely used in corrosive environments, pipelines requiring frequent disassembly, 

and systems where different materials are needed for the flange and pipe.

Working Principle of Lap Joint Flange

Stainless steel butt welding ring loose flange consists of two main components: a stub end (butt welding ring) and a loose backing flange.

First, the stub end is butt welded to the pipe, forming a secure and permanent connection. 

The backing flange is then placed over the pipe and can rotate freely around the stub end.

FAQ

What is the difference between a lap joint flange and a weld neck flange?

A lap joint flange uses a stub end and loose backing flange, while a weld neck flange is welded directly to the pipe with a tapered neck.

Why use a loose flange design?

The rotating backing flange allows easier bolt alignment and installation.

What materials are used for butt welding ring loose flanges?

Common materials include stainless steel 304, 304L, 316, and 316L.

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