Preparation of weld joints in pipe welding

 

Preparation of joint 

In today's era, countless kilometers of pipes are being laid around the world every day. The welding process is used to connect them. Preparation of a pipe joint is an initial and essential part of the welding process to achieve welding quality.

One of the main causes of welding defects is also an improper technique of joint preparation. Usually, the preparation of a joint consists of the following steps.

Bevalling (Preparing edges), Cleaning of joint surfaces, Fit-up the joint, and Tack-weld.

Edges Preparation      

The following points are followed to create an ideal joint. 

• The joint angle should be 37.5° and included angle should be 75° degrees ± 3°.
• The root face of the joint should be made from 1.5 mm to 2 mm.
• The root gap of the joint should be 1.5 mm to 2.5 mm.

It may vary slightly according to certain parameters, or in certain types of joint.

There are two methods used for bevelling in the pipe.

• Manual and
• By Pipe Bevelling Machine.

With the new technology, many companies have developed machines in this area, which simplifies the beveling process and saves time...

Pipe Bevelling Machine.

In pipe and pipe fittings are usually beveled by machining. Which is mainly done by gas cutting (oxyacetylene).

After the use of this method, the surface needs to be cleaned with a grinding machine.

Cleaning of Joint surface

Using the oxyacetylene cutting process, the surface of the joint is roughed and also containing oxide film, so the surface must be completely free of oxide film before any welding. There must be a process after cleaning a joint. This is done to remove all types of dust, rust, oil, dirt and iron particles which can cause welding imperfection.

Fit-up the joint

The fit-up process is initiated after the joint is cleaned.

See details about joint

Welding joints