Post Weld Heat Treatment Services

Post weld heat treatment, or PWHT, is a controlled process that involves heating and cooling metals to relieve residual stress and improve their mechanical properties. The process can also make structures more resistant to stress cracking and other forms of damage during dynamic loading conditions. PWHT can be used on structural, piping and pressure vessel components. It is a critical step in many welding projects, and failure to perform it correctly can cause problems like weld defects and corrosion in the weldment.

What is heat treatment procedure?

The need for Post weld heat treatment services depends on the specific material and service requirements, such as the likelihood of failure by stress cracking. Some standards require PWHT for materials over a specified thickness, while others may recommend it based on their micro-structural makeup or the welding parameters used. The decision to use PWHT should always be balanced against cost and potential adverse effects.

Among the problems that can result from not performing PWHT is an increased susceptibility to stress corrosion cracking in a corrosive environment. This type of cracking occurs when the welded material is subjected to both stress and a corrosive environment, and can be very difficult to detect. PWHT can significantly reduce the likelihood of this type of cracking, and can improve a welded structure’s resistance to corrosion.

Using PWHT can also help reduce the hardness of a weldment, which makes it easier to machine and form. It can also make the weldment more resistant to cracking and brittle fracture, and increase its strength and ductility.

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