In our day-to-day maintenance we have to resort to repair by welding to many system elements, some equipment and structural members. There are a large number of variables involved in welding by repair; safety of personnel /equipment / systems / premises being of prime importance.
The article linked in this Blog entry covers the gamut of repairs by welding, highlighting the questions that need to be asked before taking up any such work.
My personal experience in repairs by welding ranges from simple welding on structural elements to building up critical machine components using specialised welding techniques.
Welding temperature plays an important role in the decision on the electrodes to be used (Low thermal or normal?). The current setting on the welding transformer also plays an important role. There is a need to avoid changes in the crystalline structure of the parent metal. Overheating could lead to change in physical properties and in the case of some metals and alloys lead to inter-crystalline corrosion.
Heat treatment needs, before and after the weld deposition is another question. This aspect is not very well understood by many of us. Proper heat treatment is essential for many alloy steels so as to retain the component structural integrity.
The compatibility of the parent metal and the material to be deposited is the next question.
The class of welding needs to be ascertained since some of the critical applications such as welding on pressure vessels require to be validated by radiography. In this case the welders are to be qualified for this class of welding.
Please read the linked article for more information.
Five key questions management should ask before repairing by welding
Walter J. Sperko, P. E.Avoid the welding “uh-oh.”
Safety is paramount in welding operations. Hot work permits and essential. Additional requirements such as permission to work at heights, work within confined spaces etc also may be required depending on the job being executed.