Qualificazione del processo di placcatura, normativa applicabile.

Weld overlay is one of the most critical welding processes for pressure vessels, reactors, valves and pipelines construction. Welding parameters control, influencing mechanical properties of weld metals, is obtained - as well as other welding processes - through the use of welding procedure specification (WPS), necessary to provide a welding operations plan. Production of welding procedure specification is a basic factor, but it is not enough to ensure welded joints requirements. Some defects and chemical compositions of clad metals can be evaluated by nondestructive methods while it is not possible to check metallurgical imperfections with non-destructive methods. These factors require a proper quality control, before and during overlay welding, essential for qualification of welding procedures. [ABSTRACT FROM AUTHOR]