Material Considerations Non-metals

The following are some considerations to be evaluated when applying non-metals in structures such as piping  

The concerned fabricator should follow the fabrication procedures introduced by the designer precisely, and use the specified methods and materials prescribed. 

In addition, the contractor and fabricator should give consideration to aU factors affecting fabrication that in turn facilitate improvement of the resistance of equipment and structures to corrosion. When an engineer is responsible for the whole construction, they are also responsible for the performance of first-class fabrication. 

It is not unusual to find that, although the wrought form of a metal or alloy is resistant to corrosion in a particular environment, the welded counterpart is not. Further, welds can be made with the addition of filler metal or can be made autogenously (without filler metal). However, there are also many instances in which the weld exhibits corrosion resistance superior to that of the unwelded base metal, as well as times when it behaves in an erratic manner, displaying both resistance and susceptibility to corrosive attack. 

Corrosion failures of welds occur in spite of the fact that the appropriate base metal and filler metal have been selected, industry codes and standards have been followed, and welds have been deposited that possess full penetration and have the proper shape and contour. It is sometimes difficult to determine why welds corrode however, one or more of the following factors are often implicated  

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