TESTING OF STAINLESS-STEEL WELDS FOR VARIOUS APPLICATIONS

In several investigations, potentiostatic, potentiodynamic, and standard ASTM-G48 test techniques have been used to evaluate the corrosion properties of stainless steel welds. Testing for various applications is discussed, and test methods are recommended. Tests should always be performed for the least resistant parts of a system, usually as-welded field welds and/or narrow crevices. The 6% FeCl3 test solution is often more severe than the real environment because of the higher potentials obtained. Therefore, excessively low, critical temperatures are measured. Testing according to ASTM-G48 seems to be relevant for highly alloyed stainless steels for exposure to oxidizing chloride solutions that raise the potential in the range of 400 to 700 mV SCE In order to perform realistic testing relevant to practical applications, the maximum free potential obtained in real environments should be known. Potentiostatic tests, using the maximum potential for the actual environments, are recommended for testing of stainless steel welds in most environments, i.e., chlorinated and natural seawater and oxygen-free well fluids. Testing can be performed using simple equipment since the authors' experience shows that important parameters to control are potential, temperature, and chloride level.