SAE 304 stainless steel optimal high temperature strength. The carbon content of 304L (UNS 30403) is restricted to a maximum of 0.03%, which prevents sensitization during welding. Sensitization is the formation of chromium carbides along grain boundaries when a stainless steel is exposed to temperatures in the range of ~–. The subsequent formation of chromium carbide results in reduced corrosion resistance along the grain boundary leaving the stainless steel susceptible to unanticipated corrosion in an environment where 304 would be expected to be corrosion resistant. This grain boundary corrosive attack is known as intergranular corrosion. The carbon content of 304 (UNS 30400) is restricted
Corrugated stainless steel tubing and FAC tubing does not have a plastic sheath. On FAC tubing the corrugations are visible. CSST’s plastic sheath covers its corrugations. CSST is used as an alternative to the older standard “black iron” (steel) gas pipe. The inner stainless steel layer of typical residential CSST is .2 to .3 mm thick while the wall thickness of typical residential “black iron” gas pipe is 3 to 4 mm thick. CSST is more expensive than “black iron” gas pipe. However, CSST requires fewer joints, may be safer during earthquakes, and may be easier to install. CSST is alleged to have an