Stress corrosion cracking cast iron

Some austenitic cast iron types may show a level of sensitivity to stress corrosion cracking in seawater and salt solutions at higher temperatures [96]. At high nickel contents of around 35%, pitting corrosion increases [97]. 

Stress corrosion cracking of austenitic cast irons in seawater and brine, and its prevention... 

The following environments cause stress corrosion cracking of cast irons ... 

Stress corrosion cracking. SCO is observed in cast irons under certain combinations of environment and stress, and under certain conditions, SCC can be a serious problem. Because imaUoyed cast irons are generally similar to ordinary steels in resistance to corrosion, the same environments that cause SCC in steels are likely to cause problems in cast irons. Environments that may cause SCC in unalloyed cast irons include ... 

Shipment nd Stora.ge, Sulfur monochloride is minimally corrosive to carbon steel and iron when dry. If it is necessary to avoid discoloration caused by iron sulfide formation or chloride stress cracking, 310 stainless steel should be used. Sulfur monochloride is shipped in tank cars, tank tmcks, and steel dmms. When wet, it behaves like hydrochloric acid and attacks steel, cast iron, aluminum, stainless steels, copper and copper alloys, and many nickel-based materials. Alloys of 62 Ni—28 Mo and 54 Ni—15 Cr—16 Mo are useful under these conditions. Under DOT HM-181 sulfur monochloride is classified as a Poison Inhalation Hazard (PIH) Zone B, as well as a Corrosive Material (DOT Hazard Class B). Shipment information is available (140). 

A more serious threat to the materials compatibility of CNG fuel systems is condensed water vapor. Water can cause steel and cast iron to rust and aluminum to corrode. Any corrosion of components that must withstand high pressures is a concern, since corrosion stress cracking can occur which can result in failure of the component with disastrous results. The presence of water greatly accelerates the corrosion properties of the hydrogen sulfide that might be found in the natural gas. For these reasons it has been recommended that the way to control corrosion in CNG systems is to remove sufficient water vapor to prevent it from condensing in the system under static conditions [3.13]. Natural gas dryers have been developed to help reach this goal. 

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