If a 300 series stainless steel component is under tensile stress, either because of operation or residual stresses left during manufacture, chloride induced pitting will deepen even more. Since the piece is under tensile stress cracking will occur in the stressed piece. Usually there will be more than one crack present causing the pattern to resemble a spider's web.

Chloride stress cracking is a serious problem in industry and not often recognized by the people involved. In the seal business it is a serious problem if you use stainless steel springs or stainless steel bellows in your seals. This is the main reason that Hastelloy C is recommended for spring material. Here are some additional thoughts about chloride stress cracking that you'll want to consider:

If it's necessary to insulate stainless steel pipe, a special chloride free insulation can be purchased, or the pipe can be coated with a protective film prior to insulating.

See: Corrosion - problems with the 300 series of stainless steel 4-1

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