The wrapping degrades the stainless steel.
Trevor
I would be interested to see any evidence of this.
There are two mechanisms that I know of that could lead to this type of degradation;
Increase in temperature may increase the rate that any degradation will occur, and;
Chloride stress corrosion cracking; assuming the headers are Austenitic (304, 316 and various others) then chloride ions (salt) held in the fibres of the wrap may attack the metal particularly if there is residual stress from forming or welding the material.
