Whatever the owner wants. I have seen 1/8" used on a few projects; however, that number is meaningless because you have not provided enough information for anyone to guess at the potential corrosion issues. When all is said and done, once you determine if corrosion will be an issue (both under the insulation and inside the pipe) you can make a recommendation to the owner and let them decide.
Is this a B31.1 or B31.3 line? What code are you building the line to?
Actually we have a Steam Super Heater in our Reformer package that it's interconnection piping, is in Reformer vendor's scope of work, and Vendor has said in his proposal, don’t consider any corrosion allowance for these pipes(High Pressure Steam Pipes) as per ASME but has not defined, which part of ASME.
"Vendor has said in his proposal, don't consider any corrosion allowance for these pipes(High Pressure Steam Pipes) as per ASME but has not defined, which part of ASME"
ASME piping and pressure vessel codes define a "corrosion allowance" to enable the designer to consider the effects of future wastage.....either corrosion or erosion or whatever.
The specific allowance for "corrosion" always comes form the piping or vessel purchaser.....it is not stated within any ASME code or standard.
This is because only the purchaser knows his particular process conditions.