Jack,
I'm not very experienced in welding of austenitic SS pipes but it seems to me that your question is somewhat beyond the Code requirement based on basic SAFETY consideration. Probably the answer would not in Code books.
Let's take a look at B31.3-2010, INTRODUCTION
"
The Code sets forth engineering requirements deemed necessary for safe design and construction of pressure piping. While safety is the basic consideration, this factor alone will not necessarily govern the final specifications for any piping installation. The designer is cautioned that the Code is not a design handbook; it does not eliminate the need for the designer or for competent engineering judgment."Table 330.1.1 doesn't address specific interpass temperature control for P No.8. Table 331.1.1 doesn't address PWHT for P No. 8 either. But always remember this is just for basic SAFTY. (Let's imagine the ASME Code Committee people finish the writing of the Code book and conceitedly say to themselves, "Okay, that's safe enough!
")
Never treat the Code books as encyclopedia.
Beyond the basic safety, there should be engineering judgement. I was told that a good practice for welding of 300 series include but not limited to the control of heat input to minimize the sensitization which degrade the anti-corrosion ability of the material. (refer to ASME Section II, Part D, A-320 INTERGRANULAR CORROSION for some info.)
To my knowledge and experience, for certain grades of 300 series, some engineering companies even require the control of fillet weld size (to minimize the heat input) and require the PWHT (solution annealing) for the welded parts. These considerations are for the pursuit of optimal serviceability beyond the basic safety.
In theory, generally, the rapid cooling for 300 series is beneficial and no need to consider the preheat, hardenability, slow cooling rate, martensite transformation, etc. as we do for ferritic steels (The things done for ferritic steels are even harmful for 300 series in some cases).
Back to your question.
If your boss applied his knowledge for carbon or low alloy steels to 300 series, he might be wrong;
If your boss was worrying about the compressed air with uncontrolled moisture or other contaminations, he might be right.
I will be happy to learn if someone else on this forum could share more ideas.
Thanks,
Jovi