Cladding thickness vs backing thickness

[crosby84]

Hello,

I'm staring at a U-1 that reads:

Shell: SA-264 20% Type 316 S/S on SA-285-C Backing, Nominal thickness 3/8 in.

My question, is it:

a) 20% of the 3/8 is clad, with an overall thickness of 3/8

or

b) 3/8" CS plus 20% clad, so an overall of 0.450", 0.075" of which is stainless clad?

Edit: after speaking with a few colleagues I feel pretty confident that option a is correct, but I'd still like to get others' opinions.

Thanks

 

[mk3223]

IMO, a) is correct.

 

[SnTMan]

no way to tell...

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[EdStainless]

Since only the backing is used in the pressure rating I would think that the dimension is strictly the backing, but from the wording there is no way to tell.

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P.E. Metallurgy, Plymouth Tube

 

[Christine74]

Section VIII Division 1 requires you to put list the uncorroded thicknesses on the U-1, and normally cladding and weld overlay are considered to act as the corrosion allowance, so the answer appears to be (a).

However, 80% of 3/8" is 0.300", which is not a standard plate thickness. You would have to pay a premium to get plate that's 0.300" thick, but for what purpose?

I think option (b) is more likely.


-Christine