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# 12" Sch 80 Pipe 1 mile underwater

## 12" Sch 80 Pipe 1 mile underwater

(OP)
Hello all-
New here, But I have an interesting question that I've gotten a lot of conflicting information on.

12" Sch. 80S (.5" Wall thickness) 304L Stainless steel. 24" long. Welded on both sides.
Can it withstand being 1 mile underwater (2,350 PSI external) assuming standard 1ATM inside?

A. If not, would up to two vacuum rings welded to the outside solve the problem?
B. Would matching the external pressure by depth- I.e Filling the inside of the pipe to closely match external pressure- solve the problem?
How greatly is external water temperature going to affect strength- assuming around 30F

Thanks!

### RE: 12" Sch 80 Pipe 1 mile underwater

What do you get when you run the external pressure calculations on 12.75" OD x 0.437" wall (minimum)?
I get something just over 750psi.
Stiffeners won't help this.
You need more wall, and/or less OD.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

### RE: 12" Sch 80 Pipe 1 mile underwater

What's the end of this cylinder?

A won't work,
B will work
Temp like that makes no difference

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: 12" Sch 80 Pipe 1 mile underwater

Too weak stainless steel grade, it's likely to buckle or collapse on load wave variations.
Go thicker or stronger.
Pipe-in-pipe or externally thick coated could be alternative options

* Finding a solution is great * Knowing how to implement it is fantastic * Believing it is the only one and best is naive ?

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