SA53B ERW for Shell 1

[stanrick]

Hello All,

I'm new to the ASME Sec. VIII, Div. 1, and wish to clarify my understanding. I tried searching the threads for this, but perhaps my question is too elementary.

Assume a vessel constructed of SA53B ERW pipe (K03005) and semi-elliptical heads, type 2 welds, no radiography. For shell thickness, is it correct to use S=14600 and E=1 in UG-27(c) Eq (1) , and S=17100 E=0.65 in Eq (2)? Notes G3 and G24 in Sec. II, D seem to imply that the pipe is spot x-rayed by the manufacturer.

I look forward to attending ASME BPV training soon, but in the mean time this question keeps nagging me.

Thanks.

 

[eliebl]

Spot radiography by the pipe manufacturer does not get represented on the manufacturer's data report. That inspection has not been performed by the fabricator. In you case there are a couple of items at play here. The efficiency of the head (not head to shell joint) would be 0.85 as the requirements of UW-11(a)5(b) have not been met. See UW-12(d) and try and understand where the 0.85 comes from.

The circumferential joint will have an efficiency but it will seldom govern unless there are other loads to be considered. Given this is a pipe material spec it is unlikely that this vessel will be large enough to be worried about that.

In calculating the required thickness of the pipe shell, you would also consider the joint efficiency of 0.85 under UW-12(d) because the longitudinal seam in the pipe already has the joint efficiency applied to the allowable stresses in Part II D.

In direct response to you questions above,

EQ (1) would have E=0.85, S per Part II(D)
EQ (2) would have E and S per above but it really doesn't matter.

As you start to learn the code you will find there are many areas where you just put a statement in your calcuations to cover an area without haveing to do any calculations.

1 example would be, if you have twice the required wall thickness (it does sometimes happen using pipe for vessel shells) you could simply state that nozzle reinforcement calculations are not required as the shell will easily have enough excess material for the opening to be adequately reinforced. This is of course only applicable it large openings are not a problem etc, etc, etc.

EJL