Tangent length of hemispherical head 1

[pjoxygenis]

Hello I have some problem about thiner hemispherical head attached to shell base on ASME sec.8 div.1
Which is corectly tangent length in this case between yellow line or red line(center of head)?
If you have any reference will be good.
THank for you advised.

 

[racookpe1978]

Those tangent lengths (on elliptical heads) are usually 3 inches to provide an easier welded joint and weld prep. Link is not connecting.

 

[pjoxygenis]

Sorry for that link
According from ASME sec.8 div.1 2010edition Fig.UW-13.1(j)
If i use thiner hemispherical head attached to shell and cut back the head.
What is corectly tangent length in this case between
1.The original center line of head which attached to shell before cut back.
2.The line which begining taper.

 

[prex]

The tangent line is at the point of tangency, or at the end of the full hemisphere. The taper starts at the same point, as the cylinder cannot be made thinner.

prex
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[Shmulik]

Hemispherical head is not expected to have a cylindrical section (vs. elliptical or torispherical heads). For that reason a circumferential welded joint connecting hemispherical head to main shell is under "Category A" (see UW-3).
For Tapered Transition requirements: see UW-9(c) and FIG. UW-9