Ref : Non-Mandatory Appendix L

I would like to understand the meaning of "UW-11(a)(5)(b) Not MET E = 0.85" For Seamless Head, in the Flow Chart Fig. L-1.4 - 2 Joint Efficiency and Weld Joint Type - HEADS

In this Flow Chart, against Seamless Head (after not selecting Full RT Mandatory UW-11(a)), there are 2 joint Efficiencies for 2 different conditions.

Condition 1: UW-11(a)(5)(b) MET E = 1.0

Condition 2: UW-11(a)(5)(b) Not MET E = 0.85 (1)

Can any one interpret the meaning of condition 2?

Is it the same which I think.....?

a. All Category A Joints are not fully radio graphed

And / OR

B. All Category B Joints of vessel are not spot radio graphed as per UW-11(a)(5)(b)

Please elaborate on this.

And now the main question:

The question arises - when we are using the SEAMLESS head, whatever may be the RT selection for the entire vessel, why we can not take joint efficiency as 1.0 for calculating the thickness of only head.

(d) Seamless vessel sections or heads shall be considered
equivalent to welded parts (consider as with a "virtual" type A weld in it) of the same geometry in
which all Category A welds are Type No. 1. For calculations
involving circumferential stress in seamless vessel
sections or for thickness of seamless heads, E p 1.0 when
the spot radiography requirements of UW-11(a)(5)(b) are
met. E p 0.85 when the spot radiography requirements
of UW-11(a)(5)(b) are not met, or when the Category A
or B welds connecting seamless vessel sections or heads
are Type No. 3, 4, 5, or 6 of Table UW-12

We are not assumed to explain the "why" of the Code rules, we are requested to comply with them in Code construction. I may only guess that the circumpherential weld (type B) connecting head to shell is not subject to a simple longitudinal stress but also to bending stress due to the tendency of the pressure acting on the formed head, to open it.
Mauro

Gonzaga is correct.

UW-12(d) discusses seamless shells/heads that have imaginary Type 1 long seam welds with the equivalent of 100% radiography as required by UW-11(a).

UW-11(a)(5)(b) is ASME's way of providing a means to ensure confidence in the quality of connecting weld (Category B or C weld) attaching vessel shells/heads.

What is difficult for many to understand is that the weld for which radiography is being conducted is not the joint to which the efficiency is being applied. The Spot RT requirement can be classified as a "quality shot" for confidence when determining the joint efficiency of the intersecting (imaginary or real) longitudinal joint.

_________________
A question properly stated is a question half solved.

Gonzaga,

Thanks for the detail explanation.

Mac