SecVIII UG53(c) circumferential ligament for adjacent long. rows

[termoguven]

ASME Sec VIII, UG53 instruct Ligament efficiency determination.
I try to design a collector pipe (D:273mm) with drilled holes
(similar to figure UG-53.1)
24 holes with (d:50mm, p:89mm)
and 2 rows of holes,
distance between two adjacent rows:65mm
As per UG-53(c), can you tell me steps to determine circumferential ligament?

second question:
65mm is distance from top view of rows,
can I consider the distance as "Arc Length" on Collector pipe? (to determine circumferential ligament)

 

[MarcoE]

Termoguven,

The circumferential ligament efficiency chosen for your design depends on how you are doing the radiography. E = 1 if the radiographic requirements of UW-11(a)(5)(b) are met.
E = 0.85,if no radiaography is to be done, for circumferential butt joints and longitudinal butt joints connecting seamless vessels, vessel sections or heads provided that these welds are type 3, 4, 5, or 6 joints as described in UW-12.

hope this helps

 

[prex]

1) Long.p=65 mm, d= 50 mm
long.efficiency (p-d)/p=0.23
2) In my opinion you are required to consider p=the arc lenght at mid header thickness.
As you have only two rows of holes on the header circumference, you could consider also the reinforcement per UG-37. However with your figures the circumferential ligament shouldn't be governing, so OK go on with UG-53. prex

http://www.xcalcs.com

Online tools for structural design

 

[deanc]

In my opinion"prex"is correct. With due respects to MarcoE,
beware of the UW-12 trap. E=1 in this case. Please refer to
Interpretation VIII-I-92-32 and VIII-I-01-63. Seamless pipe is treated the same as welded and you are penalized in UW12e

 

[MarcoE]

The number figured by Prex is correct for the longitudinal joint efficiency, however, the 'circumferential efficiency' (what termoguven is asking for) is not figured by the equations given in UG-53(b)(1).