Joint Efficiencies for Nozzles

[dskjockey1]

UW-11(a)(2) states that radiography is not required for Cat B and C butt welds in communicating chambers that do not exceed 10 NPS. If I have a vessel with Full Per Code RT and nozzles which are 6"-RFWN nozzles, can I take credit for a JE = 1 in my calculations for these nozzles even though x-ray will not be performed? Or must I use .85%

Thanks!

 

[SnTMan]

dskjockey1 assuming seamless pipe, common practice is to use E = 1 even for spot RT vessels, see UW-12(d).

Regards,

Mike

 

[dskjockey1]

E = 1 even though the nozzle weld will not be subjected to any RT? Remember, the shell may be radiographed but the nozzle does not have to be RT examined per code.

 

[SnTMan]

Did you see UW-12(d)?

 

[dskjockey1]

Yes I did. You are correct when you spot RT smls pipe you can claim a JE = 1. But per UW-11(a)(2) when full RT per code (not 100% all BW) is called for on a vessel, nozzles which have weld neck flanges attached to them that are < 10" NPS do not need to be radiographed in order for the vessel to be stamped RT-1.
As a result you can have a fully radiographed head and shell seam but no RT performed on the nozzle to flange welds that are on that very same vessel.

So do these nozzles that are < 10" NPS have a JE = 1 in the code calculations?

dskjockey1

 

[SnTMan]

dskjockey1, yes, any seamless nozzle does per UW-12(d), and they need not be RT'd per UW-11(a)(2).

Regards,

Mike

 

[wsmith22]

I'm still confused. Per UW-12(d), E=1 when the spot RT req't of UW-11(a)(5)(b) are met. Since no Spot RT is done on the nozzle to flange butt weld, doesn't this force you to the E=.85?

 

[smith4464]

Personally, I wouldn't mind a little clarification either with respect to wsmith22's question....

 

[dskjockey1]

See UG-37(a), Definition of "E" and "E1"

 

[Fizza453]

If you do full RT of all but welds in shells and heads but not those B and C in nozzles and communicating chambers that neither exceed NPS 10 nor their thickness exceeds 29 mm, efficiency would be 1 as per UW-11(a)(2).

UW-12(d) does not apply to seamless nozzle pipes connected to butt welded flanges. Rather it applies to vessel seamless sections and heads. Vessel seamless sections means shell courses made from seamless pipe, seamless cones etc.

UW-12(a) says E=1 if UW-11(a) is satisfied in addition to especially UW-11(a)(5). Again note that UW-11(a)(5) does not apply to seamless nozzles pipes connected to butt welded flanges.

This is what how I read UW-11 and UW-12.


Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN