UW 11(a)(5)(b)

sharjeelfaiz · **Joined:** Mon Oct 15, 2007 6:54 am **Posts:** 128

Hello.

What is the significance of UW 11(a)(5)(b). Is it used to determine the joint efficiency requirements of longitudinal seams of shells/heads?

Thanks a lot.

Juergen Fleischfresser · **Posted:** Sun Dec 07, 2008 12:41 am

Hello,

UW-11(a)(5)(b) is referenced by UW-12(d) and UW-12(e) and is applicable to seamless vessel section, seamless heads and welded pipes and tubes as mentioned in UW-12(d) and UW-12(e).

Code:

UW-12 JOINT EFFICIENCIES

(d) Seamless vessel sections or heads shall be considered equivalent to welded parts 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 = 1.0 when the spot radiography requirements of UW-11(a)(5)(b) are met. E = 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.

(e) Welded pipe or tubing shall be treated in the same manner as seamless, but with allowable tensile stress taken from the welded product values of the stress tables, and the requirements of UW-12(d) applied.

Please find the following useful link http://www.authorizedinspector.com/Joint_Efficiencies/Joint_Efficiencies.htm

sharjeelfaiz · **Joined:** Mon Oct 15, 2007 6:54 am **Posts:** 128

Thanks a lot.

I had been through the website. i am quite perplexed by the fact that when we start designing a vessel, we define the degree of Radiography, i.e. RT1, RT2, etc.

But UW 12(d) provides another set of joint efficiencies. So how do they fit?

Regards,
Sharjeel

AI-OR-US · **Posted:** Thu Dec 11, 2008 8:34 am

Sharjeel,

In simple terms, it is all about money. To satisfy UW 11(a)(5)(b) requirements, you need to do one more RT shot per UW-52. It gives you E=1 for the head and you can save on the material thickness for that head. All depends on which component, head or shell is critical for the design calcs.

Regards from Oregon.

AI-OR-US

TONYQ · **Posted:** Thu Nov 19, 2009 4:07 pm

Juergen Fleischfresser wrote:

Hello,

Please find the following useful link http://www.authorizedinspector.com/Joint_Efficiencies/Joint_Efficiencies.htm

Hi all,

Do you think the joint efficiency on the above link are all correct? I doubt! at least the one on left head is not.

Tony

Jackal · **Posted:** Thu Jun 10, 2010 6:29 pm

The paged linked above can now be found here: http://www.boilerinspectors.com/Joint_E ... encies.htm
The domain AuthorizedInspector.com is now under new ownership. Expect to see it in the near future.

If you want to see what the old site looked like as it existed from 2003 through 2010, you can find it at http://www.boilerinspectors.com

Regarding your question TonyQ, The head efficiency of 1.0 (for a seamless head) is justified as the intersecting seam shows Spot RT per UW-11(a)(5)(b)....colored in Blue.... as stated in UW-12(d)

Ikram · **Joined:** Fri Apr 17, 2009 6:53 am **Posts:** 66

You may understand the UW(a)(5)(b) as:
1. Catagory A welds 100% RT
2. Catagory B and C welds are type 1 and type 2
3. Catagory B welds Spot RT

If all of the above three conditions are satisfied then we may say that the condition for UW (a)(5)(b) are met. Further, if you go through the defintion of RT2 in UG-116, you will see the above three condiitons. So we can say that if the condition of UW(a)(5)(b) are met so go for RT2 simply. And for RT2 type welds you have to peform full RT. This should be remember that full RT does not always mean 100% RT. It may be 90% for Type 2 joints.

Hope you have find your answer.

Regards

Ikram

Shrinath Desai · **Posted:** Fri Jan 06, 2012 11:57 am

Please provide guidance

I have a welded shell and a seamless 2:1 head.
Both long. & circ. seam is Type no. (1)
RT for long. seam is 0% & circ. seam is 10% at "T"-joint only.
Thus, my data is following:

Shell: Welded, RT = NO, E = 0.7
Head: Seamless, UW-11 (a) (5) (b) SPOT = "Yes", E = 1.0

Now for supplemental load calculation of Appendix L-2,
joint efficiecy for circ. stress (long. seam) Ec = 0.7
But, what about
joint efficiency for long. stress (circ. seam) El = ?.
Can I use 0.85 here for UW (a) (5) (b) spot or I will need to take another 10% at another portion on the circ. seam?

BTW: All above links are dead; boilerinspector is giving me http error 403.

Frohnert · **Posted:** Mon Jan 09, 2012 5:54 pm

The UW-11(a)(5)(b) spot will be used for the E=1 of the seamless head(s). Thus the efficiency of the non radiographed circ. joint is 0,7 for long. stress, since there is no UW-11(b) radiography. This means more radiography is required for 0,85, however, not 10% but acc. to UW-52.

Code:

UW-11(a)(5)(b). 
[...]
Spot radiographs required by this paragraph shall not be used to satisfy the spot radiography rules as applied to any other weld increment.

Michael

Shrinath Desai · **Posted:** Thu Jan 12, 2012 11:10 am

Thanks for the answer & your reference to UW-52. It was about time that I should read it thoroughly.

I don’t know why but everyone in my company is using the word 10% for spot RT.
It may be because generally we make small vessels. Though, UW-52 (c) says min. length should be 6 in. so mentioning the percentage of RT does not make any sense. Thanks again for passing it on.

Rathnam · **Joined:** Fri Jul 09, 2010 7:57 am **Posts:** 79

Percentage is defined in UW 52 .i.e 1%
One Radiograph of minimum length 6 inch for every 50 feet of weld joint.

Shrinath Desai · **Posted:** Fri Jan 13, 2012 12:20 pm

Yes, but 1% would be for weld length of 50 ft only.
What if weld length is less than 50 ft? Let's say weld length is about 10 ft. then still min. reqd. length will be 6 inch. So radiography percentage should be 5%. isn't it?

Frohnert · **Posted:** Sun Jan 22, 2012 6:28 pm

Exactly.

Code:

(b) MINIMUM Extent of Spot Radiographic Examination
(1) One spot shall be examined on each vessel for
each 50 ft (15 m) increment of weld or fraction thereof
for which a joint efficiency from column (b) of Table UW-
12 is selected.

UW 11(a)(5)(b)

Who is online