tubesheet to shell butt weld joint radiography

[Mech Engg]

Dear Experts

We ordered one Double tubesheet exchanger to vendor. Both Tubesheets are welded to shell with Butt weld as per FIG UW-13.3.
Now as per vendor he cannot perform Radiography on this weld due to Tube hindrance and cannot perform UT due to 10 mm joint thickness.

he is suggesting PT.

What is your opinion pl

 

[weldstan]

Radiography is done prior to tube insertion so that should not be a problem.

 

[r6155]

Also no problems with UT on 10 mm welds
You can do UT during fabrication and in-service inspection

http://www.bindt.org/downloads/NDT2012_1A2.pdf

Regards
r6155

 

[Mech Engg]

Thanks All

Is this normal to weld all these tubesheets to shell on both side and then insert tubes one by one ?
there is no clear view how tube is travelling inside tubesheet until tit comes out from other side tubesheet

 

[marty007]

Our shop always completes these welds AFTER the bundle has been stuffed, exactly for the reason that you mention. Also, these welds do not require RT and/or UT.

 

[Mech Engg]

Dear marty007
Thanks for your response, can you guide for code exemption if the exchanger is in Lethal service ? thanks in advance

 

[r6155]

Mech Engg
Why didn't you mention it before? (lethal service).
Another important data is comming from you?

Regards
r6155

 

[Mech Engg]

Hi r6155
Sorry for late info, can you suggest any code exemption or provision of code cases or nay practical way of performing RT. Appreciated your time.

 

[sharmass]

Refer UW-51(a)(4) of Code Section VIII-1-2015
As an alternative to the radiographic examination all welds in material 1/4 in. (6 mm)and greater in thickness may be examined using the ultrasonic(UT) method per the requirements of 7.5.5 of Section VIII, Division 2. Which is automatic or semi automatic recordable UT examination.

2017 edition words are different but intention is same (it refers to UW-53b that cross refers to 7.5.5 of VIII-2)

This method is acceptable for Lethal Service.

Probably TOFD and Phased Array combination will work. Talk to automated UT expert.

 

[Mech Engg]

Dear sharmass
Thanks for your valuable input. It really helps.
So does it means all Tubesheet hub type connections with Shell in Lethal will be UT performed due to Tube Hindrance ? UW-2(a)(2&3) provides some waiver on inside Tube Butt joints and consider this is not possible to perform RT, then Why this Tubesheet to Shell Butt joint is also not included in this list of waiver. Just as thought to share.

 

[marty007]

I apologize, I didn't look clearly enough at your attachment. I had assumed it was a corner joint.

For your joint type, RT would be required (or UT per rules of ASME).

Cheers,

 

[Mech Engg]

Thanks marty007
What is your opinon to perform RT on these joints, will you put all tubes after RT of Tubesheet to Shell weld ? is it Practical and normal to pass tubes after welding Tubesheet to shell from both ends ?

 

[r6155]

Do not give more laps with RT. Forget RT in this case. Use UT

Regards
r6155