Is tubesheet attachmen to shell a butt joint?

[eeromatti]

My question is about a tubesheet to shell joint of fig. UW-13.2 (b), (c) and (d). Is this type of joint a butt weld? Section IX defines butt weld and according to it, it's not a butt weld.

This is because degree of NDT of the joint and does it fall under the scope of UW-2(c) which reads "...all butt welded joints shall be fully radiographed.."(yes, it's in steam boiler)

And also, is nozzle attached to shell really butt welded? According to section IX it seems more like corner joint to me.

 

[doct9960]

My question is about a tubesheet to shell joint of fig. UW-13.2 (b), (c) and (d). Is this type of joint a butt weld? Section IX defines butt weld and according to it, it's not a butt weld

This is because degree of NDT of the joint and does it fall under the scope of UW-2(c) which reads "...all butt welded joints shall be fully radiographed.."(yes, it's in steam boiler)

Joints in Fig. UW-13.2 are corner joints. The title says it...ATTACHMENT OF PRESSURE PARTS TO FLAT PLATES TO FORM A CORNER JOINT". For unfired steam boilers with design pressures greater than 50 psig, the tubesheet to shell joint should be butt weld as shown in Fig. UW-13.3

And also, is nozzle attached to shell really butt welded? According to section IX it seems more like corner joint to me.

Except for butt welded nozzles shown in sketches (f-1) thru (f-4) of Fig. UW-16.1, the rest of the nozzles in Fig. UW-16.1 are corner joints.

 

[eeromatti]

Could you please explain where it is said that for unfired steam boilers with design pressures greater than 50 psig the tubesheet to shell joint should be butt welded (as shown in fig UW-13.3) instead of corner joint (as shown in fig. UW-13.2). Thank you for your answer! I just want to make this as clear to me as possible.

 

[doct9960]

My reply..."For unfired steam boilers with design pressures greater than 50 psig, the tubesheet to shell joint should be butt weld as shown in Fig. UW-13.3"...is INCORRECT.

Tubesheet to shell joints for unfired steam boilers can be corner joints as shown in Fig. UW-13.2. What I should have said is that butt welded tubesheet-to-shell joints (as shown in Fig. UW-13.3) are joints that require full radiography.

 

[eeromatti]

Thank you! Highly appreciated

 

[jehan17718]

eeromatti,

butt welded joints connecting tubesheet to shell are required if this joint is required to be radiographed. a corner joint cannot be radiographed. You need to also check the client specifications as they sometimes address this issue. hope this helps.

-jehan

 

[eeromatti]

If it's a butt welded category C joint, radiography is required. Radiography is not required for corner joint and it's impossible. That's how I understand it.

However, our qm states that shell to tubesheet joint is butt welded and it cannot be designed according to fig .UW-13.2 (b), (c) and (d) because they are butt weldes too (!!) and ndt is required by the code and cannot be done for welds like that. I just can't agree that.

 

[jehan17718]

eeromati,

Fig UW-13.2 (b), (c) and (d) are NOT butt joints and thus cannot be radiographed. Also please note that these joints are NOT applicable for tubeshhet to shell joint.

For corner joint tubesheet to shell joint you require the kind shown in UW-13.3 (h), (b) and (c).

For butt welded tubesheet to shell joint (with tubesheet NOT extended as a flange, you require the kind shown in UW-13.3 (a) and (b).

You Quality person is correct to say that Fig UW-13.2 (b), (c) and (d) are corner joints and thus cannot be radiographed.

Hope this helps.

-jehan

 

[doct9960]

jehan,

Fig UW-13.2 (b), (c) and (d) are NOT butt joints and thus cannot be radiographed. Also please note that these joints are NOT applicable for tubeshhet to shell joint.

Why are they not applicable for tubesheet to shell joints?

 

[jehan17718]

doct9960:

Sorry for my mistake.

Fig UW-13.2 (b), (c) and (d) can be tubesheet to shell joints. However, these corner type jointrs cannot be radiographed.

Also, please note that SOME of the joints depicted in Fig UW-13.2 (a)-(g) are NOT allowed by certain standards like PIP.

-jehan