Reinforcement of Welded Branch Connections

[AlejandroFernandez]

Hi, I have a issue about a reinforcement design, acording to ASME B31.8. And is on point 831.41 General REquirements... specifically on section "e" "The area of reinforcement ...is defined as a rectangle whose length shall extend a distance, d, on each side of the transverse centerline of the finished opening and whose width shall extend a distance of 2 1?2 times the header wall thickness on each side of the surface of the header wall..." Appendix F figures5

The length of this rectangle is two times internal diam. (2*d), this measure is a maximun or minimun limit?
Can i do it shorter than 2*d?
thanks

Alejandro Fernández
I+D&I
Sitelca

 

[jte]

Alejandro-

This is a maximum limit. Your reinforcement may extend beyond this limit but you cannot take credit for area replacement which is beyond it. The reinforcing pad may have a smaller diameter than this limit, or if the area required is relatively small, may consist simply of a larger weld.

Not a likely scenario on pipelines, but on vessels it is not uncommon to have a reinforcing pad diameter exceed the area of reinforcement limits in order to accomodate piping loads on the nozzle. So one calc is performed for area of reinforcement which determines the area within the limits of reinforcement, another calc is performed to determine the stresses due to the nozzle loading.

jt

 

[AlejandroFernandez]

ok Thanks A lot.. for it..
I have another question... ASME B31.8 allow me to use Weldolet on top of a reinforcement pad?... The final assembly look like a split Tee.

Alejandro Fernández
I+D&I
Sitelca

 

[jte]

No idea of whether it would be code legal... But why would you want to, and would you expect to gain the benefits of reinforcement from the 'olet if it is welded to a rolled repad?

jt

 

[AlejandroFernandez]

Yes I am expecting to make a very good reinforcement welding this olet to reinforcement pad... i will get a perfect round surface and this will work like a pipe and a reinforcement.


Alejandro Fernández
I+D&I
Sitelca

 

[ColonelSanders83]

I have to say that welding a Weld-O-Let on top of a repad is a bad idea.

If you need the reinforcment from both the Weld-O-Let and the Repad, then you should weld on the Weld-O-Let to your header first with the correct full pen weld(omit the backup fillet). Then after the Weld-O-Let is installed you can weld the repad to the branch connection. This will meet the code weld detail requirements.

 

[AlejandroFernandez]

Hi, ColonelSanders83. I don't understand you... why it's seems a bad idea?

Alejandro Fernández
I+D&I
Sitelca

 

[JohnGP]

I don't like it either - instead of having the weldolet attached to the pipe with a full penetration weld, you would be relying on the fillet weld on the reinforcing pad. Not good, especially if there is fatigue loading.

Additionally (if I understand correctly) with your proposed arrangement, there is a crevice between the pad and pipe that is exposed to process fluid and pressure.

I don't like it at all.

John

 

[ColonelSanders83]

Please see the attached sketch.

 

[AlejandroFernandez]

Ok I can see your point and you're right... but the welding of weld-o-let over full encirclement pad is made on factory w/full penetrant welding... after this the assembly is welding to the header... All calculation is performed to get proper width and length of the reinforcement and weld-o-let.
I seen this arrangement in some refinery in Venezuela.

The main idea is perform a welding of the reinforcement pad to the header in the outside... Doing this the pad can act like a pipe... see Fig. I3 (Welding Details for Openings With Complete Encirclement Types of Reinforcement) on ASME B31.8

Your opinion plis.. ?


Alejandro Fernández
I+D&I
Sitelca

 

[DSB123]

AlejandroFernandez,
You say you have seen this type of arrangement on a refinery in Venezuela? Well it's an accident waiting to happen. I would not visit the refinery anymore!!

 

[ColonelSanders83]

You absolutely can not take credit for full reinforcement of a joint with the configuration you have described, end of story.

Just because this has been done incorrectly (and dangerously) in the past does not mean you can allow it to continue. We’ve always done it that way is a sorry excuse used to cover up the fact that it has been done incorrectly.

I would never allow that joint to be built into a system I was responsible for, if I saw it in a pipeline that I inherited; I would force its replacement at the next shutdown. This is a terrible joint configuration (and a blatant code violation) and as DSB123 says it is an accident waiting to happen.

 

[merrillwalt]

Alejandro, the basic reason for using a weld-o-let is that it is self reinforcing! Very puzzled as to why you think you need to add a reinforcing pad.