1/4" thick repad to reinforce branch connection

[csquaredng]

Hi guys,

I have typically designed with a minimum repad thickness of 1/2" on welded branch connections. This time around, I am dealing with a 4" branch on a 36" run pipe. The problem is with a 1/2" repad, I have a weld proximity issue where the repad weld toe is only 1 mm away from the adjacent small fitting weld. While using 1/4" repad provides enough reinforcement as per B31.4 calculation, it also contradicts the common practice where repad thickness equals the header thickness. I read on another thread that repad thickness is 0.75 x header thickness at minimum and 1.5 x header thickness max. Any of the experts here can provide some explanations on the minimum repad thickness limit?

Much appreciated!

 

[akpipelineengr]

I don't see that the Code specifies a minimum thickness (assuming B31.4 is your design code). I would be concerned about getting a poor, hard weld if that 1/4" fillet gets made in a single pass. The thinner repad only gives you an additional 1/4" of clearance from the other weld, which is still closer than may companies allow.

Why not use a weldolet in this application? Smaller footprint, fewer welds, and integrally reinforced.

 

[csquaredng]

akpipelineengr,

B31.4 do not specify that but thank you for sharing the possible hard weld problem. I'm not yet well-versed in welding. As for the weld proximity, the client spec has a provision for small fitting that allows minimum weld spacing; I simply want to maximize this spacing as much as I can.