Weldolet vs Flat Weldolet

[impeller1]

Hey all,

I'm fairly new to fabrication and welding, so I wanted to find out if there is a difference between a weldolet and a flat weldolet. I have to specify one for replacement, and according to my Isometric, its specifying a flat weldolet. I did a little digging and saw somewhere that flat weldolets are most used for flat surfaces (which makes sense I guess), but this particular application is a 36" pipeline, so I'm not really sure why it specified a flat. This particular one was never replaced before so I can't say for sure what is actually on the pipe. Can anyone shed some light here for me please? Thanks in advance

 

[LittleInch]

Up to a 36" pipeline you can get profiled weldolets, but for 38" and beyond, up to 6" standard weldolet, the curvature is so small that the flat weldolet will actually be the same or so close that it makes no difference. So whie 36" is theoreticlly a profiled weldolet, especially for sizes of 3" and below, a flat one will be acceptable.

For 1" and below, the same weldoltet will actually do for all sizes from 12" to 36"

See

http://www.bonneyforge.com/resources/BC.pdf‎

for more details (page 38)

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way