Slipon Flange Welding
Slipon Flange Welding
(OP)
We are welding a 48" 150RF B16.47 slipon flange to a 3/8" wall pipe. For fitup adjustment, B31.3 gives minimum depth equal to pipe wall thickness for the internal weld. What's the maximum we can move the flange out? I found nothing in B31.3 for the maximum. ASME Sec VIII Div 1 and 2 show the maximum is pipe wall plus 1/4"; we need pipe wall plus 5/8". Our boilermakers say that their practice is to use 1/2 the thickness of the flange as a maximum (dimension "C" in B16.47).
In general, what's the maximum permissible projection of a slipon flange off the end of the pipe?
In general, what's the maximum permissible projection of a slipon flange off the end of the pipe?
Larry





RE: Slipon Flange Welding
Larry
RE: Slipon Flange Welding
The dimensions make it fall under Sect VIII so the t(n) + 1/4 is correct.
The half thickness is used all the time when you are not looking.
Does it have a Hub (Crane)?
What is the total thickness?
Is it a 16.47 A or B or an MSS.
RE: Slipon Flange Welding
OD of flange (O): 59.25"
Thickness of flange (C): 3"
Length through Hub (Y): 4.25"
Diameter of hub (X): 52"
Hub is not tapered, so Hub Diam. Top (A) = 52"
Dimensions don't seem to match any 150 lb rating, neither B16.47 nor MSS SP44. It's pretty close to the Class 125 in my 1976 Taylor Forge catalog.
I'd guess that extending the flange past the Div 1 1/4" distance would effectively give a shorter hub, and increase stress at the back of the hub.
Larry
RE: Slipon Flange Welding
Larry
RE: Slipon Flange Welding
I think you will be OK for your conditions with no problems. If there is any question you might slightly bevel the Hub for additional reinforcement.
Being an old hand you can remember when they didn't routinely weld the inside of slip-on flanges.
Our specification for stainless slip-ons flanges calls for the toe of the inside weld to be 1/2" from the flange face. This is to insure that heat input to gasket surface is minimized.
We have plenty of steam (175) lines that don't have the inside welded (1952). Probably all the plant air lines (90psig) were installed the same way.
RE: Slipon Flange Welding
Your opinions agree with mine, so we'll go with the 1" setback on the 3" thick flange.
Have a good day.
Larry
RE: Slipon Flange Welding