slip on pipe flange 5

[spike]

If you use a slip on flange on the end of a pipe, where and how would you weld the flange. I assume that fillet welds would be used, but would not know what size of weld to use. This is on a low pressure pipe.

 

[Christine74]

In my experience, the size of the fillet weld for a slip-on flange is usually set to the same as the thickness of the pipe to which it is attached.

You first set the flange so that it projects (pipe thickness + 1/8") from the edge of the pipe, then you make the internal and external fillet welds around the circumference.

I believe extra 1/8" is provided to protect the gasket surface from distortion.

-Christine

 

[JStephen]

The extra 1/8" dimension will vary from zero to 1/4" or so, depending on what code you're using.

If pressure is very low, the weld sizes could probably be reduced- depending on what code or standard pipe is designed under (if any).

 

[GenB]

Always fillet both sides even for low pressure,
and as minimum weld, cover the pipe but not less than 1/4" legs. I assume that this is not a Coded job.
ER

 

[MJCronin]

Spike,

The answer to your question is contained in the fabrication section of the ASME B31.1 and B31.3 piping codes.....

By the way, S.O. flanges should always have two fillet welds (inside and outside the pipe)to attach them to the piping systems.

Check this thread...

http://www.eng-tips.com/viewthread.cfm?qid=105019

and this one...

http://www.welding-units.co.uk/Flanges/about_flanges.htm#Slip-On Flanges

MJC

 

[bvi]

The size of the outside fillet is set by the applicable Code (e.g. 1.4 times the nominal pipe thickness or the width of the hub available for welding, whichever is less).

The set back distance is to avoid damaging the flange face with the inside weld, and for pipelines, pigging considerations. Some codes specify a dimension, others such as ASME B31.3 do not. The set back dimension is not signficant with respect to strength or fatigue considerations.

The inner weld is always preferred, but not always required. You need to check the applicable code for requirements. When required, it is generally a small fillet weld (e.g. 1/4 inch or the thickness of the pipe, whichever is less).