B31.3 pipework

[thedecimalinch]

Why can you not easily change a design of liquid and gas pipework from having welded butts to have a section of pipe flanged to allow for the maintenance of other components?

 

[TD2K]

What are you being told is the issue? I've been involved in many jobs designed under B31.3 that we put in flanged spools. Sometimes you add these in because the client decides they want a blind point late in the project or they want to minimize welding so we end up putting in flanged spools.

If it comes in late, it potentially impacts the P&ID (some clients show these flanges, others don't), 3D model updated, the isometrics have to be redone, stress might want to look at it depending on the size, material and temperature. Bill of materials will have to be updated and POs updated depending how materials are being handled.

 

[pennpiper]

I am not sure what you are talking about here but I think you have the wrong impression of what can and cannot be done.

As far as I know there is no restriction in ASME B31.3 against having Flanged construction mixed with Butt Weld construction.

Can you give more detail about your situation and what you are trying to do along with what you may have been told that you cannot do.


prognosis: Lead or Lag

 

[stanweld]

There is nothing in B31.3 which precludes using both welded and flanged joints. In fact both methods are addressed and have been used since the Code's inception.

 

[thedecimalinch]

Sure more details. We have a breathing air stainless steel line which is in the way of installing and removing a component on site. Rather than chop it every time I was thinking iof having a short section of it flanged off for for ease of maintenance.
But people say its not possible... Would it matter if the line had nitrogen in it etc?

 

[MickMc]

As already posted there is nothing in code precluding flange connections but preference is for welded connections to minimise potential leak paths, it is normal practice to utilise flanged spools for connecting to equipment requiring removal for maintenance purposes.

 

[MJCronin]

thedecimalinch;

Those people who say it is not possible...... don't take advice from them anymore.

I agree with pennpiper ad TD2K...

I have been involved in industrial piping design and analysis for 30+ years and have never heard such a thing...

 

[DSB123]

thedecimalinch,
Probably the guy who is telling you it is not possible was the original designer and does not want to look stupid if he originally insisted that the line had to be fully welded!!!!