50mm is a good general rule for proximity of Pressure retaining joints, however
it is possible to apply a spacing of less than this distance, but the
consequences could result in PWHT. Some inspectors will allow distance of 4x
thickness of pipe or square root of Dxt, but you should always consult your
welding inspector before breaking this 50mm golden rule.
Hope this helps
-----Original Message-----
From: tomcruz55 [mailto:tomcruz55@yahoo.com]
Sent: 26 March 2003 19:04
To: <a href="/group/PipingDesign/post?postID=-EshK7ydkPA-7vF1Tg7fVXKfd8WMnIvzDrEniItGETY_vb3BRXqloW-4y4etfd46Wcv68fBjOA6OqljFARpDbF5T">PipingDesign@yahoogroups.com</a>
Subject: [PipingDesign] Re: Minimum distance between Fittings
The HAZ width in butt weld joint is very very narrow. So what's with
the 50 mm pup piece? We've welded a pup piece less than this to make
up for the shoratge in the "short lenght" gate valve without a
problem. As long as it pass the NDE and hydro and matl is usitable
for service, chances are your fabricated pipe spool will be OK.
For the criteria related to dimesnion of fabricated spool, ive go
with the PFI Standard.
- In PipingDesign@yahoogroups.com, "Glenn Dillon"
<glenn.dillon@t...> wrote:
> Hitesh, assume these are butt weld fittings. Fitting to fitting is
> preferred but where not possible I work on minimum pup spool
distance of 50
> mm to allow for weld effected zone and weld efficiency. Haven't
had any
> failures yet. With steam, elbows can be highly stressed and its
best to
> ovoid short pipe sections and layout distribution to allow fitting
to
> fitting.
>
> Hope these comments of some help. Best regards Glenn
>
> -----Original Message-----
> From: Ashok Dani [mailto:ashokdani@t...]
> Sent: Friday, March 22, 2002 4:29 PM
> To: 'pipingdesign@yahoogroups.com'
> Subject: [PipingDesign] Minimum distance between Fittings
> Importance: High
>
>
>
> > What is the minimum distance required between Bend-Tee or Tee-Tee
for
> > Steam
> > line or as per B31.1?
> > Thanks in advance
> > Hitesh
>
>
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Received on Thu Mar 27 05:07:00 2003