pipe with a wall thicness of under 3/4 inch will normally not
require a PWHT (unless service/material requires it - like caustic
or Cr-Mo). The HAZ is no wider than 6 mm. Both could not be the
reason for maintaing a certain min. dist between the weld joint.
ASME Section VIII Div section UG talks about 4t (if i remeber it
right, i could be wrong).
having spent a long part of my professinal practice in the shop
floor making vessel,storage tanks, heat exhc and pipe spool among
others and fixing em at site here's my 2 cents worht of opinion.
- to account for the residual stress.
- to make the job the pipefitter easy. he'll need a lil space to
rig up a clamp or something to line up the joint.
- to facilitate NDE - xray and MT.
- In PipingDesign@y..., Conor Walshe <conor.walshe@a...> wrote:
> I recall it is a Heat treatment issue, the 50mm is taken from the
below
> paragraphs. i.e. twice the 25mm heat affected zone. I recall the
distance
> should be 50mm or 5 times the wall thickness.
>
> Refer to paragraph: 331.2.6 & 330.1.4, I cannot recall where I
read the 5xT.
>
> But anyway,if the welds are within that distance you need to
consider heat
> treatment as the heat affected zones will have overlapped.
>
> -----Original Message-----
> From: mapte@t... [mailto:mapte@t...]
> Sent: Wednesday, 2 October 2002 14:23
> To: pipingdesign@y...
> Subject: [PipingDesign] Weld to weld clearence.
>
>
> Hi,
> As a convention the toe to toe distance between two welds (
circumferential
> or branch ) on a pipe should be 4 times the pipe wall thickness or
50 mm (
> Some say 40 mm ) which ever is greater. Generally this is
mentioned in the
> project specifications.
> The question is where in the piping standards is it written. I
went through
> B 31.3 but could not find any.
> In section VIII , I found the mention but can that be generalised
for
> piping ?
>
> -Mandar.
>
>
>
>
> Texas Flange - a good source for information on industrial
flanges, all they
> ask is for referrals for designs they help with.
> 877-610-8924.
> www.texasflange.com
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Received on Thu Nov 14 22:58:00 2002