RE: Re: Butt Welded HDPE Pipe

From: <Steve>
Date: Tue May 18 2004 - 17:21:00 EDT


Hi Pete

I let the supplier/installer know my opinion and presumably he has contacted his client; I will find if there has been an outcome. Removing the bead will be a pain. If the need arises, the first step is to find out what others have done; may even have some fun and ask the client how he wants it done. If we have no luck will try cutting off the bead with some sort of sharp edged thingie, perhaps some form of pneumatic chisel with guides. HDPE hot works quite nicely but the bead would cool before we finished hot trimming it. Dry grinding just makes a big mess; wet grinding may work but would be very slow.

I suspect common sense will prevail, but I have been wrong on this assumption before.

Cheers

Steve

-----Original Message-----
From: Pete's Mail [mailto:peteburn@optonline.net] Sent: Tuesday, May 18, 2004 12:31 PM
To: <a href="/group/PipingDesign/post?postID=GilDffUrf_yLmTwn0kYHO-htvPDfO0D4BP2RQoKBixB3oet6BQNk3y2E5khIoyerCGZiHHUBPMWCAXeQd2HocW0eVIIc">PipingDesign@yahoogroups.com</a> Subject: Re: [PipingDesign] Re: Butt Welded HDPE Pipe

Steve
I've been following the bead situation. I just want to hear how you resolve it. Don't leave us hanging. I'm curious how you are going to get rid of it too.

Pete

Thanks Tony
I reckon the Re is about 2 million so there you have it. Surprised the
laminar transition would have such an effect. Must check it out. One
day.............

Cheers

Steve

-----Original Message-----
From: Tony Paulin [mailto:tony@paulin.com]
Sent: Monday, May 17, 2004 5:01 PM
To: <a href="/group/PipingDesign/post?postID=GilDffUrf_yLmTwn0kYHO-htvPDfO0D4BP2RQoKBixB3oet6BQNk3y2E5khIoyerCGZiHHUBPMWCAXeQd2HocW0eVIIc">PipingDesign@yahoogroups.com</a>
Subject: [PipingDesign] Re: Butt Welded HDPE Pipe

Re: Weld beads and pipeline friction

Hans Bos passed on the following comment I thought might be helpful:

Whether it is important or not depends on the Reynolds number. If flow is
low and the design Reynolds number is in the laminar tubulence transition
the bead could make the boundary layer change to turbulent and then the
friction increases. If the flow is turbulent anyway the bead should hardly
be of importance.

Tony

-----Original Message-----
From: Steve McKenzie [mailto:mechproj@xtra.co.nz]
Sent: Friday, May 14, 2004 4:35 PM
To: <a href="/group/PipingDesign/post?postID=GilDffUrf_yLmTwn0kYHO-htvPDfO0D4BP2RQoKBixB3oet6BQNk3y2E5khIoyerCGZiHHUBPMWCAXeQd2HocW0eVIIc">PipingDesign@yahoogroups.com</a>
Subject: [PipingDesign] Butt Welded HDPE Pipe - Friction Loss Due To
Weld Beads

Gents
an HDPE supplier/installer has been asked by his client to debead the
weld inside an HDPE pipeline. The reason given is thought to be
increased pipeline friction due to the weld beads.
The line is 1400mm OD (18m lengths), 56mm wall and the beads are said
to be 10mm high (which seems a little low to me). I did a few rough
sums treating the weld as an orifice plate. The outcome was that the
weld friction loss is less than 3% of the pipe friction loss, which
didnt surprise me.
I am looking for an authoritative (quotable) study/reference on this
subject.
Any leads?
Thanks

Steve

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Received on Tue May 18 17:21:00 2004

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