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: PipingDesign@yahoogroups.com
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

[Non-text portions of this message have been removed] Received on Mon May 17 01:00:00 2004