Hi Robin
oddly enough, was thinking about using a buzz plane this morning. If I can
modify the trailing shoe to a curve, and the blades dont get too hot, it
could be a winner. If the blades get hot, I may be able to blow some
compressed air through, or water and use a comp air motor instead.
Yes we always use chainsaws on large PE pipe; there is nothing better. I'm
told they also work well on ABS but havent tried - yet.
Cheers
Steve
-----Original Message-----
From: Robin Badcock [mailto:rbadcock@vision.net.au]
Sent: Thursday, May 20, 2004 1:45 PM
To: PipingDesign@yahoogroups.com
Subject: Re: [PipingDesign] Re: Butt Welded HDPE Pipe
Hi Steve,
I should have known better than to think that you had not tried or thought of such a fix for your poly problem. However, have you considered the use of an 100mm electric planer? As you only have beads 10mm in height and possibly 20mm or so in width one of these units will have enough grunt to cut your material off. Ok, it comes of as a chip and will make a mess unless you couple the discharge port to a vacuum system for non-stop operation (you don't have to empty the bag). The obvious advantage with this system would be that there is no heating required, no fumes nor blocked abrasive grinding discs as the material is physically cut. Does this sound like a possible plan? I have not used this technique myself although I can see no good reason as to why this would not be successful. Most of our work is done on pipelines of a much smaller diameter than what you are quoting.
Please do not ask me if we use chainsaws for the trimming of poly pipes, as we most certainly do not even though they are wood working tools also. Have seen it done in the wild west though.
Cheers,
Robin Badcock
> Hi Robin
> I made one of these years ago in an attempt to trim polyurethane foam
> quickly. Had completely forgotten about it Used a stepdown transformer and
> nichrome wire as the "bowstring" on a fibreglass bow. Apart from the foam
> giving off poisonous fumes (not a problem with HDPE) bits of plastic
> carbonised on the wire and breakages were frequent. Also it was very slow.
> Sharp knives worked better.
> However a hot knife continuously heated by a big LPG torch might be the
way
> to go if we can get enough heat into the blade.
> Thanks for the idea.
> Cheers
>
> Steve
> -----Original Message-----
> From: Robin Badcock [mailto:rbadcock@vision.net.au]
> Sent: Thursday, May 20, 2004 12:07 AM
> To: PipingDesign@yahoogroups.com
> Subject: Re: [PipingDesign] Re: Butt Welded HDPE Pipe
>
>
> Steve,
>
> Have you considered a hot wire gun? This could be the thingie that you
seek.
> Two electrodes with a piano like hot wire between them that is obviously
hot
> (set the thermostat) and leaves a nice clean cut and is quick. This is
> somewhat temperature dependent (as well as operator) as to time taken.
Just
> an idea!
>
> Cheers,
>
> Robin Badcock
>
>
>
>
>
> ----- Original Message -----
> From: "Steve McKenzie" <mechproj@xtra.co.nz>
> To: <PipingDesign@yahoogroups.com>
> Sent: Wednesday, May 19, 2004 7:21 AM
> Subject: RE: [PipingDesign] Re: Butt Welded HDPE Pipe
>
>
> > 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: PipingDesign@yahoogroups.com
> > 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
> > ----- Original Message -----
> > From: Steve McKenzie
> > To: PipingDesign@yahoogroups.com
> > Sent: Monday, May 17, 2004 2:39 AM
> > Subject: RE: [PipingDesign] Re: Butt Welded HDPE Pipe
> >
> >
> > 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: PipingDesign@yahoogroups.com
> > 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: 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]
> >
> >
> >
> >
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Yahoo! Groups Links Received on Wed May 19 23:28:00 2004
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