RE: [PipingDesign] Pig

From: <Geoff>
Date: Thu Sep 11 2003 - 17:48:00 EDT

Hi Steve,

I believe intelligent pigs do have devices for pig locating. These may be radio based but I am unsure. You need to talk to the specialists.

For slipliners CPChem (Driscopipe) have some data in their manuals. There are a number of techniques. The squeeze of PE , pull through and let it expand. Limited to about 500m at a time. There are spiral wound uPVC Rob Loc, Folded PE blown up by steam. Check out your local Tyco office. They have a division in Australia that specialises in it.
Geoff
--- Steve McKenzie <Mechproj@xtra.co.nz> wrote:



Hi Geoff

We have a positive Langalier index so the line is scaling more than it is corroding. At present there is a water shortage so I am reluctant to close down the line too long, especially for condition assessment only. After much head scratching, I think I will fit a booster pump part way up the hill to restore flow, and then carry out the pigging operation when water is more abundant.
Can you get a pig with an ultrasonic transmitter/receiver built in? If it jams then we could locate it by signal transit time. Whats the story about slip liners? Any websites that give a good intro?

Cheers

Steve

-----Original Message-----
From: Geoff Stone DD&D Australia [mailto:blenrayaust@yahoo.co.uk] Sent: Thursday, September 11, 2003 9:53 AM To: PipingDesign@yahoogroups.com
Subject: Re: [PipingDesign] Pig

Steve,

A risk analysis of this operation will drive you to find out more about the condition of the pipe before rushing in and pigging the line.

The problems with a steel line could be scaling, high levels of corrosion or local blockage. Running an intelligent pig htrough a small section (uphill) and
reversing it out(compressed air downhill) may give some idea as to the problem.
Also you may be able to get a CCTV into places such as air valve or scour valve
locations.

If you have scaling then you are looking at an acid clean short term and antiscalant dosing in the future.

If the line is heavily corroded you may be looking at sliplining this one to keep it going and running a parallel line to meet the flow required.

If pigging is required I would pig from the bottom but make sure that I had to
hand compressed air to drive the pig in reverse. Also some good metering so That I knew how much water had gone into the line before the pig got stuck. Then a field crew could dig it up and make a repair.

Geoff
--- Steve McKenzie <Mechproj@xtra.co.nz> wrote:



Gents

I am looking at having a portion of water supply line pigged out because its friction loss is around 4 times what it was. The line is 10" steel, 3/8" wall and is a rising main taking water from a pond to the top of a hill about 330m higher up. The pipe length is 3900m, reasonably constant incline (but a few level portions at road crossings) and currently flows at about 70 l/s. Line pressure at the bottom end is 44 bar and there is an atmospheric vent as the top end.

I have no experience in pigging and am unsure what the outcome will be and the best way to do it.
My nightmare is blocking the line; I can take it out of service for a few days, but longer than this would cost millions as it would shut down a processing plant.
The pig supplier suggested going from the top to the bottom using compressed air to force the pig down the line (there is no water supply at the top of the hill).
The pigging contractor thinks going from the bottom to the top using water to drive the pig up the line is the best way to go. I can see pros and cons with both options, but am tending to favour the water (uphill) option because of the flushing action of the water.

But what do I know?

Any experience or suggestions would be appreciated.

Cheers

Steve McKenzie

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Information presented on this list is given as helpful advice, nonsense, carefully-considered calulation or any combination of the above. The intent is to spark discussion and encourage knowledge-sharing amongst professionals. If you blow yourself up by doing stuff remotely described by info gleaned from reading this list, you are an idiot.

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Information presented on this list is given as helpful advice, nonsense, carefully-considered calulation or any combination of the above. The intent is to spark discussion and encourage knowledge-sharing amongst professionals. If you blow yourself up by doing stuff remotely described by info gleaned from reading this list, you are an idiot.

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Design Detail and Development (a division of Blenray Pty Ltd) We specialise in pipe network and waterhammer analysis, pipe stress analysis, the design of buried pipelines and thermoplastic pipe systems.

Overseas tel 61 2 402 35 2313 fax 61 2 8850 2313 mobile 0402 35 2313 Mail Address PO Box 1351 Castle Hill NSW 1765 Australia



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Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com Received on Thu Sep 11 17:48:00 2003

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