Shrinkage of HDPE Pipes Outer Diameter
Shrinkage of HDPE Pipes Outer Diameter
(OP)
Dear Forum Members,
We would like to hear from the forum experts that, Is HDPE pipe outer diameter (OD) will get shrink after manufacture with time and temperature? If so, what could be the problem?
We have received huge quantity of various sizes of pipes (OD 110 - 400 mm, SDR 36,) from a manufacturer around 8 months before for which the Outer diameter of pipes were found in specified standard limits during production and pipes were produced under controlled process conditions. The temperature of pipes was at almost ambient conditions (@ 25 - 30 Deg.C) when measured 100% pipes before despatch during manufacturing through Third-party inspectors (TPI) services. These pipes shall be used for lining services inside carbon steel spools where the OD of Pipes acts a major role.
But now , we have found reduction in outer diameter (1.5 - 3.0 mm) for all pipes irrespective of pipe size.
(Temp. at site was 15 - 18 Deg.C)
The reduction in Outer diameter of pipe is 1.0 mm for smaller size for 110 mm and 2.5 - 3.0 for 400 mm pipes..
Please lets know the technical justification for reduction of outer diameter of HDPE pipes.
Thanks in Advance.
RAM
We would like to hear from the forum experts that, Is HDPE pipe outer diameter (OD) will get shrink after manufacture with time and temperature? If so, what could be the problem?
We have received huge quantity of various sizes of pipes (OD 110 - 400 mm, SDR 36,) from a manufacturer around 8 months before for which the Outer diameter of pipes were found in specified standard limits during production and pipes were produced under controlled process conditions. The temperature of pipes was at almost ambient conditions (@ 25 - 30 Deg.C) when measured 100% pipes before despatch during manufacturing through Third-party inspectors (TPI) services. These pipes shall be used for lining services inside carbon steel spools where the OD of Pipes acts a major role.
But now , we have found reduction in outer diameter (1.5 - 3.0 mm) for all pipes irrespective of pipe size.
(Temp. at site was 15 - 18 Deg.C)
The reduction in Outer diameter of pipe is 1.0 mm for smaller size for 110 mm and 2.5 - 3.0 for 400 mm pipes..
Please lets know the technical justification for reduction of outer diameter of HDPE pipes.
Thanks in Advance.
RAM






RE: Shrinkage of HDPE Pipes Outer Diameter
RE: Shrinkage of HDPE Pipes Outer Diameter
Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
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RE: Shrinkage of HDPE Pipes Outer Diameter
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Shrinkage of HDPE Pipes Outer Diameter
Between moulding and one hour later it can be quite pronounced. The longer the time after moulding the slower the rate. If you graph size vs time after moulding, you will get an asymptote.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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RE: Shrinkage of HDPE Pipes Outer Diameter
Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com
RE: Shrinkage of HDPE Pipes Outer Diameter
I'm not sure what nucleating agents do to the processing properties when extruding pipe and trying to control size in the calibrator. Typically amorphous resins are easier to control.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules