Effect of Sun / UV on strength of Fiber Glass piping 1

[gasoperations]

We have recently experienced failure of 12" fiber glass water pipe ( about 40 years old ) operating at ~ 50 psig. The failed section of the pipeline was exposed to direct sunlight and thus exhibits erosion / deterioration of the surface epoxy coat. This is evident as some of the fibers on the surface can be seen detached.

But generally the pipe surface is rigid and does not appear to be bad. Only the smooth feeling of the surface has disappeared from the exposed section.

Could some one help if the sunlight exposure can lead to deterioration of the piping material or this failure is due to possible material defect.

Thanks

 

[SJones]

40 years is pretty good going considering that design life is usually around 20-25 years based on regression from long term testing. Try examining the failure to see if it occurred from the inside out. UV penetration effects would be typically measured in microns per year with modern, UV stabilised resins. It may be that the pipe just reached the end of its life, perhaps hastened by a higher wall temperature in the sunlight.

Steve Jones
Materials & Corrosion Engineer

http://www.oilandgaspeople.com/cv/11499664

http://www.linkedin.com/pub/8/83b/b04

 

[hokie66]

A 40 year old pipe would not have the UV stabilisation of modern fiberglass. At any rate, I don't think you can attribute failure after 40 years in the sun to material defect.

 

[gasoperations]

Thanks guys. I am also of the view that 40 years is a long period but available technical litrature indicates that initial surface deterioration due to UV actually prevents any further UV damage of the material.

This was why I was wondoring if the the failure could be due to some other reasons like surge, material defect etc.

Anyway thanks for your valuable thoughts.

 

[unclesyd]

Here is some information on the industrial fiberglass industry. They only way you got any protection from UV was when you had a high loading of Antimony Trioxide as a fire retardant. There were a lot of misguided applications of the various fiberglass products over the years, we had our share and some. We actually painted some fiberglass pipe with an epoxy paint before it was well known that UV would tear up any epoxy top coating. We had chalk on chalk.

You were very fortunate that your pipe had a long happy life.

http://www.dsm.com/en_US/html/drs/atlac_history.htm

 

[rconner]

The literature referred to obviously talks a good game; however, the water line discussed at the bottom of page 11 of the book at

http://www.itacanet.org/eng/water/S...ibution Modelling and Managment/WDM_Ch_01.pdf

(with sections of flanged piping exposed on piers) actually made it three hundred years.

“By nature, men love newfangledness.”
Geoffrey Chaucer 15th Century

 

[corrosionman]

Some years ago we had a complex demin water distribution system 30 yrs old, 8 inch dia,total length approx 1.5 miles, press approx 80 psi, it regularly burst, anywhere round the circumference, always on warm sunny weekend afternoons, at randomly different regions of the site and a long way from any shut off valves - - we were able to take samples from the pipe walls adjacent to bursts and invariably they showed strengths able to withstand approx 500 psi. We considered everything, fatique, water hammer, sunlight,localised poor workmanship , accident damage, etc etc. We never figured it out - soon afterwards we lost the repair contract so never found the answer but we often wondered if waterhammer could send shock waves back up the pipe causing peak pressures miles from any valve.
Best of luck with your problem.
Corrosionman