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Pit stop for site water system

 

Connect, November/December 1998

Pipework section as removed from the site water system at Abingdon
Pipework section as removed from the site water system at Abingdon

A typical example of pitting corrosion in a site water system was investigated recently by TWI specialists at the JET Joint Undertaking facility in Abingdon, Oxfordshire.

Corrosion pits are a type of localised attack where only a small area of surface is affected. However if leakage occurs as a result, the performance of a whole pipe system or vessel may be affected. Once a pit is formed it will continue to grow unless the bulk environment changes significantly or preventative procedures are taken. Measures to avoid corrosion of carbon steels include inhibition, cathodic protection and protective coatings.

Corrosion tubercles are clearly visible in this view down the inside of the pipe
Corrosion tubercles are clearly visible in this view down the inside of the pipe

A section of the leaking pipe was removed and inspected and a thorough failure investigation was carried out on return to TWI. It was concluded that corrosion pits had caused the pipe failure, probably because of a low inhibitor concentration in that pipe section.

JET Joint Undertaking have replaced the pipe using stainless steel and the system is back in operation. In addition, a review of the inhibitor dosing procedures is underway to avoid future failures in other areas of the site water system.

For help with corrosion failures or other corrosion issues, please contact us.

For more information please email:


contactus@twi.co.uk