A half day seminar was held on 30th November 2016, prior to the Institute AGM. Three presentations were given on the topic of “Pipelines and Stray Current Corrosion”.
Patrick Lydon, IACS Corrosion Engineering Ltd, discussed “Pipeline coatings past and present” and gave a brief introduction to the commonly used pipeline coating systems and information on their typical properties. The primary topic of the paper was the use of a 3 layer polyethylene coating system on a UK gas industry pipeline project, and the reasons why this system was selected for sections of the pipeline in preference to the conventional fusion bonded epoxy coating system. Some of the issues that the project faced in terms of coating repair and inspection requirements were discussed, together with the requirements for field joint coating prequalification.
David Buxton, Intertek Production and Integrity Assurance, presented “Managing stray current from UK rail systems” which focused both on the management and control of corrosion, caused by stray currents. An introduction to stray current was provided along with a description of typical stray paths, and the importance of controlling stray current at the design stage, during construction and finally during operation, was stressed. The impact of interference was discussed and illustrated with some examples of failures, including recent data collected from the Midland Metro system where an earthing issue at a traction substation resulted in a temporary increase in interference and long range interactions.
The final presentation, given by Bill Whittaker, Cathodic Protection Engineering Ltd (CPEL) was entitled, “Pipeline AC Corrosion, examples and latest thinking”. Pipelines routed parallel to HV overhead cables will have an AC voltage induced in them, caused by changing electro-magnetic fields. During the positive part of the cycle, passive behaviour is induced; during the negative part of the cycle, metal loss occurs. Older pipelines and those with poorer coatings are more prone to this type of corrosion and will corrode at higher rates. Electrical factors affecting AC corrosion include: configuration, current loads, load balance between phases of power lines, electrical resistance of coating(s) and soil resistivity, which can be counteracted by insertion of zinc (or less commonly, copper) ribbons to isolate “active” migration.
At the end of the technical talks, Jim Preston, Corrosion Protection Ltd, was presented with an award given by S.E.E for the best P.R.I. (Professional Review Interview) for registration as a Chartered Engineer in 2015, by Mr Peter Vincent, President and Prof M Leonardo de Calcina, Past President and Trustee of the Society of Environmental Engineers (SEE). SEE is a fully-licenced body of the Engineering Council, with which ICorr has an agreement (along with seven other Professional Affiliates of the Engineering Council) to oversee ICorr registration for CEng, IEng, Tech Eng. The award came in the form of a framed certificate, SEE medal and a cheque for £250. It is indeed an honour that an ICorr person should receive this.