TPT January 2008

C oating, J acketing & Galvanizing Technology

The work involved was especially complex as welding can cause material shrinkage and distortion. Because the overlay cladding process requires vessels to go through two welding cycles, there were risks that needed to be assessed and addressed. The Arc Energy welding and fabrication teams therefore needed to take considerable care, both with the initial setup and the welding

vital component, connecting with onshore facilities. Because media temperatures of 120ºC in the splash zone create a very corrosive environment, the project required Arc Energy to fully clad the riser externally using 16 plates of 3mm alloy 59. The new procedures had to be qualified in accordance with ASME IX and other international standards. The test welds and subsequent mechanical testing was witnessed by independent inspectors.

Following completion of the seal welding, the cladding was subjected to 100 per cent DPI followed by a pressure test using an inert gas at a pressure of 1 bar. The pressure test was held for 15 minutes minimum and the sealing weld was visually examined to ensure that no leaks were evident.

Arc Energy Resources – UK Fax : +44 1453 823623 Email : sales@arcenergy.co.uk Website : www.arcenergy.co.uk

sequences, to ensure that allowances were made for distortion. It was essential that the customer received the vessel to the exact specification ordered. A second contract won by Arc involved cladding four very large elbows as part of a bigger project for Langfields Ltd, one of the UK’s leading component fabricators. The project at Shell’s Stanlow Refinery required overlaying four 36" carbon steel elbows with stainless steel. Shell’s senior welding engineer, Mr Wayne Griffiths, states “The technical skills and knowledge of welding procedures required were so demanding that not many companies can, or even want to, handle this type of work. Arc Energy Resources were able to ship the elbows to their factory in Gloucestershire for weld overlay cladding.” Elbows are always difficult to handle but to accommodate the unusually large diameters for this project Arc Energy also needed to design and build two special jigs. To meet the tight delivery schedule both workstations operated 24 hours a day for the duration of the contract. In addition, Arc Energy was responsible for proving the quality of its cladding prior to delivery, by 100 per cent non-destructive testing. Arc Energy’s third big contract involved the corrosion-proof cladding of an 8.65m-long, 16" diameter superduplex riser for Mardale, a leading supplier of pipeline packages for the oil and gas industries. The pipe is destined for a sour oil reservoir located approximately 10km offshore in the Gulf of Suez. Oil and gas from the field will initially be produced from a single, unmanned nine-slot platform with a 16" multiphase pipeline. The riser is a

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J anuary 2008