Arc Energy Provides Specialised Welding And Fabrication For Vector PLR Arc Energy Resources has successfully completed a contract to carry out its highly specialised welding and fabrication services on a pig launcher and retrieval system (PLR) destined for a time-critical application in the Cascade Chinook oilfield in the Gulf of Mexico, where operator Petrobras is laying an additional subsea pipeline to increase production
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The contract, for the subsea division of Vector Technology Group, involved Arc Energy welding a soft landing arm system to the PLR as well as fabricating a structural split flange support to enable the hub of a Vector OPTIMA subsea connector to be attached to pipeline end terminations (PLETs). In addition, Arc Energy fabricated and welded a number of specialised components to produce lifting brackets and control panels that needed to meet similarly demanding welding procedures for the Vector specification. All the components were fabricated to high standards and close tolerances by Arc Energy in accordance with the American structural welding codes, AWS D1.1 and ASME VIII. Output from the Cascade Chinook field has a high hydrogen sulphide content, which necessitates the use of very tight welding parameters in order to adhere to the demands of NACE. As a result of the long pipe lengths, the internal surfaces of the pipe quickly become coated with hard scale and wax deposits, reducing production by restricting the delivery of oil ashore. ‘Pigs’ are introduced into the pipeline using specially designed launching and receiving vessels to clear debris, and to batch and clear residual product. Frequent ‘pigging’ is required to ensure that production is optimised. Vector‘s subsea division, which was awarded the contract for the 15,000psi rated pig launcher by Technip Group of Houston, completed the design for the Cascade Chinook field and, as part of the development programme, sent a team of engineers to Arc Energy’s Gloucestershire facility to discuss the critical welding elements of the project and carry out a design review for manufacture. Commenting for Vector, Executive Vice President Chris Lee says: “We have worked with Arc Energy for a number of years and have a framework agreement in place for inlaying the hubs used in our Techlok and Optima subsea connectors. More recently due to increased demand from
customers, the company is working with us on specialised fabrications, primarily against American specifications such as the demanding AWS D1.1 and ASME, for which Arc Energy is already pre-qualified. On this project the PLR is welded to the pipeline and the combination of our Optima connector and the customer’s valve enables the pig to be introduced safely into the pipeline and closed off.” Arc Energy’s welding engineers, led by managing director Alan Robinson who has a Masters degree in welding and is one of a small number of UK registered International Welding Engineers, helped the Vector team develop its drawings to a ‘designed for manufacture’ stage. The two companies then worked on a joint-venture basis to produce the fabrications that connect to the Vector PLR, which is 3.5 metres tall 2 metres wide and weighs approximately 5 tonnes. Alan Robinson says the Vector PLR was both time and safety critical for the Cascade Chinook field, so during fabrication inspectors from Vector, Technip and Petrobras spent several days at Arc Energy’s Eastington factory to approve manufacture and testing. The Vector PLR is one of two contracts awarded to Arc Energy for the Cascade Chinook oilfield and Chris Lee reports that Vector was so impressed with Arc’s ‘designed for manufacture’ approach that the second project is currently undergoing a similar process.