TWI Annual Review - July 2008

Achievements in 2007

• Initiated a major research and development programme on flexible risers
• Provision of expert witnesses to support Members around the world
• Series of high profile topside, subsea and refinery failure investigations including on-site work
• Significant growth in training and certification in the Middle East and South East Asia
• Asset integrity management of upstream and downstream oil and gas facilities in the Middle East
• Completed several JIP/GSPs on sour service and sweet operation to support pipeline and riser applications
• Significant qualification test programme for deepwater pipe welds
• Engineering critical assessment of offshore pipelines worldwide
• Fatigue performance of welds for LNG applications
• Life extension of ageing platforms in the North Sea

Future Plans

• Launch further JIP/GSPs on integrity of welded joints in sour environment
• Launch projects on repair and life extension of aged offshore structures
• Launch strain-based design Group Sponsored Project
• Inaugurate Group Sponsored Project on clad pipes
• Expand training courses in the USA, Middle East and South East Asia
• Expand business in Libya
• Present key papers at NACE and OMAE conferences
• Technical workshops with key pipeline contractors

Case Study Metallurgically clad pipes were used for the mainline pipeline in a gas production project. The pipes were manufactured from clad steel plate using a hot roll metallurgical bonded process that included a series of mechanical and thermal heat treatment processes. The girth welds between the pipes were made with a MIG process using a duplex welding wire. In order to assess the condition of the welds, TWI undertook a series of finite element analyses (FEA) to derive J driving force versus applied axial strain for various sizes of circumferential flaws and carried out fracture toughness tests of the material in which flaws might be located. By comparing the fracture toughness required from the FEA derived driving force curve with the experimentally determined fracture toughness, it was possible to provide an estimate of the maximum tolerable flaw size to avoid failure for a given set of loading conditions. TWI's FEA-based ECA allowed the client to produce a table of tolerable flaw acceptance criteria for girth weld inspection during the installation of the pipeline. This work also helped to reduce incidences of weld repair and to meet the tight pipeline installation schedule. As a result, significant cost savings were made in relation to the pipeline project and its future maintenance operations.