Project news, January - February 2011
For a full list of proposed, active and closed Group Sponsored Projects, please contact gsp@twi.co.uk Risk based integrity management of FPSO hull structure
Project launch: 11 November 2010
Project leader: Ujjwal Bharadwaj
Maximising the availability and productivity of an FPSO (Floating Production, Storage and Offloading facility), whilst operating safely and with minimal impact on the environment, is a major concern of operators. FPSOs have certain constraints, loading characteristics and damage consequences that make them different to other offshore installations and conventional ships, and often more challenging to maintain and operate. This proposed group sponsored project (GSP) aims to develop a risk based approach to FPSO hull structure integrity management and to establish agreed good practice.
The scope of work on FPSO hull structure integrity management will reflect the preferences of the industrial sponsors and may include the following topics: techniques for assessing damage, inspection planning, assessing appropriate repair techniques, assessing state-of-the-art hull condition monitoring techniques, and trending and managing the data that is generated. Software will be developed to implement the approach and a good practice document will be produced.
The project will take account of recent developments; for example, many classification bodies are adapting their technology for assessing ship hulls to FPSOs. It will take account of other work in this field in developing the risk based approach. In particular, recently developed ship hull structural management software Risk Based Expert System for Through-Life Ship Structural Inspection and Maintenance and New-build Ship Structural Design (RISPECT) will be enhanced and applied to implement the risk-based approach. The database structure within RISPECT that enables recording, processing for reliability analyses, sharing and storing of relevant data will be developed for integrity management of FPSO hull structures. TWI Ltd is an active participant in the RISPECT project which completes in 2011.
Industry standardisation of SENT testing
Project launched: 25 January 2011
Project leader: Rajesh Patel
The single edge-notched tension (SENT) fracture toughness specimen is rapidly gaining acceptance and being more widely used as a substitute for the single edge-notched bend (SENB) specimen for assessing the integrity of pipeline girth welds subjected to plastic strains. Generally, SENT tests result in higher fracture toughness being measured than with SENB tests and they are more representative of pipe behaviour. However, SENT fracture toughness testing and analysis methods are not standardised. This is a potential problem as the results are often used to make critical decisions about the integrity of pipelines that contain flaws. Furthermore, because more testing laboratories are employing SENT specimens there is a need to minimise inter-laboratory variations that can give potentially contradictory results. It is therefore important to standardise fracture toughness testing of SENT specimens for parent material but, in particular, for weld metal and heat affected zone of girth welds which often exhibit the lowest fracture toughness.
This Group Sponsored Project (GSP) will critically review existing literature and develop a standardised industry procedure for the fracture toughness testing of SENT specimens in particular for weld material. To achieve this goal the programme of work will be divided into four phases: (1) review existing knowledge, (2) testing and analysis, (3) round-robin testing, (4) proposing a SENT industry standard (ie BS 7448: Part 5).
The results will help to improve quality, safety and promote best practice in the fracture toughness testing of SENT specimens and be of relevance to all companies associated with pipelines, especially to offshore pipe installers and operators.
