TWI Industrial Member Report Summary 512(I)/1995
N V Challenger, R Phaal and S J Garwood
Fracture is an important consideration when evaluating the integrity of welded structures. Fracture mechanics assessments procedures, such as BSI PD6493:1991 ('Guidance on methods for assessing the acceptability of flaws in fusion welded structures'), have become well established in industry. For such procedures to be used with confidence for the assessment of fracture critical components, it is essential that the procedures be validated by comparison with large-scale experimental results generated from structurally relevant tests, such as wide plate and pressure vessel experiments.
This report presents the results of PD6493:1991 fracture assessments for a range of large scale fracture mechanics tests performed at TWI. These tests cover several material groups, including pressure vessel steels, pipeline steels, stainless steels and aluminium alloys. Ninety-two wide plate and pressure vessel tests have been reassessed following Levels 1, 2 and 3 PD6493:1991 procedures. In total, over 400 assessments have been performed, examining many features of the fracture assessment procedures. This work forms part of an ongoing programme to validate PD6493 procedures. Work is continuing, to include published data, additional TWI data, and actual structural failures in industry (Parts II and III).
BSI PD6493:1980: 'Guidance on some methods for the derivation of acceptance levels for defects in fusion welded joints, was published by the British Standards Institute in 1980. Substantial revisions to PD6493 were published in 1991, following recommendations of the WEE37 committee. This committee is likely to re-convene to consider further revisions to PD6493, and the results from the analyses described in this report will provide the WEE37 committee with some guidance on areas where PD6493 could be improved.