Bodycote have recently announced that its Daventry Laboratory has validated a new testing procedure for fracture toughness testing. The procedure known as Single Edge Notch Tension or SENT had been developed specifically in response to technological advances in the oil and gas pipeline sector and Bodycote wished to provide a commercially available alternative service.
It had become established practice in this field to use pipeline specimens tested under bending to derive a value of fracture toughness [K, Crack Tip Opening Displacement (CTOD), J Integral or J-resistance curves] for use in the calculation of a critical defect size through the various levels of an Engineering Critical Assessment (ECA). This provides a guide for the acceptance or rejection of defects found during pipeline construction and in-service.
It has long been accepted that, in some circumstances, fracture mechanics toughness values derived through testing specimens in bending were over-conservative and not wholly representative of real life operational conditions. The constraint conditions existing in a pipeline during construction and service are often better represented by testing in tension, hence the selection of the SENT geometry specimen. The applicability of the SENT geometry for this purpose has been gaining acceptance and expected to become widely specified, hence Bodycote’s interest in developing a validated commercial procedure.
Bodycote Daventry has 30+ years experience of fracture toughness testing covering a wide range of materials and specimen configurations for oil & gas, aerospace, nuclear power, defence and other leading edge businesses. This experience was applied in developing and validating the new SENT procedure, which has recently been used successfully on a live pipeline project.
The new SENT testing service is now accessible through any of Bodycote’s 40 laboratories within it’s global network. In due course, the validated SENT procedure will be made available to selected Bodycote laboratories with Bodycote Daventry providing technical support where necessary. Inter-group sub-contracting will be handled seamlessly by Bodycote so that the tests can be performed at a centre of excellence for fracture toughness testing.