Fracture Toughness Testing of Steels Subject to Sour Service
Status: Completed
Date Announced: March, 2012
Project reference: NA00533
Fracture toughness is a critical parameter for Engineering Critical Assessment (ECA) of planar (crack-like) flaws. In steel, the presence of hydrogen can lead to a significant reduction in fracture toughness due to its embrittling effects, for example: such a reduction can have a significant influence on the flaw tolerance of hydrogen-containing components. In some cases, this could result in the maximum tolerable flaw sizes being much smaller than workmanship criteria would deem acceptable.
Standards such as:
- BS 7448
- BS EN ISO 15653
- ASTM E1820
Provide detailed guidance on performing fracture toughness tests on non-charged materials in air and inert environments. However, procedures for determining the fracture toughness of steel components relevant for assessing flaws exposed directly or indirectly to a hydrogen source are neither accepted nor well-established at present.
The project has also aimed to determine whether data (normally obtained from conventional constant-load tests), in sour environments, can be inferred from R curves obtained from rising load tests conducted under low strain rates in identical sour environments.
The results of this project have aided the quality and safety within fracture toughness testing and ECA of steels in sour service, ultimately promoting the specialism’s best practice. Relevant to companies involved in onshore, offshore and subsea sectors, the results offer an insight into the integrity management of steels in sour service for those concerned.
If you are interested in finding out more, download the PDF Summary Outline using this link.