Project Code: 34244
Start date and planned duration: February 2021, 24 months
- Provide indication of the severity of the corrosion stage by comparing acoustic emission (AE) signals with pit depth and pit density obtained in laboratory experiments.
- Localise the source of corrosion using AE signals and differentiate them between pitting corrosion, crevice corrosion and pitting corrosion caused by coating breakdown.
- Provide evidence of AE sensitivity to corrosion that can be used in qualifying structural health monitoring (SHM) procedures for detecting corrosion in marine structures.
For the safety and integrity of steel structures in marine environments, it is desirable to supplement periodic visual inspections with monitoring solutions that will increase the probability of detecting and monitoring corrosion, particularly around welds. Firstly, this may assist inspection by giving an early indication of the location of newly corroded areas at weldments. Secondly, it may assist with continuously assessing the condition of already identified corroded areas. Finally, monitoring may identify non-visible pits or cracks underneath protective coatings. By use of effective monitoring, instances of unexpected damage identified at inspection may be reduced and the length of time between service intervals may be extended. This will significantly reduce operating costs while also ensuring structural integrity.
Acoustic emission (AE) testing is a promising monitoring technique, potentially capable of detecting and monitoring pitting/crevice corrosion initiation and subsequent fatigue crack propagation, including spatial localisation. AE from plastic deformation ahead of a crack tip is detectable, as is physical crack extension. Subject to development of robust procedures, AE techniques could provide advance warning of active corrosion (or cracking) before it can be detected by other non-destructive testing (NDT) methods.
The project concept is to develop an AE procedure for detecting pitting and crevice corrosion in a representative marine steel in a laboratory seawater experimental facility, with a view to moving towards industrial trials. In addition to detecting and locating early stage corrosion in parent steel, the project will assess whether the AE signals emitted by corrosion of a weld is significantly different from that emitted by corrosion of parent steel.
Oil and Gas
Benefits to Industry
The marine industry and other sectors facing pitting, crevice corrosion, and pit-to-crack transition will find value by implementing corrosion monitoring into their current corrosion management plans and tailoring the technology for their specific applications. Benefits include cost savings associated with reduced inspection workloads, longer service intervals and reduced asset risk.