Project news, November - December 2010
For a full list of proposed, active and closed projects ... e-mail gsp@twi.co.uk Improving the integrity management process for bonded hoses
Project launch: 22 September 2010
Project leader: Richard Shepherd
There are many applications for bonded hoses in the oil and gas Industry; these include moored offloading systems, ship to ship transfer and risers. Generally their materials of construction include; elastomers and other engineering polymers combined with metallic elements, such as wires, cords, woven fabrics and strips, forming a composite structure that provides flexibility and strength. However, by virtue of the materials used and their construction these hoses are rendered essentially 'un-inspectable' by conventional means such as ultrasonics due to the high attenuation of the polymer(s). Since most hose failures initiate from one or more elastomer/polymer layers, due to fatigue crack growth or debonding from the metal end fitting, an NDE solution for inspecting such areas of the hose is highly desirable.
This project sets out to validate the use of non destructive examination (NDE) methods such as x-ray and gamma source radiography to enhance the current (limited) inspection methodologies available to operators of bonded elastomer hoses. New NDE procedures will increase the confidence in integrity management of bonded hoses and reduce the risk of in-service failure.
Benefits for Sponsors are:
- Reduced risk of in service failure and associated hydrocarbon spillage.
- Eliminate the requirement to hydrotest pipes and associated loss of remaining life.
- Enhanced inspection capability giving informed data for integrity management.
- Long term cost reductions
Advanced Ultrasonic Phased Array technique for the detection of flaws at the dissimilar interface of subsea joints and assessment of their criticality
Project launched: 22 September 2010
Project leader: Capucine Carpentier
Dissimilar joints are an integral part of subsea oil and gas systems. The joints of interest incorporate low-alloy steel forging and nickel-alloy buttering layers. Fabrication flaws can be found at the buttered interface that may lead to failure. This project aims to develop an NDT technique using phased array in order to detect and reliably characterise these flaws at the dissimilar interface.
This project will address the issues of the inhomogeneous and anisotropic dissimilar joints by fully accounting for the propagation of the ultrasound through the weld metal and improve signal over noise. Technique performance will be then demonstrated on realistic flaws to quantify inspection capabilities.
Having established a reliable method for detecting, sizing and classifying flaws, this information can be used for structural integrity assessment of dissimilar interfaces. Such an assessment will be conducted as part of a parallel GSP project proposal PR 14296-2, that will lead to identifying which flaws are critical with respect to the integrity of the joint in order to avoid unnecessary repair.
Benefits for Sponsors are:
- An NDT technique that allows detection of critical flaws at the buttering interface.
- Increased reliability and safety for operating the joints.
- Minimise costs by avoiding unnecessary repair/replacement without compromising structural integrity.
