Tue, 25 February, 2025
We are now inviting Industrial Members to join a new joint industry project (JIP) focussed on the challenge of undertaking full volumetric inspection of critical subsea sensor welds to API standards.
Manufacturers of subsea sensors currently have to design welds that are larger than necessary to meet standards or use substandard inspection techniques that can leave defects undetected in service.
Subsea Sensors, Standards, and the Need for an Inspection Solution
The oil and gas industry uses subsea sensors to deliver data for the control of a subsea well to topside control stations for monitoring. This data is vital for controlling the well’s integrity and infrastructure, allowing assets to be managed in terms of recovery, production rate and safety. These sensors are critical to effective reservoir production and safety management, so it is important that they are reliable so as to avoid leaks in service.
The sensors are typically assembled using autogenous electron and laser beam welding, and manufacturers use surface inspection techniques, helium leak tests, and pressure testing to detect welding defects. However, the API-6A specification also requires the volumetric inspection of Wellhead and Christmas Tree equipment, where these sensors can be located, using either radiography or ultrasonic testing.
Currently, a lack of access for ultrasonic inspection or large and complex material paths inhibiting radiographic inspection are limiting the coverage for volumetric inspection of a significant percentage of the typically small, autogenous welds forming the pressure boundary of subsea sensors. Manufacturers cannot therefore meet the standards required by industry, leaving them with the choice of:
- Having larger instruments then necessary with larger non-autogenous welds in order to meet the volumetric inspection criteria, increasing cost through all stages of the system lifecycle (manufacturing, transportation, deployment and decommissioning)
- Accept non-conformances and the possibility that potentially serious defects will remain in the welds, which may then lead to a leak during service
Solving the Issue
This joint industry project aims to develop and qualify innovative and improved NDT techniques and procedures specifically designed to detect the types of defects that occur in the small, autogenous electron beam and laser welds that form the pressure boundary of subsea sensors. The project will align with the requirements of API-6A for Subsea Equipment with a plan to present the JIP findings in the relevant committee.
This project work will lead to the creation of a best practice guide that will be made available to the project sponsors. The guide will include evidence from experiment and modelling that manufacturers can use to support technical justifications for inspection qualification and advice regarding automation and personnel training and certification.
The JIP will not only deliver increased confidence in performance, safety and reliability of subsea sensors, but will also provide a cost effective inspection solution that satisfies the requirements of relevant codes, standards and industry stakeholders, as well as offering potential cost reductions across sector.
How to Get Involved
TWI is inviting companies in the oil and gas sector who are specifying, manufacturing and operating subsea sensors to join a consortium of sponsors for the project. The consortium will have exclusive access to the best practice guide for a period that the consortium agrees. The project will enable manufacturers and operators of subsea sensors to achieve better compliance with current standards and a more reliable product through improvements in the quality of welds and the reduction of defects, creating competitive advantage and benefits for safe and continuous production.
You can find out more about the project, ‘Development of a Qualification Methodology for Volumetric Inspection of Pressurised Welds in Subsea Sensors,’ here.