Valves and actuators are key building blocks to realize subsea processing plants. Both isolation and control valves are key elements for operating processes such as water treatment and injection, boosting and separation. In order to increase the performances and to eliminate the hydraulic lines within the umbilicals, a retrievable configuration to drive both types of valves sharing the same electric actuator has been developed.
For a subsea water treatment application, and to manage its backwashing function, a dedicated development and qualification plan has been implemented, to cater for the associated high number of cycles.
This requirement was new considering that common subsea applications call for a total number of actuations in the order of around one hundred, while to implement these backwash sequences, isolation valves need to be capable of thousands of complete cycles and control valves of hundreds of thousands of small adjustments.
This paper addresses how the design of subsea valves and actuators has been qualified to TRL4 through both analysis and test campaigns on dedicated prototype units in compliance with API 17N or DNV RP A203, API 17F, API 6A and API 17D.
Saipem performed a market review to map the existing technologies and understand potential gaps against the needed performances for isolation valves, control valves and relevant actuations. Based on the results of this review, the key providers were selected to undertake the technology qualifications required to close the identified gaps.
Working in team with the technology providers, three dedicated technology qualification plans were defined to ensure the suitability of each technology. The activities identified in these plans include both analyses and performance/endurance tests on prototypes. These activities were considered to mitigate risks associated with the failure modes identified during the FMECAs.
The envelope of the performance set as the basis of each technology qualification plan allows the extension of the deployment of these technologies in different subsea processes.
The isolation valve qualification plan was successfully completed in 2018, while the control valve and the electric actuator qualification plans will be completed by end of 2019, establishing a new reference for the utilization of subsea valves in complex subsea processes, such as subsea water treatment and injection systems or subsea separation systems.
The presentation and paper will introduce the elements of novelty and will describe the process, the challenges and the results of the technology qualification.
The technology qualification plans will be presented, including the initial readiness level assessment, the outcomes of the FMECAs and the qualification activities, which include:
high-cycling isolation valves: analyses, mock-up tests, prototypes hyperbaric and endurance tests;
high-cycling control valves: analyses and endurance tests;
high-cycling all electric actuators analyses, mock up tests, temperature of electronic boards, pressure, shock and vibrations tests (API 17F) and prototype functional and endurance tests.