Author: Eric Bucci, Oil & Gas Segment Manager, Trelleborg Sealing Solutions
Seven years ago, engineering firm Schoolhill Hydraulic Engineering was tasked with designing a high-flow, safety-critical subsea Quick Exhaust Valve (QEV) for a subsea HIPPS (high-integrity pressure protection system) for a major oil supplier’s fields in the South Caspian Sea.
It was in January 2013, that Schoolhill decided they needed to work in partnership with a sealing expert to find a custom solution. The company approached Trelleborg, which very quickly identified the issues preventing Schoolhill from moving onto the next stage of the project. The seal had to slide across mating surfaces that had dimensional changes so a customized version of an effective and reliable low friction seal using a high modulus thermoplastic was developed for the QEV.
The valve developed can handle 22 liters of fluid in five seconds to meet critical requirements. Due to high pressure drops across seals and the fast performance speed of the valve (17 milliseconds) a number of sealing solutions were tested and did not pass. Schoolhill sought a solution that would be able to handle the large fluid volume and extremely rapid operation time.
Testing to Meet Qualifications
“It seems a long time ago since we started this project. At the onset we knew we were taking on a lot with the specifications we had to satisfy, notwithstanding the documentation and reporting required when working with a major oil and gas operator,” says Schoolhill Hydraulic Engineering Director, Ronald Whyte.
Schoolhill produced a total of six prototype valves for qualification testing. Testing was rigorous, with 30,000 cycles required for a valve that will only be operated two or three times a year. Additionally the valve had to be certified and meet several API standards.
This seal was deemed the best option due to its exceptional ability to work in multiple applications and because it is retained in a split groove. The groove prevents the sealing surface from being damaged by a counter part with variable diameter or when passing holes.
Safety in Extreme Conditions
The final sealing solution helped Schoolhill release a valve, which not only has a 30-year design life with a valve qualification water depth range of 3.000 meters/ 9.842 feet, but also has a safety integrity level (SIL) rating of SIL3 with 30,000 accumulated cycles.
“It’s been a huge learning curve for Schoolhill, a small company with limited resources. However, we are forward looking and believe that the step change provided by HIPPS for the oil and gas industry will see many more operators going along this road,” Ronald Whyte adds.
Oil and gas Industry suppliers have come to understand that they need to really push the envelope in terms of science, technology and engineering know-how. Material providers are partnering even more closely with equipment manufacturers in order to meet the increasingly demanding needs of exploration companies today. Schoolhill is a great case in point.
For more information, visit tss.trelleborg.com.
About the Author
Eric Bucci is Segment Manager, Oil & Gas Americas for Trelleborg Sealing Solutions (tss.trelleborg.com). He has a BSME (Bachelor of Science in Mechanical Engineering) degree from the University of Texas and started working for a Houston seal company as a seal design engineer in 1992. After four years he moved to Busak+Shamban (purchased by Trelleborg in 2007) as an applications engineer and has now worked there for 20 years. His responsibilities include market development and identification of future growth trends for Trelleborg Sealing Solutions products.