Severn Glocon valve technology aims for maritime safety advance
22 Oct 2019
Extreme technical demands associated with a critical safety system on an offshore platforms are being addressed with a new valve technology from Severn Glocon Group.
Modern critical safety systems used on offshore sites are often highly sophisticated in order to cope with the extreme natural conditions and industrial challenges with which they must contend.
They come with extreme technical demands but must manage physical ones too; systems that need to feed water to combat fires have to be tough enough to cope with the corrosive effects of the sea.
Seawater service valves play an integral role in the process and their heir ability to either supply or isolate sections of the water line is a vital safety feature. Therefore, eliminating galvanic corrosion while maintaining firesafe credentials has been an enduring challenge for the industry.
A hybrid valve seal eradicated the need for graphite, whilst retaining all the inherent advantages of a triple offset valve
International valve engineering specialist Severn Glocon has a lengthy experience of the issues involved. So its help was sought by the owner of a gas compression platform located off the Caribbean’s most south easterly island state, Trinidad and Tobago.
Bi-directional isolation valves needed to achieve repeatable zero leakage and meet stringent fire safety testing standards. In addition, the end user specification required avoidance of wetted graphite inside the valves.
Severn Glocon’s answer was 17 high-performance triple offset butterfly valves to control seawater in the fire safety system.
Triple offset butterfly valves are typically constructed with graphite packings, gaskets and laminated metal/graphite seals. In normal operation this material provides good service, but increased risk of galvanic corrosion in seawater applications is an ongoing concern for offshore operators.
Avoiding contact between graphite components and the line media, without compromising fire safety credentials or overall valve performance, presented a significant technical challenge.
To address this, the engineering team devised an innovative adaptation of Severn’s patented Oblique Cone Technology (OCT®). Introducing a hybrid valve seal eradicated the need for graphite, whilst retaining all the inherent advantages of a triple offset valve.
The double-flanged valve bodies are manufactured in aluminium bronze for general seawater resistance, and they also incorporate internal and external anti-blowout protection. This advanced safety feature ensures the shaft cannot blow out, even if all external bolting is accidentally removed.
Simon Walker, Severn’s technical authority – butterfly valves, who led the development processsaid:
“Standard, catalogue valve products couldn’t satisfy the specification for these valves, so we were enlisted to solve the issue for our client. However, there is also an enduring industry need to overcome the galvanic corrosion problem.
“We set out to create a solution that could benefit the entire market, not just a single bespoke application. It was a challenging task, but as we specialise in arduous valve applications, we were well-equipped to handle it.”
Severn Glocon’s OCT®SW valves are exposed to stringent fire testing involving a 30-minute burn where they are bathed in flames with valves monitored for leakage. After forced cooldow, they undergo further testing designed to simulate the time required to extinguish a fire, ensuring the valves can perform during and after an incident.
Testing demonstrated that the technology developed was not only reliable but also repeatable. It was also completed in sufficient time to allow shipping to the end user one month ahead of schedule.
