The experts at AC Valve Alliance explain the challenges of jet fuel storage and maintenance
Not many people know that civil airports in the UK hold very little jet fuel storage capacity. The fuel is stored off site in strategic locations around the UK. There is a connecting pipeline grid that feeds the airports 24 hours a day in order to keep the capacity of fuel needed. This strategically designed grid was installed many decades ago and went through a complete upgrade starting in 2019 of all the equipment and controls. For safety reasons, storage of the bulk of fuel used is kept away from the airport terminals. Jet fuel storage requires large capacity tanks and all the associated pumps and valves for operation.
Traditionally, tank isolation was achieved with a single gate valve or ball valve. In this case study of a UK airport, the end user required upgrading to actuated double block and bleed shut off for
each tank inlet and outlet. When tasked with providing a solution,
AC Valve Alliance’s team of experts selected zero leakage, fire-safe Zwick triple offset valves for main isolation, fitted with failsafe electrohydraulic actuators, in combination with Pekos ball valves for vents and drains.
Ac Valve Alliance’s Solution
The challenge presented was fitting new double block and bleed into the existing installations without pipework alterations, due to the very limited space available in the valve chambers.
To overcome this challenge, AC Valve Alliance designed a special assembly of two Zwick valves with a spool piece that fitted into the available spaces. The spool pieces housed all the appropriate vents, drains and instrumentation connections. The company then had to customise the length of each assembly to suit each site as they varied considerably.
Due to the proximity of the actuators on the valves, the specifically designed, bespoke extension kits had to create a staggered mounting arrangement. AC Valve Alliance then surveyed each site in turn to take measurements and ensure that each assembly would fit in the envelope available, producing 3D models in each case to insert into the site layout models, confirming the fit of each individual assembly before
manufacturing the valves, actuators and associated instrumentation.
By providing the complete package and utilising its in-house engineering facilities and expert team, AC Valve Alliance is able to provide the customer with peace of mind that the scheduling, manufacturing and testing were all carried out under strict quality control.
Designed To Keep Processes Operating
Triple offset valves outperform traditional valves with increased durability, reliability and lower ownership cost. The seat of the triple offset valve is designed to eliminate wear, provide lower maintenance cost and extend service life. The zero leakage sealing capabilities of triple offset valves provides the performance to keep your processes operating reliably at top efficiency even in extreme operating conditions. All of these benefits also come with a large weight saving when compared to many other valves, making for much easier installation and maintenance.
In this case, the customer was required to meet the new stringent environmental regulations which the Zwick valve was able to comply with. The patented sealed shaft bearings and packing meets the ISO 15848 Fugitive Emissions Standards and prevents leakage. As the jet fuel is highly flammable, another requirement was that the valves were firesafe to the latest addition of API607.
Valve Automation And Maintenance
The Zwick valve has a unique seat angle of 25°. This means that when closing there is no contact between the disc seal and the seat until the moment of closure. This is true ‘cone-in-cone’ sealing and is a frictionless seal. This minimises the wear in this area and reduces the torque required to close the valve. The benefit of this is it requires a smaller actuator than on other types of valves.
Triple offset valves are easily maintained as they have minimal parts to replace. There are no exposed threaded stems to lubricate, or body gaskets to leak. In essence, triple offsets are maintenance- free.
