Posted to News on 29th Oct 2007, 21:43
Dampers control large doors subject to wind loading
Industrial Gas Springs (IGS) has provided large dampers to control a set of doors on a storage bunker at an oil refinery situated on the coast of West Wales.
Aker Kvaerner Engineering Services approached IGS in August 2006 in the course of carrying out work at an oil refinery situated on the coast of West Wales, with a view to addressing a potential safety hazard. David Nicholetts, structural designer for Aker Kvaerner, explains: "I asked IGS to recommend a suitable gas spring/shock absorber for two fully clad 2m wide by 4m high doors, due to safety concerns. The doors needed to be able to take a wind load of 3kN when opening/closing but the dampers were not required to assist in opening/closing operations or in restraining the leaves in their open/closed positions."
The request was followed up by project engineer Owen Derrick, who sent IGS some initial drawings and dimensions of the doors that were to be installed on a storage tank radiation bunker.
Jean-Philippe Duvillard, IGS' commercial manager, says: "We started to look at all the requirements for this project and consider possible solutions. All of them were limited by the wind pressure the doors would be subjected to; the pressure was finally specified to be equivalent to 1500Nm2.
"In order to damp the opening of these doors, we had to use the largest gas springs we could manufacture. It was also necessary to limit the stroke to minimise the risk of the dampers buckling, while keeping the length sufficient to keep the forces applied onto them below 11,000N, which is the safety limit on our size 20 dampers. Finally, the amount of damping was calculated so the doors would open slowly in gusty wind conditions and the dampers would be completely free when the doors are being closed.
"We recommended using five dampers with a size 20mm rod and 40mm body diameter for each door, fully oil-damped in compression and free in extension.
The dampers have proved very effective, according to project engineer Owen Derrick: "We are really pleased with the final result. While it is a somewhat slow process to open the doors when there is no wind, there is no need to exert any force on them - they will not open faster and the operator simply has to 'walk with the door' as it opens."
