Being able to perform effectively in a harsh environment for a sustained period of time is imperative to any tidal river barrier system. When the Department of Social Development sought to refurbish one of the largest civil engineering projects ever to be undertaken in Northern Ireland, Lagan Weir needed a reliable hydraulic system to get the job done.
Situated across the River Lagan in Belfast, Northern Ireland, the Lagan Weir plays a crucial part in maintaining the tidal river at an artificial constant level between high and low tide, preventing floodwaters from reaching the densely populated surrounding areas.
Constructed in 1994, the £14million structure controls the level of water upstream via a hydraulic fish-belly flap gate. The wall sections of the application rotate from a vertical to horizontal position, thereby varying the height of the water which can fluctuate by three metres between high and low tide. The five gates are powered by five hydraulic cylinders which enable Lagan Weir to hold up to 4.8km of fresh water whilst maintaining a flow capacity of 250 cubic metres per second.
Lagan Weir operates in a harsh saltwater and marine environment where the hydraulic cylinders and rods are immersed on a twice daily cycle. Having been subjected to the rigorous tidal flows of one of the longest and most corrosive rivers in Northern Ireland for almost two decades, the Department of Social Development took the decision to refurbish the hydraulic power pack cylinders and piston rods amid concerns for the durability of the thermal coating protecting the hydraulic system.
“We discovered a problem with the coatings and took the decision to completely refurbish the hydraulic power pack cylinders and rods”, said John Byrne, River Warden at Lagan Weir.
Lagan Weir contacted Bosch Rexroth due to its extensive expertise in the hydraulic field, especially fabricating and constructing cylinders of ceramic rods used in barrier systems.
The management team at Lagan Weir acted decisively and instructed the Rexroth team to provide two new hydraulic cylinders and conduct a rolling refurbishment of the remaining four cylinders which were experiencing corrosion on the piston rods, but not in need of replacement. The work would need to be completed under major time constraints as only two gates can be out of operation at any one time.
Bosch Rexroth specialises in the development and production of project cylinders built specifically for use in applications in harsh corrosive conditions, perfect for use in a saltwater and marine environment. Rexroth engineers have developed a new coating method called Enduroq 2200 which is a high-speed spraying process of metallic compounds with carbon. The metal-matrix layer provides extra corrosion protection which further improves long-term functional operation in aggressive environments.
Enduroq 2200 was applied to the two new intake cylinder rods and formed part of the refurbishment of the existing four cylinders. The installation and maintenance work was carried out over a two year period and Lagan Weir was subject to extensive testing once the work was fully completed.
The results surpassed all expectations and given the critical public safety factors involved, it was important to provide a solution which could function to its maximum capability for a sustained period of time.
John concluded: “Working with Rexroth was a fascinating journey of technical discovery. The advancement in hydraulics and Enduroq 2200 coated rods since the original 1994 installation was astonishing. We knew nothing of Enduroq 2200 and were surprised that a product existed that could be of help to us.
“We had a level of confidence in Bosch Rexroth’s expertise and also in the Enduroq 2200 coating due to the fact that it is used extensively in harsh offshore marine environments. Since the job was finished the Rexroth products have performed extremely well, the hydraulic power pack cylinders and rods are expected to have a 20 year design life but we are confidently expecting them to go well beyond that.”