Posted to News on 23rd Sep 2015, 16:21
Protecting large hydraulic cylinders in extreme environments
Fast-moving rivers present one of the most challenging environments for UK engineers. Brackish water, inclement weather and debris are just some of the threats to large-scale engineering projects. Fortunately, as technology and knowledge has increased, the ability to protect engineering components and parts in even the toughest conditions has vastly improved. However, for those infrastructure projects commissioned in the last century reliant on earlier technologies, the risk remains.
In 1991 construction began on the 160m-wide Tees Barrage, designed to control the flow of the River Tees, preventing flooding and the effects of tidal change. The barrage features three water piers, each of which has a "sector gate' controlled by specially made hydraulically driven cylinders. During a regular maintenance inspection by mechanical engineers at the Canal and River Trust, it was noted that one of the cylinder rods had begun to deteriorate. The Trust contacted Bosch Rexroth which had designed, manufactured, installed and commissioned the cylinders in the early 1990s. Bosch Rexroth immediately undertook a detailed review of all aspects of the cylinder rod, shell, pipework, cabling and mounting elements to identify any further damage and potential causes.
It was ascertained that the likely cause of the cylinders deterioration was the result of a heavy impact, which had worsened due to harsh environmental factors including brackish water, inclement weather and river debris. If left unchecked, this would have eventually led to seal damage and ultimately operational failure.
To address the issue, the design of the cylinder was reviewed and re-engineered to the latest specification and standards. The new unit was a direct physical replacement of the original cylinder, with the added benefit of an advanced measurement control system and Enduroq 3200 dual-layer coating, which Bosch Rexroth specifically developed for under water applications.
Martin Hoskins, industrial manufacturing equipment sector manager for Bosch Rexroth, who led the project, says: "At the time, the CEREMAX ceramic coating was the highest-specification protective coating available for this type of application. However, one of the limitations of ceramic coatings is their susceptibility to very high impact damage, as evidenced by the original cylinders fault."
To tackle this flaw, Bosch Rexroth developed the Enduroq 2200 dual-layer surface technology in the intervening 20 years. Using a combination of thermal spraying and overlay welding with a cobalt-based alloy, Enduroq 2200 benefits from having no porosity and zero permeability, making it suitable for even the most strenuous applications.
Harsh underwater conditions
Martin continues: "The Enduroq 2200 dual layer, which became commercially available in 2011, has been developed for the harshest underwater conditions. Typically found in applications including hydro dam outlet valves, mitre gates for ship locks, steel production, dredging, piling barges, offshore riser tensioners and active heave compensation, Enduroq 2200 can withstand impacts of up to 8 Joules, and is highly resistant to corrosion.
"As an added benefit for the Tees Barrage operators the new unit also comes equipped with the latest CIMS hydraulic cylinder monitoring system to help spot potential issues before they occur."
Speaking about the project and working with Bosch Rexroth, Jon Bennett, Senior Project Engineer for Kier, the main framework contractor for the Canal and River Trust, says: "The replacement of the cylinder rod was seamless. The newly re-engineered rod was built to specification, meaning we were able to remove the damaged component and install the new version within a week, limiting any negative impacts on the barrage."
If properly maintained the new cylinder will last indefinitely. To find out more about Bosch Rexroth visit www.boschrexroth.co.uk.
