High-pressure stop valves are used in the most extreme high pressure and temperature applications. Eskom remains one of the largest consumers of these valve types, with thousands of units required in power plants across the country. Up until now, there has been no local manufacturing capability to produce the valves required to specification. With no local capability available, cost for the purchase and maintenance of these valves remains high.
In answer to this challenge, Mitech has been working in close consultation with Eskom over the last two years, to conceptualise, design and locally manufacture a high pressure stop globe valve that will fulfil the technical and safety requirements as well as the local content requirements as set out in The Department of Trade and Industry’s (the dti) designation Instruction Note for the procurement of valves and actuators.
General Manager for Mitech, Pieter Badenhorst highlights the degree to which the unit is locally produced stating that “although we have to import some of the material used in the manufacturing process such as bar-stock which is not produced in the country at present the valve remains 80-90% locally manufactured.” Using Mitech’s design, locally sourced materials, local castings, machining, assembly and testing, the valve conforms to all the criteria for local content.
Badenhorst explains that it would be very difficult to simulate the extreme conditions that would be required to test their valve in the laboratory, and therefore, Eskom has agreed to install the valves at appropriate test sites for a trial period at their power plants, to fully evaluate the valve’s performance. Mitech has committed to providing technicians working on Eskom’s plants with training as well as a full service manual to ensure effective incorporation of the valve into the power plants.
CEO of Mitech, Alli Alberts is confident that their product will meet and outperform those that are currently being imported. He highlights the importance of local manufacturing in addressing unemployment in South Africa, and the positive knock-on effect that this will have for the economy. “Projects such as this should start to make a real difference,” he states.
The High Pressure Globe Stop Valve demonstrates some impressive specifications. The key to the design concept has been simplicity, robust engineering and minimising maintenance costs.
The whole unit comprises of 33 components, most of which are easy to maintain. The body of the valve is a one-piece investment cast design, eliminating threaded or bolted pressure retaining parts. The unit has a fully replaceable seat, which can be extracted while the valve remains welded into the line.
The inner components of the valve can be refurbished using standard tools, as well as two specialised tools, on site. The valve boasts a long lasting packing configuration with live loading as an option. The anti-rotation pin on the stem ensures that there is no torsion applied to the packing system. The unit features a universal yoke flange making it easy to accommodate various actuator designs. The stellited seat and hardened plug material ensure a tight shut-off making it highly resistant to erosion.