This project came from the need for the Stanwell Power Station to replace outdated components in its Special Hazard Water Deluge Fire Suppression system which were no longer made by the Original Equipment Manufacturer. In addition there weren’t any spare parts available and the OEM had stopped providing maintenance or overhaul services. The Multi-Jet Control (MJC) valves had been in service for 20 years and consideration was being given as to how best to service/maintain them to ensure another two decades of performance-critical protection for the site’s four coal fired generating units which supply 1460-megawatts to the Queensland power grid.
One alternative available to Stanwell Power Station was to approach other OEM’s and change over to their type of valve. This would lead to a number of cost and logistical issues. The introduction of different valves which would require modifications to the interfaces and fire suppression pipework. Modifying the system would require it to be shut down for a length of time. Another factor was that the existing valves had a metal to metal seal design which was prone to leaking and the other OEM’s had the same design.
Stanwell Power Station preferred the option of commissioning Archer to come up with a more efficient solution. This suited us because for many years we have specialised in problem solving for complex projects and performance-critical systems.
We presented a solution which involved designing and manufacturing new-generation components which were compatible with the existing system. We would improve the old design to prevent further water leaks and there would be no need for a lengthy shut down. Furthermore, we would be able to meet their deadline.
This project involved many of the capabilities that we have in our world-class Manufacturing Centre of Excellence at Somersby Industrial Estate on the Central Coast of NSW: CAD design, CAM technology, precision machining, precision fabrication, disassembly and assembly, and hydrostatic pressure testing. Everything we needed was here under the one roof.
We have worked with power stations and large performance-critical sites such as Bluescope Steel and NZ Steel in the past so we were well prepared to handle this one.
“We proposed a ‘swap out-swap in’ approach”, said Operations Director Russell Byrne, "We decided to design and manufacture an exchange set of 60 valves for the first unit which could be installed in just four days during a scheduled shut down of the fire suppression unit. Then, we would receive the older valves back at our facility where they would be stripped and upgraded. These would then be installed in another unit and the ‘swap out-swap in’ process would be repeated until all four units were completed."
Aware of the failings of the original valves, we came up with new internal and actuation mechanism designs for their new MJC valve which included a new sealing seat and piston, actuation linkage mechanism and Archer FL505 Glass Bulb Fusible Link - the specialised heat sensitive actuation mechanism which actuates/opens the valve in the case of the valve being activated by heat from a fire. These were incorporated in a valve body designed with the same connection-to-connection dimensions/pattern as the existing OEM MJC valves to allow connection straight into the existing system without modification of existing pipework.
The improved design offered an additional benefit beyond improved performance. MJC valves require off-site performance testing of a representative percentage after 20 years of service and then every 12 years thereafter. The performance test is a destructive test, destroying the heat sensitive actuation mechanism. Currently all other available OEM valves on the market, once put through this “sensitivity” performance test, are not able to be re-built and re-used as the other OEM’s don’t offer the spare parts required nor offer such a service back at their factories. Essentially the MJC valves are scrapped and complete new valves have to be procured - a costly exercise.
“We purposely made the new generation valves so that the actuation mechanism was modular in design. This means the MJC valves can be re-built and re-used after performance testing by simply replacing the Archer FL505 Glass Bulb Fusible Link on the valve”, said Managing Director Bradley Byrne.
The new MJC valve was designed using latest-generation 3D CAD/CAM software which was integral to programming the tool paths required for the precision machining on our 9-axis Okuma Multus B300-W machine centre. The components were manufactured from stainless steel 316 and brass 385. The valves were hydro-statically pressure tested in the Archer on-site laboratory and then road freighted to Stanwell Power Station in a purpose built crate for safe and secure transit. The robust crate was specially designed by Archer and allowed for the multiple return journeys to and from Archer and Stanwell Power Station.
“When the first batch of 60 OEM MJC valves for overhaul arrived here we pulled them down and discarded the 20 year old and compromised OEM internal components. The only parts we kept were the gunmetal valve body casting pieces. The castings were cleaned up and precision machined to allow for re-assembly and installation of our proven new generation design and components. The existing OEM MJC valves, having been overhauled to include our design, now included the same benefits of the new Archer MJC valves initially manufactured and supplied for the first swap out-swap-in. Once the MJC valves had been overhauled and fully reassembled they were hydrostatically pressure tested and then sent to Stanwell Power Station for the next unit’s swap out-swap in and we repeated the process again. Each batch was required by a strict time table set by Stanwell Power Station”, added Russ.
“We enjoy the projects that others regard as being too hard”, said Brad, “This is why companies and organisations from around the world come to us for advice and solutions. The conventional course of action in any industry would be to find a new OEM supplier but Stanwell Corporation showed that Aussie initiative and know-how was the smarter option."
“Stanwell Power Station is very pleased with the outcome of working with Archer. We were impressed that they were quick to understand our situation. They came up with an innovative and cost effective solution which enabled us to keep providing uninterrupted power supply to our customers throughout Queensland, and they were able to deliver it to us on time. Their ability to think outside the square, their workmanship and constant communication throughout the project was outstanding”, said Stan Beattie the Stanwell Corporation’s Project Manager, SPS Asset Services.
Stanwell Power Station holds the Guinness World Record for the longest continuous operation of a power plant turbine: 1073 days and 1 hour. Archer is proud to be a contributor to the ongoing reliability and success of the Stanwell Corporation facility.