It is not often that 36 inch (900mm) control valves are required on a liquid application; they are normally associated with gas pipelines, so when four of these valves were required for Saudi Arabia, Weir was quick to respond.
The Saudi Aramco Ras Tanura Re-Route Pipeline will strengthen the infrastructure in the Ras Tanura area on the East coast of Saudi Arabia, but more specifically, the pipeline is 48 inch and links the Juyamah Thermal Tank Farm in the Eastern Province of Saudi Arabia. This is a 100% Saudi Aramco owned project.
In producing such large valves there are many challenges, not least the most basic requirement of finding a foundry capable of producing heavy castings in the right time and to the right quality. In the case of this project Weir selected a foundry which has been an approved supplier to both Weir and Saudi Aramco for many years. The castings were individually produced and passed all associated x-ray and non-destructive examination testing requirements.
The next challenge is then to have a machinist with suitably sized machine tools and lifting capability to be able to produce a high quality valve body.
The valves are a cage trim design, where the cage is specified to reduce the pressure recovery and give a more stable control of the oil flow. In such large valves, the cage is drilled with a large number of radial holes. Because of the large diameter cage, there were few suppliers who could accurately drill the number of holes required on such a large diameter. The cages were designed as a two piece component to simplify production, but mostly to minimise the cost of spares for the customer.
The valves were assembled in the Weir, Elland facility. All four valves successfully passed hydro test with flying colours. In fact, the required customer leakage is Class IV, which has an allowable leak rate of approximately 36 litres per minute. The test on these valves resulted in a leak rate of virtually zero, significantly better than Class V – in effect a valve that is at least ten times better than the customer required.
