Hobbs Double Block and Bleed Valves
Double Block and Bleed Isolations are required on the Sellafield Steam Lines before any maintenance work can be carried out downstream of this point. Triple Offset Double Block and Bleed Butterfly Valves were offered as a solution to this problem as the necessary isolations could be carried out using a single valve. However the usual manufacturer of these valves had a full order book and was quoting horrendous lead times on their valves (delivery in around 52 weeks in some cases), forcing Sellafield Designers to switch back to standard single isolation valves.
NW Total worked closely with Hobbs Valves while they produced a design for a new Triple Offset Double Block and Bleed Butterfly Valve, making this available on a much shorter lead time (usually less than 20 weeks). An initial witness test and audit was carried out at Hobbs Valves factory by Sellafield Engineers, whom subsequently approved the valve for use. When an initial order of these valves was ready for testing, another inspection / witness test was carried out to ensure their suitability which was passed OK. These valves are now in use on the Main Steam Lines at Sellafield.