ME Case Study One

Caisson Tank Valve Test

Babcock, Installation Delivery

WGM Engineering was initially engaged to provide a condition/seating report of all the valves associated with the caisson flooding and blowing tank arrangement.  To provide pressure test/integrity report of all the pipework associated with the caisson assess the condition of tank pressure gauge, pipework and pressure relief valves and carry out a statutory inspection of the pressure vessel within the caisson.

The “J” caisson comprised a large watertight chamber, tidal chambers which is open at the bottom from which the water is kept out by air pressure. The Caisson had undergone an extensive refurbishment being fully shot blasted and painted prior to WGMs arrival on site. This resulted in the atmosphere being of a high-risk nature due to the lack of free-flowing air within each of the compartments and the epoxy-based paint used in the coatings within the caisson.  Local Extraction Ventilation (LEV) was temporarily installed in each of the compartments.  Although this did dilute the atmosphere considerably there was still a high-risk element to the works due to the construction of the vessel preventing a free flow of air within the confined space.

As a result of the testing that was carried out within the Caisson was the recommendation of WGM Engineering that the pipework and valves were in need of replacement prior to the caisson being put back into service. The gearboxes and linkages for remote operation of the valves were stripped and freed off to allow the valves to be operated from the deck level. Using the existing sounding tubes, WGM then fabricates a manifold that could be mounted on the deck where all valves were visible. This negated the need to strip out and replace the existing pipework and cut down fabrication time. All future maintenance could then be carried out without the need to enter the confined space.

WGM Engineering


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