Accessory obviates power station shutdown

Paul Boughton

A new compressor installation, to be completed within a short window of time, was going well until a problem was discovered. The design drawings failed to show that a cold-water valve extension handle clashed with the air inlet pipe of the compressor.

Critically, this was the only isolating valve from the cooling water main header and could not be moved without closing the cooling water system. This would have also meant shutting down the whole Power Station, which was not an option.

Potential solutions included, re-routing the inlet pipework of the compressor and Contracting in, a specialist Pipe Freezing Company to enable the valve to be moved.

All initial potential solutions would have taken time to organise, which could have affected the timely completion of the project.

Freezing was considered as the best option but this valve was welded into place and freezing would have to be made far enough up stream not to be adversely affected by the applied heat from the grinding and rewelding operations.

The water pipe was also three-inch (75 mm) diameter which eliminated being able to acquire one of the commonly available domestic or commercial plumbers freezing kits that only have a capacity up to 2 inch (50 mm).

As time was of the essence an internet search discovered a Pipe Freezing Kit for 3 inch, pipe available from the Pipestoppers Division of Huntingdon Fusion Techniques Limited (HFT).

The HFT Technical team were quickly able to reassure us that Qwik Freeze pipe freezing systems were a proven option for this size of pipe.

Installation was easy and CO2 bottles were obtained from our local BOC gas supplier. The freeze worked well taking around an hour to freeze the pipe. This freeze allowed time to grind out the welded valve plus a length of pipe and re-weld a flange back on to the pipe at a new position and install a new valve. The job took around two hours to complete in total and at cost of around 25 per cent of a specialist contractor.

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