Cyril W Bishop Engineering Services Ltd. Pipefreezing Examples 3

 

This pipefreezing operation was one of the largest ever undertaken: three 24" pipes containing a water/glycol mixture were frozen simultaneously to allow modifications to a pipework system at a chemical works in Northern England.  Working within an excavation raises important safety issues, as nitrogen vapour can collect and cause asphysiation.  See the Safety page.

 

	Bishop personnel setting up the freeze site. The three pipefreezing jackets (red) can be seen on the pipes, along with the insulated liquid nitrogen supply lines. Trunking has been used to gather the nitrogen vapour from the jackets, and move it out of the excavation.
	Once the freezing operation has commenced, the excavation is isolated to prevent anyone entering the nitrogen-rich atmosphere. Bishop personnel working in the vicinity wear harnesses.
	Once the freeze isolations have been effected, air movers are used to ensure the nitrogen content in the excavation is kept down, and the contractors move in to install the modified pipework.

 

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