NGN Grouting of Vacant Sleeve Annuli. M223

Northern Gas Networks


Project Overview

Existing high pressure steel gas pipelines are housed in protective steel sleeves where they pass below roads, rivers and underground utilities. The annulus between the gas pipeline and the sleeve was left vacant when they were originally constructed. This vacant space was filled with an inert gas which over time has depressurized, the depressurization can potentially allow the ingress of moisture which in turn increases the potential for corrosion thus reducing the life expectancy of the pipeline. The remedial works were to fill the annulus with a high pH grout which provides the corrosion protection required.

Description of Works

Each end of the sleeve is exposed by excavating small access pits. A circular hole is carefully cut in the sleeve and valved injection/breather pipes are installed. Using a site batched bentonite cement grout the vacant annulus is filled by pumping the grout under pressure into the injection point until it runs freely from the breather pipe at the opposite end of the sleeve. The valves are closed and permanently capped followed by reinstatement.

Study Project Date  
Culvert Replacement at Lund Terrace FAS, Ulverston UTX, Cumbria. M240 03/04/2017
Grounting of redundant Fuel Pipelines, Fradley Junction, Staffordshire. M223 05/12/2016
Timber Heading at Seaborne Library, Chester University. M230 15/11/2015
Culvert Replacement and Repair at Ferryhill. M228 07/09/2015
NGN Grouting of Vacant Sleeve Annuli. M223 09/03/2015
Culvert Refurbishment at Shaw Brook. M220 02/03/2015
Culvert Repair at Winnings, Newcastle upon Tyne. M211 16/06/2014
Culvert replacement at Ellergill Culvert UTX, Nethertown, Cumbria. M197 02/09/2013
Culvert Replacement at Willowburn, Alnwick. M195 01/07/2013
Culvert works at Jepsons Clough, Horwich, Bolton. M189 04/02/2013
Culvert Repairs at Millfield Lane, Walbottle, Newcastle upon Tyne. M186 02/07/2012
Culvert Replacement at Antley Syke, Accrington. M182 29/06/2012
Culvert Repair at Harwood Brook, Great Harwood - Manholes B2 to B3 relining. M165 30/11/2011
Culvert Refurbishment at HIRPS, Hockery Brook, Hindley. M171 01/04/2011
Culvert Repair at Harwood Brook Culvert Lining and retaining wall, Great Harwood. M165 31/01/2011
Culvert Repair at Riley Lane, Kirkburton, Huddersfield. M152 30/04/2010

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