Providing assistance to GNI in maintaining their Transmission Gas Network


The project involved the isolation, decommissioning, removal, inspection, overhaul and reinstatement of Inline Heat Exchangers on various GNI AGI sites within the ROI. These units ranged in size from 2” up to 16” and weighing up to 3ton. All the works where carried out in live operational high pressure gas installations with overhauling, pressure testing revalidation and specialist NDT being carried out at our bespoke testing facility in Newbridge.  UT, MPI, DPI, Eddie Current Inspection, Radiography and Borescope was all carried out   utilising experienced in house personnel and equipment, ensuring that the overhauls where carried out with no delay to the project timelines.


Decommissioning, revalidation and commissioning of units carried out in line the GNI design requirements

Removal of units from within operation Pressure Reduction Skids ensuring that operational continuity was maintained with no interruption to supply.

Lifting operations took place under fully permitted conditions ensuring that the integrity of the network was maintained at all times.

Internal inspection of Gas Tubes with an ID of <12mm required the utilisation of specialist fibre optical internal Borescope equipment.

Work was carried out to strict project program constraints with minimal downtime permitted for each of the heater units, with a typical overhaul period of 2.5 days from isolation of the system from the network to recommissioning back into operation.


The requirement to work on sites with limited or restricted access to remove units for overhauls led Murphy to utilise an articulated tractor unit with a modified fifth wheel short radius trailer and Palfinger crane capable of lifting 4t at a 15m radius.


  • Over 190 units revalidated, tested and overhauled during the course of the project
  • Work carried out accident free
  • No disruption to the GNI Transmission Network

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