SVI Flowstopping techniques used on Mitcham Gas Holder Station Decommissioning Project

April 1, 2021

The Steve Vick International Contract Service team recently assisted JDT Utilities in deactivating a 24” cast iron main, part of the wider Mithcham Gas Holder Station decommissioning project.

Using SVI FOAMBAG™ technology, the team attended site on four separate occasions to carry out  flowstopping operations on a 6 metre lateral section of 24” low pressure cast iron main.  Three of the flowstop operations were two-way fed and one, one-way fed.  The team installed four double skin FOAMBAG’s™, which took just two hours, at each end of the section. Once the expanding foam was cured, the main was then vented and purged.  This allowed the team to safely cut out and cap off the abandoned section, using the SVI N450 Keel Cutter.

A total of eight cuts were carried out, two on each of the flow stops.  The cuts took approximately twenty minutes each to complete.

The SVI FOAMBAG™ technique is particularly beneficial for decommissioning pipework at gas holder stations because it seeks out and seals loose particles, therefore reducing issues relating to rust or contaminants.  SVI FOAMBAG™ is suitable for non-standard sizes, tapers, bends and vertical pipework.  It is ideal for use where space is limited because the FOAMBAG™ can be inserted through a 2” bsp hole resulting in less pipe length needing to be exposed over conventional methods.   The system is a well proven technique and meets UK gas industry standard T/SP/E/59 and is low cost and easy to use.

The N450 Keel Cutter was the obvious choice for the SVI Contract Service team to use for cutting the cast iron pipe.  The cutter automatically tracks around the pipe and has a fast cutting time, typically 8 minutes to cut a 300mm diameter cast iron pipe.  Only 200mm to 250mm clearance is required, making it ideal for tight spaces and the cutter can work in water if required.  The N450 Keel Cutter is lightweight and easy to use and in addition to cast iron can cut steel, ductile iron, asbestos, cement and plastic pipe.

Dave Taviner, Site Manager at JDT Utilities commented:

“We were delighted with the work Steve Vick International’s Contract Services Team carried out for us on this project.  The SVI FOAMBAG™ technology and N450 Keel Cutter were the ideal solutions for aiding us in decommissioning the 24” pipe.  The work was carried out safely, efficiently and cost-effectively.”

History of Mitcham Gas Holder Station

Mitcham Gas Holder Station produced town gas from around 1867 to 1960, but following the discovery of natural gas in the 1960’s, the need for holder stations went into decline.  Many of them have been abandoned for decades but slowly they are being decommissioned one by one.