Gas Solutions

Flow Stopping & Pipe Sealing

Some two decades ago, we developed a low-cost flow stopping system called FOAMBAG™ based on the use of expanding resin foam. The effective yet simple technique works on all types of pipe material including cast iron, steel and PE. Extremely versatile, it can be used on vertical or tapering pipes, bends and non-standard diameters.

Although developed for flow stopping natural gas pipes, FOAMBAG™ can also be used to seal pipes carrying other gases and fluids.

The major advantage of using FOAMBAG™ over conventional flow stopping bags is that far less pipe needs to be exposed resulting in considerably smaller excavations and reduced reinstatement costs. FOAMBAG™ has become an industry standard technique in the UK and has been used in many areas overseas including mainland Eruope, the USA, Scandinavia and the Far East. The technique works by inserting a semi-porous bag into the pipe to hold the foam in place as it expands. At full expansion, some of the foam seeps through the semi-porous material to adhere to the pipe wall.

Products meet GIS/E59
Specification Patent No. 2157390

We have developed a number of other specialist flow stopping and sealing systems based on the FOAMBAG™ principal:

FOAMSTOP™

For flow stopping small diameter pipes up to 3”

Live Stub End Abandonment

This is offered as a Contract Service for the final abandonment of short live short stub ends of gas mains, typically 2 to 20 metres in length. The technique was jointly developed by Steve Vick International and National Grid Gas as a means of avoiding unacceptable disruption caused by excavation, for example at busy road junctions.

Using our proven resin foam technology in conjunction with CCTV equipment, it is possible to excavate down to the stub end at a non-sensitive location. It can then be rendered gas free from the point where it meets the parent main to the cap end previously fitted, preventing further leakage problems.

Process meets GIS/TE/E1.9 Specification

SEALBACK™

This technique, developed jointly by National Grid Transco and Synthotech Special Products, uses foam sealant technology developed by Steve Vick International. It allows old iron mains, tees and stub ends to be inserted, remotely, with new PE pipe under live conditions. We offer SEALBACK™ as a Special Contract Service.

Mini Purge Ejector

Our Mini Purge Ejector is designed as an alternative to the large purge ejectors which have been in use since the mid 1980s. It works on the same Venturi principle but is lighter and easier to handle. Designed for use on mains from 3” to 12” in diameter, it ensures an efficient purge of gas mains to be abandoned.

Product Name	Description	Kits & equipment Available	Applications
Resin foam based systems
FOAMBAG™	A unique flow stopping system for live gas pipework to be abandoned	Kits for pipe diameters up to 10” Injection standpipe Applicator guns Modified Wask Night Cap Contract Service for large diameters and medium pressure	Kits available for use on mains up to 10” diameter running at pressures up to 75mbar. Contract Service available for larger diameters and medium pressure mains. For diversions and emergency shut-offs. Abandoning sections of gas main e.g. prior to the
FOAMSTOP™	Flow stopping technique for small diameter live gas pipes to be abandoned	FOAMSTOP™ kits Applicator guns	For pipework up to 3” diameter provides a ‘no gas’ method of cut-off. Particularly effective on medium pressure services and siphon repairs
Dead End Seal	Fabric muff tailored to seal the gap where an inserted PE pipe enters the old main then filled with expanding foam.	Standard Kits available for pipe combinations up to 400mm in 24”. Larger sizes to special order.	Sealing the annulus on dead inserted gas mains. Also sealing off abandoned water and sewerage pipes to prevent re-instatement slump and tracking of water etc.
FOAMCAP™	An low-cost fabric cap, filled with foam, for abandoned gas mains and other pipework	Kits available for pipe diameters up to 24”. Contract service available for larger diameters	An alternative to mechanical caps for capping off pipes following abandonment.
SEAL™	Stub End Abandonment Live. A method of sealing off short lengths of redundant gas main without disrupting supply in the remaining network.	Special Contract Service	Secure and final abandonment of short stub ends of natural gas pipes in difficult to access locations.
SEALBACK™	Allows old iron mains, tees and stubs to be inserted, remotely, with new PE under live conditions.	Special Contract Service	Renewing stub ends of main, especially where the connection to the parent main is under a busy road junction or in other difficult to access location.
Duct Sealing Kits	Specially designed FOAMBAG™ used to seal the space between pipes and ducts.	Kits supplied to order Special Contract Service available	Preventing the ingress of water into pumping stations, control rooms, plant rooms and chambers.
Special Encapsulations	Specially designed fabric muff, filled with foam designed, to fit around pipe joints or tees.	Kits supplied to order Special Contract Service available	Preventing corrosion and providing protection during backfilling
Cement grout based systems
RATSTOP™	Remotely placed cement filled fabric bag seals off abandoned pipes	Kits and application equipment available for 4”, 6”, 8” and 10” diameter pipes. Larger sizes available to order. Special Contract Service available	Remote and permanent sealing of disused surface water drains or lateral sewer pipes, in particular to prevent the movement of rats.
Grout sealing	Specially formulated grout is pumped into unwanted voids.	Special Contract Service	For filling abandoned pipework. Sealing the annulus in inserted pipework, sleeved pipework and cable ducting. Filling unwanted underground voids such as redundant storage tanks etc.

MINI PURGE EJECTOR	Compact purge ejector just 1.2m high weighing 8kg. 1.25m extension tubes available.	Mini Purge Ejector available with optional extension tubes	For purging gas from metallic and PE gas mains during pipe abandonment