SVI 18” Annular Sealing Bags Assist in Eliminating Odours and Water Ingress

August 19, 2021

The SVI Contract Services team were recently recruited by a contractor, working in partnership with a Gas Distribution Network, on the GD1 mains replacement programme, to seal the annular space of an 18” gas main.

The main had reports of residual gas smells and water ingress.  In order to prevent this recurring, the annular space in the host pipe required sealing to prevent water entering, or odours escaping.

The edges of the main were jagged and so it was not possible for the SVI Contract Service team to use an SVI Dead Endseal, instead the SVI Annular Sealing Bag offered the ideal solution.  The benefit of Annular Sealing Bags is that they can be installed without the added process of a straight cut.  They are also quick and simple to install.

The Annular Sealing Bags are made up of compartments which house the standard SVI FOAMPACK sachets. FOAMPACK™ is an annular sealant that can be used when a steel service has been inserted with PE pipe. FOAMPACK™ comprises PU foam and a hardener contained in a two-part sachet. Once the central strip is removed from the sachet, the contents can be thoroughly mixed together without the operator coming into contact with the sealant.

Being an expanding sealant, FOAMPACK™ provides an extensive distance of travel when longer lengths of annular space need to be filled.  Once the sachets are mixed, the foam expands inside the bag giving it the crescent moon shape and then excess foam leaks from the porous panels to create a barrier eliminating gas movement and water ingress around the PE. This results in the annulus being completely sealed.