Large Diameter Mainspray Injection

Mainspray is a two component anaerobic polymeric compound formulated for sealing leaking spigot and socket joints on cast iron and steel gas mains, conforming to GIS/LC12 specification. ALH Systems has developed a 3ltr pressure pot to directly inject Mainspray under pressure to reinvigorate and seal joints.

Leaking joints can now be treated without leaving the surface. This can have a big impact where a series of joints needs to be treated at frequent intervals along a main road. Long reach tooling allows the back of a socket to be drilled and tapped to accept a standard brass injection nipple. The repair product is injected into the joint using long delivery tubes and our 3litre or 1litre pressure pot.


  • Single injection point
  • Reduced excavation size
  • Reduced time spent in excavation
  • Low cost equipment
  • Simple operation
  • No waste disposal problems
  • No on cost
The ALH 1ltr and 3ltr Mainspray pressure pot are designed for 3bar maximum working pressure. Both pots work in conjunction with the back of socket long handled tooling for above ground working.


1. Back of socket long handled tooling. This system is used to drill, tap and fit a brass injection nipple from above ground.

2. 1Ltr pressure pot, ideal for tier 1 joints. Portable, easy to use, requires very low maintenance.

3. 3ltr Large diameter pressure pot, suitable for 3”-48” joints. This system uses a spring balance to accurately measure the amount of sealant being dispensed.

The video below demonstrates how the Large Diameter Mainspray Injection system works.