FBOS – Foambag Operation On Stubs
FBOS (Foambag Operation on Stubs) is a method of replacing short lengths of T1 stubs, stranded mains, or those found on mains replacement schemes. For diameters of 4” up to 8”, including one-way fed, in sensitive locations or where access onto the main is restricted.
Where a short length of T1 main, 4”- 8”, has been left from a previous replacement scheme, the FBOS technique is able to remotely replace this section and fully decommission the annular space. It is often impractical to replace shorter lengths of T1 main, which are commonly located in areas of engineering difficulty, for example, close to busy roads or junctions. However, the FBOS technique allows an excavation to be made in a non-sensitive area and from this remote position, the T1 main is replaced under ‘live’ conditions.
It is suitable to use on all metallic mains, for dimensions of 75mm in 4” and 140mm in 8”.
Using remote deployment, typically 10-13 metres from where the pipe intersects with the parent main, the annular space of the old metallic main can be fully decommissioned up to the final transition joint, avoiding the possibility of future leakage.
Benefits of FBOS
- Enables short sections of main, up to 25m to be replaced under ‘live’ conditions
- Can be used on one way fed mains
- Nose cone designed to negotiate bends, existing services and plugs
- The annular space of the old metallic main is fully decommissioned up to the final transition joint, avoiding the possibility of future leakage
- Ideal in traffic sensitive locations where access onto the main is restricted
- Replacement is undertaken from a remote location, typically up to 25 metres from where the pipe intersects with the parent main
- Trenchless Technology reduces environmental impact by minimising excavation and disposal of spoil
- Traffic Disruption is minimised
Technical Specifications of FBOS
- For Low Pressure up to 75mbar
- Maximum lengths around 30m
- Approved internal weld FBOS nose cone
- Scalable for 9-12” hose mains
- Typically takes 3-4 hours