Laminar Pte Ltd Singapore

Laminar Pte Ltd

Pipe Solutions

Twin Bagtube PE Line Stopping

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Group 1 1


The gas-free low-pressure PE twin bagtube system, commonly called the ‘Bagging off kit’ platform, is designed for 90mm to 315mm PE pipes. This system offers an easy and efficient way to isolate gas main sections without requiring squeeze-off equipment. 

The Twin Bagtube Kit is a novel technique for flow control in PE gas distribution systems. Gas bags are inserted through a hot tap connection as a temporary valve in the pipe wall. They are released through an entry valve into the pipe to stop gas flow. Upon completion of the procedure, one can remove the gas bags and use an integral plug to seal the hot tap connection. 

Our Twin Bagtube method provides gas-free flow-stopping with the entire procedure carried out through a series of valves while recovering the valves, making the technique even more appealing.

The Challenge

Isolating a section of PE pipe, especially 125mm to 315mm SDR 11, is challenging, as squeezing thick HDPE pipe can be difficult and time-consuming, and unknown risks are associated with it.

Gas distribution operators are used to squeeze polyethylene (PE) pipe to isolate a section of pipe or carry out a branch installation. Modern testing and plastic pipe manufacturing techniques have highlighted many concerns associated with squeezing PE pipe, such as slow crack growth (SCG) propagation. 

No specific data suggests there will be damage to the pipe during a squeeze-off as long as proper squeezing procedures are followed and proper squeeze tools are used. However, the pipeline’s integrity when carrying out squeeze-off operation depends on applying a correct procedure. Therefore, it depends on people and ‘Behaviours.’

Squeeze-off procedures create several concerns:
  • PE damage at the squeeze points.
  • Lifting equipment required to mobilize large squeeze-offs.
  • Large excavations increase reinstatement costs.
  • The squeeze-off tool may not completely stop the gas.

The Solution

Laminar Bagtube Flowstopping System provides an easy-to-use and cost-effective alternative to squeeze-off on polyethylene (PE) mains for maintenance, repair and modification of gas distribution networks while maintaining the continuity of supply.

Operators can use the Bagtube system for PE mains of standard diameters up to 630 mm a diameter operating at pressures up to 75 mbar. It is more cost-effective than squeezing off because it requires a smaller excavation. 

There is no sterilization of the pipe as with squeeze-off applications, no damage to the pipe wall and no axial stresses induced on the PE pipe. More importantly, repeated re-entry at the exact location is possible, should this be necessary. 

The system significantly reduces excavation requirements, reducing the probability of damage to other buried apparatus. It also reduces landfill waste and imported materials and meets our environmental sustainability requirements.

Low Pressure Twin PE Bagtube Fowstopping System

  • One system for 4” – 24” pipes.
  • Lightweight aluminium construction.
  • Integrated sectional vent/purge pipe complete with flame arrestor.
  • No squeeze-offs.
  • Gas bag design creates more pipe contact for a gas-free stop.
  • Positive placement bag insertion tubes.
  • Regulated bag inflation.
  • Quick connects for easy operation.
  • Max Pressure Rating: 1 psi.

PE Gas Bags

Offer superior sealing, easy removal, quality deployment, and excellent gas bag construction. Self-centering cylindrical bags maximize bag-to-pipe wall contact while minimizing gas bypass. The inner bladder has excellent durability, tensile strength, tear-resistance, and resilience, which is held inside a thin yet strong outer synthetic fabric. 

Our Bagtube range uses a semi-supported inflatable bag, gas-free, designated E20A. It incorporates an extended neck and a backbone, eliminating the risk of a “twisted bladder.”

The E20A bags have a bladder construction using double-layer “virgin” rubber, with a cover made from high-tenacity unproofed nylon (all conforming to GIS/E20 specification). The lowest burst pressure is 54 psi, providing a bag safety factor of eight times over the current British standard for Iris Stop operations (5 psi). 

Based on the straightforward bending moment, we have calculated that the support post can withstand six times the maximum load when used as an Iris Stop secondary bag.

  • Rated up to 1 PSI.
  • Each bag assembly is pressure tested before shipping.
  • The Bagtube Assembly includes a bag deployment “shoe” that protects the bags from tearing and provides secure placement in the main for added safety.
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