Case Study

Hot Tapping: Gerringong Water Main Renewal

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Case Study Hot Tapping
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What is hot tapping?

Hot Taps or Hot Tapping is the ability to safely drill or cut into an existing pipe that is in use and under pressure.


The project scope of works was to install a new section of a water main underneath a railway line. To ensure continued supply of water while the existing main line was replaced, a temporary 250mm PE bypass to the existing main was required. Using Plasson Large Bore Saddle and hot tapping tool, the hot tap was performed by safely cutting into the existing 500mm PN16 PE pipe that was in use and under pressure. The newly installed pipe system is fully functional and will be reliable for the future.

“This wasn’t an easy task considering the difficult site conditions. Plasson was able to present a reliable solution that gave us the confidence to perform a live tap that works. On top of it, we highly valued the ease of installation of products as well as the time-saving and cost-effective element that comes with it.”

Damien Heffernan, Project Engineer, KenKar Plastics

 

Initial Situation

During the construction of a new section of water main for the local water authority Polyethene pipeline installer, KenKar Plastics were asked to connect a bypass line to the existing main to ensure continuous water supply to the residents. It required the installation of a Plasson large bore electrofusion saddle onto the existing polyethylene mainline that could then be live tapped to connect the temporary bypass line. 

The project was completed successfully by using Plasson’s new range of large bore saddles and live tapping tools (Hot Tapping). The project site was on a section where the pipeline crossed underneath a railway line. This made the installation conditions extra challenging due to restricted access to the saddle installation site. The saddle was successfully welded to the pipe, and a live large bore DN250 connection was drilled into the pipe and an isolation valve installed. The project was completed on time and to specification.

Task

Plasson was asked by KenKar to present a solution to perform simple and reliable live tapping. For this line stopping job, KenKar Plastics were looking for:

  • Ease of installation of products
  • Assembly on a “live” pipe
  • Cost-effective solution
  • Minimum lead time of the required products
  • Uncomplicated and leak-free hot tapping and firmly welded connection through the electrofusion process
     

Solution

To perform hot tapping Plasson is the only supplier that can offer a complete system which includes the saddle, hot tapping tool and profile clamping tool. Given the technological advantages of hot tapping, the main was still running, and the water supply to the town was ensured for the entire time.

The installation into the existing main was underneath the water table, so continuous pumping was necessary to be able to conduct the weld and perform the hot tapping. The Plasson Large Bore Saddle 630-500mm x 250mm was installed in place with minimal digging and lightweight equipment. A Weld Integrity Test port is incorporated into the Plasson Large Bore Saddle to enable a pressure test before cutting into the pipe.

The Clamping Tool leaves a mark on the saddle to show if the correct sized clamps have been used at the correct tension. A Tension Force Indicator (TFI) is built into the strap mechanism – larger sizes are tightened with a torque wrench. The unique design of the Plasson Large Bore Saddle increases the weld zone past the area of the highest stress, which ensures a good weld to the extremity of the fitting. The weak point of the weld is removed and therefore, leads to increased durability under hard operating conditions.

The entire job was completed within 1.5 days. On the first day, the saddle was put on the pipe, and the pressure test was executed; on the second day, the live tapping was performed. Long-term functionality and pipe bonding are guaranteed. The saddle is used as a hydrant point.

 

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Project summary

 

Project Steps

1. Run temporary bypass main and install saddle on the main line

2. Hot tap bypass into main 

3. Shut down main while bypass is in operation by closing valves

4. Replace section of existing main and re-connect 

5. Recommission main by re-opening valves

Requirements

- Safe cut into the existing pipe under pressure

- Simple and leak-free performance during hot tapping

Products used

Plasson Large Bore Saddle 500-630mm x 250mm

Plasson Hot Tapping Tool

Plasson Variable Profile Clamping Tool

Project Duration

1.5 days, October 2018

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