 Hot Tapping of PE Gas Pipe with the Branch the same Size as the Main
Successful Practice: The gas industry can now perform hot tapping of PE without shutting down the system or building a bypass installation.
Traditional Approaches:
- Install a bypass line around the area where the tap is to be performed followed by placing squeeze tools on both sides of the tap point within the area being bypassed.
Install multiple tapping tees and manifold them into a single larger line to allow greater capacity than one of the tees alone can provide.
- Place a squeeze tool on the upstream side of the tap point resulting in a shutdown of all portions of the system downstream from the tap point. This third process has the disadvantage of possibly causing interruption of service to customers.
Typical Experience: Higher Costs, Safety and Customer Disruption
- More fittings--a bypass requires at least 2 tees as well as other fittings. Installing a manifold so means more fittings--using multiple tapping tees feeding a full size branch also requires several fittings and joining procedures.
Cost to remove the bypass and materials cannot be reused.
Potential 3rd party damage if bypass is not removed and is not mapped.
Worker and public hazard- squeeze offs are not always possible or 100%.
- Excavation is much larger.
Smart Practice: Use MTD/Daeyoun hot tapping system. They have developed fittings, equipment and procedures for hot tapping PE gas pipe with the branch the same size as the main as well as new high volume tapping tees.
The featured process involves electrofusing a large port ball valve to a full port electrofusion saddle tee. Special adapters and cutters are then used with a TDW T-101b-XL tapping tool to tap the main. After fusing on the tee and valve assembly the joints should be pressure tested prior to tapping. The tapping tool is connected to a specially threaded end on the ball valve using a special adapter. The valve is opened allowing the insertion of the cutter and the cutting of the pipe sidewall. As with steel tapping, measurements must be taken and the tapping done carefully to prevent running the cutter through the opposite side of the main. The design of the cutters allow for all chips and shavings to be captured behind the cutter and keeps them from being deposited in the pipe. When the tapping is complete, the cutter is retracted through the valve, the valve is shut off and the tapping machine can be removed. The threads on the end of the valve are then cut off and the branch can be run from the valve outlet by standard joining procedures.
The system currently is available with 2", 4" and 6" large port valves. (Valve port ID's actually 1.81" for the 2", 3.54" for the 4" and 5.24" for the 6") Tees are available 3x2, 4x2, 4x4, 6x2, 6x4, 8x2, 8x4, 8x6, 10x4, 10x6, 12x4 and 12x6. Cutters and adapters are available in 2", 4" and 6" sizes.
Successful Practice Advantages:
- The elimination of the need for squeeze off tools in the process and the potential for them not attaining a complete shut off as well as a smaller excavation.
The main being tapped only needs to be exposed sufficiently to allow the attachment of the saddle tee. No extra area must be excavated for squeeze tools or bypasses.
There is also no waste of materials necessary with the installation of a bypass. Room is needed perpendicular to the main being tapped for the installation of the valve and tapping tool but this area is typically excavated for the installation of the branch anyway.
- Total time to install a branch connection is reduced using the hot tap process offsetting the additional cost of the fittings and tools. The tool investment can be recovered with the installation of just a few taps. Two persons are necessary to complete the tapping process but in most cases there would be at least two persons involved with any other process.
The second process introduced by MTD/Daeyoun is still under development and involves high volume tapping tees in 4x4 and 6x4 sizes. These tees are approximately the same height as competitors 2x2 tapping tees making them suitable for most applications when adequate cover can be maintained. The tees are attached by electrofusion and special tools are required for the tapping process.
For More Information on the equipment, go to www.mtdeason.com or call them at 800-633-7131. MEA sends a special thank you to Jim Shepherd of Alliant Energy for capturing this successful practice at the 83nd Midwest Energy Annual Gas Operations Conference and providing it to Energy Delivery News and Solutions. or call them at 800-633-7131. MEA sends a special thank you to Jim Shepherd of Alliant Energy for capturing this successful practice at the 83 Midwest Energy Annual Gas Operations Conference and providing it to Energy Delivery News and Solutions. |
