Flange Adapter Spool Repair
Once pipeline damage has been reported, the size of the pipeline and the DR needs to be established. The correct flange adapter and backup ring size is selected and (4) are required for the repair. The water valve is then shut off and the area excavated and planking installed.
Cut the damaged pipe from the piping system. Make sure that the length removed is long enough for the flange adapter spool assembly to be installed.
Caution: Butt or Electro-fusion joints cannot be made with water flowing through the pipes. Make sure the water valve shuts-off the water flow 100% and make sure no water is flowing. If a small amount of water is flowing, a towel or pneumatic bladder can be inserted in the valve end to dam up the water long enough to make the butt fusion joint. Be sure to remove this item before making the final connection.
A butt-fusion machine capable of fusing the pipe size is installed in the ditch on planking and clamped to the main pipe. A proper sized flange adapter/back-up ring assembly is installed in the movable jaw. Face the pipe and the flange adapter end
to mechanical stops. Remove the pipe chips from the area and align the pipe ends. Using the pipe manufacturer’s recommended butt fusion procedures, fuse the pipe to the flange adapter/back-up ring assembly and allow the joint to cool under pressure.
When this joint is cool, remove the fusion machine from the pipe and install the fusion machine’s fixed end on the other end of the pipe. Install the proper sized flange adapter/back-up ring assembly in the movable jaw. Face the pipe and the flange adapter end to mechanical stops. Remove the pipe chips from the area and align the pipe ends. Using the pipe manufacturer’s recommended butt- fusion procedures, fuse the pipe to the flange adapter/back-up ring assembly and allow the joint to cool under pressure. Also, refer to PPI TR-33.
Once the flange adapters have been fused to the existing pipe ends, measure the inside distance between the flanges. Using the pipe manufacturer’s recommended butt fusion procedures, fuse the other two flange adapter/back-up ring assemblies to a piece of pipe with the same OD, DR and specification as the existing pipe to produce an assembly that matches the inside distance between the flanges on the existing pipe. Install the spool piece between the two flanged pipe ends. Bolt the assembly together using the manufacturer’s recommended guide for alignment and bolt torque. This will result in a fully restrained joint that does not require thrust blocks or thrust restraints .
Minimum Recommended Length of Pipe to Remove for Repair Spool
Minimum Length of Pipe to be Cut Out for Repair