Installing a valve between HDPE flanges 2

[ghkskn]

We had to complete the HDPE underground water piping installation before we receive the valves so we had prepared and used flanged pipe spools having the valve length and diameter sizes. Now we cannot take them out. They are stuck between the HDPE flanges. Even if we take them out installing the valves with gaskets will be a nightmare.

Any experience/advise/guidance ?

 

[BRIS]

You are correct it is impossible to install a valve between two fixed flanges. You should have provided a dismantling joint (flanged socket) at one side of the spool. You now need to cut off one of the flanges and install a flange adaptor. I prefer valve bodies to be in tension and would cut off the downstream flange but it depends on the amount of thrust the closed valve may have to carry and how you propose to deal with this.

http://www.smith-blair.com/water_products/HDPE/high density.pdf

 

[ApC2Kp]

To gkes,
The flanged pipe spools at the valve locations could be cut by torch or saw, and the spool pipe pieces then removed.
Keep the steel(?) spool flanges in place for pushing the HDPE pipe. The HDPE flanges will need to be pushed apart. Port-a-Power hydraulic jacks should be placed between the steel spool flanges to carefully push and compress the HDPE piping on each side of the gap. The HDPE pipe could be softened by heating to a warm temperature of approximately 140 to 180 deg F or hot water. You may need to heat and soften a short length of several feet behind each HDPE flange. When the hydraulic jacks are removed, the piping will tend to spring back, so push the HDPE piping a small amount beyond the length required for the valve and gaskets. Depending on the size of the pipe, a single hydraulic jack could do the push for sizes to possibly NPS-6, or multiple jacks could be required for large sizes of pipe.