PEX tubing is used in ShapeArray (SAA) construction to protect the communication cable from damage and to provide a secure way of retrieving the ShapeArray. The PEX tubing is resistant to twist and helps maintain azimuth control for the ShapeArray when the top of the ShapeArray is not visible at the surface. Each ShapeArray comes with 1.5 m of PEX attached at the top. The PEX Extension Kit is used in situations where this length is not enough to reach the surface or end of a borehole.
Figure 1: PEX extension kit - (A) Extra PEX, (B) PEX couplers and crimp rings, and (C) PEX crimping tool
Note: In most cases, the length of PEX being added is greater than 3 m, and it may be preferable to use PEX which has been reeled up. In this case, it is better not to rely on the PEX for setting the azimuth of the X-mark. Instead, use the PVC conduit, which resists torsion for this purpose. The PEX will still be used to apply axial compression from the top.
Step 1 - Extend PEX for SAA+PVC Installations
Lay out and assemble PVC conduit so that it is approximately the same length as the additional PEX. Push the PEX into the PVC conduit. The PVC conduit will help straighten out the PEX tubing, making it easier to feed the ShapeArray cable through the PEX. Use a cable fishing tool to pull the ShapeArray cable through the PEX. Make sure that the crimp rings and coupler are placed between the two pieces of PEX to be attached.
Figure 2: From left to right - existing PEX on ShapeArray and rings, PEX coupler, and additional PEX with rings installed in conduit
Step 2 - Assemble the PEX Extension
Make sure to mark the X-mark on the PVC conduit containing the ShapeArray.
Figure 3: The X-mark from the ShapeArray marked on the PVC conduit
Connect the PEX tubing using the methods described in the How to Use the PEX Extension Kit guide.
Figure 4: PEX extension attached to existing PEX on the ShapeArray
Glue the PVC conduit pieces together.
Figure 5: PVC conduit glued together after PEX extension has been assembled
Step 3 - Complete the SAA+PVC installation
Mark the X-mark on the PVC containing the PEX for later use during the alignment procedure. Attach the bottom half of the top stack included in the SAA Install Kit to the top of the PVC conduit.