K60 on a Directional Drill? WPCT on a Road Bore?
I don't exactly understand why, but in the last few months I've had more questions about these two products (WPCT and K60) being used on Road Bores or Directional Drills than I have had in my previous 20 years. No less than 20 times have I walked a contractor, an end user or a reseller through the reasons that WPCT and K60 are not approved for use on applications where the shrink sleeves will be exposed to massive external forces.
It is important to note: since Covalence WPCT and Canusa K60 are now both owned under the Seal for Life umbrella; for the first time, both share the same sales force and same technical people. For the sake of simplicity here, I'm going to say that WPCT and K60 are similar products. Both utilize a crosslinked polyolefin backing (with no reinforcement within it) and both use a soft mastic sealant.
While the backing and sealant that those products use (WPCT and K60) are well suited for many applications, neither is designed for use on road bores or directional drilling applications.
Why is that?
First let's look at some of the specific forces that are put on a sleeve during a road bore or directional drill. Keep in mind, these forces are even more significant if the directional drill is a bundled bore - where more than one line is pulled through a pipeline at the same time. In those cases, the forces can be absolutely immense. What are these forces?
Shear - imagine that you put a piece of duct tape on the sole of your shoe. As you walk around, that piece of tape slides back toward your heel as it is exposed to shear forces. In the case of K60 and WPCT, the soft mastic of the sleeve exhibits dramatically less shear resistance than a product like the DIRAX system. DIRAX utilizes an epoxy bonding agent AND a high shear hot melt adhesive to eclipse the performance of a WPCT or K60. What might this mean on a directional drill? It could mean that your WPCT and K60 slide down the pipe during the pull through and those sleeves end up many feet away from where they were originally installed (not good).
Peel - picture peel as this: you place some duct tape on your table top. You then pry up a corner of that tape with your fingernail; grab that corner with your fingers; and lift up. You would be able to to do it fairly easily; duct tape doesn't have great peel resistance. Certainly less than would be expected from a pipeline product. On a directional drill; picture that a tree root or a rock lifts the edge of a WPCT or K60 sleeve. Now picture that through the next 1000 feet of that road bore pull through; that lifted edge continues to be battered by rocks, roots, mud, dirt, etc. The softer mastics of the WPCT or K60 shrink sleeves have less strength than a DIRAX as an example. Again, we are comparing a soft mastic with the epoxy bonding agent and anti-peel technology of the DIRAX hot melt adhesive. What might happen to a WPCT or K60 on an incredibly demanding road bore or directional drilling application? Some of those installed sleeves may very well disappear during transit; violently pulled from the pipe.
Penetration Resistance - think of this as some kind of force that pokes directly through a sleeve. This hole or gash could could give the environment another avenue to put a section of the sleeve into shear or peel. WPCT and K60 utilize simple PE backings. DIRAX on the other hand, utilizes a multi layer backing including two layers of polyethylene laminating a fiber weave material to give it excellent penetration resistance. In addition, while the soft mastic of a WPCT or K60 sleeve is not going to have much of an impact in penetration resistance, the tough hot melt adhesive of the DIRAX system actually adds to its penetration resistance. It really is a fantastic bonding agent. What could happen to a K60 or WPCT if it runs into multiple really bad roots or rocks during a pull through? There could be holes in the backing. What if those sleeves were installed on top of a bumper or something? Those holes will likely allow those bumpers to 'escape' and your bundle will not have bumpers in place when it reaches its final resting place.
Tensile Strength - how strong is the backing itself? Looking up at Shear Strength up above, that is really an evaluation of the sealant or adhesive. Tensile is a similar test of the backing. Everything said about Penetration Resistance applies to Tensile Strength (for the most part). The complex structure of the DIRAX backing gives it dramatically improved values here.
What you will find if you look even further is that the manufacturer does not approve either WPCT or K60 for road bore and directional drilling applications. That is not the sort of thing they were designed for. Those are not applications where they can be expected to excel. So anyone out there looking to use a product for an application that the manufacturer explicitly warns against: let the buyer beware -- you are taking those risks on yourself.