Cable Hardware FAQs
Subsea Cable Hardware FAQs
Q. What is the difference between the EVERGRIP™ and the DYNA-GRIP® Termination?
The EVERGRIP and DYNA-GRIP Terminations are both full-strength mechanical terminations which protect against fatigue of your cable system under severe dynamic loading. The advantage of the EVERGRIP Termination is that it can be readily installed on your cable for immediate use and removed at a later date and reinstalled with new rods and insert (Retermination Kit). Installation of the DYNA-GRIP Termination requires an epoxy fill (with overnight cure) and is intended for a more permanent installation.
Q. What is a Retermination Kit?
Many of our field-installable products incorporate helical gripping rods as part of the kit. At times, it may be necessary to remove our product to replace helical rods affected by excess corrosion or to refurbish the cable connector. A PMI Retermination Kit is a cost-effective way to reinstall many of our products. The kit includes replacement helical rods, fasteners, and any consumable machine parts required to facilitate installing our product with the reusable items.
Q. Can I install a DYNA-HANGER® Suspension System (DHSS) on a seismic lead-in with hair fairing?
The DHSS is designed to be installed on a lead-in cable with hair fairing with the “hair” removed. Hair fairing (braided DACRON with loose strands or “hair”) increases the cable diameter with material which is not uniformly round or dense. These properties can subtract from the holding performance of helical gripping products. Therefore, to maximize the performance of the DHSS on cables with hair fairing, the fairing “hair” should be removed (cut) from the braid for the length of the 1st Layer DYNA-HANGER Rods. This installation approach provides a uniform diameter and density for transferring the helical gripping rods’ radial clamping pressure through the braid and into the underlying cable.
It is important to inform PMI at the time you request a DHSS proposal design that you intend to install the DHSS on the lead-in with fairing. The fairing braid adds approximately 2mm (.080”) to the cable diameter and this increase must be considered in our design calculations.
Q. How does the “Helical Gripping Element” work?
Our helical gripping element functions with the geometry and behavior of the wire. Axial load in the cable decreases as radical compression increases, resulting in the gripping effect. This gripping technology helps spread out forces that can affect the cable, which ultimately prevents damage to the cable and reduces the risk of high stress concentration. Download our guide, The Gripping of Helical Elements, to learn more.
Q. How do I determine my cable lay direction and why is it important?
When installing one of our helical products on an armored cable, we need to match the lay direction of the helical rods with the cable armor lay direction. Matching the lay directions achieves the highest holding strength with a helical gripping device. The only exception to this rule is a three-strand wire rope where we match the lay direction of the wires in a single strand. If your cable is jacketed, the helical gripping rods lay direction is not a factor. Click here to view a PDF on how to determine the lay direction of an armored cable. If you need more information, please contact us.
Q. Why are PMI helical gripping products considered only one-time-use items?
Each new set of rods has aluminum oxide grit glued to the ID. Essential to gripping, the aluminum oxide grit remains trapped between rod sets and against the cable until removed. After use, however, the adhesive will give way and the grit will fall off the unwrapped rods making the rods unsuitable for reuse.
Q. What does “Rated Holding Strength” on a product data sheet indicate?
Rated Holding Strength is the load in pounds we would expect the product to hold if installed directly on an armored cable and loaded in axial tension. For most of our helical gripping products, the Rated Holding Strength is a calculated value based upon the helical wire material strength.
Q. Can I use PMI terminations on jacketed cables?
Yes, but we strongly recommend testing your cable to determine the holding strength prior to field use. Please contact us to discuss in more detail.
Q. What is the difference between a CABLE-GRIP™ and a STOPPER-GRIP™ Termination?
The CABLE-GRIP Termination is designed for cable and wire rope diameters under 1.0” in diameter. It is generally rated as a full-strength product and should exceed the breaking strength of any cable in its range. The STOPPER-GRIP Termination is designed for cables over 1.0” in diameter. It is ideal for routine cable handling operations and may not be rated to hold the cables’ breaking strength.
Q. What do I need to consider when passing helical gripping rods over a sheave?
When passing a helical product over a sheave, the sheave diameter needs to be at least 40 times the diameter over the helical rods (cable + applied rods). To prevent the rod ends from lifting off the cable when passing over a sheave, use tape and/or metal bands to serve the rods ends in place.