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Inspection Guidelines for Ruftraks UK Limited
Plasma® Synthetic 4x4 Winch Lines.
Prepared in association with Puget Sound Ropes.

 Plasma synthetic winch lines were introduced to the off-road vehicle markets in the late 1990’s, and have rapidly become a must-have accessory for hard-core dirt trekking enthusiasts. 
Based on experience gained during off-road challenges and adventures since their introduction, several specific end-use conditions and hazards have been identified which can be harmful to Plasma ropes.  The presence of these conditions can best be determined by periodic inspection of the lines and the hardware on which it operates.  This guidance document presents recommendations for periodic inspection by the end user.  These guidelines are aimed particularly at the serious off-road driver, who will be using their tow cables every week if not daily. 

Conditions to be avoided in Plasma Lines 

There are three areas where close attention needs to be paid to Plasma lines.  Below are descriptions of these conditions and likely signs of their presence.

1.  Repeated lateral abrasion against sharp edges is to be avoided.  While HMPE is one of the most cut-resistant polymers available, hard rough-surfaced materials (rocks, sharp metal) can prove to be stronger than Plasma in a long-duration abrasion event.  Signs of excess abrasion include strand pull-outs, heavy chafing, and/or cut strands in a single area.  It should be noted that normal light fuzzing of the Plasma rope surface is to be expected in normal use.  This light fuzzing does not reduce the rated strength of the line, and actually creates a protective layer on the rope that helps to prevent further damage.  External protection against chafing (e.g. woven chafe sleeves or socks) should always be used where the rope will contact sharp or abrasive objects.

 2.  Plasma begins to lose strength above about 70 ºC, and has a zero-strength temperature around 150 ºC.  If the winch is overheated by extreme use (e.g. extensive backing down or lowering under load) then the winch drum can transfer heat into the rope and cause the rope to be degraded.  Signs of high temperature damage include melted areas, fused (inseparable) strands, and significantly reduced diameter.  Using the winch in accordance with the manufacturer’s recommendations should cause no overheating of the rope.  It should be noted that sometimes the rope remaining on the winch drum might appear to be fused, melted or deformed.  However, this is not caused by overheating but is a result of compressive flow and set of the rope coating.  This can occur when the winch line is heavily loaded while there are two or more layers of rope on the drum.  If necessary, flexing the rope by hand to separate the strands can soften up this stiff section, a process that causes no damage to the fibers.

 3.  Plasma lines can lose strength if overstrained.  Overstraining is the result of exceeding the recommended working load limit, whether instantaneously (by transient peak loads during dynamic loading events) or for an extended time period (by overworking the winch/rope system).  The working load limit of the line (the minimum breaking load decreased by a design factor) should be chosen based on experience in the end use, along with consultation with the winch and rope supplier if necessary.  Loading at high angles or around small bends can also cause excessive strain, for example in a choker configuration.  Signs of overstraining can be subtle but include localized thinning and elongation, and loss in flexibility (for example the rope becomes rigid).

 Inspection Guidelines for the Rope / Winch System:

 Below are some suggestions for inspecting Plasma lines and their winching mechanisms for the above damage conditions.  Each end user should develop their own method of routinely inspecting these lines for damage prior to each use.  The method and frequency of inspection will depend on the end users experience and usage level.

 1.  Pull the rope out from the winch as you walk to the nearest tree or other fixed object and secure the end of the line using a suitable method.  If you have not yet done so, put a brightly colored mark on the line at a point just beyond where the rope is secured.  This will be a reference mark for future measurements, and should be made as permanent as possible (one suggestion is to tie a bright ribbon through one or two strands of the rope).

 2.  As you are walking back from the tree, visually inspect the rope for any signs of abrasion, localized thinning, or melting.  Signs to look for (as noted above) include pulled strands, heavy fuzz, stiff regions, regions of inseparable strands, and thinned areas.  This inspection should include the portion of the line wrapped around the tree, and the portion of the line between the tree and the winch.  Make a note of any damage areas.

 3.  Pull the rope out from the winch, visually inspecting it as you do so, until the minimum recommended line length remains on the winch drum.  (Alternately, if you primarily use the front portion of the line, only pull out the most commonly used length.)  If you have not already done so, put a bright mark on the line at the point where the line now exits the winch.  This will be a reference mark for future measurements, and should be mounted securely, as in step 1 above.

 4.  Carefully inspect the winch drum, winch flanges, and any winding aids, rope guides, or running surfaces where the rope comes in contact with metal portions of the vehicle.  Feel these surfaces by hand to ensure they are free from nicks, burrs, rust, or sharp edges.  All running surfaces should be rounded to at least the same diameter as the rope.   Check rolling surfaces to make sure they turn freely.

 5.  Check the rope that remains on the winch drum for signs of melting, thermal fusing, or thinning.  (Coating flow has a similar appearance to fusing – see above comments.)  Check that the drum surface is smooth.

 6.  Using the vehicle and the winch, put a small (less than 10% of break load) but repeatable load on the line.  In subsequent inspections a similar load should be applied again, so determine a method that will give approximately the same line load each time.

 7.  Walk back to the tree, again visually inspecting the line as you go (again, note any damage areas).  Using a flexible tape measure, measure the length between reference marks.  Write down this reference length and compare it to previous measurements.

 8.  Return to the vehicle, remove the load on the line, disconnect the line from the tree and rewind onto the vehicle.

 9.  Keep a record of the line reference length as well as any damage areas and their approximate locations relative to one or both reference marks.   Future inspections should be used to monitor minor damage areas for signs of growth.

 Inspection Frequency

 The end user should determine the frequency of rope inspections.  For heavy off road enthusiasts, the rope should be carefully inspected prior to each application.  The user should also perform a quick visual inspection (without length measurement) prior to any use of the rope, for example just after connecting to an anchor point while walking back to the vehicle.

 Rope Disposition:

 Ropes that show severe damage should be replaced, repaired (damaged areas cut out and butt-spliced), end-for-ended, or down-rated to other applications.  Examples of severe damage in Plasma rope include (but are not limited to):

 a.  two or more strands severed within a 0.5 meter segment

b.  thermally fused segment that is no longer flexible (strands 
                 not separable)

c.  localized diameter reduction of more than 20%

d.  strands melted through on one side, inseparable strands

e.  rope that has lengthened (between reference marks) by more
                than 10%

 Each end user should determine through experience which signs of damage are more indicative of impending failure.  (For example, the critical damage mode of a rope that fails in service might be identified if the location of the break can be traced to damage noted in a prior inspection.)

 Summary:

 Plasma lines represent a brilliant technological breakthrough in the off-road industry, one that can make the slog through the mud to the nearest tree just that much more enjoyable.  Like any new high-tech piece of kit, Plasma lines have a much better chance of meeting the high-tech trekker’s expectations when coupled with careful maintenance and periodic inspection.  Suggestions for inspection of these lines are offered above.

Andrew G. Thomlinson - 5th April 2002