This section is concerned primarily with harnesses, but also applies to other equipment made from webbing, such as slings, quickdraws, lanyards, and strops. Generally harnesses are made from polyester webbing, though nylon is sometimes used. Slings, strops, and quickdraws are invariably made of nylon.
Webbing equipment may be retired for various reasons, which could include:
- Ultra-violet degradation
- Damage by abrasion
- Worn attachment protection
- Corrosion of metallic components
- Stitching damage
- Chemical damage
- Glazed (melted) areas
- General appearance, including dirtiness
Most of this article is based on the author’s prejudices, vague impressions, occasional tests, hearsay, and half-remembered second-hand reports from decades ago. Reliable data is hard to come by. However, the intention is to refine this article in time by incorporating the results of test programmes and overseas reports. Any additional information would be appreciated.
To be able to use age as a retirement criterion, obviously the age has to be accurately known. Therefore record the date of purchase of all webbing equipment with the inspection records.
Retiring webbing equipment due to its age is based on the belief that polyamide (nylon) deteriorates spontaneously over time. This was true in the 1960s when nylon was new technology, but advances in processing nylon have resulted in a much more stable fibre.
As a single criterion, it is difficult to justify mandatory retirement of webbing in less than ten years. If the equipment has been kept in a dark cupboard and not used, 15 years is probably not an unreasonable time. However, in most cases UV degradation or obvious damage will force the decision before ten years is reached.
Dynamic climbing ropes should be considered differently from webbing items, as they may suffer a loss of elongation through ageing. The lower stretch may render them unsafe even if the laboratory strength is still adequate.
Nylon and polyester yarns are subject to slow deterioration by the chemical effect of ultra-violet rays. The rate of deterioration varies with the type of yarn, with colour and type of dyestuffs, and the weave of the material. Normally fading of the dye is present if the webbing has had severe ultra-violet exposure.
Preliminary tests show that, though highly variable, polyester webbings lose about 10-20 % strength after the equivalent of one year in sunlight in Wellington (approximately 2000 hours), while nylon loses about 20-30 %. With these losses the materials are still more than adequately strong, but caution suggests a greater amount of exposure may be unwise.
If webbing equipment is routinely used in sunlight for several hours a day, it may be necessary to assess the likely damage resulting from this. For example, four afternoons’ use per week on a sunny cliff may amount to over 3000 hours’ exposure after about five years, and retirement may be wise at this time. However, if the location used is a shady gorge, then ultra-violet exposure is not an issue.
Judging by the limited testing done so far, general overall abrasion damage – wear and tear – has a greater effect on webbing strength than a single instance of acute damage, such as a significant cut on the edge of the webbing. However, if such a cut is at a critical point, such as where the webbing passes through a buckle, the situation is more serious.
Abrasion damage is particularly hard to assess, as it is difficult to quantify the amount of damage that the item has sustained. The recommended approach is to select suitably worn items of each type of equipment and define them as examples for comparison, so that an item under inspection would be rejected if it appears to be more worn than the defined example. While the decision is still arbitrary, this enables the people carrying out inspections to make judgements which are reasonably consistent from year to year and from person to person. For each type of equipment there could be two type examples: a very worn one which is the basis of comparison for retirement on this criterion alone, and one less worn, so that if an inspected harness falls between the two examples, it might be retired on other criteria.
Most harnesses have some means of protecting the attachment point from wear caused by the constant rubbing of descender carabiners, etc. Usually this is a small piece of fabric or webbing. When it becomes worn through, subsequent wear takes place on the structural webbing underneath, which is weakened as a result, and can become a failure point if the wear continues.
In the case of the Adventure harness, a small square of PVC material offers initial protection. Under this is a piece of black webbing which protects the main structural webbing. Below this again is a thicker piece of blue webbing. While the PVC commonly wears through after a year or two, the webbing underneath will sustain much more wear and is unlikely to ever be worn right through. Other harnesses, though, rely solely on the PVC or other material, and should be watched carefully in this regard.
Harness buckles are usually made from steel, or occasionally from aluminium or stainless steel. Steel buckles are protected from corrosion by electroplating, usually by zinc, though there are other possibilities, including cadmium and nickel. On the more expensive harnesses the buckles often have an additional “powder coating” applied by a spray-painting process, usually in a black colour.
Zinc plating discolours fairly rapidly, and is poor in a corrosive environment, such as sea cliffs. It should generally stand up to 10 years of ordinary use, but occasionally breaks down earlier and allows corrosion to start. If a buckle has severe rust the harness probably should be retired.
Webbing equipment is always stitched together, so it seems obvious that if the stitching is damaged, the item will be weakened. However, this depends whether the weakened join is normally the weakest part of the harness. If the webbing (for example) breaks at a lower load than that particular join, then the article may not be weakened at all. This of course can be difficult to assess.
Aside from safety in the sense of strength, there is also the possibility of the item disintegrating and becoming non-functional or difficult to use.
In the case of webbing slings, the stitching may be the weakest point (although this can depend on the test method), and it’s obvious that damaged stitching could produce a failure, as nothing else is holding the sling together. With harnesses an assessment is much more difficult. Classic harnesses have no critical load-bearing stitching. Adventure harnesses have never failed at stitching during testing, and all the structural stitching (four areas) is protected by not being exposed on the outside of the webbing – you can only see it on the inside. Most recreational Aspiring harnesses share this feature.
Generally stitching is robust, but if structural stitching does become significantly abraded, it is obviously a case for instant retirement, unless it can be repaired. Often this is difficult to do.
This category is to include damage to the webbing which should not ordinarily happen; however it often does. The three possibilities are cuts, chemical damage, and melting. Each one can seriously weaken the webbing. The seriousness depends on the position; for example a burn on the very end of a buckle tail strap is of absolutely no consequence, whereas a small cut on the edge of the webbing just where the buckle usually fastens could lead to the webbing tearing there in the worst case scenario, such as severe leader fall.
Cuts are quite common, and are generally caused by a sharp edge of rock, or some other sharp object, passing across the webbing while it is being used, especially if under tension.
Melting is sometimes said to be caused by abseil devices becoming too hot and glazing the webbing. It is probably more often caused by a rope passing across the webbing during a fast abseil. If minor, it will have relatively little effect on the strength of a harness, however if there is significant damage the harness must obviously be retired.
Chemical damage is rare, as nylon and polyester are immune to most common chemicals, including detergents, lubricants, paints, solvents, and fuels. Spilling petrol on a harness will have absolutely no effect on it. However, nylon is attacked by acids of moderate strength, and polyester by alkalis, so sources of these, such as lead acid batteries and alkaline cleaners, must be identified, and care must be taken to isolate them from webbing equipment. Bear in mind that a harness made from polyester webbing may be sewn with nylon thread.
An organisation will be judged by its equipment, so if the webbing equipment looks rough, this alone may be a suitable reason for retirement. No-one is happy putting on a harness which has the auxiliary straps frayed and tatty, even though the safety of the item may not be in doubt. A related issue is cleanness. It is good practice to wash webbing equipment occasionally, perhaps to coincide with a six-monthly or annual inspection. Use a mild soap
The retirement chart below shows eight separate criteria on which a harness might be retired. Each criterion has three categories, which might loosely be termed good, satisfactory, and bad. An organisation could set up a colour coding system, in which column one is green, column two is orange or yellow, and column three is red.
It is intended that the chart be used as follows: If under any single criterion the item falls into the third column, it should be retired. If three or more assessments fall into the second column, the item be retired also. For example, a seven year old harness with a rusty buckle and wear starting in the attachment area is probably not worth retaining.
|Age||0-6 years||7-10 years||over 10 years|
|UV History||up to 1500 hrs||1500-3000 hrs||over 3000 hrs|
|Abrasion Damage||minor wear||moderate wear||severe wear|