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Test of 10 years old harnesses

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An operator of an adventure park sent me three of his "worst" harnesses. He wanted to know if he must discard them or if it is possible to make a risk analysis based on a breaking load test. The harnesses were obviously used: First I put it on my dummy and testloaded it with 15 kN. This load is required by the EN 12277, the standard for mountaineering harnesses. All three samples passed this test. Edit: I do not know the original breaking load. In the Norm test the samples are loaded only up to 15 kN, but not until failure. Therefore I do not know theweakening factor due to wear.  Then I did a test which is not required by the standard, but I think it is important:  I made all loops as large as possible. This size would not fit on any dummy, but it could be that the damage on the webbing is closer to the end. I took a big shackle and attached legloops and waist belt to it. The breaking load (in Kn) was as follow: The harnesses broke either...
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Answer from a manufacturer

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I sent my thesis to most of the manufacturers of PPE and one of them wrote an answer with a couple of arguments, why the lifespan should be limited. He gave permission to publish them anonymously and shortened. He said, it is his personal opinion and not approved by his company. I hope I did not change his ideas by shortening. Reasons for a limited lifespan Argument 1 Murphys Law: Storage and transportation increases the risk over the time that unforeseeable things happen: Chemical contamination, dirt, UV Radiation,… Argument 2 “Normal” users are no experts in using PPE correctly. Therefore one can assume that we see negative influences due to misuse: (little falls, bending effects on carabiners,…) The normal user cannot assess these influences and when to discard the PPE. Argument 3 PPE Regulation, EN and UIAA require a clear “lifespan of the product or how to assess it”. Safety factors >2 are industry standard for riskproducts and therefore of course app...
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Discard criteria of PPE - confirmend by science

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Result # 1.: Age/time is no discard criterion.   PPE does not degradiate over time to an extent that it becomes dangerous to use. Even 40 year old ropes ropes  are safe if the sheath is intact and the core is consistent. Only wear and/or destruction   Result # 2.: Webbing (tubular or flat) is not reliable if left in the outdoors. Slings which have been exposed to sun and wear for some years can fail under body weight (toprope, rappell ...). Result # 3.: Multiple bending around small diameters destroys the core of ropes. Permanent topropes in climbing gyms should used only for toprope purposes.  Do not use them for heavy loads like static factor 2 falls or tyrolian traverses. Result # 4.: A major fall or load does not reduce safety.  If the visual and tactile inspection shows no defects it is fit for use. Result # 5.: Following discard criteria are confirmed: All textile PPE: Chemicals, especially sulphur acid c...
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