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Re: [wiki] Bolt tester:
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USnavy
Jan 15, 2010, 8:25 AM
Views: 20882
Registered: Nov 6, 2007
Posts: 2667
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I use 1/2" Power-Bolts or more commonly, glue-in bolts with a failure strength of 40 kN. But that's irrelevant. No I promise you, your body will not break first. Do you think the UIAA pulled that 25 kN requirement out of their ass? They require bolts to hold 25 kN in sheer and 20 kN in tension because 20 kN is the approximate force the top anchor is subjected to with a factor 1.78 fall w/ 80 kg on a rope with an impact force of 12 kN with the pulley effect in play. Also the anchor must be robust enough to withstand big falls without deformation. If the anchor has a failure strength of 15 kN, repeated 10 kN loads can cause the anchor to fail as the anchor may bend with every load.
Thus there must be an additional margin of strength well beyond the maximum load the anchor will be subjected to on a regular basis. That’s the whole reason why the term "Safe Working Load" exists. SWL is generally 20% of the breaking strength of the product for non-critical applications and 1/15th the breaking load for life support applications. That additional margin exists to account for product deformation under serious loads, general wear, improper use, and many of the other situations that can cause a product to fail.
(This post was edited by USnavy on Jan 15, 2010, 8:34 AM)
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Edit Log:
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Post edited by USnavy
() on Jan 15, 2010, 8:27 AM
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Post edited by USnavy
() on Jan 15, 2010, 8:28 AM
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Post edited by USnavy
() on Jan 15, 2010, 8:30 AM
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Post edited by USnavy
() on Jan 15, 2010, 8:32 AM
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Post edited by USnavy
() on Jan 15, 2010, 8:34 AM
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