Bolts and screws are not something that occupies a lot of our reliability thoughts. After, the life of an appropriate bolt in a non-aggressive environment has been extrapolated to something like 11,000 years. Yet if you use the wrong fastener, it is bound to be very aggravating. It may not even survive its own virgin installation!
Luckily, there are some visual cues to help guide against using the wrong fastener. The following table shows grading of common US and Metric fasteners.
Maybe one day we will only have just the same system and less confusion. But you know the saying; “US is changing to the Metric standard inch by inch.”
US Bolts (SAE J429)
Metric Bolts (ISO R898)
*Load= Minimum load bolt must handle without permanent deformation.
**Strength (tensile)= Minimum load bolt must handle before braking or fracturing.
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