The Knowledge: Bolts

10 things to know about bolts:

1. Bolts generally provide sound protection and belays. Reported failures are rare.
2. A bolt is only as good as the rock it is placed in. Check for nearby cracks, edges and loose blocks.
3. Beware worn bolts. Don’t wear out belay bolts by direct top-roping. Use quickdraws or screwgates and only thread the belay bolts for the last climber down. Don't know how to thread a lower off?  Watch this video to find out how.
4. A bolt which moves in its hole should be regarded as suspect. Loose hangers on expansion bolts can usually be retightened by turning the nut.
5. Rusty bolts are weakened. The damage is often worse where you can't see, inside the hole.
6. Be very wary of any bolt where part is still shiny and elsewhere it is rusty - e.g. shiny hanger and rusty bolt.
7. A salty environment, even several kilometres or so from the coast, can speed up corrosion dramatically. 
8. The manufacturing and placement processes are crucial. You can only hope that the installer has chosen well - and this includes the glue.
9. Never assume a bolt is safe to use, whoever has placed it.  YOU are responsible for deciding whether or not to use it. Whenever possible avoid relying on a single bolt for safety.
10. Understand the gear you are using. Read the Bolts: Users Guide

Want to know more? OK then, check out the Basics: