Proof Stess

Proof Stress- Googlei-

http://www.google.co.in/#hl=en&biw=1276&bih=541&sa=X&ei=v7GETaPLPNOccd-X7J4D&ved=0CB8QvwUoAQ&q=proof+stress&spell=1&fp=d2d7c6a1e0c3a4b4

Proof Stress - fsteners

http://www.google.co.in/#hl=en&biw=1276&bih=541&q=proof+stress+fasteners&aq=f&aqi=&aql=&oq=&fp=d2d7c6a1e0c3a4b4

Wiki- http://en.wikipedia.org/wiki/Bolted_joint

Was it so difficult?

Not sure about bolts, But there was a program on "dicovery" or "history" channel about ropes and chains. They show proof stress testing for every chain before it leaves the plant. In it they pull the chain way beyond its rated stress, if it does not break it is sent out as "proof tested"

oilcan13