ABOUT BOLTS : MARKING

A bolt is a bolt. Is that completely true? There are so many kinds of bolts and so many standards, sometimes is difficult to choose the right one. What standard, what diameter, what pitch, what material to choose ? There is huge documentation you can find, here is just a very short guide to help making a choice.
METRIC BOLTS IDENTIFICATION | INCHES BOLTS IDENTIFICATION | ||||
MARKING | Proof strength (Mpa) | Tensile strength (Mpa) | MARKING | Proof strength (psi) | Tensile strength (psi) |
![]() |
225 | 400 | ![]() |
55,000 | 60,000 |
![]() |
310 | 420 | ![]() |
85,000 | 105,000 |
![]() |
380 | 520 | ![]() |
120,000 | 150,000 |
![]() |
580 | 830 | ![]() |
100,000 | |
![]() |
650 | 900 | |||
![]() |
940 | 1040 | |||
![]() |
970 | 1220 | |||
![]() |
700 |
![]() |
How to calculate necessary bolt diameter: d1= (4βP / πσt)1/2 where: P – longitudinal force necessary to tight β = 1.25 - 1.35 – torque coefficient |
I am a GME – Graduate student. I want to join as Junior Engineer. pls. assist me.