20.5.2 Thread Form

Care must also be taken to ensure the correct thread form and diameter are used as mismatched threads are extremely dangerous. Eyebolts to some standards are marked with the thread designation and size. Where there is any doubt as to the thread size and type of the female thread into which the eyebolt is to be fitted, this must be carefully checked to ensure the correct eyebolt is selected.

All eyebolts intended for lifting purposes should have a thread runout under the collar. This ensures that the collar seats fully without binding on the thread. Commercial pattern eyebolts (particularly dynamo pattern) not intended for lifting purposes usually have rolled threads or threads produced with a die head. This gives a taper to the shank where it meets the collar. Under no circumstances should such eyebolts be used for lifting purposes.