22.5.1 Type (1)
Clamps should have been tested to a proof load of twice the working load limit without showing permanent deformation and in samples tested to destruction they should not have released the load at less than three times the working load limit.
In the case of clamps designed to lift at an angle to the side plate of the clamp, there should have been an additional test at the maximum angle permitted, of twice the working load limit for that angle.
A design that permanently incorporates a short length of chain connecting the clamp to the crane hook is strongly recommended in preference to an eye.
Proof tests should be carried out on the thinnest plate practicable within the clamps range.
The range of thickness that may be lifted should be indicated on the clamp.
Gripping cams and jaw teeth should be easily replaceable.
Some designs of clamp, particularly those with a moving cam action jaw where the initial grip is provided by a spring, have a minimum load and minimum plate thickness they can safely lift. Wherever possible refer to the manufacturer’s instructions but in the absence of specific guidance the load should not be less than 20% of the SWL and the plate thickness not less than 20% of the maximum.