This Standard specifies the requirements for hot-dip galvanized bolts, including step bolts, with ISO metric coarse pitch series threads for normal and low temperature applications in tower construction, and associated nuts and washers.
Nominal bolt sizes and lengths are as follows:
(a) Single-nut type tower bolts in diameters from 12 mm to 30 mm inclusive, with lengths from 35 mm to 160 mm inclusive.
(b) Double-nut type tower bolts in diameters from 12 mm to 30 mm inclusive, with lengths from 50 mm to 125 mm inclusive.
(c) Step bolts 16 mm, 20 mm, and 24 mm in diameter with lengths from 180 mm to 290 mm inclusive.
NOTE: Tower bolts have a thread length/bolt length relationship to enable threads to be excluded from shear planes when assembled.
This Standard uses the terminology ‘bolt’ to mean both tower bolts and step bolts. Where the terminology used is ‘tower bolt’ or ‘step bolt’, the reference only applies to tower bolts or step bolts, respectively (see Clause 1.4).