Section 72(a) in The Building And Other Construction Workers '(Regulation Of Employment And Conditions Of Service) Central Rules, 1998
(a)all chains other than briddle chains attached to derricks and all rings, hooks, shackles and swivels used in hoisting or lowering of such derricks are effectively annealed under supervision of a competent person and at the following intervals, namely:-(i)such chains, rings, hooks, shackles and swivels which are not more than twelve and a half millimetre of length are so annealed at least once in every six months; and(ii)all other such chains, rings, hooks, shackles and swivels are so annealed at least once in every twelve months:
