Okla. Stat. tit. 45, § 45-513: Quality and testing of chains

The main coupling chain, attached to the socket of the wire

rope, shall be made of the best quality of iron and shall be tested

by weights, or otherwise, to the satisfaction of the mine inspector

of the district where the mine is located, and the bridle chains

shall be attached to the main hoisting rope above the socket from

the top cross piece of the carriage or cage so that no single chain

shall be used for lowering persons into or hoisting them out of the

mine.