Abstract: A system for locking a chain-operated valve to prevent unauthorized and inadvertent operation of the valve. The system includes an elongated tube for receiving both lengths of a chain encircling the valve and a locking arrangement positioned at one end of the tube. Both lengths of the chain extending from the valve enter one end of the tube and exit the opposite end of the tube adjacent the lock arrangement. The lock arrangement includes a bracket secured to the tube and extending outwardly from the tube. The bracket preferably includes apertures for receiving a lockout hasp extending through the chain links and the bracket. A conventional padlock or other security locking device may then extend through the hasp to prevent opening of the hasp.

Abstract: A master link for a standard chainwheel chain, having a substantially planar shackle body having a bore located thereon and first and second extensions extending from the shackle body and terminating at respective ends thereof. The extension have longitudinal axes and are twisted about 90.degree. along their longitudinal axes. The respective ends of the extensions have bores therethrough. A tab member is positioned parallel to the shackle body and has a bore therein in substantial alignment with the bore in said shackle body. A 180.degree. bent portion connecting said shackle body and said tab member. A first pin connects said bores in the extensions and a second pin connects the bores in the shackle body and the tab member.