OSHA lockout tagout is a procedure familiar to those that work in an industry setting with dangerous machinery. Lockout tagout prodedures are in place to protect workers from hazardous energy by controlling it.
Hazardous energy from machines or equipment includes pneumatic, hydraulic, mechanical, thermal, or electrical.
Injuries resulting from hazardous energy sources include fracturing of body parts, amputation of body parts, electrocution, burns, crushing of body parts, lacerations, and cutting. These injuries can be serious and sometimes even fatal.
Lock out tag out kits will include a scissor clamp, a tag, and some sort of locking device such as a padlock.
Lockout tagout locks the hazardous power source so that it can not be turned on without being unlocked. A tag is then put on the locking device indicating that the power source should not be turned on.
Lockout tagout training would tell you that if two subcontractors are working on a large system the device that is locked out is secured with a folding scissor clamp. Padlocks then hold the scissor clamp closed.
Lock out tag out kits should be acquired by any company that uses dangerous machinery and train employees on the lockout tagout procedure. After all, it is a safety measure. Reference materials.