A seemingly simple question hides a fatal trap.
On Friday afternoon, maintenance technician Mr. Zhang completed half of the maintenance work and hung his red safety lock on the isolation valve of the reaction tank before leaving the workshop. On Saturday morning, the production urgently needed to restore the operation of this production line, but Mr. Zhang was unable to come to work due to a sudden illness. The workshop director looked at his colleague Li and said, "You help him remove the lock, the production can't wait." 
This scene is played out in factories all over the world every day. A seemingly reasonable request - "Can my colleague help me unlock it?" - touches upon one of the most fundamental safety principles of the LOTO (Lockout Tagout) system. The answer is not simply "yes" or "no", but rather a single legal path with strict preconditions. 
This article will systematically address this question, clarifying the regulatory boundaries, operational procedures, liability attribution, and common misunderstandings, to help every industrial professional understand: when you are unable to be present, how should your locks be handled, who has the authority to handle them, and how the procedures must be carried out. 
I. The Iron Law: "Whoever locks it, shall unlock it" - This is not a suggestion, but a mandatory regulation.
1.1 Clear Language from OSHA
The United States Occupational Safety and Health Administration (OSHA) states in 29 CFR 1910.147(e)(3):

"Each lockout or tagout device must be removed from the energy isolation device by the authorized personnel who installed the device." 
This is not a "recommended practice" or "best practice" - it is a mandatory requirement under the regulations. There is no room for ambiguity such as "should", "try to", or "in principle" in the wording. 
1.2 Correspondence with Chinese Standards
The seventh step "Release and Restoration" in the Chinese standard GB/T 33579-2017 "Mechanical Safety - Methods for Hazardous Energy Control - Lockout Tagout" also stipulates: 
"Who locks it, who unlocks it." 
The standard also explicitly adds: "No one is allowed to remove any other person's locks or labels."

2. The sole exception: Emergency removal by proxy - but not "colleague assistance in removal"
2.1 Original text of the OSHA 1910.147(e)(3) exception clause
"When the authorized personnel who installed the Lockout or tagout device are unable to be present to remove it, the device can be removed under the guidance of the employer, provided that: specific procedures and training have been developed, documented, and incorporated into the employer's energy control procedures. The employer must prove that this specific procedure provides equivalent safety guarantees to the removal of the device by the authorized personnel themselves." 
Pay attention to the three key limiting words: 
"Under the guidance of the employer" - It is not the colleagues who decide to remove it on their own, but the employer (management) has officially authorized and supervised the execution.
"Specific procedures have been formulated, recorded and incorporated" - It cannot be decided on the spot through casual discussion; there must be a written procedure already in place.
"Equivalent safety guarantee" - The safety level of the procedure must not be lower than that of the person removing it.