Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at

July 7, 1994

Mr. Joseph P. Zemen
Contractor Safety Engineer
Amoco Chemical Company
225 North Michigan Avenue
P.O. Box 7516
Chicago, IL 60680

Dear Mr. Zemen:

This is in response to your December 27, 1993 letter, requesting interpretation of the Control of Hazardous Energy (Lockout/Tagout) standard 29 CFR 1910.147. Please accept our apology for the delay in responding. Your questions and our replies follow:

Question 1: If a valve has the capability of being locked out via a chain and lock combination, a lockable valve cover, etc., does this meet the intent of "capable of being locked out" and/or 1910.147?

Reply: As defined in 1910.147(b), "capable of being locked out" includes a chain and lock combination, a lockable valve cover, and other means to lockout energy isolating devices if lockout can be achieved without the need to dismantle, rebuild, or replace the energy control devices or permanently alter its energy control capability.

When used in conjunction with energy control procedures required by the lockout/tagout standard and when used as an effective lockout means for the particular workplace application, a chain and lock combination, a lockable valve cover or other means to lockout energy isolating device that meet the 1910.147(b) definition of "capable of being locked out" would be considered favorably when determining compliance with the 1910.147 - Control of Hazardous Energy standard.

Question 2: If Amoco is building a new process unit, must a new valve installation have a hasp device on it at the time ofinstallation or does the installation of a "valve capable of being locked out" meet the intent of 1910.147(c)(2)(ii)?

Reply: In the context of the reply to question 1 above, the installation of a "valve capable of being locked out" would meet the requirements of 1910.147(c)(2)(ii).

We appreciate your interest in employee safety and health. If we can be of further assistance, please do not hesitate to contact [the Office of General Industry Enforcement at 202-693-1850].


John B. Miles, Jr., Director
Director of Compliance Programs

[Corrected 11/5/02]