Providing Safety
Alternative risk reductions for LOTO

Alternative risk reductions for LOTO

Even though Lockout Tagout Tryout (LOTOTO) has no legal basis in Europe, it is the most widely used way to safely service machines to make them comply with European regulations on de-energising and safely working on machines.

Alternative risk reductions for LOTO

Compulsory mechanical interlock systems

The OSHA 1910.147 standard covering LOTO-procedures, uses guidelines prepared by ANSI (American National Standard Institute) and others. The latest version of this guideline ANSI.ASSE Z244.1-2016 contains practical examples of alternative risk reductions for LOTO.

ANSI/ASSE Z244.1-2016 controlling hazardous energy Lockout-Tagout and alternative methods
This document is considered a “must have” for factory and maintenance managers who want to implement Lockout-Tagout procedures.

Employers are often faced with difficult decisions when it is found that employees have not or not fully followed the LOTO-procedures . For example, employees may forget to apply a step of such procedures. The question is whether, when LOTO procedures are violated, it is better to take disciplinary action or to look at improving the procedures. Violations can also be prevented by making technical adjustments.

Directive Z244.1 contains examples of alternative risk reduction for LOTO such as, Trapped Key Interlocks technology. Trapped Key Interlocks can be used as an enhanced and coercive version of Lockout-Tagout.

For applications requiring main power isolation, a Trapped Key Interlock system can be used at the access points to the installations. The mechanical key system ensures that full electrical disconnection takes place before access can be gained.

ANSI/ASSE Z244.1 provides the following recommendations for the use of a mechanical Trapped Key System for isolation of the main circuit.

  1. “Disconnection by using forced contacts via a shaft-mounted locking system. This method is suitable when the power is small enough to allow it to be switched off directly via the torsion of the key.”
  2. “A cam mechanism and a bolt lock module when powers are too great to be operated directly by a mechanical lock.”

Z244.1 also includes a useful image of a key switch and cam lock controls to visualise an application at multiple access points.

In general, the standard thus provides leeway for supplementing LOTO procedures with coercive mechanical interlock systems in order to reduce risks in critical processes or in LOTO applications where the risk of noncompliance is high.

USP offers a wide range of both LOTO solutions and Trapped Key systems for safe access to machinery. For electrical applications, think of safety key switches or bold locks in combination with a door lock. For valves, valve interlocks, which only allow key release in the closed position.

Are you interested in non-binding advice on LOTO or Trapped Key Interlocks? Get in touch with our sales engineers.

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