Lock Out Your Cooling System
Lockout/tagout is needed and required for all process cooling systems using any refrigerant. Take steps to control hazardous energy during repair and maintenance or suffer the consequences, which can include serious injury, death and large fines. Use lockout/tagout procedures to ensure that equipment is isolated and "dead" before working.
Protecting yourself and your employees from hazardous energy is easy -- just follow these three basic concepts before working:
- Isolate equipment from all sources of hazardous energy: electric supply, refrigerant lines and the cooled medium. Use locks to enforce the isolation if at all possible.
- Ensure that all energy stored inside the equipment is relieved safely by pumping out, purging, checking voltages, etc.
- Keep checking during work if energy can creep back in through a leaky valve or other means.
The Occupational Safety and Health Administration (OSHA) requires lockout/tagout for every source of hazardous energy in a facility, including the cooling system. Electrical lockout has its own separate standards, but all other energy (including mixed equipment with electric and, say, thermal hazards) comes under the "Control of Hazardous Energy" standard (29 CFR 1910.147).
The lockout/tagout standard requires an organized energy control program incorporating written energy control procedures, training for all employees involved or affected, and periodic inspections of procedure effectiveness. Each lockout procedure must be certified annually by the employer to be correct and adequate after an inspection of an employee actually carrying out the work. There are specific requirements on locks, tags and even on the design of process cooling equipment.
OSHA's concentration on lockout/tagout was the most interesting part of the settlement. According to OSHA Area Director Kimberly Stille, OSHA's citations to the food processing company are intended as a warning to all industrial refrigeration facilities -- large, small, ammonia, Freon -- that lockout/tagout compliance is an area of concern to regulators.
"Lockout/tagout is an important requirement for all refrigerated facilities. Our Strategic Plan includes targeted enforcement in the food processing industry. Chemical lines, like those containing refrigerants, ammonia or otherwise, are sources of stored energy, and so they're subject to the lockout/tagout standard," says Stille.
For facilities that use ammonia or certain other refrigerants, the OSHA "Process Safety Management of Highly Hazardous Chemicals" standard (29 CFR 1910.119) also applies. The PSM standard, as it is called, requires written operating procedures for the cooling system as well as the use of "safe work practices" like lockout/tagout.
OSHA encourages integrating lockout/tagout with PSM. Having one set of "operating procedures" and another set of "lockout procedures" for the same tasks is an invitation to disaster. Most of the time, technicians will blend the two or use neither procedure at all.
Lockout is critical to safety during maintenance and repair. In refrigeration and cooling facilities, we often give it inadequate attention. Take a hard look at your maintenance lockout procedures today.
Sidebar:Two real-world examples demonstrate the need for adequate maintenance lockout procedures.
Don't Let This Happen at Your Ammonia Refrigeration Facility
In December 2001, at a Madison, Wis.-based food processing company, one worker was killed and another seriously injured, reportedly while servicing a rotating ammonia heat exchanger used in meat processing. After a six-month investigation, OSHA fined the parent company more than $200,000 for safety and health violations. Citations included serious violations in the areas of stairs and exits, electrical requirements, lockout/tagout, ma-chine guarding, permit-required confined spaces and the process safety management (PSM) standard. The citations attributed about three-quarters of the penalty to lockout/tagout-related problems, including lack of procedures and improper employee training.
Notable among the terms of the settlement agreement is the food processor's promise to impose a "permitting system" on all line-breaking and equipment-opening work at the Madison facility. This expands on the PSM standard's requirements for safe work practices for such activities and ties in closely with lockout/tagout requirements.
In September 1997, at a meat processing plant in Philadelphia, two contractor workers repairing a water chiller were doused with ammonia when they opened a pipe union without properly verifying that the chiller was empty. One worker received serious burns and the other was treated for ammonia inhalation. The burned worker left his job as a refrigeration technician, suing the facility along the way. The plant and the worker came to an undisclosed settlement.
The contractor apparently had no written lockout/tagout procedures for opening ammonia equipment. The technicians had isolated and pumped out the chiller (which was leaking) according to their common practice. After isolating the chiller (without locking it out), the technicians proceeded to bleed residual ammonia pressure into a bucket of water.
An investigation found that the bleed/drain valve was clogged, preventing the removal of ammonia. The technicians were not wearing personal protective equipment such as full-face respirators, which contributed to the injuries.
Always be sure that equipment is completely de-energized before opening. A proper lockout/tagout procedure would have prevented, or at least mitigated, this accident.
Sidebar:Most likely, you have lockout/tagout procedures in your plant, but are they adequate? Examine your process cooling equipment and see if you have any of these common lockout/tagout problems.
6 Mistakes You Don't Want to Make
Using tags when the equipment can be locked out. Tags are a last resort; if it can be locked out, it must. Specialized lockout devices are available for most kinds of valves, and seal-cap valves should have a handwheel attached for lockout. Since 1991, it has been illegal to install equipment that cannot be locked out.
Locking out just the electrical lines and neglecting refrigerants and cooling media. Lock out all energy sources that might pose a hazard. A simple refrigerant evaporator might have electric power to fans and solenoid valves, refrigerant chemical, thermal and pressure hazards on multiple lines, and air- or hydraulically powered dampers.
Not using written procedures for lockout/tagout. The "Control of Hazardous Energy" standard does have an exception for certain situations. Unfortunately, it is nearly impossible for process cooling equipment to qualify for the exception -- there are eight separate criteria, all of which must be met. The most stringent requirement is that there be no potential for energy to leak in after shutdown. While electrical switches and breakers do a good job of isolation, "no leaks" is difficult to guarantee in any piped fluid system.
Using the wrong locks or tags. Locks must be sturdy, standardized (for the facility), specifically and only used for lockout, and personally assigned to (and labeled for) individual employees. Tags are subject to even more detailed requirements about permanent attachments and breaking strength. Swiping a lock from the tool cabinet or using a Post-It Note does not meet standards.
Poor procedures. Make certain that equipment is isolated and de-energized, and take extra steps if you cannot be certain. Use care to ensure that energy does not build up again. A leaky valve easily can pressurize an exchanger or vessel to full operating pressure, especially if left overnight. Incorporate frequent checks for hazardous energy into your maintenance program.
Using one lockout device for an entire crew. "Group lockout" does not mean that one worker locks out the equipment for everyone. Group lockouts are useful for coordinating multiple trades, shifts, etc., but they require special care. Generally, one worker is assigned to maintain the locked-out status of the equipment, and each crew member applies his or her own lock to a group-lockout device. Special procedures must be used for lockout and for shift changes to ensure that lockout protection is maintained.