Lockout/Tagout (LOTO) of Manually Operated Hand Valves
In Section 1910.147(a)(1)(i), it states, “This standard covers the servicing and maintenance of machines and equipment in which the unexpected energization or startup of the machines or equipment, or release of stored energy, could harm employees. This standard establishes minimum performance requirements for the control of such hazardous energy.”
Note that applying locks to maintain manual valves in a given position during normal operation does not fall within the scope of 1910.147(a)(1)(i). An example would be locking open a valve that a process hazards analysis team has recommended should be locked open to reduce the possibility of trapped liquid causing overpressure in some part of the system. A lock might also be applied to keep a valve closed that feeds a portion of the system that has been pumped down and is temporarily out of service. (Parts of the system permanently out of service should be isolated by removal of the ammonia and disconnection from the active system).
Typically, application of 1910.147 would be the isolation and electrical lockout/tagout of a compressor, a condenser fan and/or pump, an evaporator, electrically controlled valves, etc. When referring to manual operated hand valves, some argue this is a grey area since manual hand valves cannot be unexpectedly automatically opened, but could they release stored energy? Obviously, anhydrous ammonia, which is used as a refrigerant, is considered an extremely hazardous substance and safe work practices must be followed. However, manual hand valves require intentional operation to change their position, and bumping a valve is not usually likely to cause it to unexpectedly open. So, when do hand valves get locked out and/or tagged out? Some viewpoints include:
- Manual hand valves that are within a qualified operator’s or technician’s control would not unexpectedly open or release stored energy. The area of “control” could be within sight of the
operator or technician. It could be argued that someone else could manually operate the valve, but since the manual hand valve(s) is within sight of the controlling person, such an occurrence would be extremely unlikely. - Most manual hand valves in a refrigeration system are not required to have their position changed in the normal operation of the system. The control of refrigerant flow is most often by electrically or pneumatically operated control valves. Also, if a manual hand valve position must be changed, it is only done by a trained and authorized individual. In addition, quite often manual hand valves, as well as control valves, are located in restricted areas and/or areas requiring equipment to access each valve’s location.
- In an emergency, manual hand valves can be used to reduce a potentially dangerous release or greatly limit a release. For example, while trying to reduce the amount of ammonia released, some manual hand valves may be closed while others remain open to allow the pump-out of the portion of the system or equipment involved in the incident. This timely action can have the potential to greatly reduce the amount of refrigerant released. Locking out these manually operated hand valves could actually make the situation more dangerous and/or could cause a delay in responding to control and stop a leak.
- Anecdotal information suggests there are instances where the lockout/tagout of manual hand valves is not commonly done. Following are a few examples:
- During a pump-out, some portion of the system will have the liquid and/or hot gas sources shut off using manual hand valves while the pressure (and any refrigerant) are reduced to a zero pressure (potential energy) state. At that point, the suction manual hand valve is closed isolating the portion of the system being pumped out. Once it is verified that there is no remaining refrigerant in the isolated section, the intended work can continue. If appropriate, the rest of the system can be placed back into operation as intended. If a valve unexpectedly leaks while the work was being done on the isolated portion and the valve was locked out, a person would not be able to immediately respond to stop the leak. This can happen if the active (charged) portion of the system builds pressure after the isolating manual hand valve has been closed, perhaps from heat gain. The valve itself may gain heat and expand slightly causing what was once a tightly closed valve to weep.
- Replacing pressure gauges is a common task, and this procedure is commonly done without a LOTO procedure being followed. The manual hand valve for isolating the pressure gauge is within total and exclusive control of the technician during the entire process.
- During maintenance work on a control valve, the technician typically uses the manual hand valves to isolate the control valve. The technician has complete control of the manual hand valves associated with the control valve and remains at the assembly until the control valve is placed back into a safe operational state.
- Oil draining manual hand valves are most often not locked out, however, they should have a plug or cap at the outlet of the valve or the valve’s extended draining pipe line when not in use. Typically, oil draining manual hand valves and their piping discharge arrangements are located in restricted areas. The plug or cap is removed from the manual hand valve or from the end of the draining pipe line as part of the draining procedure. The oil draining manual hand valve is not locked out at any time during the procedure, even though the improper opening of this manual hand valve can (and has) lead to a significant release. Following LOTO procedures in an oil draining process typically would not make sense.
Another challenge is that interpretations of the LOTO Standard in other industries are not completely applicable to our refrigeration industry, resulting in questionable citations. When it comes to manually operated hand valves, the language is unclear and our own industry has not published any clear guidance on this issue.
In an effort to better understand what is being done in the refrigeration industry, the IIAR Safety Committee developed a list of questions for a survey, which was done in December 2018. There were 127 responses to the survey. Briefly, the survey indicated the following:
- Most companies, small or large, do have a LOTO program and do feel a LOTO program should apply to their refrigeration system, including manual hand valves.
- Over 80% responded that they believe their LOTO program is being applied to every manual hand valve in their system, even for routine tasks. This raises the question of whether the results are accurate, or if possibly those responding to the survey are not the refrigeration technicians who work on, or operate a system. Field observations have shown that use of LOTO may not be used in small or large companies as much as the people filling out the survey think.
Additional information about the survey results will be presented at the Workshop “Lessons Learned in Ammonia Refrigeration: Making Our Industry Safer”, at the IIAR Annual Conference in Phoenix, AZ on March 5th, at 1:10 pm to 2:55 pm.
The refrigeration industry should have a guideline for the application of LOTO. There should also be consistency in its use. There should not be a gap between what we think is being done and what is actually occurring. If an industry-developed guideline is created, regulators would naturally refer to it rather than citing interpretations of the LOTO standard that might not be entirely applicable in the refrigeration industry. The survey is just one step in a process to develop a guideline specifically for the industrial refrigeration industry. It is hoped that with input from the Safety Committee, other members of IIAR, IIAR Staff, and other stakeholders, a guideline can be developed that can be widely accepted by our industry and eliminate or greatly reduce the gray area that presently exists in application of the LOTO Standard.
