Anhydrous Ammonia and PSM
(Presented at OSHA Update
September 19, 2014)
Simple Refrigeration System
Note: graph not created by
Susan Monroe (original source
not available)
Some Anhydrous Ammonia
Properties
Pure Ammonia, without almost no water
Gas at room temperature
Boils at -28 degree F
Efficient refrigerant
IDLH 300 ppm
PEL 50ppm 8 hr TWA
Low odor threshold 20 ppm or less
Important Industry Guidelines
IIAR Process Safety Management Guidelines
for Ammonia Refrigeration
ANSI/ASHRAE 15 (2001) Safety Standard for
Refrigeration Systems
Oil Draining Guidelines. International Institute
for Ammonia Refrigeration (IIAR), (1996).
Describes procedures for safely draining oil
from equipment.
Important Industry Guidelines
Bulletin No. 110. Guidelines for Start-Up,
Inspection, and Maintenance of Ammonia
Mechanical Refrigerating Systems. International
Institute for Ammonia Refrigeration (IIAR),
(1993, March).
Storage Vessel Design. Provides additional
information by ASME, ANSI, IIAR, and ASHRAE
about the design and installation of pressure
vessels and associated equipment
OSHA PSM Requirements
Employee Participation
Process Safety Information
Process Hazard Analysis
Standard Operating Procedures
Training
Contractors
OSHA PSM Requirements
Pre-start up review
Mechanical Integrity
Hot Work Permits
Management of Change
Preventive Maintenance
Emergency Response
Audits
Common Myths vs Reality
Outside leaks are not a problem because they will blow upwards away from employees evacuating (actually sometimes the cloud descends directly onto evacuating employees)
Ammonia warning properties are good; you will not stay around to be overexposed, so no need to worry about permanent lung injuries or fatalities (evacuation problems are common, and people get trapped even outside the plant after evacuating, plus, even in upper lungs, it is caustic)
Six Anhydrous Ammonia
Fatalities in One Year
May 14, 2009: American Cold Storage,
Louisville, KY 2 fatalities
June 20, 2009: Mountaire Farms, Lumber
Bridge, NC 1 fatality
July 15, 2009: Tanner Industries,
Swansea, SC ? fatality
November 16, 2009: CF Industries,
Rosemount, MN 2 fatalities
Example Problems in
Refrigeration w/ Anhydrous
Ammonia Standard wiring or ventilation in the
engine room (not designed for flammable environment)
NH3 leaks out of its pressurized system
Catastrophic leaks due to not locking out during maintenance, not opening stop valves after maintenance, or striking a component (one example---forklift w/ raised prongs crashes into overhead evaporator)
Explosions
Safety Culture Problems in Facilities Using Anhydrous Ammonia (Subjective Observations, Not OSHA Policy Statement)
Some mechanics and maintenance personnel not completely accepting new Process Safety Management regulations
PSM Engineers sometimes younger, less authority, sometimes more formal education, reporting to Safety Manager, not fully integrated with operators and mechanics, who report to Maintenance Manager
PSM Engineers challenged with older systems which have enlarged over time and paperwork is missing/outdated/hard to obtain sometimes due to culture gap
Other Safety Factors/Problems
in Ammonia Refrigeration plant Shift work is hard on the human body, usually
12 hours, often rotating shifts, leads to poor sleep, inattentiveness
Mechanics on-call at night, awoken from sleeping, have to drive to plant and take care of a hazardous situation when they just woke up
Refrigerated plants are cold, can add to stress of being awoken in the night, going from warm bed to freezing areas
None of this is regulated; unlikely to change
Typical citations:
No or inadequate emergency evacuation plan
Examples:
Pig slaughter operation added on many rooms over time, could not hear alarms in some added rooms
No one knows the alarm signal
Employees do not know that they are supposed to evacuate (non-English speaking)
Typical Citations:
Employees not trained to pull alarms/ not empowered to look for hazards
No ammonia monitors where it is likely to leak
No practice drills or contact with local emergency entities or private spill response teamsoften no outside entity knows
Not replacing valves per industry standards (ex: pop-ups every five years)
Operators not trained on PSM
Typical Citations:
Operators not trained to wear SCBA when approaching, for example, the king valve to turn it off during an emergency
SCBAs located in the engine room (where the leak is likely to occur)
No wind socks to determine which direction to evacuate
Management or employees not aware of wind sock purpose or how to use that information
Typical Citations
Engine rooms not having proper electrical classification wiring (very common)
Engine rooms not having proper emergency ventilation systems (or vent calculations missing)
For older systems, original P and IDs are missing or still being used with no updates even though inventory has increased tens of thousands of pounds
Typical Citations
Relief calculations not available
Relief not re-calculated after system increases or changes
Management of change overlooked:
Valves not replacement in kind
Gasket material changes during replacement
Lack of documentation of MOC
Everything being MOC, even replacement in kind (usually MOC in this case is all approved by one person)
Checklist Items
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Checklist Items
Goodyear Tire Company
Houston 2008
Con Agra 2009
Con Agra 2009