Process Hazard Analysis – “What-if” Checklist / Facility: / Page 2 of 8
Date Last Conducted: / Conducted by:
“What-if” / Consequences / Immediate Action / Engineering & Administrative Safeguards / Recommended Change /
Storage Tank Failures
Storage tank rupture due to defect / Complete loss of ammonia at a high rate / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / Seasonal inspections of storage tank. Repair defects immediately using “R” stamp weld shop.
Storage tank rupture due to overfilling / Complete loss of ammonia at a high rate / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / Seasonally inspect % full and temperature gauge to ensure proper functioning. Operational procedure not to unload transport unless storage tank can hold entire contents. Monitor % full and temperature gauge when filling. Adjust filling level for ambient temperature but never fill tank over 85%.
Storage tank rupture due to vehicle collision / Complete loss of ammonia at a high rate / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / Concrete filled pipe, a minimum of 4” in diameter, buried at least 3’ deep, spaced 4’ apart surround the tank.
Storage tank rupture due to force of nature (e.g. earthquake, tornado, etc.) / Complete loss of ammonia at a high rate / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / None
Storage tank rupture due to train derailment / Complete loss of ammonia at a high rate / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC.
Storage tank failure due to corrosion / Continuous release of ammonia at a low rate until tank is empty / If safe to do so, pump off ammonia liquid, else secure and evacuate immediate area and notify local emergency authorities. Notify NRC. / Seasonal inspections of storage tank. Sand blast and paint as needed.
Storage tank leaks due to defect / Continuous release of ammonia at a low rate until tank is empty / If safe to do so, pump off ammonia liquid, else secure and evacuate immediate area and notify local emergency authorities. Notify NRC. / Seasonal inspections of storage tank. Repair defects immediately using “R” stamp weld shop.
Storage tank leaks due to vehicle collision / Continuous release of ammonia at a moderate rate until tank is empty / Secure and evacuate immediate area and notify local emergency authorities. Notify NRC. / Concrete filled pipe, a minimum of 4” in diameter, buried at least 3’ deep, spaced 4’ apart surround the tank.
Storage tank overfill resulting in PRV release / Continuous release of ammonia vapor at a moderate rate for a short duration / If safe to do so, pump off ammonia liquid into transport or nurse tank, else secure and evacuate immediate area if necessary and notify local emergency authorities. Notify NRC if loss over 100 lbs. / Seasonally inspect % full and temperature gauge to ensure proper functioning. Operational procedure not to unload transport unless storage tank can hold entire contents. Monitor % full and temperature gauge when filling. Adjust filling level for ambient temperature but never fill tank over 85%.
Storage tank PRV malfunctions opening under normal operations / Continuous release of ammonia vapor at a low rate for a potentially long duration / If safe to do so, close manifold and replace PRV. If you cannot stop release safely, secure and evacuate immediate area if necessary and call for emergency assistance. Notify NRC if loss over 100 lbs. / Replace PRV every 5 years per code CGA G-2.1-2014.
Storage tank PRV vents due to large increase in ambient temperature / Release of ammonia at a low rate for a short duration / If safe to do so, pump off ammonia liquid into nurse tank, else allow to vent. / Adjust filling level for ambient temperature. Offload ammonia into empty nurse tanks until volume/pressure below relief setting.
Nurse Tank Failures
Nurse tank rupture due to defect / Complete loss of ammonia at a high rate for a short duration / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / Seasonal inspections of nurse tank. Nurse tanks with defects are permanently taken out of service or repaired immediately using “R” stamp weld shop. All tanks with missing or illegible data plates are integrity tested every 5 years per DOT rules.
Nurse tank rupture due to overfilling / Complete loss of ammonia at a high rate for a short duration / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / Seasonally inspect % full and temperature gauge to ensure proper functioning. Monitor % full and temperature gauge when filling. Adjust filling level for ambient temperature but never fill tank over 85%. Open the 85% bleeder to verify the liquid level gauge.
Nurse tank rupture due to vehicle collision / Complete loss of ammonia at a high rate for a short duration / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / Park out of vehicle traffic when not in used.
Nurse tank failure due to corrosion / Continuous release of ammonia at a low rate until tank is empty / If safe to do so, tow nurse tank to a remote location down wind of populated areas and allow to vent, else secure and evacuate immediate area if necessary and notify local emergency authorities. Notify NRC. / Seasonal inspections of nurse tank. Sand blast and paint as needed.
Nurse tank leaks due to defect / Continuous release of ammonia at a low rate until tank is empty / If safe to do so, tow nurse tank to a remote location down wind of populated areas and allow to vent, else secure and evacuate immediate area if necessary and notify local emergency authorities. Notify NRC. / Seasonal inspections of nurse tank. Repair defects immediately using “R” stamp weld shop.
Nurse tank leaks due to vehicle collision / Continuous release of ammonia at a moderate rate until tank is empty / Secure and evacuate immediate area and notify local emergency authorities. Notify NRC. / Park out of vehicle traffic when not in used.
Nurse tank overfill resulting in PRV release / Continuous release of ammonia vapor at a low rate for a short duration / Tow nurse tank to a remote location down wind of populated areas and allow to vent. / Seasonally inspect % full and temperature gauge to ensure proper functioning. Monitor % full and temperature gauge when filling. Adjust filling level for ambient temperature but never fill tank over 85%. Open the 85% bleeder to verify the liquid level gauge.
Nurse tank PRV malfunctions opening under normal operations / Continuous release of ammonia vapor at a low rate for a potentially long duration / If safe to do so, tow nurse tank to a remote location down wind of populated areas and allow to vent, else secure and evacuate immediate area if necessary and notify local emergency authorities. Notify NRC. / Replace PRV every 5 years per code CGA G-2.1-2014.
Nurse tank PRV vents due to large increase in ambient temperature / Release of ammonia at a low rate for a short duration / Tow nurse tank to a remote location down wind of populated areas and allow to vent. / Monitor % full and temperature gauge when filling. Adjust filling level for ambient temperature but never fill tank over 85%. Open the 85% bleeder to verify the liquid level gauge.
85% bleeder tube breaks off inside nurse tank / Potential overfill and rupture of nurse tank resulting in a complete loss of ammonia at a high rate for a short duration / Call 911 and notify local emergency authorities. Secure and evacuate immediate area and provide information to incident commander. Notify NRC. / Listen for the sound of loose metal inside nurse tank when moving. Take nurse tank out of service if it determined bleeder tube is broken.
85% bleeder tube breaks off inside nurse tank / Potential overfill of nurse tank resulting in a PRV release of ammonia at a low rate for a long duration / If safe to do so, tow nurse tank to a remote location downwind of populated areas and allow to vent, else secure and evacuate immediate area if necessary and notify local emergency authorities. Notify NRC. / Listen for the sound of loose metal inside nurse tank when moving. Take nurse tank out of service if it determined bleeder tube is broken.
Thieves or vandals cut discharge hoses on nurse tanks / Release of ammonia vapor at a low rate for a short duration / Remove hoses from nurse tanks when not in use. / Remove hoses from nurse tanks when not in use. Hoses are kept with toolbars/applicators.
Nurse tank rollover occurs breaking tank connection / Continuous release of ammonia at a moderate rate until tank is empty / Secure and evacuate immediate area and notify local emergency authorities. Notify NRC. / Roll cages are in place on all nurse tanks.
Piping Failures
Vehicle collision damages ammonia piping, release rate below excess flow valve set point / Release of ammonia at a moderate rate for a short duration / Close remote emergency shut-off valve or if safe to do so, close a valve upstream from damage. After lines have bled down, repair piping. Notify NRC if loss over 100 lbs. / Concrete filled pipe, a minimum of 4” in diameter, buried at least 3’ deep, spaced 4’ apart surround piping.
Vehicle collision damages ammonia piping, release rate above excess flow valve set point / Release of ammonia at a high rate for a short duration / Immediately close remote emergency shut-off valve or when safe to do so, close a valve upstream of damage. After lines have bled down, repair piping. Notify NRC if loss over 100 lbs. / Concrete filled pipe, a minimum of 4” in diameter, buried at least 3’ deep, spaced 4’ apart surround piping.
Buried piping failure due to corrosion / Continuous release of ammonia at a low rate for a potentially long duration / Isolate by closing valves on both ends of buried piping. After line has bled down, replace buried piping. Notify NRC if loss over 100 lbs. / Implement hydrostatic test program of buried piping once every 5 years, or implement a cathodic protection program, or relocate piping aboveground.
Aboveground piping failure due to corrosion or erosion / Continuous release of ammonia at a low rate for a potentially long duration / Isolate by closing a valve upstream of piping. After line has bled down, replace piping. Notify NRC if loss over 100 lbs. / Seasonal inspections. Sand blast and paint corroded piping as needed. Repair or pad worn piping as needed.
Thermal expansion causes leak in isolated section of piping / Release of ammonia at a low rate for a moderate duration / Allow isolated section of piping to vent. After line has bled down, repair piping. / Install hydrostatic relief valves per CGA G-2.1-2014.
Hose Failures
Partial leak in transfer hose, release rate below excess flow valve set point / Release of ammonia at a moderate rate for a short duration / If safe to do so, close a valve upstream from leak. If you cannot stop release safely, call for emergency assistance. Notify NRC if loss over 100 lbs. / Drivers and operators inspect hoses prior to hook up per operational procedures.
Transport or nurse tank pulls away before disconnected causing complete rupture of transfer hose, release rate exceeds excess flow valve setting / Release of ammonia at a high rate for a short duration / Immediately close remote emergency shut-off valve or when safe to do so, close a valve upstream from hose. After lines have bled down, replace hose. Notify NRC if loss over 100 lbs. / Transport: Set brake and chock wheel. Back check valve on liquid line. Emergency shutoff valve on vapor line.
Nurse tank: Chock wheel and pull hitch pin. Breakaway couplings on risers.
Transport or nurse tank pulls away before hoses are disconnected causing complete hose rupture, release rate exceeds excess flow valve setting but excess flow valve fails to close / Release of ammonia at a high rate for a potentially long duration / If safe to do so, close remote emergency shut-off valve or flow valve between storage tank and hose. If you cannot stop release safely, call for emergency assistance. Notify NRC. After release stopped and lines bled down, replace hose. Transfer liquid ammonia out of storage tank and vent. Replace excess flow valve. / Transport: Set brake and chock wheel. Back check valve on liquid line. Emergency shutoff valve on vapor line.
Nurse tank: Chock wheel and pull hitch pin. Breakaway couplings on risers.
Valve Failures
Partial valve seat or packing gland failure / Continuous release of ammonia at a low rate for a potentially long duration / If safe to do so, close a valve upstream from leak. If you cannot stop release safely, call for emergency assistance. Notify NRC if loss over 100 lbs. / Seasonal inspection. Replace or repair as needed.
Complete valve seat or packing gland failure / Continuous release of ammonia at a moderate rate for a potentially long duration / If safe to do so, close a valve upstream from leak. If you cannot stop release safely, call for emergency assistance. Notify NRC if loss over 100 lbs. / Seasonal inspection. Replace or repair as needed.
PRV manifold on storage tank seat fails when changing PRV / Continuous release of ammonia vapor at a moderate rate for a potentially long duration / If safe to do so, replace PRV and tighten. If you cannot stop release safely, call for emergency assistance. Notify NRC if loss over 100 lbs. / Do not change PRV until storage tank is empty.