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Morris missile: Anhydrous ammonia nurse tank explosion



The photos below are from a 1,000-gallon anhydrous ammonia nurse tank explosion June 6, 2005, at the Cenex Co-op yard in Morris, Minn. The explosion released approximately 841 gallons of anhydrous ammonia to the atmosphere.

Prior to the incident, an employee filled the subject nurse tank to 85 percent capacity with anhydrous ammonia at approximately 3:30 p.m. After the tank was filled, it remained at the filling-station dock and the employee vacated the yard.

The explosion was reported to emergency response teams at approximately 6 p.m. They discovered a ruptured 1,000-gallon anhydrous ammonia nurse tank that was in two pieces. A portion of the rear head was lying near the filling dock and the remainder of the tank was approximately 100 yards away. Upon explosion, the vessel ricocheted off the earth, skipped across the yard and slammed into a parked utility tractor and an automobile before coming to rest. Other pressurized anhydrous ammonia tanks were in the yard. The ruptured vessel missed these tanks by 25 yards.

No employees or customers were on site. No fatalities occurred. A local farmer who lives three-tenths of a mile to the west was taken to the hospital for ammonia inhalation treatment.

Forward end of vessel showing impact damage.

Tank details:

National Board #

NB 175175

Manufacturer

Chemtrol Chemical Co.

Year manuf.

1973

Capacity

990 gallons

MAWP

250 psi

Width

40.5"

Length

192"

Min. head thickness

.2306"

Min. shell thickness

.321"

Click on the image for a larger view

Forward end of vessel showing impact damage. Severed tractor and damaged automobile. The ruptured vessel missed these tanks by 25 yards.

Forward end of vessel showing impact damage

Severed tractor and damaged automobile

The ruptured vessel missed these tanks by 25 yards

     
Portion of vessel rear head. Arrow points to small crack in vessel head. Lifting lug on fragmented vessel head.

Portion of vessel rear head

Weld deposit and arrow pointing to small crack in vessel head

Lifting lug on fragmented vessel head

     
Vessel level indicator float assembly. Vessel filling and gage components. Vessel bleeder valve and level indicator gage.

Vessel level indicator float assembly

Vessel filling and gauge components

Vessel bleeder valve and indicator gauge

     
Point of vessel where fracture meets circumferential weld. Vessel safety valve. Vessel internals looking in from opened end.

Point of vessel where fracture meets circumferential weld

Vessel safety valve

Vessel internals looking in from opened end

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