February 17, 2015
Taiyo Nippon Sanso Corporation
Notice Regarding a Report on the Investigation Results of the Accident
at the Oita Sanso Center(Final Report Regarding the Accident at the Oita Sanso Center)
With regard to the accident at the Oita Sanso Center on December 12, 2014, Taiyo
Nippon Sanso Corporation (TNSC) would like to apologize to neighboring residents
and others concerned for the inconvenience and anxiety this accident may havecaused.
TNSC subsequently held accident investigation committee and accident prevention
committee meetings to investigate the cause of the accident and formulate
countermeasures for preventing a recurrence. TNSC hereby announces that it has
finished submitting a report on the investigation results and countermeasures to therelevant administrative authorities.
The following is a summary of the report.
1. Overview of the accident
Accident location
Oita Sanso Center Co., Ltd.
Affected facility
No. 3 liquefied gas drainage tankTime of accident
The tank burst at 9:06 a.m. on Friday, December 12, 2014
(after release of liquefied gas began at 8:00 a.m.)
Human damage
None
Property damage
The entire drainage tank burst (along with damage to therelated piping)
Perlite (powdery insulator) spilled out from damaged
peripheral gas liquefaction equipment
Fragments of the drainage tank scattered within a sphere of
approximately 650 meters (with some fragments flying
outside the plant compound and causing property damage)
2. Overview of the burst drainage tank
The drainage tank was installed to prevent liquefied gas released from the air
separation unit and related equipment from coming into direct contact with otherparts of the plant facilities and the ground, etc.
Model

Ambient air heating, non - pressurized cylindrical stainlesstankDimensions

Diameter 4,000 mm x height 6,000 mm x thickness 3 mm
(at the sidewall)
Drainage inflow pipe 200 A
Duct (for releasing the gas)
Outer diameter 1,016 mm x thickness 6 mm
Manufacturing date February 1977
3. Estimated cause of accident
It appears a considerable amount of water left in the drainage tank froze andformed ice when it came in contact with the drainage inflow of low-temperatureliquefied gas. We estimate that this ice caused the tank to burst by trapping theliquefied gas inside and raising the internal pressure.
4. Countermeasures for preventing a recurrence
The Oita Sanso Center and TNSC will implement the following countermeasuresfor preventing a recurrence.
The Oita Sanso Center’s countermeasures(1) Facility, work, and operation management
・ Rules and efforts will be made to make certain water is removed from thedrainage tank.
・ A full inspection of the facility and work procedures will be conducted.
・ Management procedures will be established, in addition to clarifying theobjectives of work procedures and other instructions.
(2) Employee education
Lessons learned from this accident will be used to educate all employees,
promote safety activities on a daily basis, and thereby enhance their risksensitivity.
TNSC’s countermeasures(1) Full inspection of related business sites
・ Internal inspections of other liquefied gas drainage tanks were completed,and the work procedures for operating the tanks will be revised.
・ Checks on factory management functions will be made more rigorous.
(2) Lessons learned from the accident will be reflected in the design of liquefied
gas drainage tanks and other aspects(3) Lessons learned from the accident will be shared and built upon with theusers TNSC supplies and other industrial equipment manufacturers