CUI Major Incident# 11: Yara Ammonia Plant Explosion
Sep 14, 2020
Date and Place of Incident:
On 27 June, 2009, an explosion occurred at Yara-owned fertilizer plant in Tertre, Belgium
Summary of the Incident:
The gas fire was occurred in the high-pressure synthesis loop because of the ruptured bypass pipe. The process unit was the ammonia synthesis high-pressure loop at 230bar. The ruptured bypass pipe on the gas feed piping to the start up heater caught fire involving the two adjacent boiler feed water (BFW) preheaters E501A/B.
Root Cause:
- The rupture was occurred by the severe wall thinning of the pipe because of the corrosion under
- The ruptured pipe was insulated but not in working. The main pipe was continuously kept in warm conditions. The small bypass over the manual valve was cold (approx. 80⁰C).
- This temperature variance combined with the damaged insulation and water ingress possibilities was lead to CUI and cause rupture.
Environmental Impact of the Incident:
No environmental reported in the incident.
Fatality and injury:
2 minor injuries and no fatalities were reported in the incident.
Financial loss to Freedom Industry:
The plant shut down for 12 months which affect the production with the annual capacity of 420,000 tonnes of ammonia and 920,000 tonnes of nitrate,
Non-Compliance of Safety Guidelines and Reliability Practices:
- The insulation of pipe was made by the poor quality material with water ingress
- This pipeline was inspected partially in 2004; however, this affected section close to the supporting systems was not inspected.
- The combination of quality and integrity of insulation and coating was the main cause of incident.
Recommendations to Avoid Corrosion:
- Use of vapor retarders is a good defense method to avoid such incidents.
- Painting and coatings prevent water contact with critical equipment. These materials provide good metal surface preparation and prevent the corrosion under insulation.
- Proper Insulation shall be applied to prevent water ingress. Type of insulation has major role in these conditions
