Ammonia storage tank decommissioning and inspection

Periodically, refrigerated anhydrous liquid ammonia storage tanks must be inspected internally for integrity checks.

This is a complex task which requires an appropriate level of competence and experience of ammonia storage tank design and operations.

Some operators have only one single ammonia tank without spare capacity. This creates an additional pressure in terms of project managing the shutdown, decommissioning and inspection of the tank as well as reducing the total downtime since the production impact is highly costly.

With a background in plant operation, we understand these challenges very well and we develop a comprehensive decommissioning and inspection plan together with our partner Global Remote.

Global Remote is a company that provides advanced plant inspection capabilities by using rope access techniques. This method provides a cost-effective alternative to traditional access methods, such as scaffolding or mobile elevated working platforms. Using work-positioning techniques, industrial rope access is a proven method of achieving a safe work position at height or in areas of difficult access.

By combining our ammonia tanks operation experience with rope access techniques during tank inspection we minimise the downtime and reduce the out of production time for anhydrous liquid ammonia storage tanks.

Our work methodology includes:

  • Detailed job risk assessment
  • Decommissioning and inspection HAZOP study
  • Planning activities based on existing site condition
  • List of equipment and materials required
  • Detailed decommissioning and commissioning procedure that includes following stages:
    • Emptying the tank
    • Tank heating up process with hot nitrogen vapours
    • Key process parameters
    • Tank valve isolation for heating purpose
    • Inerting of system and purging with nitrogen
    • General inerting procedure
    • Key process parameters
    • Gas sampling
    • Tank blinding location and specifications
    • Over-rides
    • Manway opening sequence
    • Danger of asphyxiant gas
    • Purging the tank with air
    • Readiness for confined entry

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