Closed-Roof Storage Tank (Fire Water, Potable, DM)

Planys conducted underwater  inspection for a closed-roof potable water storage tank inside a Petro-chemical plant. Since construction, the tank was never inspected due to other priorities during shutdowns. The client wanted to inspect the tank in online conditions (without de-watering) to pro-actively plan for the upcoming shutdown & maintenance.

Scope of Work: Underwater visual inspection of a tank shell & roof (diameter 25m and height 18m) and wall thickness measurement of tank floor/base plate in live/online (without taking shutdown or de-watering) condition.

Planys Solution: The inspection was performed using Planys’ ROV Orca equipped with high resolution camera, ultrasonic thickness (UT) measurement probe mounted on a gimbal, altimeter and depth sensor.

  1. Deployed through the roof manhole, ROV Orca covered the shell in grid of 2m spacing.
  2. Gimbal mounted UT probe was placed on the belly of the ROV and collected very reliable/repeatable data for bottom plate thickness
  3. Defects identified were categorised by severity (moderate/minor) & along with UT measurements were geo-tagged on the tank drawing visible through the Planys Analytics Dashboard (PAD).
  4. Overall, the tank was in pristine condition and this helped the client take a decision to completely fore-go the planned upcoming shutdown thus saving time, cost and resources.

 Images show ROV deployment & setup and bottom camera feed while taking UT readings         

Images show minor corrosion captured on the roof, near the sump and on the shell of the tank;

Tank floor CAD drawing with UT measurements geo-tagged against position within the tank