Case Study

Black Oil Tank Clean

10 June 2024

Scope of works

This job was part of the statutory inspection and maintenance schedule on site at one of our valued UK clients. To enable the internal inspection, Re-Gen Robotics was tasked with pumping down tank level to de-inventory residual product, sludge removal/recovery and internal clean of tank to hot work standard SA2.


Tank Details



Roof Type

Floating Roof

Internal Furniture

Heating Coils, Roof Legs

Estimated Quantity


Tank Contents

Heavy Cycle Gal Oil

Tank Clean Process

Upon technical and operational review of the SOW and in consultation with our client, the job method was set out in the following defined phases.

Site Mobilisation
  • Equipment set up in accordance with hazardous zoning regulations.
  • Auxiliary equipment placed in safe zone. Site Safety Inductions completed.
  • Permitting Authority – PTW.
  • Vehicle Inspection by client.
  • Equipment inspected by site operator.
  • Product level above manway access
  • Suction from drain line
  • Sludge pumped to Vac tanker
  • Waste processed into IBCs for disposal
Robotic De-Sludge
  • Pre-Entry Checks & Inspection.
  • Robot Entry via 24” Manway.
  • Robot powered from Hydraulic power pack (Zone2).
  • De-Sludge process begins.
  • Suction head removes sludge via 4” or 6” hose.
  • Sludge pumped into Vac tanker.
  • Waste processed into IBCs for disposal.
Robotic Wash
  • Access hard to reach areas such as tank walls and around internal furniture.
Hot Wash Final Clean
  • To remove final residues.
  • Tank now certified gas free.
  • Tank ready for inspection to EEMUA 159 standards.
Tank Sign Off
  • Tank sign off with Client Tank Team.
  • Tank handed back for inspection or return to service.
Site Demobilisation
  • Full clean of equipment used.
  • Packing and removal of on site equipment.
  • Bund area cleaned.
  • Depart site.

Phase 1 – Site Mobilisation

Co-ordinated planning with our Operations and on-site teams in collaboration with the client tank team minimises the duration of this phase.

Phase 2 – Pumpdown

Pump Down tank with residual contents removed to levels below the manways to allow robotic entry to begin de-sludge phase.

Operators using 4” suction hose and progressive cavity pump removing material from the tank before transfer to our IBC filling station and into IBCs.


Creation of temporary ‘bund’ to ensure containment of oil should any be present when the flanged joint is broken.

This was part of a controlled spill at the request of the client.


Residual contents processed from Vac tanker to IBC fill station and into IBCs for waste disposal.


Throughout pumpdown and de-sludge , Re-Gen Robotics demonstrated its ability to work a 2 shift system with two 10.5 hour shifts per day.

The client was impressed with how we maintained our productivity across both shifts in response to their desire to return the tank to service as soon as possible.

Phase 3 – Robotic De-sludge

We began with robot checks prior to tank entry.


Robot entering tank with operative controlling from our self-contained control room.


The robot uses a combination of heat and cutting agent to reduce the viscosity of the material before removal to our Vac tanker via 6” suction hose.

Tank Contents

The residual contents in the tank which are Heavy Cycle Gas oil which is heavily contaminated with catalyst fines.

As you can see from the images below, this material is extremely viscous, presenting a stubborn challenge to remove it. This job showcases our ability to deal with heavy and persistent oils.

Key Facts

Site Mobilisation

Duration: 1.5 Shifts.


Duration: 52 Shifts.

Waste Removed: 741m³

Robotic De-Sludge

Duration: 65 Shifts.

Waste Removed: 1235.5m³.

Peak weekly average was 32m³ per shift.

Peak shift output: 40m³.

Robotic Wash

Duration: 27 shifts.

Waste Removed: 135.5m³.

Hot Wash Final Clean

Duration: 19 shifts.

Waste Removed: 2m³.

Tank Sign Off

Duration: 0.50 shifts.

Site Demobilsation

Duration: 10 shifts.

Hear from our clients…

“We currently have six tanks out for cleaning and the tank you are working on is the only one which has not caused us problems”

“We are very impressed with both your kit and the workforce operating it”

“Any challenges you have faced have been overcome by the fantastic problem- solving ability of your site teams”