Abrasive consumption was reduced by 80% by using UHP and the production increased by 20%

Background

Our client approached us looking for a solution to a project that they were tendering on, involving the removal of epoxy coating from steel fuel storage tanks.

They were wanting to offer a solution to the facility owner that could be shown to be safer than conventional abrasive blasting while at the same time provided greater productivity.

The coating on the tanks was an epoxy coating with an average thickness ranging from 275 microns up to 300 microns, and was generally in poor to average condition.

The contractor had previously stripped the tanks on this site using a manual dry abrasive blasting process in which the blasting operator worked from a boom lift.

Production rates for removal of the old coating using this method were typically in the 15-25 m² per hour range.

Suggested proposal

VertiDrive Multi Purpose Robots

For this application we recommended the Vertidrive M4 convertible system which enables UHP Waterjet work and then can be reconfigured for open Abrasive Blasting. This process enables the coating to be removed rapidly with UHP water followed by abrasive blasting to create the required profile.

Simulated Trial

For the purpose of the trial, a section of ‘tank wall’ was prepared several weeks in advance This was abrasive blasted to a SA 3 White Metal finish with a surface profile of 70 microns This was then coated with an epoxy tank coating to a dry film thickness of 300 to 320 microns

Two methods of cleaning were trialed with the Vertidrive M4:

1. Captive UHP Waterjet operating at 2800 bar 26 LPM, and
2. Dry Abrasive Blasting using two #8 (1/2″ orifice) blast nozzles at 690 KPA air pressure, and using GMA Speedblast Garnet as the abrasive medium.

Results – VertiDrive M4 – UHP configuration

The VertiDrive M4 UHP configuration was trialled initially. Vacuum extraction was provided by a Vermeer trailer mounted vacuum system.

The paint removal rate when using UHP was calculated to be 49 m² per hour on a straight run stripping a 400 mm wide path.

Maneuvering time for subsequent runs reduced the overall production rate to an average of 41 m² per hour.

The resultant finish was to an SSPC SP WJ 1 Waterjet standard flash rust was not noticeable in the 2 hours following the trial.

Results – VertiDrive M4 – Abrasive Blast configuration

The VertiDrive M4 abrasive blasting configuration was trialled the following day. The area that had been stripped using UHP had been hosed down and left overnight until a medium flash rust had formed on the bare steel.

The paint removal rate when using the Vertidrive M4 abrasive blasting configuration was calculated to be 69 m² per hour on a straight run stripping a 1 5 M wide path Cleaning rate when blasting the flash rusted steel increased to 75 m² per hour.

The resultant finish was to a SA 3 White Metal standard.

Wrap up

Abrasive consumption was reduced by 80% by using UHP and the production increased by 20%.