Our client approached us looking for a solution to a project involving the removal of epoxy coating from steel fuel storage tanks.

Foremost, they wanted to offer a solution to the facility owner, showing a safer blasting method without compromising productivity.

The epoxy coating had an average thickness ranging from 10.8-11.8 mils (275-300 microns). Additionally, it was in poor to fair condition.

Previously, the contractor had stripped the tanks on this site using a manual dry abrasive blasting process in which the blasting operator worked from a boom lift. Using the dry blasting, production rates for removal of the old coating were typically in the 162-269 ft² (15-25 m²) per hour range.

VertiDrive Multi Purpose Robots

For this application, we recommended the VertiDrive convertible system. The VertiDrive enables UHP waterjet blasting and can be reconfigured for open abrasive blasting.

The coating is removed rapidly with UHP water jetting.  Subsequently followed by abrasive blasting to create the required profile.

In advance, we prepared a section of the tank wall. Secondly, we blasted the wall to a SA 3 white metal finish with a surface profile of  2.76 mils (70 microns). Thirdly, we applied an epoxy tank coating to a dry film thickness of 11.8–12.6 mils (300-320 microns).

Our trial:

VertiDrive – UHP Configuration

Initially, we tested the VertiDrive UHP configuration. We used a Vermeer trailer-mounted vacuum system for vacuum extraction.

During UHP usage, we calculated the paint removal rate to be 527.4 ft²/hr (49 m²/hr) on a straight run stripping a 400 mm wide path.

However, maneuvering time for subsequent runs reduced the overall production rate to an average of 441 ft²/hr (41 m²/hr).

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

In conclusion, we reduced abrasive consumption by 80% by switching to UHP blasting. Additionally, production increased by 20%.