abrasive blast – Advisory Council

Microscopic Analysis of Steel after Waterjet Cleaning

In the late 1990’s, I received a report from Materials Evaluation Laboratory. The report is copyrighted. The pump company had cleaned UHP WJ on panels supplied by a major oil company. Materials Evaluation Laboratory analyzed the substrate with microscopy and metallurgy compared to abrasive blasting. This was at the time that UHP WJ was scarce and people were wondering what was happening at the surface. Would the surface be stressed?

Their conclusions:

1. Pressurized water effectively removed rust and other corrosion products from metal surfaces. This was done
with minimal disturbance of microstructural features.
2. Methods using abrasive particles were necessary for the removal of adherent mill scale. Those techniques cause
severe distortion of the metal surface.
3. The pressurized water method was considered the best preparatory cleaning for non-destructive inspection.
It offered a more “authentic” representation of the surface than the other methods evaluated.

This material is copyrighted. Please acknowledge the source. The Advisory Council can use it for educational purposes. It is not considered an endorsement nor recommendation.

Materials Evaluation Lab effect on surface 1991

Materials Evaluation Lab effect on surface 1991 Page 1 sanatized

Comparison of Wet Abrasive Blast (WAB) and Dry Abrasive Blast Cleaning

There are many methods of wet abrasive blast cleaning (WAB) in surface preparation to remove coatings.

Since the 1980’s, Carolina Equipment and Supply Co. (CESCO) has been supplying WAB equipment along with recycling methods.

Recently CESCO sent me two youtubes to directly compare traditional dry abrasive blast cleaning and Wet Abrasive Blast Cleaning using their AquaMiser (TM) equipment. I would like to share the youtubes with you.

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Dry Blast (Traditional Abrasive Blast Cleaning) Surface Preparation

Parameters: 375 cfm compressor at 100 psi using a # 8 venturi nozzle

The panel was 54” x 28” (137 cm x 71 cm) (10.5 sq. feet) and was coated with an epoxy primer and poly urethane topcoat.

Abrasive: Dupont Starblast 101 using 18 lbs per minute at a cost of $.22 cents per lb (total abrasive cost $23.76)

Time: 6 minutes

Dry Abrasive Blast Cleaning

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Aqua Miser Wet Abrasive Blast Cleaning (Surface Preparation)

Parameters: 35,000 psi 3 gpm using the F40 Abrasive Fan Gun with a 15 degree tip

The panel was 54” x 28” (137 cm x 71 cm) (10.5 sq. feet) and was coated with an epoxy primer and poly urethane topcoat.

Abrasive: Dupont Starblast 101 using 2lbs per minute at a cost of $.22 cents per lb (total abrasive cost was $1.32)

Time: 2 minutes 43 seconds

Wet Abrasive Blast Cleaning (CESCO)

Lead Based Paint on Bridges- Cost Effective Alternatives- FHWA

I get questions about relative cost for various surface preparation methods and the pros and cons. I refer people to this study as they can plug in their own numbers.

“COST EFFECTIVE ALTERNATIVE METHODS FOR STEEL BRIDGE PAINT SYSTEM MAINTENANCE” CONTRACT NO. DTFH61-97-C-00026

was published by the FHWA with Corrpro in September 2001. The final product was a series of reports- found on the Advisory Council downloads page and an excel sheet so that contractors, specifiers, and owners could plug in their own numbers.

A cost model for bridge painting maintenance was developed to aid specifiers in
evaluating the costs associated with currently available painting technologies. A myriad
of design approaches, surface preparations, and coating systems are currently available to
engineers tasked with maintaining painted bridges. This cost model allows quick and
easy comparisons between many of the current options for steel bridge painting. The
information used for the model is based on actual field observations1 and current industry
practices. This “User’s Guide” describes the model’s primary components and features
and the basic operation of the cost model.

The following are two powerpoint presentations given on this project by Corrpro. The reports are found on Advisory Council Downloads page which is in the upper left as I appear to have two different pages entitled “downloads”.

corrpro_TNRCC FHWA LBP July-2002

97C26 overview presentation Corrpro FHWA LBP Bridges Costs