EVEN COOLER THAN WATCHINGPAINT DRY!

2010 RISK TAKEN

2011 PROVEN SUCCESS

By John Brodar P.E., SALT RIVER PROJECT

In 2010 painting the interior walls of the Reactivators presented

some problems.

1. Abrasive blast cleaning of the open top tank would generate a lot of dust.

2. Painting of this tank was not a scheduled outage task. It was late February when we

decided to paint the tank. Even in March in Page, AZ it might rain, snow or freeze.

It was time for some innovative

painting.

Exciting!

Wet abrasive blast cleaning was used for surface preparation.

The water would control the dust and eliminate the need and expense of tenting the 135’

diameter tank.

The entire tank wall was blast cleaned to near white metal with Chlor-Rid in the dust

suppression water.

What blast cleaning standard is this surface?

It was abrasive blasted to near white, but with the water ring it was expected to rust. It was not just a water blast cleaned surface either. Industry standards have not yet caught up to real life applications.

“A Brush-Off Blast Cleaned surface, when viewed without magnification, shall be free of all visible oil, grease, dirt, loose mill scale, loose rust, and loose paint. Tightly adherent mill scale, rust and paint may remain on the surface. Mill scale, rust and paint are considered tightly adherent if they cannot be removed by lifting with a dull putty knife.”

The specification required:

1. A near white level of

initial cleaning,

2. The use of a water ring

for dust control,

3. the use of Chlor-Rid to

decontaminate the steel.

4. The finished surface was

to meet the requirements

for Brush Off Blast

Cleaning, SSPC-SP 7

THIS IS A CLOSE UP PHOTO OF THE TIGHTLY ADHERING RUST LEFT AFTER A NEAR WHITE METAL ABRASIVE BLAST CLEANING. A WATER RING WAS ATTACHED TO THE BLAST NOZZLE FOR DUST

CONTROL. CHLOR-RID WAS ADDED TO THE DUST SUPPRESSION WATER. NOTE THE EVEN LIGHT BROWN RUST; IT IS INDICATIVE OF A STEEL SURFACE FREE OF NON-VISIBLE CONTAMINANTS. THE DARKER AREA WAS FROM DISTILLED WATER USED TO TEST FOR CHLORIDES AND SULFATES. THE

BLACK AND WHITE SPOTS ARE REMAINING COAL TAR AND OTHER EPOXY COATINGS.

CONTRAST THE EVEN LIGHT BROWN COLOR OF THE PREVIOUS PHOTO WITH THIS ONE. THE DARK BROWN SITES ARE HEAVILY CONTAMINATED WITH CHLORIDES AND SULFATES.

THE BRIGHT YELLOW POTASIUM FERRICYANIDE TEST PAPER TURNS BLUE WHEN IN CONTACT WITH DISTILLED WATER APPLIED TO A STEEL SURFACE CONTAMINATED WITH CHLORIDES AND SULFATES.

PAINTING OVER THE CHLORIDES AND SULFATES WILL RESULT IN COATING FAILURE IN 6-36 MONTHS.

THE PAINT SELECTED IS A LOW TEMPERATURE VERSION OF THE CARBOLINE CARBOGAURD 235 SURFACE TOLLERANT EPOXY WE HAVE BEEN USING IN THE

CIRCULATING WATER LINES FOR THE LAST TWO OUTAGES.

THE PAINT CONTRACTOR, KEENE COATING, DID AN OUTSTANDING JOB.

THIS IS THE INTERIOR PAINTED SURFACE OF REACTIVATOR 2. IT WAS PAINTED IN 2010 OVER “TIGHTLY ADHERING RUST”. BUT THE STEEL WAS DECONTAMINATED OF

CHLORIDES AND SULFATES WITH CHLOR-RID. THIS AND SUBSEQUENT PHOTOS ARE FROM 2011, AFTER 1 YEAR OF IMMERSION SERVICE.

THE LOWEST FOOT OF THE WALL REVEIVED AN EXTRA COAT OF PAINT IN 2010. EVEN THE STEEL TO CONCRETE INTERFACE WAS

ENTIRELY FREE OF RUST.

THIS 8” NOZZLE HAD BEEN IN SERVCE AND WAS RUSTED PRIOR TO THE 2010 PAINTING.

AFTER DECONTAMINATION AND PAINTING, EVEN THE THREADS ARE FREE OF RUST ONE YEAR LATTER.

OF THE 10,200 SQUARE FEET OF TANK WALL THAT WAS PAINTED IN 2010, THIS IS THE ONLY VISIBLE RUST IN 2011 AFTER 1 YEAR OF IMMERSION

SERVICE.

REACTIVATIOR 1 IS SCHEDULED TO BE PAINTED USING THE SAME SYSTEM IN MARCH 2011. THE CATHODIC PROTECTION SYSTEMS FOR THESE TWO TANKS WAS

COMPLETELY REBUILT. WITH NEW WIRE ANODES AND RECTIFIERS, THIS COATING AND THE CATHODIC

PROTECTION SYSTEM SHOULD PROVIDE A MAINTENANCE FREE SERVICE LIFE FOR THE

TANK SHELL AND CENTRAL SUPPORT FOR THE NEXT 20 YEARS.