Industrial, Marine Failure Analysis Coating Inspection

Industrial, Marine Failure Analysis

Coating Inspection (415)244-6429

www.westcoastcoatingconsultants.com

Project: Stockton 14 Mile Res North Tank Coating Assessment Date: 12/7/2020 Contractor: West Coast Coating Consultants Crew Size: 1 Structure: North Tank Interior Coating Assessment Job No. 1573 Inspector Greg Whiting Senior NACE Level III Inspector #9264 Hours: 8

DAILY SUMMARY: WCCC Senior NACE Level III Coatings Inspector Mr. Greg Whiting arrived on site at the City of Stockton 14 Mile Reservoir North Tank Site to perform an assessment of the existing interior coatings on the 5 MG Capacity North Tank. As part of the assessment, this Senior NACE Level III Inspector performed the following. A visual condition assessment was preformed along with a dry film thickness survey on areas that are accessible. The results of my assessment are as follows.

Interior Roof, Rafters, Knuckle & Dollar Plate:

1. Underside roof plates have moderate corrosion between roof plates & support rafters. 2. Sporadic pin point rusting on approximately 5% of underside roof plates. 3. Rafter lips have pin point rusting on approximately 25% of the areas accessible. 4. Knuckle & knuckle supports have moderate corrosion & pin point rusting on approximately 25% of

the areas accessible.

Interior Ladder Cage & Tank Shell: 1. Ladder cage structure has corrosion and pinpoint rusting on 20% of the structure. Pack rust is

forming on back sides of ladder rungs and ladder supports. 2. Tank shell appears to be in fair condition with approximately 10% having spot rusting and or pinpoint

corrosion.

Interior Floor, Support Columns & Overflow Pipe: 1. Interior floor is covered with silt & mineral deposits but when cleaned, various areas were found to

have sporadic blistering on approximately 25% of the interior floor. Blisters range in size from 1/16 to 2 inches in size.

2. Support column base plates have sporadic pinpoint rusting present at the seams with the support columns having sporadic spot corrosion at the bases & approximately 25 feet up columns

3. Overflow pipe has isolated spot corrosion at a few locations.

A dry film thickness survey was also performed on the interior and the following results were found: • Dry film thickness range on accessible underside roof & rafters 19.5 to 33.0 mils. • Dry film thickness range on accessible shell & floor 14.0 to 24.5 mils.

WCCC Senior NACE Level III Inspector Mr. Greg Whiting Recommendations:

Due to the extent of the sporadic blistering on the floor, corrosion & pin point rusting at various locations throughout the interior structural components. West Coast Coating Consultants recommends a complete removal of the interior coating system and replacement with a new coating system withing the next 1 to 3 years. The North Tank may be put back in service at this time.

Greg Whiting Senior NACE Level III Inspector #9264

http://www.westcoastcoatingconsultants.com/




14 Mile Res North Tank Site.

Positector 6000 Field Calibration.





Underside roof, rafters & knuckle dry film thickness range 19.5 to 33.0 mils.

Pack rust forming on knuckle support brackets.





Isolated pack rust & corrosion forming on rafter lips & flanges.

Tank shell in fair to good conditions.





Dry film thickness range on shell & floor 14.0 to 24.5 mils.

Tank shell in fair to good condition.





Heavy spot corrosion on support columns.

Heavy spot corrosion on floor plates.





Sporadic blistering on approximately 25% of floor plates.

Heavy spot corrosion on support columns.





Sporadic blistering on approximately 25% of the floor plates.

Sporadic blistering on approximately 25% of the floor plates.


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Industrial, Marine Failure Analysis Coating Inspection