Large Chambers-Case Studies

Large Chambers

Introduction
Video Demonstration
Case Studies

Large Chamber Raw Water Storage Tank project - Bethlehem, New York

Challenge faced

The steel tank was built in the 1970’s and was not coated but had been fitted with cathodic protection system which apparently had not worked correctly. The interior wall of the clarifier was uniformly pitted to a depth of 3mm and rust had penetrated to a depth of 6mm. Stratified rust between 6mm and 18mm covered the interior walls. Once cleaned the surface appeared scalloped, the rust in some places penetrating the tank walls.
The client considered three options; Total replacement of clarifier with stainless steel structure, Painting with NSF approved coating and the installation of cathodic protection or using a NSF approved structural epoxy coating – Ultracoat to restore the integrity of the damaged steel. The client chose the third option as it negated the requirement for cathodic protection - which had previously failed.

About the project

The tank measures 4.2m deep by 15m diameter . To ready the interior of the clarifier for coating the rust was removed and the surface was prepared to SSPC-SP 5 , white metal finish with a 4 mil profile by abrasive blasting.
The tank was then washed down and allowed to dry overnight. The flash rusting was removed next morning by blasting with dustless polishing staurite abrasive media.

Ultracoat structural epoxy primer was then spray applied to the walls at a thickness of 1mm .

An intermediate coat of fibre reinforced Ultracoat structural epoxy was then applied to a thickness of 6mm. ( In tests structural epoxy has a yield strength of 10,000 psi at this thickness – the same as 6mm thick aluminium)
The top coat a third formulation of the cycloaliphatic epoxy was was applied at a thickness of 2mm.

Summary

The job was completed within the budgetary and timescale parameters agreed and on completion pull tests indicated adhesion of Ultracoat at over 1000psi and no delamination was observed.

In addition to the cost savings achieved the client saved time once the project was complete. Because Ultracoat structural epoxies have no solvents the client could immediately fill the tank once washed down with chlorine.
Key Benefits
- Structurally reinforces corroded structures or weakened substrates
- No harmful VOCs (Volatile Organic Compounds) - safe for use in confined spaces, addressing many Health and Safety issues.
- Proven adhesion to damp substrates
- Up to 50 year project guarantee provided
- Over 20 epoxy matrices available; for potable water, fast cure, flexible, fire retardant, high build, gloss finish and others.
- Numerous independent test results and accreditations
- Monolithic coating, with no primer required - quick application
- Superb chemical resistance from pH 2 to 14 including high levels of H₂S
- Very high build thickness without slumping - up to 20mm in one application.
Third Party Testing