Termarust Laboratory Panels + Testing Protocol

                This protocol is specifically designed to determine the effectiveness of a coating system with regard to pack rust and crevice corrosion. The protocol will also provide an excellent indication of the coating system’s general performance, and can also be used in conjunction with field trials on larger panels designed and prepared the same way.

Laboratory Test panel Specification:

3-in. wide x 6-in. long mild steel panel. 1/8-in. thick

2-ea. ¾-in. mild steel angle irons, 1/8-in. thick and 3,1/4-in. long.

2-ea. 1/4 in steel bolts ¾-in. long with steel nuts and washers on nut side.

The angle iron is drilled and bolted together and then welded a distance of ¼ of an inch from the bottom of the plate, each side is welded and the base and top are left open.  This leaves a gap for crevice corrosion to develop between the two back to back angles.

The plate is designed to fit inside a Q-UVB cabinet fixture and easily fits into racks in the prohesion cabinet and freezer.

As per the example, the panels are pre rusted using the salt fog cabinet and exterior exposure. The time in the salt fog cabinet and on our exterior racks will vary as per the amount of corrosion that is required to duplicate the field conditions of the structural steel we will be coating. The salt fog treated panels can also be left in the field in the particular environment the coating will be used in if other contaminates are present which are important. The example panel had three cycles alternating one-month in the salt fog with one-month on our roof rack and then six consecutive months on the roof through one winter. This rotation duplicates the same amount of crevice corrosion produced in the most severe conditions encounter on the field. Crevice corrosion will develop and the joint will also be forced apart by the freezing through the winter. (Note: you can also accelerate the damage from trapped water and freezing by using a freezer)

Surface Preparation:

Depending on the requirements, the steel is prepared using SSPC Standard preparations. We use everything from abrasive blasting to water washing to hand and power tool cleaning, and verify that the chloride levels are below SSPC-SP12-SC2 by using the Chlor-Test kit. The coating is then applied as per manufacturers specification and cured for 30 days before testing.

Testing Protocol:

We use a 21-day cycle alternating between:

            9-days prohesion cabinet

            9-days Q-UVB cabinet

            3-days freeze at –30°C.

Criteria used for Evaluation of the Coating Systems:

For recoated steel the coating must pass 10-cycles when applied to a prepared substrate with no remaining coating.  Surfaces may be prepared by abrasive blasting to SSPC-SP6, SSPC-10 SSPC-SP5, water jetted to SSPC SP12 WJ3 WJ2 or WJ1 or SSPC-SP11 surface preparation

For overcoating and existing rusted substrates prepared to SSPC-SP7, SP2, SP3, or SSPC-SP12 –WJ4.        

The coating system must pass 6 cycles.

Some Criteria for Failure of the system would constitute:

Leakage from the pack rusted joints ( a priority)

ASTM D714 Blistering on score line

ASTM D610 Area % Rust Breakthrough and undercutting at scribe

ASTM D3359 Adhesion

ASTM D4541 Pull-Off Adhesion lbs.  per square inch

ASTM D523 60° Gloss Retention

ASTM D2244 Colour Change Lab Scale, 2° observer, SCI, Delta E