Atmospheric Coatings

Dear Experts;<o:p></o:p>

The subject of query is related to "surface cleanliness on small damages prior to touchup paint application" on base plate of hot dipped galvanized structural members which were fully coated with surface tolerant epoxy mastic paint. <o:p></o:p>

Paint damages found at base plate of several structural columns, the damages occurred due to washer plates (06nos.) welded on a base plate of hot dipped galvanized column, the reason galvanization layer is fully removed and substrate is visible from base plate, damages are adjacent to weld beads of washer plates including the extended heat-affected zone (HAZ) area which is approximately 25mm at all around the weld beads, See the below image PIC-2 for reference. The affected area is calculated by considering the maximum length and width of damage at base plate of a column which is less than 0.1m², See below calculation. <o:p></o:p>

CALCULATION: (By choosing maximum length and width of damage)<o:p></o:p>

Area affected due to welding in surrounding of one bolt is 130*30*4 sides= 15600 mm²,                                                                                                                Area affected due to welding in surrounding of six bolts is 15600*6nos.=93600mm²=0.093m²,                                                                                                      Affected area is 0.093m² which is less than 0.1m². <o:p></o:p>

 PREPARED THE SURFACE AROUND WASHER PLATES AT ONE COLUMN: The surfaces were prepared according to project requirements by using combination of tools represented in SSPC-SP2-hand tool and SSPC-SP3-Power tool, rusts and other contamination were fully removed as shown in PIC-1 that may detrimental to a coating system. Our company is proposing to give assurance of life span of applied coating by carrying out Peel-off adhesion test over cured coating with reference to ASTM D3359 type 'A'.<o:p></o:p>

But our client is not accepting the proposed methodology of surface cleanliness for applying touchup paint application by recommended paint that is surface tolerant epoxy mastic coating. <o:p></o:p>

In other hand, client is asking to check anchor profile on substrates those prepared in accordance to SSPC-SP2 & SP3 which is not included in our best practice. NEED EXPERT SUGGESTION.<o:p></o:p>

Are these surface preparation methods (SP2/SP3) are acceptable for small damages on hot dipped galvanized surface or need sweep blast.?

Dear Experts;

The subject of query is related to "surface cleanliness on small damages prior to touchup paint application" on base plate of hot dipped galvanized structural members which were fully coated with surface tolerant epoxy mastic paint. 

Paint damages found at base plate of several structural columns, the damages occurred due to washer plates (06nos.) welded on a base plate of hot dipped galvanized column, the reason galvanization layer is fully removed and substrate is visible from base plate, damages are adjacent to weld beads of washer plates including the extended heat-affected zone (HAZ) area which is approximately 25mm at all around the weld beads, See the below image PIC-2 for reference. The affected area is calculated by considering the maximum length and width of damage at base plate of a column which is less than 0.1m², See below calculation. 

CALCULATION: (By choosing maximum length and width of damage)

Area affected due to welding in surrounding of one bolt is 130*30*4 sides= 15600 mm²,                                                                                                                Area affected due to welding in surrounding of six bolts is 15600*6nos.=93600mm²=0.093m²,                                                                                                      Affected area is 0.093m² which is less than 0.1m².

 PREPARED THE SURFACE AROUND WASHER PLATES AT ONE COLUMN: The surfaces were prepared according to project requirements by using combination of tools represented in SSPC-SP2-hand tool and SSPC-SP3-Power tool, rusts and other contamination were fully removed as shown in PIC-1 that may detrimental to a coating system. Our company is proposing to give assurance of life span of applied coating by carrying out Peel-off adhesion test over cured coating with reference to ASTM D3359 type 'A'.

But our client is not accepting the proposed methodology of surface cleanliness for applying touchup paint application by recommended paint that is surface tolerant epoxy mastic coating.

In other hand, client is asking to check anchor profile on substrates those prepared in accordance to SSPC-SP2 & SP3 which is not included in our best practice. NEED EXPERT SUGGESTION.

Are these surface preparation methods (SP2/SP3) are acceptable for small damages on hot dipped galvanized surface or need sweep blast.?