757 SECTION 687 SHOP PAINTING METAL STRUCTURES
687.1 -DESCRIPTION : The shop painting (coating) of metal structures shall follow the provided requirements set forth in this spe cification unless otherwise noted in the Contract. This specification shall apply to surface preparation, coating application, contractor/fabricator responsibilities, environmental and worker protection, and waste handling/disposal.
687.2 -GENERAL : 687.2.1 -Surface Preparation: Shall meet the requirements of this section.
687.2.1.2 -Blasting: The compressed air used for nozzle blasting shall be free of water or oil. The cleanliness of each compressed air system shall be verified at least once per shift using the blotter test in accordance with ASTM D4285, “Standard Test Method for Indicating Oil or Water in Compressed Air”.
687.2.1.2.1 -Commercial Blast: Shall meet the requirements of SSPC -SP 6 / NACE 3 prior to painting. The appearance of the steel surface after blast cleaning shall correspond to the applicable and current SP 6 pictorial standards of SSPC Vis 1.
687.2.1.2.2 -Brush -Off Blast: Shall meet the requirements of SSPC -SP 7 / NACE 4 prior to painting. The appearance of the steel surface after brush off blast cleaning shall correspond to the applicable and current SP 7 pictorial standards of SSPC Vis 1.
687.2.1.2.3 -Near White Metal Blast : Shall meet the requirements of SSPC -SP 10 / NACE 2 prior to painting. The appearance of the steel surface after blast cleaning shall correspond to the applicable and current SP 10 pictorial st andards of SSPC Vis 1.
687.2.1.2.4 -White Metal Blast : Shall meet the requirements of SSPC -SP 5 / NACE 1 prior to painting. The appearance of the steel surface after blast cleaning shall correspond to the applicable and current SP 5 pictorial standards o f SSPC Vis 1.
687.2.1.2.5 -Blast Media: The abrasives used for all blasting shall meet the guidelines set forth in SSPC AB1 for mineral and slag abrasives, and AB3 for ferrous metallic abrasives. Any additive mixed with the abrasive shall be approved by the Division prior to use. The abrasives used shall produce a height of profile between 1.0 and 3.0 mils. In addition, the container or bag of abrasive shall include the name of the abrasive, the name of the manufacturer, and the size of the abrasive. If any additive has been included with the abrasive, the name and the percentage of the additive shall be on the container or bag.
687.2.2 -Post-Surface Preparation: Surface prep operations shall be performed in such a manner that no damage is done to p artially or entirely completed portions of the work. After surface prep, any areas that are repaired by welding shall be prepped again. Areas repaired by grinding or other means shall have the anchor pattern restored by abrasive blasting. Visible deposits of oil, grease, or other contaminants shall be removed according to SSPC -SP1"Solvent Cleaning" prior to painting. Dust, loose residues , and the removal of abrasives from pockets and corners shall be removed from prepared surfaces by
758 brushing, blowing off with clean, dry air, vacuum cleaning. The prepped surface shall be checked for cleanliness by wiping a clean, dark cloth across the su rface. If residue is present, the surface shall be cleaned again and rechecked. All blast cleaned surfaces shall be painted prior to any rust bloom or flash rust occurring or within 24 hours, whichever comes first. After blast cleaning, surface imperfections that remain (e.g., sharp fins, sharp edges, weld spatter, burning slag, scabs, slivers, etc.) shall be removed. Any damage to the surface profile resulting from the removal of surface imperfections shall be re -blasted.
687.3 -PAINT APPLICATION REQUI REMENTS : 687.3.1 -Weather Conditions: Painting shall not be done when the ambient temperature is below 40°F or above 100°F, or the relative humidity above 90 percent (90%) . The temperature of the steel must be at least 5°F above the dew point. Painting shall not be performed when the surface to be coated is sufficiently hot to cause blistering of the film or too rapid solvent release.
687.3.2 -Paint Storage: Paint and thinners shall be stored in a temperature -controlled environment between 40°F and 100°F. At no time will paint be used beyond the manufacturer’s shelf life.
687.3.3 -Paint Application: The blast cleaned surface shall be painted within 24 hours. In the event rust bloom or flash rusting occurs, the effected members shall be re -cleaned by blasting. The paint shall be ap plied by spray methods, except those areas inaccessible to spray application may be brushed. Brushes, when used, shall have sufficient body and length of bristle to spread a uniform coat. Small touch -up areas may be brushed, if approved by the Engineer. Use of an agitated pot shall be mandatory in spray application of Zinc primer. The agitator or stirring rod shall reach within one ( 1) inch, of the bottom of the pot and shall be in motion at all times during paint application. Coatings shall be mixe d in strict accordance with the coating manufacturer’s written instructions. Under certain conditions, it may be necessary to thin or adjust the solvent balance of the paint. The type and amount of solvent to be used shall be that listed on the coating m anufacturer’s product data sheet for that material. Upon thinning, the dry film thickness requirement shall still be met. Application requirements and drying times between coats shall be in accordance with the manufacturer’s written instructions. Dry film thickness requirements shall be specified in the contract documents. Exposed steel surfaces of expansion dams shall be painted as specified for structural steel. Spray guns must be equipped with the recommended size tip for the paint product being app lied and shall be held perpendicular (90 degrees) to, and at, the proper distance from the receiving surface. Complete protection shall be provided by the fabricator against paint spatter, spillage, overspray, wind -blown paint, or similar releases. For t he fully shop painted bridge, the entire top of the top flanges for the full length of the girders will only get primer at two (2) mils dry. For weathering steel bridges, the ends of the girders, to the length specified in the plans, are painted with t he whole system, and the top of the top flange at the end of girders is primed only at two (2) mils dry. The remaining lengths of the girders are left unpainted.
687.3.4 -Painting Sequence : Shall be in accordance with the following:
687.3.4.1 -Materials : The primer shall meet the requirements of subsection 711.6 or
711.20. The fabricator responsible for the largest percentage of the painting will choose a
759 Zinc Rich, Low VOC system. Primer coat shall have a maximum VOC of 3.5 lbs/gal. Intermediate and t op coats shall have a maximum VOC of 2.8 lbs/gal.
687.3.4.2 -Paint systems: 3 COAT: Primer, Intermediate, Top Coat 2 COAT: Primer, Top Coat 1 COAT : Epoxy Mastic only
INORGANIC PRIME COAT: All edges, corners, crevices, bolt heads and nuts, all rivet heads, edges of flanges and plates, welds, sharp edges, in general all edges, shall receive a dusting coat, by spray application, of the same primer as the Full Prime Coat. The dusting shall ext end a minimum of one (1) inch from the edge. The full prime coat shall be applied immediately following the dusting coat. No dry film thickness is specified for this coat. Inorganic Zinc Primers are NOT to be tinted.
ORGANIC PRIME COAT: All edges, co rners, crevices, bolt heads and nuts, all rivet heads, edges of flanges and plates, welds, sharp edges, in general all edges, shall receive one stripe coat, by brush application, of the same primer as the Full Prime Coat. Striping shall extend a minimum of one (1) inch from the edge. The prime coat shall at a minimum, be set -to-touch before the stripe coat is applied. No dry film thickness is specified for this coat. This coat shall be tinted as allowed by the manufacturer to be in contrast to the full prime coat and intermediate coat. The tinting agent shall be the paint manufacturer’s approved tinting agent.
FULL PRIME COAT: The structure shall receive one coat of a primer meeting the requirements of Section 711 of the Specifications. The primer u sed for the full prime coat shall be of the same type and shall be from the same manufacturer as the primer used for dusting and striping.
INTERMEDIATE COAT: The structure shall receive one uniform coat of a paint meeting the requirements of If tinting is required, the tinting agent shall be the paint manufacturer’s approved tinting agent.
CAULKING: Caulking shall be applied before the application of the topcoat. This includes all seams between diaphragm connections to stiffeners and splices; and seams between any connection that is riveted or bolted. Any welded connections that are not fully sealed by the weld shall be caulked with a paste type caulk. The caulk shall be pressed into the seams between the adjoining surfaces, by wetted finger or specialty tool, to insure bond and provide a smooth uniform surface. Caulking in a 3 -coat system shall be applied after the intermediate coat has cured. Caulking on a 2 -coat system shall be applied after prime coat has cured. The top coat shall not be applied until the caulking has fully cured in accordance with the manufacturer’s recommendations. The caulking material shall be compatible with the paint system being applied and shall be by written recommendation of the paint