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506.21 Surface Preparation Abrasive blast-clean the steel to a minimum of SSPC-SP 6,
Commercial Blast Cleaning (SP6) prior to galvanizing. Grind all corners exposed in the assembled product to a 1/16 inch radius prior to galvanizing.
506.22 Repairs Repairs to galvanizing shall be in accordance w ith ASTM A780,
Standard Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings (A 780), Annex A1 or A3. Zinc-rich paints for repairs may only be used with approval of the Fabrication Engineer.
506.23 Top-coating Galvanized Surfaces Areas of galvanized sur faces to be top-coated
will be described on the Plans or in the Special Provisions. Do not use chromate quenching or other types of quenching after galvanizing. Remove runs, sags, dross and other deleterious material from surfaces to be painted. Provide a smooth uniform surface, free of heavy build areas or other disc ontinuities that will project through the finish coat. Perform repairs to galvanizing in acc ordance with A 780. Remove visible surface contaminants in accordance with SSPC-SP 1, Solvent Cleaning (SP 1) prior to blast cleaning. Blast-clean surfaces to be coated in accord ance with SSPC-SP 7/NACE No.4-Brush-Off Blast-Cleaning (SP 7). Measure the anchor profile in accordance with ASTM D4417 Method C (replica tape). Record the results in a manner acceptable to the Fabrication Engineer. Assure that the anchor profile correspond s with the anchor profile requirements on the Manufacturer's Product Data Sheet.
506.24 Materials Provide materials in accordance with 506.11.
506.25 Mixing and Application Mix and apply in accordance with 506.14.
506.26 Dry Film Thickness Measure and record the DFT in accord ance with 506.15.
506.27 Touch-up and Repairs Perform touch-up and repairs in ac cordance with 506.16.
506.28 Handling and Storage Handle and store material in accor dance with 506.17.
506.29 Reserved
THERMAL SPRAY COATING
506.30 Description This work shall c onsist of surface preparat ion and application of
Thermal Spray Coatings (TSC) i n accordance with the Plans and t his Specification. Application of TSC to steel subs trate shall be done in accordan ce with requirements, recommendations and appendices of the current Joint Standard AASHTO S8.2:Specification for the Application of Thermal Spray Coating Systems to Steel Bridges (The Standard) and this Specification. The applicator shall provide c opies of application procedures, operator qualifications, QC Manuals and repair procedures. 5-96
506.31 Submittals Submit an application procedure and QC Plan for review by the
Department prior to beginning wor k. Submit a certified analysis of the feedstock to the Department. Submit sample copies of QC records for review. Subm it copies of applicator qualifications, job history, etc . Provide the name and qualific ations of the QCI.
506.32 Surface Preparation Prior to abrasive blast cleaning, r ound all corners exposed
in the assembled product to approximately a 3/32 inch radius. A series of tangents to the approximate radius will be considered acceptable. Remove h ardened condition on thermal cut surfaces. Abrasive blast clean all surfaces to be coated in accordance with The Standard and SSPC-SP 5, White Metal Blast Cleaning (SP 5). Use SSPC -VIS. 1 as a visual standard to determine accep table cleanliness. Inspect t he substrate immediately before spray application. The anchor profile shall be per The Standard (minimum 2.5 m ils). Measure and record the anchor profile in accordance with ASTM D4417 Method B or C (Replica Tape) or both on each plane to be sprayed or at 120 ° intervals on pipe or tu be. Measure at the frequency in The Standard. Angular blast media shall conform with The Sta ndard. If the anchor profile fails to meet the minimum required profile, re-blast th e substrate until the required anchor profile is achieved. If compressed air is used for abrasive blast cleaning, perform a blotter test in accordance with ASTM D4285 at the beginning of each shift. Empty moisture traps at the beginning of each shift and at any time thereafter when moistur e appears to be present on the substrate. Notify the QAI prior to performing the test in order that the QAI can witness the blotter test.
506.33 TSC Requirements The coating thickness shall be a minim um of 14 mils. The
DFT on faying surfaces shall not exceed the thickness tested fo r Class B slip coefficient rating. The TSC shall have a minimum tensile bond per The Stand ard. Test the tensile bond in accordance with ASTM D4541. The frequency of testing shall b e per The Standard. The test location will be as directed by the QAI. The specified ten sile force shall be applied to the TSC and removed. If the test does not reveal a failure of the TSC, the tensile bond shall be considered acceptable. Repai r or recoat unacceptable work. Tensile testing may be performed on witness panels coated by each technician on each s hift TSC is applied; notify the QAI so witness panel coating may be observed. Perform a bend test as described The Standard, at the beginning of each shift. If the bend test fails, take corrective action and perform another tes t. After performing the bend test successfully a number of times, the Fabrication Engineer m ay reduce the frequency of testing. Document the results of the tensile bond test and bend test and provide the results to the Department. Satisfactory bend test results with 7-12 mils t hickness will be acceptable. The TSC shall have a uniform appearance, free from blistering, cracks, loose particles, or exposed steel substrate when examined with 10-X magnificatio n.