SECTION 827 — THERMAL SPRAYED ZINC COATING FOR NEW STRUCTURAL STEEL 800-167 — THERMAL SPRAYED ZINC COATING FOR NEW STRUCTURAL STEEL
827.01 Description.
This work includes cleaning, preparing surfaces, and applying an application of thermal sprayed zinc coating to the surfaces of new structural steel and its components at the required locations indicated.
827.02 Materials.
Use materials that conform to Subsection M05.07.
827.03 Construction Methods.
Surface Preparation.
a.Blast Equipment. Use conventional air type blast equipment. Do not use any type of water or vapor blast. Ensure that the air supplied for blasting has sufficient pressure at the nozzle to achieve the desired profile and is clean and free of oil and moisture. Ensure that surfaces prepared for metal spraying also remain free from oil and moisture until zinc coating has been applied.
b.B last Cleaning. Perform the blasting operation in a block or sectional method and continue until all foreign matter and scale on the original surface has been removed and until the cleaned metal surface is bright and completely abraded by the abrasive. Clean all steel surfaces to a white metal condition using the methods described in the Steel Structures Painting Council Surface Preparation Specification No. 5, White Metal Blast Cleaning (SSPC-SP5). Ensure that the steel surface temperature is a minimum of 5°F above the dew point. Use an abrasive as specified above. Ensure that the blast cleaning leaves a 2.0 to 4.0 mil deep profile in a dense uniform pattern of depressions and ridges. Measure and/or verify the surface profile depth with an Elcometer surface profile gauge, or equal, or Testex Replica Tape. Remove all visible abrasive and dust from the surfaces to be thermal spayed. Transfer and preserve the erection marks for the field identification of members and weight marks. Remove any grease pencil marking by solvent wiping. The Engineer will approve the preparation of all surfaces before any thermal sprayed zinc is applied. Thermal Spraying Zinc.
a.Thermal Spraying. Ensure that all surfaces have been prepared according to Subsection 827.03.1. Do not spray surfaces that demonstrate any sign of rust, scale, moisture, or foreign matter. Apply at least one single layer of the coating within a maximum of four hours of the blasting. Overlap the sprayed metal on each pass in a cross -hatch block pattern not to exceed 2 sq ft to ensure uniform coverage. Apply the specified thickness of the coating
Part 800 — Bridge Structures August 2025
800-168 SECTION 827 — THERMAL SPRAYED ZINC COATING FOR NEW STRUCTURAL STEEL in multiple layers, and ensure that not less than two passes of the spraying are made over the entire surface. Ensure that the coating operations produce a uniform, even coating that is bonded firmly with the steel. Ensure that the coating is free from uncoated spots, lumps, or blisters, and has a uniform sprayed fine texture finish. Ensure that the coating thickness is a minimum of 8.0 mils ±1 mil. Measure the coating thickness using the methods described in the Steel Structures Painting Council Paint Application Specification No. 2, Measurement of Dry Paint Thickness with Magnetic Gauges (SSPC - PA2). Remove and recoat all steel coated with impure, unsatisfactory, or unapproved coating material. Respray areas not meeting the coating thickness requirements to the specified thickness after appropriate surface preparation.
b.Field Repair. Make all field repairs according to the material supplier’s recommendations and these Specifications. Ensure that new steel is shop coated, including metalizing, painting, and sealing. Notify the Engineer when performing field repairs before beginning the work. Subsequent Coatings. Ensure that any top coating over the zinc complies with Subsection 825.03.5. Approval Requirements.
a.Samples. Submit a sample steel plate approximately 12 in. × 12 in. to which zinc coating has been deposited at least 30 days before zinc metalizing application to the specified thickness, as checked with a fixed probe gauge, for acceptance by the Engineer for the grain size and texture of the sprayed metal. Take two samples — one for the Engineer and one to store at the applicator’s shop for the applicator’s reference. The plate will be used to determine the acceptance of the finished job. Prepare the s ample plates by the same profiling process, and ensure that the plates have the same surface profile as the steel surface to be thermally sprayed. If the production coating is inferior to the sample, correct the coating by an acceptable repair method and perform a job comparable to the specimen submitted.
b.Q ualification/Certifications . Provide a certification for each journeyman applicator to the Engineer before production assignment . If recertification is required, use the following procedure under the direction of the Engineer. Perform the recertification in a suitable location removed from the area of ongoing work operations. Use a qualifying test for recertification in which the journeyman applies the coating system to the test panel according to the requirements of the application procedure(s) and includes at a minimum:
Part 800 — Bridge Structures August 2025
SECTION 827 — THERMAL SPRAYED ZINC COATING FOR NEW STRUCTURAL STEEL 800-169 ● Installing the thermal spray system according to the manufacturer’s recommendations ● Adjusting the system operating parameters according to the manufacturer ’s recommendations ● Applying a steady and even application of sprayed metal to a right-angle joint to avoid an excessive buildup in the fillet area ● Repairing a defect made by means of a hammer and chisel in the test panel
c.Quality Control (Process Control) . Use the following specific process control items. Provide technical supervision for shop and field applications. Maintain daily logs of air and surface temperature, dew point, and relative humidity. Measure and retain the surface profile of each beam using Testex (or equal) replica tape. Make t his available to the Engineer upon request.
d.S afety and Health. Ensure that all personnel required to enter confined spaces are instructed on the OSHA requirements regarding the nature of the hazards involved, the necessary precautions to be taken, and the use of protective and emergency equipment required.
827.04 Method of Measurement.
Thermal Sprayed Zinc Coating will be measured by the number of square feet of steel sprayed. As an option, the Contract may stipulate that Thermal Sprayed Zinc Coating is incidental to the Pay Item for the associated structural element.
827.05 Basis of Payment.
The Department will pay for the completed and accepted quantities as follows. Pay Item Pay Unit Thermal Sprayed Zinc Coating SF The price constitutes full compensation for all labor, materials, equipment, tools, technical supervision, and incidentals required to finish the work, complete and accepted.
Referenced in this section
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Source: Standard Specifications for Road and Bridge Construction (Blue Book), 2022 (Aug 2025 compilation) Edition. Pages 536–538 of 951. View official source ↗