Special Specification 7066 Swing Span Rehabilitation

Transcription

1 Special Specification Swing Span Rehabilitation 1. DESCRIPTION This Item governs for all structural work necessary for the rehabilitation of the steel swing span portion of the historic swing bridge carrying East Roundbunch Road over Cow Bayou. The plans contain a narrative of the work to be performed under this Item. 2. MATERIALS Provide materials conforming to the pertinent requirements of the following Standard Specification Items and as indicated on the plans: Item 421, Hydraulic Cement Concrete and Special Provision for Lightweight Concrete Item 441, Steel Structures Item 442, Metal for Structures Item 445, Galvanizing Item 446, Field Cleaning and Painting Steel Item 447, Structural Bolting Item 449, Anchor Bolts 2.1. Thermal Spray Coating (Zinc Metallizing). Provide the following materials: Feedstock material consisting of Zinc/Aluminum (85/15) in accordance with ASTM B Epoxy sealer to serve as the seal coat compatible with thermal spray feedstock with a viscosity able to penetrate into the body of the TSC and seal the porosity in the coating. Sealer must be capable of providing a Class A slip coefficient when tested in accordance with the procedure outlined in Research Council on Structural Connections (RCSC) Specification for Structural Joints Using High Strength Bolts. Sealers that do not meet the required slip coefficients may be used provided the faying surface areas are masked during sealer application. Aliphatic polyurethane finish coat. Fast-curing epoxy for adhesion testing Adhesion and bend test coupons Open Grid Steel Decking. Provide hot-dipped galvanized open grid metal decking of the types shown on the plans or an approved equal. Minimum requirements for open grid metal decking are as follows: Nominal depth of 5 in. HS-20 design load for a 4 ft. center-to center stringer spacing Nominal panel width of 5 ft. Bolted connections to stringers using galvanized ASTM A-325 bolts, nuts and washers ASTM A572 Grade 50 steel, hot-dipped galvanized after fabrication Fabricate to dimensional tolerances listed in the most recent version of BGFMA TS-01, Fabrication Tolerances for Grid Decks, published by the Bridge Grid Flooring Manufacturers Association 2.3. Access Ladders and Platforms. Design, fabricate and install hot-dipped galvanized steel ladders and maintenance access platform at locations shown on the plans and as indicated below

2 3. CONSTRUCTION 3.1. Disassembly. Disassemble the swing span superstructure following the narrative in the plans and in accordance with the pertinent requirements of Item 496, Removing Structures. Submit a demolition plan per Section 2.1 of Item 496 indicating the procedures to follow during disassembly to ensure that steel items to be reused are identified and marked and not damaged during disassembly. Include in this plan the procedures to follow for the Non-Salvage Items listed in the plans that are to be delivered to Orange County for Historic Preservation. Do not use flame-cutting methods to remove existing bolts. Salvage all other steel sections not to be re-used in accordance with Item 497, Sale of Salvageable Material and Article 10 of Item 6, Control of Materials. Note that tests of the paint on the existing bridge indicated that it contains hazardous materials Cleaning Steel to be Re-used. Following disassembly, abrasive-blast clean all existing steel sections to be re-used in accordance with the requirements of Section of Item 446, Field Cleaning and Painting Steel. Meet the requirements of SSPC-SP10 or SP11 (power tool) when cleaning steel to be re-used with a minimum angular profile of 2.5 mils. Notify the Department when blasting of steel to be re-used has been completed and before starting any repairs. The Department will arrange for the Engineer of Record to inspect the blasted steel sections to determine their suitability for re-use. Allow at least 14 calendar days for the inspection process to be concluded Repair of Steel to be Re-used. Notify the Department for structural steel inspection before starting repairs. Provide at least 14 days advance notice before starting repairs. Perform repairs identified in the plans and identified in the post-blasting inspection in accordance with Item 784, Steel Member Repair and the details shown on the plans. Replace any sections determined to be unsuitable for re-use. Complete all welding before galvanizing Galvanizing Steel sections to be Re-Used. Notify the Department of the location where the steel members to be re-used will be galvanized. Provide at least 30 days advance notice before the galvanizing process starts. Galvanize existing steel sections in accordance with Item 445, Galvanizing after they have been repaired New Steel Sections. Provide new galvanized steel sections fabricated in accordance with Item 441, Steel Structures. Complete all welding before galvanizing. Notify the Department of the supplier for new steel and the galvanizing location to arrange for inspection. Provide at least 30 days advance notice before the galvanizing process starts. Galvanize new steel sections in accordance with Item 445, Galvanizing. Weld the HSS railing section to the Schedule 40 steel piping before galvanizing Thermal Spray Coating (TSC) or Zinc-Metallizing (ZM) Main Girders. Apply a thermally sprayed coating and an epoxy sealer to the main longitudinal girders as specified Item 446, Field Cleaning and Painting Steel and as modified below. TSC/ZM is considered a Special Protection System per Article 2.4 of Item 446. Before starting work submit detailed procedures outlining the equipment, application processes, and inprocess quality control and job-control records. Follow the recommendations for procedures outlined in NACE No. 12/AWS C2.23M/SSPC-CS Specification for the Application of Thermal Spray Coatings (Metallizing) of Aluminum, Zinc, and Their Alloys and Composites for the Corrosion Protection of Steel Equipment. In addition to the requirements of Section 3 of Item 446, provide the following: Metallizing Units. Provide electric arc thermal spray equipment set up, calibrated, and operated in accordance with the manufacturer s written instructions and capable of spraying the feedstock material. Provide units meeting the following minimum requirements: equipped with an application gun with a self-contained electric arc, provides a spray pattern that is elliptical in shape and has provisions for adjustments to circular pattern, has an application gun capable of operating remotely from the wire feed unit at a distance of no less than 10 ft.,

3 equipped with a wire feed unit that has moisture and oil separators provided within the unit itself, uses a push wire feed method, capable of operating at 500 amps continuous duty cycle, and able to operate remotely from the power supply unit for a minimum distance of 50 ft. or as needed to maintain the power supply outside the control environment chamber TSC Testing Equipment. Provide portable hydraulic or pneumatic adhesion testers meeting ASTM D 4541, Type III or V. Maintain calibration in accordance with NACE 12/AWS C2.23/SSPC-CS 23. Calibrate portable adhesion testers before performing any qualification testing and have their own specific calibration data utilizing an independent testing laboratory Qualifications. In addition to the requirements in Item 446, provide documentation showing the TSC contractor or subcontractor has a minimum of 2 yr. of experience in TSC work and that at least 1 similar project has been completed within the past 4 yr. Additionally, provide certificate of qualification from metalizing equipment manufacturer verifying TSC contractor or subcontractor has adequate training on use of equipment, or provide documentation that confirms an agreement with the metalizing equipment manufacturer for on-site technical assistance by a representative during thermal spraying. Provide documentation showing TSC superintendent or project manager has a certified experience record indicating at least 2 yr. experience on similar type work Thermal Spray Coating Applicator (TSCA). Submit verification the TSCA has a minimum of 1 yr. experience in the operation of thermal-spray equipment including documentation of prior training and experience using a wire metalizing arc unit on at least 1 project of a similar scope. Provide documentation that each TSCA has been certified by a technical representative of the thermal spray equipment manufacturer. Demonstrate that each TSCA has basic knowledge of the TSC process and terminology by passing standard Adhesion and Bend Tests as per NACE 12/AWS C2.23/SSPC-CS 23. Qualify each TSCA with successful completion of practical tests demonstrating the ability to set up and operate the thermal-spray equipment in the presence of the Engineer and the QC specialist. The practical tests consist of bend test coupons and adhesion tests as follows: As a minimum, have each TSCA prepare 9 bend tests for qualifications 3 tests each in the horizontal down position, 3 tests each in the vertical position, and 3 tests each in the horizontal overhead position. Apply a minimum 10 mils TSC thickness on the bend test coupons, applied to 1 side only. Provide bend test coupons 2 in. wide x 4 to 8 in. long x in. thick (before application of the TSC). To test the bend coupons, with 8.0 to 12.0 mil of applied TSCA, bend 180º around the 0.50 in. mandrel. Do not apply any other coats to TSC for bend test specimens. The pass criterion for the bend test is a smooth surface or minor cracks that cannot be lifted from the substrate with a knife blade in the area of the bend on the outside radius. Disbonding or delamination of the TSC on the outside radius of the bend test coupon results in a failure. If the bend test fails on any 1 of the 9 coupons, determine reason for failure and retest until passing. Only the position (horizontal, vertical, or overhead) for which the bend test failed need be repeated using 3 new coupons. The 9 successful bend test coupons will be identified with date and TSCA initials and retained until released in writing by the Engineer. Have each TSCA prepare a panel for adhesion test by metalizing a 6 in. x 6 in. minimum x ¼ in. thick plate. Position the plate vertical for purposes of applying the TSC. Apply TSC at 10 mils minimum thickness. Perform at least 3 adhesion tests on the test plate prior to application of sealer. Test adhesion with a calibrated portable hydraulic or pneumatic testing apparatus with a minimum target adhesion value of 1000 psi. Requalification may be required at any time at the discretion of the Engineer to retest the proficiency of the TSCA based on the quality of the workmanship Test Sections. Prior to commencing the arc-spraying operation, metalize a minimum of 3 on-site test sections with minimum dimensions of 2 sq. ft. each. Use these test sections to determine the application rate

4 for the specified thickness and the grain size, texture acceptability and adhesion strength. Select test sections representative of all the conditions present on the component. Do not apply sealer prior to installing dollies. Measure adhesion strength on test sections. Bond strength on the test sections will be measured in accordance with ASTM D4541 and this Section prior to Sealer application. Perform preliminary test areas and adhesion tests prior to production metalizing. Metalized products with less than 1,000 psi of bond strength will not be acceptable. Provide a minimum of 14 days advance notice for the application of the test patches such that the QC specialist and appropriate Department personnel may be present for the initial application and testing. Prepare and apply TSC to 12 test plates (1 sq. ft. each) provided by the Engineer for Department testing Quality Control (QC) Specialist. Provide quality control (QC) specialist to ensure quality of surface preparation and TSC work with the following qualifications: NACE International, The Worldwide Corrosion Authority CIP III or Society for Protective Coatings (SSPC) BCI 2, Minimum of 1 yr. experience in the inspection of thermal spray coatings (TSC) on steel, Minimum of 5 yr. experience in the field of corrosion control using coatings on steel structures, Quality Control Plan. Provide quality control plan to engineer for approval prior to beginning work including but limited to: methods to verify cleanness and anchor profile, methods to verify TSC thickness and bond meet requirements, and reporting information to Engineer Surface Preparation. Degrease contaminated steel surfaces in accordance with SSPC-SP 1 to remove oil and grease. Abrasive blast in accordance with Article , Abrasive Blast Cleaning, of Item 446, Field Cleaning and Painting Steel to meet the surface requirements of SSPC-SP 10 with a minimum surface profile of 2.5 mils. Other means of surface preparation may be necessary along plate edges that have previously been flame cut. Measure the profile depth according to ASTM D4417, Method C. Obtain profile depth measurements at a minimum of every 100 sq. ft. All work required to obtain specified surface profile is subsidiary to this item Soluble Salts Detection and Removal. Determine the chloride, sulfate and nitrate concentrations using a soluble salts test kit in accordance with SSPC-Guide 15 utilizing a Class A method. Perform the tests after washing and prior to TSC application. Test three random locations in the first 1000 sq. ft. and one random location for each subsequent 1000 sq. ft. Ensure the non-visible surface contaminant concentrations on blast-cleaned surfaces do not exceed 7 g per gm 2 for chlorides, 10 g per cm 2 for soluble ferrous iron, 17 g per m 2 for sulfates and 10 μg per cm 2 for nitrates. Optionally, test conductivity of solution removed from surface and ensure surface cleanliness produces a conductivity less than 30 micro-siemens. When any representative salt concentration exceeds these levels, rewash the entire surface area and retest. If additional washing does not reduce the concentration to the acceptable level, a surface treatment or water additive may be used. Use a surface treatment or water additive that is approved by the coating system supplier and the Engineer Pre-application Testing. Verify that the tensile bond strength exceeds 700 psi for the 85/15 Zn/Al feedstock when tested in accordance with ASTM D 4541 using either a Type III or Type IV self-aligning tester. Perform one test before starting production work and then test every 500 sf. Remove and reapply the TSC if the tensile bond strength is less than the values listed. Perform bend tests in accordance with NACE No. 12/ AWS C2.23M/ SSPC-CS at the beginning of each work shift or crew change. Use carbon steel coupons of approximate dimensions 2 in. by 4 to 8 in. by in. Prepare the coupon surface in the same manner as the steel surfaces to be coated. Spray 8 to 10 mil thick TSC in crossing passes laying down approximately 3 to 4 mils for each pass. Bend the coupons in 180 degrees around a 0.5 in. diameter mandrel. The coating application passes if no cracking or only minor cracks without spalling or lifting occur. The bend test fails if the coating cracks with lifting (by a knife

5 blade) from the substrate. If the test coupon fails, re-calibrate spray equipment and re-test until the test is passed Holding Period. Apply TSC only when the steel surface temperature is 5 F or more above the dewpoint. The time between the completion of abrasive blasting or final brush blasting and the completion of the thermal spraying should be no more than six hours. In high-humidity and damp environments, shorter holding periods may be necessary. If rust bloom or a degrading coating appears at any time within this six hour window, use the following procedure: 1) Stop spraying; 2) mark off the satisfactorily sprayed areas; 3) repair the unsatisfactory TSC by removing the TSC and re-blasting to establish the correct anchor profile; 4) obtain approval of the repaired section. In low-humidity or enclosed environments using industrial dehumidification equipment, it may be possible to retard the surface oxidation and hold the surface finish for longer than six hours. In this case, obtain approval for extending the holding period for longer than six hours by determining the acceptable temperaturehumidity envelop for the work enclosure by spraying and analyzing bend coupons, tensile-bond coupons, or both as necessary. Obtain approval to apply a 1-2 mil TSC flash coat within six hours of completing the surface preparation to extend the holding period for up to four further hours beyond the complete application of the flash coat. Complete the full thickness TSC application within four hours of the flash coat application provided the TSC remains free of contamination. Validate use of the TSC flash coat using either the bend test and the tensilebond test as follows: 1) Clean and abrasive blast a representative job area and three bend test coupons; 2) apply flash TSC to the representative job area and the test coupons; 3) wait the delay period in representative environmental conditions and apply the final TSC thickness; 4) bend the test coupons and perform the tensile-bond test on the representative job area to confirm that bot tests pass the requirements listed above Coating Application. Apply the TSC/ZM system so that the coating thickness is between 8 and 10 mils when tested using SSPC-PA 2 Type 2 fixed probe gauge or equivalent. Apply in thin overlapping passes. For manual spraying, spray perpendicular crossing passes to minimize thin areas. For mechanized spraying, program overlapping or crossing passes, or both, to eliminate thin spots and stay within the TSC thickness parameters. Preheat substrate when required to improve the coating tensile bond of the thermal spray coating to the substrate by reducing internal stresses. Maintain environmental conditions including humidity and steel surface temperature per NACE 12/AWS C2.23/SSPC-CS 23 Standards. Air blast areas to be metalized immediately prior to thermal spray coating application to remove any dust or blast media residue. Provide air stream 100% oil and moisture free. Obtain the specified coating thickness with several applications in crossing passes. The coating tensile bond strength is greater when the spray passes are kept thin. At the discretion of the Engineer, the Department may request bend test coupons of thickness and metal composition same or similar as the structural components being metalized. For manual spraying, use right angle crossing passes to minimize the thin areas in the coating. For mechanized spraying (mechanized movement of the gun or work piece, or both), program the overlapping and crossing passes to eliminate thin spots and stay within the specified coating thickness. Complete abrasive blasting to achieve the specified anchor profile (or final brush blasting) together with completion of the metalizing in the same shift. If rust bloom or a degraded coating appears at any time while spraying, stop and follow the procedures described in NACE 12/AWS C2.23/SSPC-CS 23 Standard, Article Metalize continuously and un-interrupted within each component. Do not have cold overlaps of the metalizing unless specifically allowed by the Engineer for phased work. When cold overlaps are approved, do not apply sealer to the overlap area until overlap has been completed. Overlap at the beginning of the next shift. If overlap is not achieved within 24 hr., re-blast and re-metalize the unsealed overlap area in accordance with this Section. Apply sealer within same work shift as thermal spraying, whichever is shorter. If sealer cannot be applied within allotted time and if approved by the Engineer, wrap the metalized component in plastic sheeting immediately after metalizing and protect it from weather. Then prior to sealer application, verify the coating:

6 has not been oxidized or otherwise contaminated by visual inspection using a minimum 30x magnified lens, and is dust free using the clear cellophane tape test (ISO ) before applying the sealer Job Control Testing Schedule. Measure the TSC dry film thickness using an SSPC-PA 2 Type 2 fixed probe gauge. Use a measurement line for flat surfaces. Take the average values of five readings taken in line at 1 in. intervals. Use a measurement spot approximately 1.5 sq. in. for complex geometries and geometry transitions. Perform job control testing for coating thickness and tensile bond every 500 sf Sealer Application. Apply the sealer in accordance with Item 446 immediately after TSC application. Apply at a spreading rate resulting in a theoretical 1.5 mil dry film thickness. Apply sealer within 8 hours after completion of thermal spraying Reassembly. Reassemble the swing span superstructure following the narrative in the plans and in accordance with the pertinent requirements of Item 441, Steel Structures and Item 447, Structural Bolting. Submit a list of elements that will be installed in the field at the bridge site. Fully install all bolts in the shop or at the assembly site before transporting to the bridge site. Do not leave bolts in a snug tight condition before transporting to the bridge site Access Ladders and Platforms. Design platforms and ladders to conform to the applicable OSHA requirements. Submit for approval the ladder and platform designs including the method of attachment to the swing span steel girders, landing bent caps, and center pivot pier cap. Do not weld ladders or platforms to the swing span steel structure. Ensure that ladder and access attachments do not interfere with operation of the swing bridge Erection. Submit a lifting and transporting plan for approval before transporting the re-assembled swing span to the bridge site. Allow 14 days for review of this plan. Once at the bridge site, place the swing span on the center pivot in the open (closed to vehicular traffic) position. Complete span balancing operations indicated in the plans and described in other Special Specifications before rotating the swing span to rest on the landing bents. Cast armor joint concrete on top of landing bents after completion of span balancing operations and final setting of end wedge assemblies Repair of Damaged Coating. If any TSC is damaged during shipping, loading, unloading, or erection, perform repairs in accordance with maintenance repair procedures outlined in ANSI/AWS C2.18. Repair damaged galvanizing in accordance with Item 445, Galvanizing Anchor Bolts. Install anchor bolts as shown in the center pivot pier or landing bents in accordance with Item 449, Anchor Bolts". Bolts may be cast in place in the fresh concrete or may be post-installed using grout or epoxy unless noted otherwise. Submit anchor bolt setting procedures for approval Concrete Deck Infill. Once the initial span balancing operations have been completed and the bridge is in the open (to vehicular traffic) position, cast the lightweight concrete deck infill concrete to the limits shown on shown on the plans and in accordance with Item 422, Concrete Superstructures. Use polystyrene foam in accordance with Article 2.5 of Item 422 or other approval material to form the underside of the concrete infill. Finish the concrete surface so that it is flush with the top of the open grid metal decking. Use a wood float to finish the surface. Texturing is not required for the concrete surface. Perform final span balancing operations as indicated in the Item: Mechanical Construction for Swing Span Rehabilitation. 4. MEASUREMENT This Item will be measured by the Lump Sum

7 5. PAYMENT The work performed and materials furnished in accordance with this Item and measured as provided under Measurement will be paid at the unit price bid for Swing Span Rehabilitation. This price is full compensation for removing the existing swing span from the site; disassembly; delivering non-salvage elements to Orange County; removing existing paint from members to be reused; repairing and galvanizing existing members to be reused; providing new steel as indicated for floor beams, stringers, joints, decking, and railing; applying thermal spray coating to main girders; reassembly; transportation to bridge site and final erection; providing anchor bolts; casting of in-fill deck concrete; providing access platforms; and furnishing all labor, equipment, tools, and incidentals to complete the work. Span balancing operations and steel or concrete ballast needed to balance the span will be paid for in accordance with the Item: Mechanical Construction for Swing Span Rehabilitation. Steel sections to be salvaged will be paid for in accordance with Item 497, Sale of Salvageable Material