the temperature is expected to drop to 32° F. before the paint has dried. Paint shall not be applied to steel that is more than 5° F. below the air temperature or that is at a temperature less than 40°F. Paint shall not be applied to steel at a temperature over 125°F. unless the paint is specifically formulated for application at the proposed temperature, nor shall paint be applied to steel which is at a temperature that will cause blistering or porosity or otherwise will be detrimental to the life of the paint. Paint shall not be applied in fog or mist, or when it is raining or snowing or when the relative humidity exceeds 85 percent. Paint shall not be applied to wet or damp surfaces. Paint shall not be applied on frosted or ice-coated surfaces. When paint must be applied in damp or cold weather, the steel shall be painted under cover, or protected, or sheltered, or the surrounding air and the steel heated to a satisfactory temperature. In all such cases, the above temperature and humidity conditions shall be met. Such steel shall remain under cover or be protected until dry or until weather conditions permit its exposure. Any applied paint exposed to freezing, excess humidity, rain, snow, or condensation shall first be permitted to dry. Then damaged areas of paint shall be removed, the surface again prepared and then repainted with the same number of coats of paint of the same kind as the undamaged areas. If stripe painting is stipulated in the special provisions or if the Contractor chooses to do so at his option, all edges, corners, crevices, rivets, bolts, welds, and sharp edges shall be painted with the priming paint by brush before the steel receives its first full prime coat of paint. Such striping shall extend for at least 1 inch from the edge. When practicable, this stripe coat shall be permitted to dry before the prime coat is applied; otherwise, the stripe coat shall set to touch before the full prime coat is applied. However, the stripe coat shall not be permitted to dry for a period long enough to allow rusting of the unprimed steel. When desired, the stripe coat may be applied after a complete prime coat. To the maximum extent practical, each coat of paint shall be applied as a continuous film of uniform thickness, free of pores. Any thin spots or areas missed in the application shall be repainted and permitted to dry before the next coat of paint is applied. Each coat of paint shall be in a proper state of cure or dryness before the application of the succeeding coat. (2) Brush application.-Paint shall be worked into all crevices and corners where possible and surfaces not accessible to brushes shall be painted by spray, daubers, or sheep skins. All runs or sags shall be brushed out. There shall be a minimum of brush marks left in the applied paint. (3) Spray application of paint.-The equipment used for spray application of paint shall be suitable for the intended purpose, shall be capable of properly atomizing the paint to be applied, and shall be equipped with suitable pressure regulators and gages. The air caps, nozzles, and needles shall be those recommended by the manufacturer of the equipment for the material being sprayed. The equipment shall be kept in satisfactory condition to permit proper paint application. In closed or recirculating paint spray systems, where gas under pressure is used over the liquid, the gas shall be an inert one, such as nitrogen. Traps or separators shall be provided to remove oil and water from the compressed air. These traps or separators shall be of adequate size and shall be drained periodically during operations. The air from the spray gun impinging against the surface shall show no water or oil. Paint ingredients shall be kept properly mixed in the spray pots or containers during paint application either by continuous mechanical agitation or by intermittent agitation as frequently as necessary. The pressure on the material in the pot and of the air at the guns shall be adjusted for optimum spraying effectiveness. The pressure on the material in the pot shall be adjusted when necessary for changes in elevation of the gun above the pot. The atomizing air pressure at the gun shall be high enough to atomize the paint properly but not so high as to cause excessive fogging of paint, excessive evaporation of solvent, or loss by overspray. Spray equipment shall be kept sufficiently clean so that dirt, dried paint, and other foreign materials are not deposited in the paint film. Any solvents left in the equipment shall be completely removed before applying paint to the surface being painted. Paint shall be applied in a uniform layer, with overlapping at the edge of the spray pattern. The spray pattern shall be adjusted so that the paint is deposited uniformly. During application, the gun shall be held perpendicular to the surface and at a distance which will insure that a wet layer of paint is deposited on the surface. The trigger of the gun should be released at the end of each stroke. All runs and sags shall be brushed out immediately or the paint shall be removed and the surface repainted. Spray application of prime coats shall in all cases be immediately followed by brushing. Areas inaccessible to the spray gun shall be painted by brush. If not accessible by brush, daubers or sheepskins shall be used. Brushes shall be used to work paint into cracks, crevices, and blind spots which are not adequately painted by spray. (4) Shop painting.-Shop painting shall be done after fabrication and before any damage to the surface occurs from weather or other exposure. The shop coat of paint shall have a minimum dry film thickness of 1.5 mils. Shop contact surfaces shall not be painted unless specified. Unless otherwise specified, surfaces to be in contact only after field erection shall be painted except where the paint will interfere with assembly. Surfaces not to be in contact but which will be inaccessible after assembly shall receive either the full paint coats specified or three shop coats of the specified primer before assembly. The areas of steel surfaces to be in contact with concrete shall not be painted. Unless otherwise shown on the plans, the areas of steel surfaces to be in contact with wood shall receive either the full paint coats specified or three shop coats of the specified primer. If the paint would be harmful to a welding operator or would be detrimental to the welding operation or the finished welds, the steel shall not be painted within a suitable distance from the edges to be welded. Antiweld spatter coatings shall be removed before painting. Weld slag and flux shall be removed by methods at least as effective as those specified for the cleaning. Machine-finished or similar surfaces that are not to be painted, but do require protection, shall be protected with a coating of rust inhibitive petroleum, or other coatings which may be more suitable for special conditions. Erection marks and weight marks shall be copied on areas that have been previously painted with the shop coat. (5) Field painting.-Steel structures shall be painted as soon as practicable after erection. Each field coat of paint shall have a minimum dry film thickness of 1.0 mil, except that original primer coats applied in the field shall have a minimum dry film thickness of 1.5 mils. Where measurement of the dry film thickness may become difficult or dangerous unless the Contractor maintains or provides suitable means of access, wet film measurement may be authorized. In such cases the Engineer will predetermine and notify the Contractor of the required wet film thickness, for each type of paint, to comply with the minimum dry film thickness specified. Metal which has been shop coated shall be touched up with the same type of paint as the shop coat. This touch-up shall include cleaning and painting of field connections, welds, rivets, and all damaged or defective paint and rusted areas. The Contractor may at his option apply an overall coat of primer in place of touch-up or spot painting. Surfaces (other than contact surfaces) which are accessible before erection but which will not be accessible after erection shall receive all field coats of paint before erection. If possible, the final coat of paint shall not be applied until all concrete work is finished. If concreting or other operations damage any paint, the surface shall be cleaned and repainted. All cement or concrete spatter and drippings shall be removed before any paint is applied. Wet paint shall be protected against damage from dust or other detrimental foreign matter to the extent practicable. (6) Drying of painted metal.—The maximum practicable time shall be allowed for paint to dry before recoating or exposure. No drier shall be added to paint on the job unless specifically called for in the specification for the paint. No painted metal shall be subjected to immersion before the paint is dried through. Paint shall be protected from rain, condensation, contamination, snow, and freezing until dry, to the fullest extent practicable. (7) Handling of painted steel.—Painted steel shall not be handled until the paint has dried, except for necessary handling in turning for painting or stacking for drying. Paint which is damaged in handling shall be scraped off and touched up with the same number of coats and kinds of paint as were previously applied to the steel. Painted steel shall not be loaded for shipment or shipped until it is dry. Precautions shall be taken to minimize damage to paint films resulting from stacking members. 611.25 Cleanup. Upon completion, and before final acceptance, the Contractor shall remove all falsework, falsework piling down to at least 2 feet below the finished ground line, excavated or unused materials, rubbish, and temporary buildings. He shall replace or renew any fences damaged and restore in an acceptable manner all property, both public and private, which may have been damaged during the prosecution of the work, and shall leave the work site and adjacent highway in a neat and presentable condition satisfactory to the Engineer. All excavated material or falsework placed in the stream channel during construction shall be removed by the Contractor before final acceptance. Method of Measurement 611.26 Unit Basis. The quantity of structural steel to be paid for will be the number of pounds complete in place and accepted. For the purpose of measurement for payment components fabricated from metals listed in (a) below, such as: castings, alloy steels, steel plates, anchor bolts and nuts, shoes, rockers, rollers, pins and nuts, expansion dams, roadway drains and scuppers, weld metal, bolts embedded in concrete, cradles and brackets, posts, conduits and ducts, and structural shapes for expansion joints and pier protection will be considered as structural steel. Unless otherwise provided, the weight of metal paid for will be computed and based upon the following weights: (a) Unit weights, pounds per cubic foot: Steel, cast or rolled, including alloy, copper Zinc 173.0 536.0 558.0 445.0 470.0 487.0 707.0 490.0 450.0 (b) Shapes, plates, railing, and flooring. The weights of steel shapes and plates will be computed on the basis of their nominal weights and dimensions as shown on the approved shop drawings, deducting for copes, cuts, and open holes, exclusive of rivet holes. The weights of plates more than 36 inches in width include an estimated overrun computed as one-half the "permissible variation in thickness and weight" as tabulated in AASHO M 160. The weight of railing will be included as structural steel unless the bid schedule contains a pay item for bridge railing under section 612. The weight of steel grid flooring will be computed separately. (c) Castings.-The weight of castings will be computed from the dimensions shown on the approved drawings, deducting for open holes. To this weight will be added 5 percent allowable for fillets and overruns. Scale weights may be substituted for computed weights in the case of castings of small complex parts for which accurate computations of weight would be difficult. (d) Miscellaneous.-The weight of erection bolts, shop and field paint, galvanizing, and boxes, crates, and other containers used for shipping, together with sills, struts, and rods used for supporting members during transportation, bridge hardware as defined in subsection 716.02 excluding steel plates and bearings, connectors used for joining timber mem |