螺栓技术要求

螺栓技术要求 In any group of steelwork tested, if 10% or more of a weld type proves defective, the level of NDT for both of the prescribed methods in Table 1 shall be increased to 100% for the welds already completed. If any of these welds prove defective, they shall be removed, replaced and retested. 4.8 Bolting General Unless specified otherwise, bolts shall be: , High strength structural bolts (Property Class 8.8) for all bolts 20 mm diameter and larger , Stainless steel Grade A4-70 for all bolts less than 20 mm diameter High strength structural bolts (Property Class 8.8), nuts and washers shall conform to the requirements of AS 1252. Commercial bolts (Property Class 4.6), nuts and washers, if specified, shall conform to the requirements of AS 1111. Stainless steel bolts, nuts and washers shall conform to the requirements of ISO 3506. Bolted joints between aluminium extrusions and painted steel shall be made with either 316 stainless steel or 6061-T6 aluminium alloy bolts and nuts and rigid PVC or ‘Nylon’ washers. In all cases where aluminium is to be in contact with a painted steel surface, a suitable isolating medium shall be provided between the two metals. This shall be Norton 550 tape, or accepted equivalent, applied in accordance with the manufacturer's recommendations. Bolted connections shall consist of a minimum of two bolts of 20 mm minimum diameter, unless noted otherwise. Bolts, nuts and washers of 16mm minimum diameter may be used for fastening tertiary members such as purlins and girts, handrails, kickplate and minor angle bracing. Stainless steel bolts and threaded rods shall be coated with nickel based anti-seize prior to tightening and shall be provided with stainless steel Nyloc nuts and two stainless steel washers (one each under the head and nut). Impact guns (electric or air) shall not be used to tighten stainless steel bolted assemblies. Manufacturer's test certificates shall be furnished covering breaking and proof strength. All bolts shall be designed for shear forces with the threaded portion assumed to project through the shear plane (that is "threads included", N/S condition). The length of each bolt shall be such that the threaded portion will project through the nut for at least two complete threads and such that the nut will be a least one thread apart from the thread run-out. Bolts in bearing shall be of such lengths that no threaded portion shall be within the thickness of the parts joined. For the design of bolts in bearing, at least one washer, but not more than two washers, shall be placed under the bolt head or nut, whichever is to be rotated. Taper washers shall be used where the part under the bolt head or nut is not perpendicular to the centreline of the bolt. Where possible, bolts shall be positioned so that the taper washers, if required, shall be fitted under the non- rotating part. Load indicating washers shall not be permitted. Bolts subject to severe vibration, vertical bolts in tension, bolts at sliding interfaces and all bolts carrying crane and/or hoist loads shall be locked in position by a method accepted by the Superintendent. Project 227267 | File 227267-001-SW-N-001_00.docx | 14 February 2012 | Revision 0 | Page 72 Fitted precision bolts in accordance with AS 1110 shall be used in bolted splices. Each bolt shall be match marked against the appropriate hole for which it was fitted, then labelled and packaged for transportation. Holes shall be reamed to achieve a minimum interference fit in accordance with AS 1654. No bolted splices shall be commenced before obtaining the acceptance of the Superintendent. All structural steel bolts, nuts and washers shall be hot-dip galvanised in accordance with AS 1214 and coated with suitable lubricant to facilitate the initial tightening. The nuts shall run "finger free" on the bolts after galvanising of both. Bolts shown as 8.8 or 8.8/S shall be tightened to snug tight condition. Bolts shown as 8.8/TB or 8.8/TF shall be fully tensioned in accordance with AS 4100 and this Specification. Mating surfaces shall be coated with inorganic zinc silicate primer. No other coatings shall be applied to the mating surfaces. After bolts have been tightened to their specified torque, the nut or bolt shall be marked with a permanent marker or similar to provide visual evidence that the bolted connection has been completed. A manual torque wrench, with current calibration certificate, shall be provided on site by the Contractor to allow checking of bolt tightness, by both the Contractor and Superintendent’s representatives. Where shown on the Drawings or accepted by the Superintendent, bolted joints may be packed to achieve the required tolerances. Such packing shall consist of a maximum of two stainless steel packers, sized to result in a 5mm recess around the perimeter of the bolted joint. The recess shall be neatly and completely filled with a polyurethane-based flexible sealant (Sikaflex or approved equivalent) prior to top coating of the entire joint. “Finger shims”, with slots allowing installation with the bolts in place, are not permitted for this type of application. Reference shall be made elsewhere in this specification for use of “finger shims” is permitted. Installation of bolts used in snug tight condition Commercial grade bolts and high strength structural bolts used in the "snug tight" condition shall be tightened so that the joined parts shall be firmly drawn together using a standard ring spanner or podger spanner or a calibrated torque or pneumatic impact wrench. The bolts shall not be overstressed and the applied torque shall not exceed that recommended by the bolt manufacturer. In no case shall the bolt tension exceed 65 percent or be less than 50 percent of the guaranteed yield load of the bolt. Bolts shall not be used to force fit the abutting material together and any lack of fit shall be referred to the Superintendent who shall determine the action to be taken. Installation of high strength bolts used in friction grip mode All high strength structural bolts for friction grip connections shall be assembled and tensioned in accordance with AS 4100. The assembly and tensioning of high strength structural bolts for friction grip connections shall not be commenced until the Superintendent is satisfied that the team or teams carrying out the work have been instructed in the procedures to be followed and that they are capable of carrying out those procedures correctly. Where practicable, the assembly and tensioning of friction grip connections shall be carried out by the same team or teams throughout the whole of the work of the Contract. Project 227267 | File 227267-001-SW-N-001_00.docx | 14 February 2012 | Revision 0 | Page 73 Unless otherwise accepted by the Superintendent, all high strength structural bolts for friction grip connections shall be tensioned using the part-turn method. Match marking shall be permanent, preferably made with a heavy centre punch. Where bolts are not galvanised and where accepted by the Superintendent, the torque control method may be used for tensioning high strength structural bolts. All torque wrenches or pneumatic impact wrenches used for tensioning shall be calibrated on site at least once per shift, as specified in AS4100. Load-indicating washers shall not be used for tensioning high strength structural bolts. Notwithstanding any acceptance by the Superintendent of the general use of torque control methods of tensioning, the Superintendent may direct that any bolt or any number of bolts be tensioned by the part-turn method. Should the use of torque control methods be accepted by the Superintendent, the Contractor shall make due allowance in the Contract Sum for all costs and charges for materials, testing and calibration as specified above and no claims for additional payments arising out of these requirements shall be considered. Unless accepted by the Superintendent, high strength structural bolts which have been fully tensioned once, shall not be retightened and shall be discarded. Such acceptance will only be given when the bolts have been removed entirely from the joint and handed to the Superintendent for examination and acceptance. Where bolts are accepted by the Superintendent for re-tightening, they shall be tensioned by the part-turn method only. Installation of fitted shoulder bolts Where fitted shoulder bolts are to be clamp tightened, the joined parts shall be firmly drawn together using a standard ring spanner or podger spanner or a calibrated torque or pneumatic impact wrench. Care shall be taken not to over-stress the bolts and the bolt tension stress shall not exceed 65% of the guaranteed yield stress of the bolt material. Where fitted shoulder bolts are used as a trunnion pin, the nut shall be tightened firmly but so as not to prevent the joined parts from rotating as required. The nut shall be held in position with a split pin or other accepted locking device. The bolt, the washers and the faces of the rotating parts in contact shall be greased with an accepted proprietary grease containing molybdenum disulphide. 4.9 Prestressing bars Prestressing bar shall comply with AS 1313 to dimensions as detailed on the Drawings. All bars shall be super grade. Spherical nuts and washers shall be used on all bars. Manufacturer's test certificates shall be furnished covering breaking and proof strength, together with a stress-strain diagram. Bars shall carry a label showing the batch identification serial number or other mark to identify them with the test certificate. Samples of tendons shall be supplied for testing. Bars shall be kept clean and dry and all grease, oil, paint, loose rust and other foreign matter shall be removed from the steel before it is placed in the ducts. Any bar that is corroded, kinked or otherwise damaged shall be rejected. Tensioning of bars shall be accomplished using a suitable bar-jacking system as accepted by the Superintendent. Evidence of calibration of the jacks by a NATA certified laboratory shall be provided. Project 227267 | File 227267-001-SW-N-001_00.docx | 14 February 2012 | Revision 0 | Page 74