RDSO standard drawing for fabrication of composite steel Girder shall be used. The requirement of different size of plates shall be calculated from the standard drawings and procured well in time for start of fabrication work.
Based on the standard RDSO drawings the following works shall be carried out:
1.Shop Drawings: Standard RDSO drawings shall be followed for fabrication of Composite steel girder.
Changes, if any required,shall be brought to the notice of Supervision Consultant and concerned Railway Authority for suitable modification. On the basis of standard RDSO drawing the shop drawings shall be prepared for taking up.
2.Quality Assurance Plan:A Quality Assurance Plan specifying the type and frequency of checks and tests for all incoming raw materials, intermediate process, final clearance, etc. shall be prepared based on RDSO Specifications and general codes of practice. The QAP shall also specify the name of the inspection authority responsible for each check. The QAP shall be submitted to the Engineer-in-charge for approval, and shall be ultimately approved by the Railway Authority for use in the work. The approved QAP shall be strictly adhered during the execution of the work.
3.Welding Procedure Specification Sheets (WPSS):
Based on approved drawings, the agency shall submit the welding Procedure Specification Sheets for the different type of welding involved in the work .The WPSS will cover every type of weld corresponding to High Tensile or Mild Steel, and different thickness of plates and welding. Also the type of welding machine i.e., SAW or MIG and its type of consumables, flux, shielding inert gas etc. shall be specified, along with the standard limit settings for current, voltage, speed of wire, carriage, etc. This shall also be submitted to the Engineer-in-charge.
4.Welding Procedure Qualification Record (WPQR)/Welder Testing: Once the WPSS is approved by Railway, WPQR are established for the welders in order to qualify and engage them for particular machine or type of welding as required for welding on various bridge components.
5.Material Requirement & Order List As per scope of the work M/S BSC-C&C’JV’ shall work out the sections and sizes of plates and structural steel required for the work and order for procurement shall be placed for timely availability at site for start of
6.Preparations of Jigs & Templates, Layout A full scale layout will be done considering the nominal geometry of the span. All gussets jigs will be prepared
based on such layouts measurements. Nominal layout for the approved General Arrangement of the span shall be done on the layout platform constructed at site. The Joint details are marked on the platform as well as on plates to be preserved as templates during complete fabrication period. The layout is to be checked by
1.2 Testing of Raw materials: Once the QAP is approved, an inspector generally from Railway or other approved inspection agency shall be requested for necessary stamping on materials for their re-test as per QAP at NABL approved labs. After getting confirmation the materials are sent to cutting and preparation section and are cut as per approved.
1.3 Fabrication work: After clearance of raw materials cutting and preparation work is taken up. The edges are cleared properly by scrapping, grinding etc. and if required, these are straightened in straightening/rolling machines of adequate capacity. The cut materials are then sent to assembly area, earmarked for different bridge Depending on the type of components, fixtures are made to assemble and tack-weld (As per WPSS) the individual members, before shifting them to the welding zone. At this stage the tack-welded components are
checked for their correct dimension as per shop drawing and necessary records are made as stage clearance.
In the welding zone inside workshop, there would be different type of fixtures depending on actual requirement and keeping in mind the easy of handling, fixing time of job on fixture and so on.
After competition of welding on a member, it has to be checked for quality of welding i.e. size (visually) and Dye penetration test (DPT) for cracks, pin-holes etc. and for their rectification wherever necessary. Weld penetration is checked by micro-etching of run-on /run-off plates fixed at the end of each member. Records in this respect are to be maintained properly. After welding of components and inspection/checking by our QC department, The members are then checked for dimensional accuracy, warping, twisting etc. before releasing the members
for drilling, milling, grinding and so on. Once the members are checked by the supervision agency, these are then sent to machining area for drilling, milling & grinding. Drilling is done by using body jigs/end for main frame components. Components thus made ready are offered to the inspection Authority as per QAP, for final inspection. After drilling operation, the girder components will be shifted from fabrication platform.
1.4 Assembly & surface Preparation: After completion of the fabrication work the plate girders will be painted as per specification after sand blasting.
Then visual inspection and dry film thickness (DFT) measurement is done and these are cleared for onward
1.5 Stacking & Dispatch: Finally the girder elements will be stacked with proper erection marking over sleeper beds as per erection.
1.6 Test Assembly: Once all the members are manufactured for one span, these are assembled on support and checked for matching of holes for that span as per respective drawing. After above checking the intermediate point supports
are removed and the whole span is supported at bearing points alone. Subject to achieving satisfactory the Jigs.
1.7 Special requirement for fabrication work: All measurements need to be done with a calibrated steel tape. Calibration of the steel tape as per specification IS: 1270 need to be done a govt. approved laboratory.
All records of fabrication need to be maintained in the registers as per the format given in the Appendix-1 of IRS.
All fabrication tolerance will be as per Appendix-II of IRS B1-2001.
All the plates will be cut by using controlled torch oxy-acetylene flame cut machine.
All plates and sections shall be straightened and free from defects like twist and bends before they are used for
All welding to be done using SAW machine except inaccessible parts to be welded by CO2 welding using MIG. All
welding are to be done by certified welders.
All welding need to be done under covered shade.
All fillet welds need to be checked by DPT.
All butt welds need to be checked 100% by Radiographic testing.