Steel roof truss fabrication

1 scope

This technology is applicable to General steel manufacturing engineering of steel roof truss.

2 construction preparation

2.1 materials and equipment:

2.1.1 steel: according to the design drawings or 16 MN steel Q235 steel, steel quality certificate, and should comply with the design requirements and the provisions of the existing national standards.

2.1.2 connection materials: materials such as welding rods, bolts shall have the quality certificates and comply with the design requirements. Coating off or cores rusty electrode, rust, scratches or mixed batches of high-strength bolts shall be used.

2.1.3 coatings: anticorrosive paint should comply with the design requirements and the relevant provisions of the standards, and have certificates of product quality and instructions for use.

2.1.4 main tool: shearing machine, shaped steel straightening machine, steel rolling mill, drill press, drill, counterbore drill electric welding, gas welding, arc-air gouging equipment steel platform; sandblasting and spray equipment, and so on.

Tools: tools, angle square, calipers, Scriber, marking, hammer, chisel, like rush, crowbar, wrench, straightening, clamps, drills, jacks, etc.

2.2 operating conditions:

2.2.1 production according to design company before providing the design document drawing construction detail, when the ability to modify and design units to conduct negotiation procedures.

2.2.2 prepared in accordance with the requirements of the design documents and construction details the manufacturing process file (process).

2.2.3 ruler used in fabrication, installation, inspection, acceptance, and its accuracy should be consistent, and verification is obtained by the legal metrology and testing departments.

3 operational processes

3.1 process:

Processing preparing and cutting machining → → small Assembly (small pieces) → General Assembly (total pieces) → roof welding →

Support connecting plate, Purlin, seat angle fitting, welding ¡ú finished products → removing rust, paint, numbers

3.2 processing under preparation and materials:

3.2.1 layout: according to construction plot layout, layout and marking should be reserved for welding contraction and machining, go through the preflight procedures by inspectors to reinspect.

3.2.2 setting out a model (sample).

3.2.3 correction of steel: steel cutting must be carried out before modification, correction of deviation should not exceed the specification allows deviation in order to guarantee the quality of materials.

3.2.4 under on roof, no strings, not holes, holes, remaining parts should be; hot-working steel thermal processing, after cooling holes.

3.3 parts processing:

3.3.1 cutting: cutting steel cutting area before rust, dirt should be cleaned. Fracture surface after cutting edge melt tumors, flying objects should be removed. Mechanical shear plane should not have cracks and larger than the LMM short cord and wool should be cleared.

3.3.2 welding: the upper and bottom section you need long, welding and straightening. Steel connector, joint with rod steel against steel, shovel cord angle according to design requirements. Butt weld ends welding arc plate, the material and the wave shape and weld the same, cutting after welding removal and grinding.

3.3.3 drill: ends of roof truss steel drill bolt holes of the base plate application, to ensure that the bolt hole locations, dimensional accuracy. Web and connecting plate bolt holes can be the common method drill.

3.4 small Assembly (small pieces): roof truss ends t-shaped base, skylight frames bearing plates welded components in advance, the correction and then assembled on the roof. Parts welded to prevent distortion, should be used in pairs back-to-back, clamp clamp for welding.

3.5 Assembly (total pieces):

3.5.1 the sample placed on the Assembly table, in accordance with the construction drawing and welding shrinkage process arch and set aside. Assembly platform should have a certain degree of stiffness, not deformed, affect the precision Assembly.

3.5.2 in accordance with samples first, last quarter, Web positioning, such as angle steel lap welding on the Assembly table.

3.5.3 the upper and bottom plate and connection plates placed on the sample, the condemnation, and then on the top and bottom connecting plate, making it close to the orientation angle. After half a piece of roof truss bar full set, in accordance with the construction check, you can tack weld.

3.5.4 spot good half roof flips 180 degrees, to half a piece of roof trusses for bobbin Assembly roof trusses for copies.

3.5.5 on the bobbin half a piece of roof truss plate, connection and base plates. Base plate and roof skylights support, vertical rods with hole in the middle of positioning plate bolted to ensure component dimensions accurately.

3.5.6 the upper and bottom chord and Web members placed on the connecting plate and plate, clamp clamping and tack weld.

3.5.7 on the bobbin half you have spot roof flips 180 degrees, can be on the other side, and the bottom chord and Web members placed on the connecting plate and plate, steel back alignment Jig clamps, positioning spot welding, spot welding is complete new roof frame Assembly is complete, remaining truss Assembly are repeated in the above order.

3.6 truss welding:

3.6.1 the welder must have a post certificate. Place welders in welding should be commensurate with the welder's skill level.

3.6.2 welding should be reviewed before the Assembly quality and the processing of weld zone, lift the rear weld.

3.6.3 welding sequence: weld welded top and bottom chord lateral connection plates, then top and bottom connecting plate inside weld, weld welding plate and spandrel; the last welding webs, chord, bottom chord between the pads. Roof flips out after all welding, soldering on the other side, the welding in the same order.

3.7 support connection angle plate, Purlin bearing Assembly, welding: connecting plate positions of samples drawn, will align the support plate Assembly and tack weld. Also draw the angle position and assembled weld bulldozed, purlins, seat angle in Assembly location and the anchor spot. All assembled and began seat angle welding purlins, supported connection plates. After the welding, slag and spatter should be cleared. Welds and parts specified in the process, welding on steel seal.

3.8 product testing:

3.8.1 welding completed weld cooling 24h, Visual inspection and make all records. I, II level ultrasonic testing of the welds should be.

3.8.2 the use of high-strength bolt connections, components of friction surface must be sand blasted and six specimens, three of which group was shipped to the installation site, coefficient of friction for re-inspection.

3.8.3 required by the construction documents and construction norms, to check the finished contour geometry size, PIN-by-frame recording.

3.9 removing rust, paint, numbers:

3.9.1 after quality inspection, the finished product for rust, rust only after painting.

3.9.2 coating and film thickness should comply with the design requirements or provisions of the code. To salvage steel no missing coating of paint on the inside.

3.9.3 number marked on the component specifies the widget.

4 quality criteria

4.1 project:

4.1.1 production of steel roof truss before the evaluation, to conduct a quality assessment for welded and bolted connections, meeting the prescribed standards before they can proceed.

4.1.2 the varieties, specifications, models and qualities of steel must comply with the design requirements and the relevant provisions of the standard.

4.1.3 steel cutting surface must be free of cracks, slag layer is greater than the LMM's lack of information.

4.2 Basic project:

4.2.1 widget appearance the surface concave and without obvious damage, scratch depth is not greater than 0.5mm. Welding scar, spatter, Burr should be cleaned.

4.2.2 bolt holes smooth, Burr-free, deviation is less than the thickness of the vertical hole 2%, hole circle degree deviation is less than 1%.

4.3 allowable deviation, as shown in table 5-12.

Table 5-12

Project tolerance (mm) test method

Both ends of the roof truss of the outer end of holes or l 24m +3-7

Supporting the outermost distance L>24m +5-10 steel rule check

2 roof truss mid-span height ± 10

Design does not require camber +10-5

Design arch ± L/5000 cable, steel rule check

4 chords between adjacent sections of curved L/1000

5

The connector space of fixed dimension ± 5

6 bearing surface to the first mounting hole pitch ± 1

Axises intersection after the dislocation line 3 7 nodes, using tools to check

Note: l is length of roof trusses; l for chords in the distance between adjacent nodes.

5 finished product protection

5.1 when stacking components, you must pad flat on the ground, avoid pivot force. Roof truss hanging points, protection should be reasonable; should be made to prevent deflection or distortion due to poor lateral stiffness.

5.2 steel components should be coated with rust-inhibiting primer, the number shall not be damaged.

6 quality problems to be noticed

6.1 component transport, stacking variant: when transporting, stacking, cushion unreasonable, underlay wood is not on a vertical line, or deformation due to ground subsidence and other reasons. As deformation occurs, according to Jack, oxy-acetylene flame or by using other tools to correct.

6.2 component distortion: assembling steel doesn't match the season point, steel and node at the connection plate a gap between larger than 3mm should be corrected, when assembled clamp clamp. Latrun long component line, meet the requirements, and then tack weld fixing. Members turn over a long time due to insufficient rigidity may deform, be subject to the temporary reinforcement.

6.3 arch does not meet the requirements: when assembling of steel roof truss, perspective should strictly check the Assembly Jig and take measures to eliminate welding contraction effects, and control, to avoid errors.

6.4 welding deformation: the proper weld sequence and the welding process should be used (including the welding current, speed, direction, etc) or using fixed jigs, tooling components, and then welded to prevent warping after welding.

6.5-span are not allowed to: produce, lifting, check accuracy of ruler. Check component manufacture sizes, not exceeding tolerance.

7 quality records

This standard shall meet the following quality records:

7.1, connection of steel materials, and materials quality certificate, the test report.

7.2 steel structure factory certificate.

7.3 main component inspection records.

7.4 design changes and technical record of negotiation.

7.5 weld seam ultrasonic inspection report, coefficient of friction surface slip resistance test reports, coating inspection records.

7.6 component shipping and packing list.