This technology standard is applicable to the ground assembly engineering of steel grid structure with bolted ball joints, welded ball joints and welded steel plate joints.
2. 1, material:
2. 1. 1, steel and connecting materials assembled by steel grid, high-strength bolts, covered electrode and other materials should meet the design requirements, and should have the factory certificate.
2. 1.2, semi-finished products such as bolt balls, hollow solder balls, auxiliary solder balls, cone heads, sleeves, sealing plates, grating bars, welded steel plate joints, etc. Should comply with the design requirements and the provisions of the corresponding national standards.
2. 1.2.65438+ The bolt ball is forbidden to be burnt, cracked or planted, and the finished ball must be tested for the maximum tensile strength of the screw hole.
2. 1.2.3 The varieties, specifications and quality of solder ball materials used for assembly must meet the design requirements and relevant standards. Covered electrode, flux, welding wire and shielding gas for welding shall meet the corresponding technical requirements and regulations. Welding balls shall have factory certificate and steel ball bearing capacity inspection report.
2. 1.2.4, steel grid assembly plate, cone head and sleeve steel must meet the design requirements and corresponding technical standards. The sealing plate, cone head and sleeve have cracks, burns and oxidation.
2. 1.2.5. The steel plates used for assembling and welding the steel grid must meet the design requirements and corresponding technical standards. Welding materials shall have factory certificate and corresponding technical standards. The assembly welding of steel plate joints shall meet the design requirements.
2. 1.2.6. The varieties, specifications and quality of steel bars used for assembling steel grid structures must comply with the design regulations and corresponding technical standards. The connection between steel pipe members, sealing plate and cone head must meet the design requirements, and the quality standard of weld must meet the secondary quality standard in the current national standard "Code for Construction and Acceptance of Steel Structure Engineering". The strength test should be carried out on the weld between the steel pipe member and the sealing plate or cone head, and its bearing capacity should meet the design requirements.
2.2. Main machines and tools
Electric welding machine, oxyacetylene equipment, grinding wheel saw, steel pipe cutting machine, steel tape measure, steel ruler, vernier caliper, thickness gauge, ultrasonic flaw detector, magnetic flaw detector, hammer, wire brush, caliper, dial indicator and other testing instruments.
2.3, operating conditions:
2.3. 1, the assembly welder must have the welding examination certificate, and have the corresponding welding materials and welding station qualification certificate.
2.3.2 Before assembly, the assembly site shall be equipped with safety facilities and fire prevention facilities. Before assembly, the assembled fetal position should be detected to prevent the fetal position from moving and deforming. Appropriate welding deformation allowance should be left in the assembly fetal position to prevent the assembly rod from deformation and angular deformation.
2.3.3 Before assembly, the bar size, groove angle and weld gap shall comply with the regulations.
2.3.4, familiar with drawings, preparation of assembly process, technical disclosure.
2.3.5 Before assembly, the high-strength bolts used for assembly shall be tested for hardness one by one, and can be assembled only after reaching the standard value.
3. 1, process flow:
Operation preparation → ball processing and inspection → rod processing and inspection → small assembly unit → medium assembly unit → welding → assembly unit acceptance.
3.2, homework preparation:
3.2. 1. Adjustment of machines and fixtures, determination of angles and preparation of machines and tools during bolt ball processing.
3.2.2, welding ball processing; Preparation of heating furnace, adjustment of solder ball press and preparation of fixture.
3.2.3. Fabrication and installation of solder ball semi-circular surface frame.
3.2.4 Selection of welding equipment and setting of welding parameters, installation and debugging of automatic welding equipment, and installation of oxyacetylene equipment when automatic welding is adopted.
3.2.5. High-strength bolts for assembly shall be protected one by one before assembly, so as to prevent the flash base from affecting the threads during small-scale assembly.
3.2.6, covered electrode or flux for baking and heat preservation, welding material heat preservation baking should have a special oven.
3.3, steel ball processing and inspection:
3.3. 1, control of ball blanking size. And appropriate allowances should be paid.
3.3.2. Marking and processing of bolt balls, including milling, angle splitting, drilling, tapping, inspection, etc.
3.3.3 The heating temperature of solder ball materials should be between 600℃ and 900℃, and the heating should be uniform. The heating furnace is preferably a gas furnace.
3.3.4. Put the heated steel into a semicircular fixture frame and gradually press it into a semicircular ball. In the process of pressing, the area and amount of thinning should be reduced as much as possible, and measures should be taken to heat evenly. Mill scale should be cleaned in time when pressing, and the semi-sphere can change its position in fetal position.
3.3.5. After the hemisphere is cooled, use the template to correct the radian of the hemisphere, and then cut the plane of the hemisphere. Pay attention to cutting by radius, but leave a rounding allowance.
3.3.6 After hemispheric correction and cutting, grooves should be made, and the angles and shapes of the grooves should meet the design requirements.
3.3.7, ribbed hemispheres and hollow solder balls bear different forces, so the important nodes of steel grid structure are generally arranged with ribbed solder balls, and there are many kinds of ribbed balls, including single auxiliary and vertical double ribbed balls. So before assembling the balls, they should also be ribbed and welded. Note that the height of the rib should not exceed the circumferential radius, so as not to affect the assembly.
3.3.8 When assembling the ball, there should be fetal position to ensure the assembly quality. The assembly of the ball should keep the assembly diameter and roundness of the ball consistent.
3.3.9. Put the assembled ball on the welding fixture, and punch a small hole on each side to fix the ball. It can rotate the bed slowly, adjust the weld bead, adjust the height of welding wire and adjust various welding parameters. Then, use semi-automatic submerged arc welding machine (or gas shielded welding machine) to carry out multi-layer and multi-pass welding on the ball until the weld bead is flat without superelevation.
3.3. 10, weld appearance inspection, after passing the inspection, ultrasonic flaw detection shall be conducted for steel ball weld after 24h.
3.4, bar processing and inspection:
3.4. 1. Quality inspection of steel pipe components before blanking: overall dimensions, varieties and specifications shall meet the design requirements. When cutting steel bars, the length change after assembly should be taken into account. In particular, the size of the passing bar should consider many factors, such as the slight change of the bar size caused by the deviation of the ball and the deviation of the bar caused by the seasonal change. Therefore, the size of bar blanking should be carefully adjusted to prevent batch error after blanking.
3.4.2, reinforced after blanking should check whether bending, bending should be corrected if any. Slotting is required after the bar is cut, and the wall thickness of the welded club is below 5mm, so slotting is not required. Bolt club parts must be slotted.
3.4.3. Requirements for assembling steel pipe members and sealing plates: The steel pipe members and sealing plates must be assembled with positioning fixtures to ensure the length consistency of the assembled steel pipe members. After positioning the rod and sealing plate, fix them and check the depth and width of the weld. There should be 30 grooves on both sides of the bar and the sealing plate with a gap of 2 ~ 5 mm to ensure the welding quality of the sealing plate. Sealing plate welding should be carried out on the rotary welding bracket, and the weld should be thorough, full and uniform, without biting meat.
3.4.4. Requirements for assembling steel pipe rod and cone head: The rod and cone head must be assembled with positioning fixture to keep the length of the assembled rod consistent. Check the width and depth of weld bead after the anchor point of bar and cone head is fixed. Bar and taper head shall be chamfered on both sides with a gap of 2 ~ 5 mm to ensure weld penetration. Cone head welding should be carried out on the rotary welding bracket, and the weld should be thorough, full and uniform, without biting meat.
3.4.5 Before assembling the bolt ball grid, the corresponding high-strength bolts should be embedded. Before embedding, the hardness test and appearance quality inspection should be carried out for the high-strength bolts one by one. The high-strength bolts in question cannot be embedded.
3.4.6, steel welding will damage the embedded high strength bolts, such as lighter, splash, etc. Therefore, before assembling and welding steel bars, the embedded high-strength bolts should be well protected to prevent electric arcs and splashes from splashing into the threads, so a package is usually added after embedding for protection.
3.4.7 Finished product protection of steel mesh frame members: steel members should be painted with antirust paint, and high-strength bolts should be protected to prevent corrosion. Steel members of the same variety and specification shall be packed neatly.
3.5, steel grid small spell unit:
The small assembly unit of steel grid generally refers to the assembly of welded spherical grid. The bolt ball grid structure can be installed after the bar assembly and bearing assembly, without a small assembly unit.
3.5. 1. Before assembling the steel grid, the assembled steel balls shall be subjected to strength test, and the assembly can be started only after they meet the requirements.
3.5.2. Clean up the small assembly site, and pay off and draw lines according to the size and shape of the small assembly unit. According to the compiled small spelling scheme, the assembled fetal position should be made, and the convenience of assembly and delivery should be considered in the design of assembled fetal position.
3.5.3 Weld and assemble the fetal position to prevent deformation, and reinspect the assembly dimensions of each part.
3.5.4. There are two types of welded ball grids: lined and unlined. Where lining is needed, prepare the lining and fix the ball first.
3.5.5, steel grating solder ball small spell form:
3.5.5. 1, one-ball-one-rod type is the simplest form, and attention should be paid to small assembly size and welding quality.
3.5.5.2, with two balls and one rod, should prevent the rod from deforming after assembly and welding.
3.5.5.3, a ball with three rods, should pay attention to maintain the angle and size of semi-finished products after assembly to prevent welding deformation.
3.5.5.4, one-ball four-bar type, should pay attention to welding deformation after assembly to prevent deformation during stacking. Generally, temporary connecting rods should be added between legs to keep the angle and size.
3.5.6 After welding ball grid, it should be welded firmly, with full weld seam, incomplete penetration and even welding slope. After visual inspection of welds, ultrasonic inspection is required.
3.5.7. The size inspection of small splicing unit shall conform to the factory regulations: when the small splicing unit is a single cone, the chord length and cone height shall be 2.0mm；; The diagonal length of the upper chord is 3.0mm；; The center deviation of the bottom chord node is 2.0mm；;
If the small splicing unit is not a single cone, the allowable deviation of the node center is 2.0 mm
The allowable deviation between the welded ball joint and the steel pipe center is 65438 0.0mm..
3.6, welding ball grid in the spell unit:
3.6. 1. In the construction of welded ball grid structure, the assembly form from ground to high altitude can also be adopted. This assembly form can be divided into: strip assembly, block assembly, cake assembly in three-dimensional unit and so on.
3.6.2, control the size and deformation of the assembled unit, the assembled assembled unit should have enough stiffness and ensure its geometric invariance, otherwise temporary reinforcement measures should be taken.
3.6.3. In order to ensure the smooth assembly of the grille, measures such as installing bolts can be adopted at the joint of bars or blocks.
3.6.4, erection of split support, the position of the support point should be located in the bottom chord node. Support should check its bearing capacity and stability, and if necessary, carry out pressure test to ensure safety and reliability. It is also necessary to prevent the bracket from sinking.
3.6.5. For the assembly units in the grid, intermediate transportation should be reduced. If transportation is needed, measures should be taken to prevent the grid from deforming.
3.7, steel grid assembly welding:
3.7. 1, welding ball grid structure should be prepared before assembly welding process and welding sequence. Welding technology, including current, voltage, strip conveying mode, welding layers and passes, weld groove and gap, is the key to ensure weld quality. Welding sequence refers to welding between assembly points to control the deformation of components.
3.7.2, steel mesh welding technology is difficult, high quality requirements. Therefore, the grid assembly welder must have an all-position welder examination certificate, that is, the examination certificate of horizontal, vertical, horizontal and upward positions, before he can take up his post.
3.7.3 Welding materials for assembly and welding shall be baked and insulated to ensure the service performance of welding materials.
3.7.4, steel grid welding operation:
3.7.4. 1, steel pipe and steel ball welding is the main weld of steel grid. The arc striking should be 20 ~ 30 mm to the left of the center line at the bottom of the steel pipe, and the arc striking should be carried out in the weld to prevent the base metal from being burned.
3.7.4.2, after striking the arc, transport the steel bar to the right for welding. The method of transporting bar adopts oblique sawtooth technology to prevent molten iron from losing and biting meat. When using oblique zigzag process, slag backflow should be prevented.
In 3.7.4.3, when covered electrode is welded to 1/4 circle, it is necessary to gradually change the bar conveying mode, which can be changed to crescent bar conveying mode. When it is close to the upper part, it should be conveyed by anti-oblique sawtooth strip to prevent meat biting.
In 3.7.4.4, the arc extinguishing of the weld should be 20 ~ 30 mm above the center line of the weld, so it is not necessary to completely fill the arc pit.
3.7.4.5, then weld the other half of the steel pipe, start arc welding from 20 ~ 30 mm on the right side of the weld center line, convey the bar to the left, adopt zigzag strip conveying mode, and gradually weld it to the upper left until nearly 1/4 circle is changed to crescent strip conveying. When welding to the upper part, it can only be started after it meets the regulations. Reverse zigzag transportation, beautiful and full weld shape.
3.7.4.6, close the arc. When covered electrode is gradually welded to the upper part, it is crawling welding at this time, and it has become flat welding when it reaches the upper part of the steel pipe. At this point, covered electrode should continue to weld the center line for 20 ~ 30 mm and cover a weld until the arc pit is filled.
3.7.4.7, when multi-pass welding is adopted, or the groove of the weld bead is not yet filled, the welding slag of the weld bead shall be removed, and welding shall be continued in the above order until the specified weld bead size is reached.
3.8, assembling unit acceptance:
3.8. 1, check the grid length, width, diagonal and grid length of the assembled unit grid, which should be within the allowable deviation range.
3.8.2, check the quality of the solder ball, and have a test report.
3.8.3, check the steel quality and tensile bearing test report.
3.8.4, check the hardness test value of high-strength bolts, check the test report of high-strength bolts.
3.8.5, check the welding quality of the assembly unit, weld appearance quality, mainly to prevent biting, biting depth shall not exceed 0.5mm；; Weld 24h4. 1 to ensure that the project shall meet the following requirements:
4. 1. 1, the variety, model, specification and quality of steel shall meet the design requirements and the provisions of current national standards.
Inspection method: check the steel quality certificate or reinspection report. Steel rules or calipers should be used to check the steel specifications.
4. 1.2. The specifications, varieties and quality of solder balls, bolt balls, connecting plates, high-strength bolts, cone heads, sealing plates, sleeves and rods shall meet the design requirements and the provisions of current national standards.
Inspection method: check the quality certificate, factory certificate and test report.
4. 1.3. When the quality of the public consultation frame structure with a building structure safety level of Grade I and a span of 40m or more is in doubt, the following items shall be reinspected on site;
4. 1.3. 1. Welded ball joints shall be welded into test pieces with steel pipes and steel balls according to the design, and the uniaxial tensile and compressive bearing capacity test shall be carried out.
4. 1.3.2. The bolt ball joint shall be tested for the tensile strength of the thread of the largest bolt hole of the finished ball. The results should conform to the current national standards.
Inspection method: check the quality certificate and reinspection report.
4. 1.4. Before assembling solder balls, derusting shall be carried out and solderable antirust paint shall be applied.
Inspection method: observation and inspection.
4. 1.5, the grid structure shall not be forced to deform during assembly.
Inspection method: Observe and inspect the assembly records.
4.2. Basic projects shall meet the following requirements:
4.2. 1. Appearance quality of welded ball, bolt ball and bar after assembly:
Qualified: the local roughness of the ball surface should not be greater than l.5mm, and the surface oil stain and splash should be cleaned up.
Excellent: the local roughness of the ball surface should not be greater than 1.0mm, and the oil stain and splash on the surface should be cleaned up.
Inspection quantity: 5% of nodes are randomly selected, but not less than 5 nodes.
Inspection method: use arc sleeve mould, feeler gauge and observation inspection.
4.2.2. Appearance quality of assembled joint plates and steel bars:
Qualified: the surface should be free of obvious concave surface and damage, the scratch depth should not be greater than 0.5mm, and the welding scar and burr should be basically cleaned.
Excellent: the surface should be free of obvious concave surface, damage and scratches, and welding scars and burrs should be cleaned up.
Check the quantity; Spot check 5% according to the number of nodes, but not less than 5.
Inspection method: observation and inspection.
4.3. The allowable deviation items shall meet the following requirements:
4.3. 1, allowable deviation items and inspection methods of small assembled units of grid structure.
4.3.2. Allowable deviation items and inspection methods of grid bar assembly.
The inspection quantity shall be fully inspected by strip or block.
4.3.3. Allowable deviation items and inspection methods for ground assembly of grid structure.
Inspection quantity: all inspections.
Then use ultrasonic flaw detection to check the internal quality of the weld.
5. 1, the assembled small assembling units shall be packed neatly, and shall not be piled up in disorder to prevent deformation.
5.2, grid semi-finished ball, high strength bolts, etc. It should be packed in a clean place to prevent sticking and oil pollution and damage to threads.
5.3. After assembling units in the grid, transportation should be avoided to prevent the grid from being deformed due to uneven stress during transportation.
5.4 After the grid is assembled, antirust paint shall be painted in time to prevent the grid from corrosion.
6. 1. In general, the size of assembled small units of steel grid structure should be controlled within the negative tolerance range. If positive tolerances accumulate, the mesh size will increase and the axis will move.
6.2. Fixtures used for assembling steel grid structures should be inspected frequently to prevent the fixture from deforming and the small assembly unit from deforming.
6.3. Assembled steel balls and bars shall be numbered and marked to prevent confusion during use. Steel balls should also be marked with the center line, especially the use direction of ribbed steel balls is strictly regulated, so the direction with auxiliary should be clearly marked.
6.4. Packaging and delivery. When steel grating needs to be shipped after assembly, the semi-finished products should be packed. Packaging should be carried out after the coating is dried. Packaging should protect the coating of components from damage and ensure that components and parts are not deformed, damaged or lost. Packaging should comply with the relevant provisions of transportation.
This process standard should have the following quality records
7. 1. Material certificates and factory certificates of solder balls, bolt balls and high-strength bolts, as well as load-bearing tensile test reports of the above varieties and specifications.
7.2, steel material certificate and retest report.
7.3, welding materials and coating materials material certificate, factory certificate.
7.4, sleeve, cone head, sealing plate and other important steel material report and factory certificate, weldability test report.
7.5, steel pipe specifications, varieties should have material certificate or retest report.
7.6, steel pipe and sealing plate, cone reinforced should have bearing test report.
7.7. The movable (sliding) bearing of steel grid structure shall have the factory certificate and test report.
7.8, welder certificate, there is a corresponding station project, the project has the corresponding welding materials.
7.9. Inspection and acceptance data of assembly unit.
7. 10, weld appearance inspection and acceptance record.
7. 1 1, ultrasonic flaw detection report and record of weld.
7. 12, paint inspection and acceptance records.
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