Guangzhou Steel tells you: assess Steel Works Welding Technology
1, the construction unit for the first time use of steel, welding materials, welding, joint type, welding position, post-weld heat treatment, a combination of various parameters and parameters should be in front of steel structure fabrication and installation of welding procedure qualification test. Welding procedure qualification test methods and requirements, and exempt from restrictions assessment process should be consistent with existing national standards "Steel Welding Code" GB 50661 of the relevant provisions.
2, before welding construction, the construction unit should be qualified welding procedure qualification results or used in line with the conditions for the exemption procedure qualification basis, the preparation of the welding process documents, and should include the following:
(1) a combination of welding or soldering method;
(2) the base material specifications, grade, thickness and coverage;
(3) the filler metal specification, category and type;
(4) The form of welding joints, bevel form, size and tolerance;
(5) welding position;
Species (6) welding power source and polarity;
(7) clean-treatment;
(8) welding parameters (welding current, welding voltage, welding speed, welding layer and bead distribution);
(9) road between preheating temperature and temperature range;
(10) post-weld stress relief treatment process;
(11) other necessary requirements.
Ⅱ welding work conditions
3, welding, operation area ambient temperature, relative humidity and wind speed should meet the following requirements when the provisions of this article and must be welded beyond, shall prepare special programs:
(1) Operating ambient temperature is not lower than -10 ℃;
(2) Relative humidity welding work area shall not be greater than 90%;
(3) When the SMAW and self-shielded flux-cored arc welding, welding work area shall not exceed the maximum wind speed 8m / s, when the gas shielded arc welding work area shall not exceed the maximum wind speed 2m / s.
4, site altitude welding job should secure operating platform and puts up protective shed.
5, prior to welding, wire brush should be used, wheel and other tools to remove oxide surfaces to be welded at the rust, oil and other debris, weld groove should be according to the current national standard "Steel Welding Code" GB 50661 of the relevant provisions were an examination.
6, welding parameters welding procedure qualification of the job should be.
7, when the welding operation at ambient temperatures below 0 ℃ and not lower than -10 ℃, heating or protective measures should be taken, should be welded joints and welding surface in each direction is greater than or equal to 2 times the plate thickness within the range of not less than 100mm The base material is heated to a predetermined minimum preheat temperature not lower than 20 ℃ before welding.
Ⅲ tacking
8, positioning weld thickness of not less than 3mm, should not exceed 2/3 of the design throat thickness; length less than 40mm and joints four times the thickness of the thinner parts; spacing is preferably 300mm ~ 600mm.
9, positioning the weld seam with the official should have the same welding process and weld quality requirements. Multi-channel positioning weld ends should be stepped. Use of welded joints of steel liner plate, tack welds should be carried out within the joint groove. Positioning welding preheat temperature should be higher than the official welding preheat temperature 20 ℃ ~ 50 ℃.
Ⅳ arc plate, lead plate and spacer plate
10, when the arc plate, lead plate and spacer plate when the steel should be used in the yield strength of the steel is not greater than the nominal strength steel welding and welding should be similar.
11, the ends of welded joints should be set arc weld plate, lead plate. Arc welding and gas shielded arc welding lead length should be greater than 25mm, submerged arc welding seam lead length should be greater than 80mm. Welding is completed and fully cooled, can be flame cutting, carbon arc gouging or mechanical methods such as removing the arc plate , leads to the plate and be grinding smooth. Do not use a hammer shot down.
12, steel liner plate should be snug fitting connection with the base material, the gap should not be greater than 1.5mm, and should be fully weld fusion. When manual arc welding and gas shielded arc welding, steel liner plate thickness of not less than 4mm; when submerged arc welding, steel liner plate thickness of not less than 6mm; electroslag welding steel liner plate thickness of not less than 25mm.
Ⅴ preheat and interpass temperature control
13, preheat and channel temperature control should be used electric heating, flame heating and infrared heating and other heating methods, and should be dedicated thermometer measurements. Heating area should be preheated welding groove on both sides, the width should be the thickness of weldment welding at least 1.5 times, and should not be less than 100mm. Temperature measurement point, when a non-member enclosed space, preferably in the weldment the back of the heating surface of the weld groove from both sides at no less than 75mm; when the member is a closed space, preferably in the front side from the weld groove at not less than 100mm.
14, preheat temperature of welded joints and track temperatures should be consistent with current national standard "Steel Welding Code" GB 50661 of the relevant provisions; when the process of selection of the preheating temperature is lower than the current national standard "Steel Welding Code" GB 50661 The relevant provisions, should be determined by the procedure qualification test.
Welding deformation control Ⅵ
15, welding technology and welding sequence used should be minimal deformation and contraction member, Guangzhou steel welding sequence can be used to control the deformation of the following:
(1) butt joints, T-joints and cross joints, in the case of component placement conditions allow or easily reversed, should be double-sided symmetrical welding; symmetrical cross-section of members, should be symmetrical to the member neutral axis welding; symmetrical connecting rods node element, the node should be symmetrical axis of symmetry while welding;
(2) double-sided asymmetric groove welds are advised deep groove weld seam side part, then weld groove side full of light, to finalize the deep groove side seam. Special plate should increase rotation symmetrical weld cycles;
(3) long seam welding method should be used back-step, jump or more symmetrical welding method welding;
16, when members of a welding, soldering reserve should adopt anti-shrinking margin or pre-deformation method of controlling shrinkage and deformation, shrinking margins and anti-deformation value should be determined by calculation or test.
17, when the member assembly welding, weld shrinkage should be larger joints, a small amount of shrinkage after welding joints, welding joints shall be binding in smaller states.
Ⅶ stress relieved after welding
18, design documents or the contract documents after welding eliminate the stress required and be subjected to tensile stress in the butt joints or welds concentration of nodes or components by fatigue check the structure, should adopt the electric heater and partial annealing furnace annealing overall and other methods of stress relieving; when only stable structure size, vibration method can be used to eliminate stress.
19, the heat treatment should be consistent with the current industry standard "carbon steel, low alloy steel weld heat treatment after welding member," the relevant provisions of JB / T 6046 after welding. When using an electric heater for welding components for local stress relief heat treatment shall meet the following requirements:
(1) is equipped with automatic temperature controller heating equipment, heating, temperature, temperature control performance should be consistent with the requirements;
(2) Each side seam heater board member (band) width should be at least 3 times the plate thickness, and not less than 200mm;
Both sides of the member (3) An heating plate (with) suitably covered with insulating material.
20, with a hammer method to eliminate intermediate solder layer stress, you should use a hammer or a small round vibrating hand tools, should not be the root of the weld, the weld cap weld or bevel edge of the base material hammer.
21, using the vibration method to eliminate stress, vibration aging process parameters and technical requirements should be consistent with current industry standard "welded components VSR process parameters and technical requirements" JB / T 10375 of the relevant provisions. Guangzhou Steel
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