1 scope
The technology standard is applicable to industrial and civil building cast-in-place reinforced concrete structure in 14 ~ 40 mm diameter Ⅰ Ⅲ steel level in a vertical position, horizontal or oblique position of butt joint connection. When two bar diameter is not at the same time, also can use pneumatic welding connection, but it is the difference between the two diameter shall not be greater than 7 mm.
2 construction preparation
2.1 material and main equipments;
2.1.1 reinforced: reinforced level, diameter must comply with the design requirements, have the factory certificate and retest report. Imported steel shall also have the chemical second-round exam list, its chemical composition should meet the requirements of welding, and shall have the solderability test.
2.1.2 oxygen (O2) : air pressure welding using oxygen purity should be over 99.5%, in the quality accord with GB3863 Ⅰ class or Ⅱ class level of technical requirements.
2.1.3 acetylene (C2H2) : it is best to bottled dissolved acetylene, quality should accord with the requirement of GB6819. Its purity must be over 98%, phosphine content shall not be greater than 0. 06%, hydrogen sulfide content shall not be greater than 0. L %, moisture content shall not be greater than 1 l/m3, acetone content should be not more than 45 g/m3. Such as using acetylene generator direct production of acetylene, the use of calcium carbide by quality to meet the requirements of relevant standards grade or grade one.
2.1.4 major equipment:
2.1.4.1 gas supply device: should include oxygen tank, dissolved acetylene cylinder (or medium-pressure acetylene generator), dry tempering preventive device, pressure reducer, hose, etc. The use of oxygen and dissolved acetylene cylinders should be in accordance with relevant regulations of the state. Dissolved acetylene cylinder gas supply capacity must meet the requirements of the scene when maximum diameter steel welding supplies, if do not apply when using, can be used more bottles in parallel.
2.1.4.2 talkative heater with loop: oxygen - acetylene mixing chamber supplies should meet the needs of heating coil gas consumption, talkative heater with loop should be equipped with a variety of specifications of the heating coil, to meet the needs of different diameter steel welding and burning flame should be uniform, convenient to adjust the flame.
2.1.4.3 pressurizer: pressure ability should reach the biggest diameter of axial stress of steel welding when needed.
2.1.4.4 welding jig: should ensure the clamping bar, and when the reinforcement under the maximum axial pressure, no relative slip between steel bar and chuck; Should facilitate the installation of the steel bar positioning, and keep enough stiffness in the process of welding; Dynamic collet chuck should be with the concentric, and when the different diameter steel welding, should remain united.
2.2 operation conditions:
2.2.1 welder must hold a valid welder examination certificate.
2.2.2 equipment and gas supply should comply with the requirements.
2.2.3 in the field of steel pressure welding, when the wind speed is greater than 5.4 m/s, wind measures should be taken; Construction under negative temperature, heat preservation of air supply equipment should take appropriate anti-freezing measures; When the temperature is lower than 15 ℃, joint preheating slow cooling and heat preservation measures.
2.2.4 job site shall have security protection measures, formulate and implement the safety technical measures, strengthen labor protection welders, prevent burns, fire, explosion and damage for the accident.
2.2.5 note joint position, pay attention to the same extent in joint reinforced area percentage, does not conform to the concrete structure engineering construction and acceptance standard "regulations on terms, to adjust the joint position before welding.
3 operation process
3.1 process:
Check equipment, air - reinforced end preparation - installation of welding jig to test weld, as a specimen, and steel
Welds to unload jig, quality inspection
3.2 inspection equipment, air supply, ensure that in the normal state.
End preparation: 3.3 steel reinforced ends should be cut flat, and appropriate and reinforced phase axis vertical; Twice at the end of steel bar diameter length range, if has the attachments such as cement, should be removed. Steel edge burr and rust, oil, and oxidation film on face should be clean, and polished, make its metallic luster, can not have oxidation phenomenon.
3.4 installation of welding jig and steel: the installation of welding jig and reinforced, it should be two steel clamping respectively, and make the axis of the two steel bar in a straight line. Reinforced after installation shall be pressure tight, the local gap between the two steel shall not be greater than 3 mm.
3.5 test weld, a specimen: commenced prior to welding, must carry on the field under the condition of reinforced pressure weld process performance test. To confirm the operation skill pressure welder, confirm the steel weldability, welding process and choose the best. The test of reinforcement from the approach of interception. Each batch steel welding root joint 6, after the appearance inspection, tensile test of 3, 3 root bending test. After test, according to determine the process pressure welding.
3.6 bar pressure welding, should be selected according to the steel bar diameter and welding equipment specific conditions such as pressure, secondary pressure or pressure welding process three times. Or cracks in the two reinforcement and upsetting process, the reinforcement of the axial pressure, according to the reinforcement cross-sectional area, should be 30 ~ 40 mpa. In order to ensure the reinforcement of the axial pressure value, should be based on the model of the pressurizer, according to the steel bar diameter size conversion into the oil pressure gauge reading in advance, and write a good sign, so that accurate control.
The beginning of 3.7 bar pressure welding appropriate USES carbonizing flame, aim at two reinforced seams centralized heating, and make its inner flame cover the gap, prevent reinforcement end face from oxidation.
After the two reinforced seams totally closed should use neutral flame, centering on the bonding surface, within the scope of the double bar diameter on each side length reciprocating wide heating.
End of the bar suitable heating temperature should be 1150 ~ 1250 ℃; Reinforced upsetting area on the surface of the heating temperature should be slightly higher than the temperature, and with the steel bar diameter size and the temperature difference of ladder.
3.8 bar pressure welding, through the final heat pressure, should keep sub upsetting area form prescribed by the appropriate shape; Then stop heating, slightly delay, unloading pressure, remove the welding jig.
3.9 in the process of heating, if fully closed before the cracks in the reinforced end face is interrupted extinguishing phenomenon, should be reinforced to remove to burnish, installation, then lit the flame welding. If there is a completely closed after the cracks in the reinforced end face, can continue to heat pressure, complete the welding operation.
3.10 quality inspection; Welding in the welding production should be self-checking seriously, if discover the diameter and length of the eccentric, bending, upsetting enough to crack, the bonding surface offset, ring, steel surface severe burns, joint quality defects such as metal burnt, not solder, should remove heavy welding joint, and find reasons to eliminate in a timely manner.
4 quality standards
4.1 ensure projects:
4.4.1 the variety and quality of steel must comply with the design requirements and the provisions of the relevant standards.
Note: imported steel should first through chemical composition test and welding test, accord with the relevant provisions of the rear can welding.
Inspection method: inspect the factory certificate and test report.
4.1.2 of the specifications of the steel bar, the position of the welding joint, the same section with joint reinforced area percentage, must comply with the design requirements and norms.
Methods: to observe the or feet quantity check.
4.1.3 air pressure welding head mechanical performance testing must be qualified.
From each batch of joint mechanical properties test, tensile test taken 3 random cut in the joint. According to the requirements of the project, also can cut another take three joint bending test.
4.1.3.1 in general structures, with 200 joint as a batch.
4.1.3.2 in cast-in-place reinforced concrete building structure, at the same floor 200 joint as a group; Less than 200 joint is still as a batch.
Inspection method: inspect welding specimen test report.
4.2 the basic items:
Steel pressure welding head should carry on appearance inspection, the results shall meet the following requirements:
2 eccentric amount shall not be greater than 0.15 times the diameter of the steel bar, at the same time shall not be greater than 4 mm, when different diameter reinforced phase welding, press bar diameter smaller computation, when over the limit of time, should remove heavy welding.
4.2.2 two steel axis bending Angle shall not be greater than 4 °. When more than a limited, a correction shall be reheated.
Holdings upsetting diameter should not less than 1.4 times the diameter of the steel bar, when less than the set limit to, should be reheated upsetting.
4.2.4 upsetting length should be not less than 1.2 times the diameter of the steel bar, raised portion should be flat and smooth. When is less than the set limit to, should be reheated heading.
4.2.5 bonding surface deviation shall not be greater than 0.2 times the diameter of the steel.
4.2.6 joint can not have transverse crack, if found to have this crack, should remove heavy welding.
4.2.7 upsetting area surface can not have serious burns.
Test method: visual or measurement.
5 finished product protection
Welding joint, should be a little pause to unload jig, in order to avoid bending joint.
6 should pay attention to quality problems
6.1 in steel pressure welding production, should pay attention to any link of the whole welding process. Reinforced end to cut flat and perpendicular to the axis; Finish see burnish, no oxidation phenomenon; Reinforced solidarity when installation, fixture fastening, fight shake; Heating moderation, pressure to appropriate. If the abnormal phenomenon, should refer to table 4-19 to find the reason, eliminate in a timely manner.
6.2 pressure welding can be under negative temperature conditions, but when the environment temperature is below - 20 ℃. Is unfavorable for welding.
Rain and snow is unfavorable for welding, welding must be applied, effectively cover measures should be taken. Not cooling after welding joint, should avoid touching the ice and snow.
7 quality records
This technology standard should have the following quality records:
7.1 steel factory quality certificate or test report.
7.2 second interview report reinforced mechanical properties.
Steel pressure welding head welding defects and the prevent measures table 4-19
Will produce the original weld defects for prevention measures
The axis offset
(eccentric)
1. The welding jig two different clip
2. Steel joint face
3. The clamping steel for which the welding
4. The welding jig remove early 1. Check the jig, timely repair or replacement
2. Cut flat steel bar end face
3. The clamping steel welding again
4. Remove from heat and a half minutes after disassembling fixture
2
bending
1. The welding jig two different clip
2. Steel joint face
3. The welding jig remove early 1. Check the jig, timely repair or replacement
2. Cut flat steel side
3. Remove from heat and a half minutes after disassembling fixture
1. The welding jig chuck effective stroke is not enough
2. Top pressure cylinder effective stroke is not enough
3. The heating temperature is not enough
4. The pressure is not enough
1. The heating rate are wide enough
2. The top stress greater than urgent 1. Increase the heating rate range
2. When the pressure should be smooth
The bonding surface offset
Reinforced two end heating rate is not suitable
1. With two end diameter steel heating rate should be symmetrical
2. When heated, different diameter steel bar of large diameter steel
Jin slightly longer heating time
1. The heating temperature is too high
2. The high carbon and other elements in steel 1. Decrease the heating temperature
2. Check the steel chemical composition
1. The fire power is too large
2. The heating time is too long
3. The heater swinging not divide evenly
1. The heating temperature or heat distribution is not enough
2. The pressure is too small
3. The joint face is not clean
4. End surface oxidation
5. Improper midway no fire or flame
Choose the welding parameters, correctly master the operation method
7.3 imported steel chemical composition inspection report and solderability test report. Domestic reinforced brittle fracture occurred during machining process, welding performance and mechanical performance is significantly abnormal, should have a chemical composition inspection report.
7.4 steel joint tensile test report.
7.5 such as engineering required, should be reinforced joint bending test report.
No comments:
Post a Comment