Welding ball valve door welding technology processing
Welding type mainly divided into: 1, the electrode arc welding;
2, submerged arc welding (
3, co2 gas shielded welding (
Automatic or semi-automatic welding)
4, MIG/MAG welding (
Melting polar inert gas protection welding;
5, TIG welding (
Tungsten inert gas) welding
Six, six kinds of welding plasma arc welding method, the principle and application of each way is different, because is not the focus of this article, so simple known are available, the following treatment: focus on welding ball valve door welding technology welding ball valve door actually is different from ordinary welding technology, because the valve cavity with nonmetal sealing material rubber and ptfe plastic, not in the heat treatment after welding.
Welded ball valve door the thick wall of multi-layer welding process is repeated heating and cooling of the metal material, the process of its welded joint are usually designed to be thick wall narrow gap submerged arc welding, and the use of all welding of the valve body most is that the thickness of the large tubular welded joint.
So the root of the valve body welding joint gap of stress concentration, residual stress, the organization of inferior become weak link in the valve body structure, and the two kinds of processing mode is: 1.
Is the heat treatment technology;
Is the joint treatment;
The two way will produce a few times the normal working stress of stress concentration, also make the factory engineers are difficult to deal with.
Thus, how to solve the root of the gap welding ball valve gate valve body welding joint of stress concentration, residual stress, organizational inferior become the biggest problem the valve door welding, springs all welded ball valve door factory here for everyone to summarize the main points of the valve body welding technology as follows, hope to be able to help to want to know about ball valve welding technology of friends!
Is presently as follows the valve body welding process is introduced.
1, the technical requirements of the valve body
No deformation after the seam welding valve bodies, including upper and lower shaft flange (
The valve body can not be too wide and the temperature of heated area cannot be too high, otherwise it will damage the valve body sealing device.
Not a flash.
Compression of guarantee in more than 10 mpa.
More than 2, weld structure according to technical requirements, make sure the weld is not full penetration weld.
So the weld joint form to guarantee the assembly and ensure no penetration.
After test, finally determine the weld form.
3, the valve body material for the valve body for ZG15 Ⅱ, therefore before processing has carried on the analysis to the chemical composition of the valve body, the test results are consistent with the test results of during casting, comply with the design requirements.
4, the assembly of hydraulic press modified reverse foetus positioning, bolt, and around half part adjust tightness test, external sphere between the valve body and meet the design requirements.
5, welding process considering the technical requirements of the valve body, finally chose the MAG CO2 welding machine.
Welding material selection ER50 -
In accordance with the principle of welding materials such as strength, the selected ER50 -
Wire satisfied ZG15 Ⅱ requirements.
Protective gas using Ar + 82% and 18% CO2 gas mixture.
1 positioning welding because of cast steel and 45 steel hardening tendency is serious, so the location need to preheating before welding, the oxygen -
Acetylene flame on weld flanked by 2 times the thickness range evenly heating to 75 ~ 100 ℃ (
To 45 steel side)
, does not affect the sealing device shall prevail, with the far infrared thermometer to measure.
Before welding will be 20 mm on both sides of weld surface within the scope of the scale and rust with Angle grinder polishing metallic luster.
50 mm away from the edge on both sides of weld dozen anchor point 6, with a caliper measuring the distance between two points, in order to measure its shrinkage.
2 back weld by considering the ZG15 Ⅱ rigidity of materials, the characteristics of low plasticity, so in choosing welding specification should take small welding parameters, that is, small welding heat input.
On the premise of guarantee the quality of weld, as far as possible to improve the welding speed, reduce the fusion ratio, in the aspect of deformation to multilayer multichannel points 6 section of the symmetry of welding method;
Pay attention to each layer welding anchor point is measured with a caliper, to control the shrinkage, until after welding.
Except the first and the last line of each other between the hammering method for eliminating stress.
6, the last step after completion of welding by suppressing test (
After joint leakage, and sealing surface to meet the technical requirement, through X-ray flaw detection, the weld itself without porosity, slag inclusion, incomplete fusion, welding defects such as cracks, rotary valve core to meet the technical requirements.