Welded pipe vent pipe weld not only affect the density, resulting in leaking pipes, and corrosion-induced point will become a serious decrease weld strength and toughness.
Produce weld porosity of factors: the flux of water, dirt, oxide and iron, welding components and cover thickness, the surface quality of steel and steel side plate processing, welding and pipe forming process and so on.
Relevant control measures are:
1. flux components. Welding with the right amount of CaF2 and SiO2, it will absorb a lot of reaction H2, high stability and does not generate soluble liquid metal HF, which can prevent the formation of hydrogen hole.
2. the accumulation of flux thickness of 25-45mm, flux particle size, density-hour maximum accumulation of thicknesses, on the contrary take the minimum; high current, low welding speed stacking thickness of the maximum, otherwise take the minimum, in addition, summer or air humidity, the recovery of the flux should be dried before use.
3. steel surface treatment. To avoid open-book leveling off of the iron oxide and other debris into the forming process, board cleaning device should be set.
4. steel plate side processing. Steel plate edge should be set up rust and burr removal device to reduce the possibility of pores. Clear the device installed in the best position and disc cutting edge milling machine, the device side of the structure of the gap 2 position adjustable up and down the active wire wheel, upper and lower clamping plate edge.
5. Weld morphology. Weld shape factor is too small, narrow and deep shape of the weld, gas and inclusions not easily leak out, easy to form pores and slag. General control of weld shape factor 1.3-1.5, thick-walled pipe to take the maximum, thin to take the minimum.
6 reduce the secondary magnetic field. In order to reduce the magnetic blow effect, should be welded on the workpiece position is only possible to connect the cable end away from the welding, welding cable to avoid some of the secondary magnetic field generated in the workpiece.
7. Workmanship. Should be appropriate to reduce the welding speed or increase the current, and thus delay the crystallization speed of the weld metal pool in order to facilitate gas escape at the same time, if the instability strip delivery location should be adjusted in time, eliminate frequent fine-tuning through the front or rear Bridge to maintain shape, causing the gas to escape difficult.
