Wherever required, the weaving motion should be done with a semicircular motion due to good surface beads and appearances of weld metal. In such cases, the spacing between the work-pieces should be greater than when backings are not used. It is advisable to use backing strips in making single-vee butt welds. The deposited bead will have a convex surface rather than a flat or a concave surface to obtain complete fusion at the edges of the beads. Three or four passes may be required, as per nature of groove in single vee butt joint in the flat-position with down-hand type coated electrodes. The slag should be removed from each layer before depositing the next layer first pass at the bottom of the joint. In using coated electrodes, special Root face care must taken to obtain fusion to the surface and to prevent the slag from being entrapped in the weld metal (bead). This type of joint is called ‘Single Vee Butt joint in a ground position’.Ī single vee but joint is usually designed with a narrow included angle (Vee of 60°) in order to keep to a minimum the amount of weld metal required to fill it in. The edges are beveled so as to leave a root face at the bottom of the groove. On a plate more than 8 mm thick the single vee of 60° preparation is employed. Single Vee Butt Weld in the Flat Position: Uniform weld metal should be examined for sound weld metal, free from gas pockets, slag inclusions, and poor fusion. The finished bead should be inspected for correct weld and uniformity of appearance. The welding circuit should set up for the polarity recommended by the manufacturer of the electrode, and the welding current should be adjusted as recommended by the operators. In this process a slight side-to-side motion of the electrode should be used to slow up the progress along the line of weld, so that the bead builds up fully flush with the top surfaces of the plates and, at the same time, penetrates clear through into the bottom of the plate. The weld is usually made in one pass, as per nature of weld bead two passes (runs) may also be used. In order to obtain complete penetration, the plates should be spaced about 1.5-2 mm apart.
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