ROAD AND WORKSHOP by Handyman
Page 49
If you've noticed an error in this article please click here to report it so we can fix it.
Arc Welding Hints—Heat Stress and Distortion
IN butt welding, prepared plates that are
neither clamped nor securely tacked
ill most certainly distort unless the kites are pre-set. Look at Fig. 1 and t will be seen that the plates have lifted owards the heat centre after expansion ind contraction on cooling down. To avoid this it is necessary Jo pre-set the plates, between 2° and 3" below horizontal (as in Fig. 2) and then on cooling the plates will finish in correct alignment.
• To avoid distortion in single fillet welds, it is often necessary to clamp the horizontal plate firmly and offset the vertical plate 1° or 2° out. For tee fillet weds, clamp the plate and alternate the runs between each side, and remember that where runs are being made at both sides of a joint, all runs should be made in the same direction. Similarly, when welding thick plates Into right angles, and where a mitred joint has been arranged, pre-set the angle by 5"—that is to 95°—and on' welding from the root the joint will close to 90° (see Fig. 3).