Underwater welding, as the name implies, is “the welding produced inside water”. A decade back underwater welding was limited to the state of patching a hole in a sunken ship, just to get her afloat for major repairs to be carried out in dry docks. One or two of the world’s great navies might have […]

Thin-walled steel tubes, hollow sections, flange and other assemblies may be joined by an arc process which closely resembles flash welding in the type of apparatus employed. The workpieces are held in clamps, one of which can be moved on the axis of the work. Between the clamps and the joint line two solenoids are […]

By the application of external transverse magnetic field, the arc may be deflected either forward towards the direction of welding or backward. Forward deflection can be used to advantage for welding thin sections. With forward deflection of the arc the weld width increases and penetration is decreased, weld metal spreads because of arc deflection. This […]

A magnetic force acts on the arc, in this system of magnetic field, only when the angle between the direction of the electron stream and magnetic lines of force is not zero. As the arc has a conical shape and the current carrying electrons also move along the surface of the arc, their motion can […]

14.1 PARALLEL MAGNETIC FIELD According to the Flemming’s left hand rule, the arc, under the influence of parallel field will be deflected towards right or left across the weld bead length depending upon the direction of the parallel field (forward or backward). Keeping this in mind the findings of the earlier investiga­tors may be analysed. […]

Dumbell type test specimen has been proposed in the literature[5] for finding out the strength of plastic sheets with no mention about the testing of the joint strengths in welds. Dumbell type specimen as shown in Fig. 13.5, has been used for testing the strengths of the parent plate as well as that of the […]

For the welding of PVC sheets, hot-air technique is commonly used. Air is easily available and gives good results with PVC. Air flow needed for the process can be obtained by using a small air compressor, with automatic tripping device to obtain constant pressure. Supply air pressure can be measured by a mercury manometer shown […]

Plastics are finding surprisingly new and diversified applications replacing metals and ceramics. From ordinary toys and utensils to the complicated precision heart valves, the plastics have proved not only to make life more comfortable but also to extend it. Plastics have a combination of desirable properties. They have high strength to weight ratio, corrosion resistance […]

13.1 INTRODUCTION Most commonly used plastics are either thermoplastics or thermosetting plastics. Thermo­plastics could be compared to wax. They are capable of remelting and changing shapes. Ther­mosetting plastics could be compared to an egg. When boiled, an egg becomes solid and sets, it can not be brought back to liquid condition and cannot be reshaped. […]

дизайн интерьера квартир В основе современной архитектуры и дизайна сооружений лежит найденная в процессе создания проекта концепция, в соответствие с которой совершаются все этапы и процессы для воплощения в жизнь задуманного. В наши дни практически невозможно представить будущий объект недвижимости без использования концептуальной идеи. Этапом, который следует за разработкой концепции является этап разработки документов проекта. […]