Thermal Lances is used as one of the methods of boring and severing steel, cast iron, copper, aluminium, concrete and hard to clean materials without noise or vibration in a fraction of the time taken by conventional methods. The equipment is extremely simple and easy to operate, and the capital cost in comparison to drills etc. is negligible.
- The addition of power steel rods in packed form to a lance pipe, provides a greater ratio of iron to oxygen, thus providing sufficient heat to melt ferrous and non-ferrous materials. The lance is ignited by applying heat to the lance end with an oxygen-acetylene equipment. The temperature reached in the center of the combustion zone is around 4000 °C, greater than the melting point of any substance of Earth! The heat generated form the iron/oxygen reaction is sufficient to melt concrete, steel or refractory, as the melting point of most materials varies between 1800-25000 °C.
- Oxygen is continuously fed through the length of steel tube, usually ¼”, 3/8” or ½” NB, and the burning end of the lance is aimed at the spot on the material where it has to be cut. At the burning end, the oxygen combines with the iron to from a slag rich in iron oxides.
- The slag produced is very fluid which enables cutting and boring to take place.
- Assisted by the velocity of the gas and vapours expelled within it.The cutting is a manual process. Thus it depends a lot on personal skill. Proper training and safety gear is a must. Equipment Consists of :
- Steel tube packed with special steel rods (Aluminum or Magnesium are often added to the packing to increase the heat output)
- Lance Holder: Contains a gas control valve, flame arrestor and holder. The lance fits into holder
- Oxygen Supply: Usually connected to three or more 250kPa to 800 kPa, 8 / 9 m capacity cylinders
- The lance can easily be connected to the oxygen supply pipeline where available. For bigger jobs, liquid oxygen cryogenic flasks can also be used.
- Boring Operation To start the operation, the end of the lance is heated to ignition temperature by
- means of and Oxy/Acetylene torch. Oxygen is then fed through the lance promoting fusion at the lance point, and the reaction becomes self supporting. The heat generated fuses the lance and the flow of slag is assisted by the velocity of the oxygen. The boring operation is not difficult, the lance being fed into the hole as boring progresses. Holes 3 meters in length can be bored horizontally,although it would be better to incline the object, if possible, to allow the slag to flow freely out.
- Boring vertically down can be carried out successfully, but after the first 300 mm the oxygen
- pressure has to be increased to expel the molten slag. The slag produced will be expelled from the front until the complete thickness has been pierced. When starting, if a free edge is not available to commence boring then the technique is to pierce a hole through completely in the middle. When boring, the lance is kept aimed slightly downward and the slag kept in motion by a forwards and backwards motion. Sand placed beneath the slag will protect the floor.
- All connections are threaded as per BSPT Standards. Both ends are threaded. A coupling is provided at one end and a PVC cap at the other end. As a safety measure, the filled wires are terminated 50 mm away from the edge of the pipe at the holder end. 6 mm and 10 mm lances are with threaded ends. All accessories like holders, regulators, hoses and safety equipment is also available.