Flame cleaning, also known as flame gouging, [1] is the process of cleaning a structural steel surface by passing an intensely hot oxyacetylene flame over it. Mill scale and rust are removed by the reducing effect of the flame and the action of the heat, leaving the surface in a condition suitable for wire brushing and painting. [2]
Mill scale, often shortened to just scale, is the flaky surface of hot rolled steel, consisting of the mixed iron oxides iron(II) oxide (FeO), iron(III) oxide (Fe2O3), and iron(II,III) oxide (Fe3O4, magnetite).
Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Rust consists of hydrated iron(III) oxides Fe2O3·nH2O and iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3).
There are many uses for flame cleaning rather than just to remove rust and mill scale. It is also used as a removal tool for paints, bad welds, burrs, mechanical wear (scraping, cuts, gouges and more) along with other surface imperfections. The process of flame cleaning is not anything new and does not require any extra equipment than what would be found in a typical metal shop. It is just an oxygen-fuel torch that is used parallel with the surface to melt and blow off any blemishes that the operator wants to eliminate. Shown in the adjacent diagram, the surface is blasted with the oxygen-fuel torch across the surface versus the orthodox use of the flame as a cutting or gouging tool. Though the equipment is the same, the flame used in cleaning is drastically reduced to prevent excess removal of the surface. Various kinds of fuel can be run with the oxygen, for example acetylene.
A torch is a stick with combustible material at one end, which is ignited and used as a light source. Torches have been used throughout history, and are still used in processions, symbolic and religious events, and in juggling entertainment. In some countries, the word "torch" is used as the term for a battery-operated portable light.
Various surfaces can be cleaned using this process. The oxy-flame can work on assorted surface qualities and remove some of the hardest to clean substances such as lubricants and grease. Ceramics, steel constructions, offshore systems and even concrete elements can all be cleaned. Although the function of cleaning can be thoroughly accomplished, the general aesthetic look is damaged due to the burn marks by the oxy-flame. The surface is then ready for further processing such as painting, grinding or any other further operation. [1]
Grease is a semisolid lubricant. Grease generally consists of a soap emulsified with mineral or vegetable oil. The characteristic feature of greases is that they possess a high initial viscosity, which upon the application of shear, drops to give the effect of an oil-lubricated bearing of approximately the same viscosity as the base oil used in the grease. This change in viscosity is called shear thinning. Grease is sometimes used to describe lubricating materials that are simply soft solids or high viscosity liquids, but these materials do not exhibit the shear-thinning properties characteristic of the classical grease. For example, petroleum jellies such as Vaseline are not generally classified as greases.
A chisel is a tool with a characteristically shaped cutting edge of blade on its end, for carving or cutting a hard material such as wood, stone, or metal by hand, struck with a mallet, or mechanical power. The handle and blade of some types of chisel are made of metal or of wood with a sharp edge in it.
Metalworking is the process of working with metals to create individual parts, assemblies, or large-scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewelry. It therefore includes a correspondingly wide range of skills, processes, and tools.
Stone carving is an activity where pieces of rough natural stone are shaped by the controlled removal of stone. Owing to the permanence of the material, stone work has survived which was created during our prehistory.
Vehicle extrication is the process of removing a vehicle from around a person who has been involved in a motor vehicle collision, when conventional means of exit are impossible or inadvisable. A delicate approach is needed to minimize injury to the victim during the extrication. This operation is usually accomplished by using chocks and bracing for stabilization and hydraulic tools, including the Jaws of Life. Standards and regulations can be found in NFPA 1670 and 1006.
Metal fabrication is the creation of metal structures by cutting, bending, and assembling processes. It is a value-added process involving the creation of machines, parts, and structures from various raw materials.
"MAPP gas" is a trademarked name, belonging to The Linde Group, and previously belonging to the Dow Chemical Company, for a fuel gas based on a stabilized mixture of methylacetylene (propyne) and propadiene. The name comes from the original chemical composition, methylacetylene-propadiene propane. "MAPP gas" is also widely used as a generic name for UN 1060 stabilised methylacetylene-propadiene. MAPP gas is widely regarded as a safer and easier-to-use substitute for acetylene. In early 2008, true MAPP gas production ended in North America when production was discontinued at the only remaining plant in North America that still manufactured it. However, many current products labeled "MAPP" are, in fact, MAPP substitutes. These versions are composed almost entirely of propylene with minuscule impurities of propane (<0.5%).
Plasma cutting is a process that cuts through electrically conductive materials by means of an accelerated jet of hot plasma. Typical materials cut with a plasma torch include steel, stainless steel, aluminum, brass and copper, although other conductive metals may be cut as well. Plasma cutting is often used in fabrication shops, automotive repair and restoration, industrial construction, and salvage and scrapping operations. Due to the high speed and precision cuts combined with low cost, plasma cutting sees widespread use from large-scale industrial CNC applications down to small hobbyist shops.
Plasma arc welding (PAW) is an arc welding process similar to gas tungsten arc welding (GTAW). The electric arc is formed between an electrode and the workpiece. The key difference from GTAW is that in PAW, by positioning the electrode within the body of the torch, the plasma arc can be separated from the shielding gas envelope. The plasma is then forced through a fine-bore copper nozzle which constricts the arc and the plasma exits the orifice at high velocities and a temperature approaching 28,000 °C (50,000 °F) or higher.
Metallizing is the general name for the technique of coating metal on the surface of objects. Metallic coatings may be decorative, protective or functional.
Oxyhydrogen is a mixture of hydrogen (H2) and oxygen (O2) gases. This gaseous mixture is used for torches to process refractory materials and was the first gaseous mixture used for welding. Theoretically, a ratio of 2:1 hydrogen:oxygen is enough to achieve maximum efficiency; in practice a ratio 4:1 or 5:1 is needed to avoid an oxidizing flame.
Thermal spraying techniques are coating processes in which melted materials are sprayed onto a surface. The "feedstock" is heated by electrical or chemical means.
Oxy-fuel combustion is the process of burning a fuel using pure oxygen instead of air as the primary oxidant. Since the nitrogen component of air is not heated, fuel consumption is reduced, and higher flame temperatures are possible. Historically, the primary use of oxy-fuel combustion has been in welding and cutting of metals, especially steel, since oxy-fuel allows for higher flame temperatures than can be achieved with an air-fuel flame.
Oxy-fuel welding and oxy-fuel cutting are processes that use fuel gases and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material in a room environment. A common propane/air flame burns at about 2,250 K, a propane/oxygen flame burns at about 2,526 K, an oxyhydrogen flame burns at 3,073 K and an acetylene/oxygen flame burns at about 3,773 K.
A needlegun scaler, needle scaler or needle-gun is a tool used to remove rust, mill scale, and old paint from metal surfaces. The tool is used in metalwork applications as diverse as home repair, automotive repair and shipboard preservation.
Smooth clean surface (SCS) is a process applied to hot rolled sheet metal and coils to remove nearly all mill scale and clean the steel surface.
Eco pickled surface (EPS) is a process applied to hot rolled sheet steel to remove all surface oxides and clean the steel surface. Steel which has undergone the EPS process acquires a high degree of resistance to subsequent development of surface oxide (rust), so long as it does not come into direct contact with moisture. EPS was developed by The Material Works, Ltd., which has filed several patent applications covering the process. It is primarily intended to be a replacement of the familiar acid pickling process wherein steel strip is immersed in solutions of hydrochloric and sulfuric acids to chemically remove oxides.
Soldering is a process in which two or more items are joined together by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involve melting the work pieces. In brazing, the filler metal melts at a higher temperature, but the work piece metal does not melt. In the past, nearly all solders contained lead, but environmental and health concerns have increasingly dictated use of lead-free alloys for electronics and plumbing purposes.
ISO 8501-1 – Preparation of steel substrates before application of paints and related products – Visual assessment of surface cleanliness – Part 1: Rust grades and preparation grades of uncoated steel substrates and of steel substrates after overall removal of previous coatings
A blowtorch, or blowlamp (UK), is a fuel-burning tool used for applying flame and heat to various applications, usually metalworking.
Lead burning is a welding process used to join lead sheet. It is a manual process carried out by gas welding, usually oxy-acetylene.
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