Flame cleaning

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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 chemical compound

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 type of iron oxide

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).

Contents

Overview

Flame cleaning.svg

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.

Torch portable light source

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.

See also

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MAPP gas mixture

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Plasma cutting

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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

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Lead burning

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References

  1. 1 2 "Flame Gouging/Cleaning" . Retrieved 2009-09-10.
  2. "Flame Cleaning Experts". intota.com. 200-00-00. Retrieved 200-04-18.Check date values in: |access-date=, |date= (help)