Cause of Cranes Rust Hazard of Rust

The cranes rust causes and painting corrosion prevention, outdoor gantry crane rust, gantry crane rust, chemical workshop crane rust corrosion, crane corrosion, crane anti-corrosion, painting, spray paint did not deal with the situation is the crane rust Z easy to happen. Here we detail crane rust rust are those reasons and how to prevent crane corrosion rust.

Outdoor gantry crane rust corrosion, gantry crane rust is due to long-term exposure of cranes in the air, protective measures are not complete, or chemical industry workshop cranes, due to prolonged exposure of cranes to the surrounding corrosive gases or corrosive liquids for chemical reactions and the process of loss. Especially when the air is contaminated with various chemical aggressive media, corrosion will be more serious, even if the crane has been painted to protect the crane, due to the use of the wind, sun, hot and cold changes in the climate, rain and humidity, mould erosion, and mechanical impact, so that the coating is gradually destroyed and lose the ability to protect, such as not to take seriously, corrosion will accelerate the development of the crane will inevitably affect the crane’s strength and stiffness, shorten the Service life, reduce its safety and reliability. Therefore, it is necessary to analyse the hazards, laws and causes of crane corrosion, in order to take effective countermeasures against corrosion.

1、 the hazards of cranes rust easily:

Crane rust hazards, not only for the surface thickness of the uniform thinning, and produce local larger rust pit, causing stress concentration, prompting early destruction of the local structure, especially for the direct bearing of power loads and in the low-temperature region of the steel structure, more fatigue to promote the permissible stress is greatly reduced and the steel resistance to the decline in cold embrittlement performance. If the crane corrosion is too serious, not only will reduce the working performance of gantry cranes, but also will lead to the occurrence of gantry crane operations in the process of collapse accidents, and even the occurrence of major injuries and fatalities.

2、the law of cranes corrosion:

1, (according to the national lifting equipment testing centre to provide the law of crane corrosion) did not brush the crane protective paint or paint quality is lacking, and the crane steel structure in the atmosphere of the corrosion rate is different every year, the initial speed faster, and then gradually slow down.
2, (according to the national lifting equipment testing centre to provide crane rust law) in different areas of operation, the steel structure of the atmosphere by the degree of corrosion varies greatly, coastal and air pollution is more serious in the region of the rust is more obvious.
3, in the same area of operation, subject to the influence of the season, in the rainy season gantry crane rust serious.
4, there are painted cranes or electroplated crane steel structure of the corrosion rate, than no rust layer of the gantry crane rust 5 times slower.
5, outdoor crane steel structure corrosion rate of about 4 times the indoor crane.

3、cranes rust and and crane rust causes:

Cranes rust and and brush over the anticorrosion paint crane surface rust causes , crane rust and antirust paint is destroyed, with the temperature and humidity of the environment around the building, the content and vitality of the erosive medium in the atmosphere, the amount of dust in the atmosphere, the environmental conditions in which the components are located, as well as the crane painting process and the quality of the materials of the steel structure, etc., and the main reasons are:

• 1, chemical corrosion: crane steel structure non-electrolyte or dry gas, the chemical reaction caused by corrosion, known as chemical corrosion. Such as gantry crane steel structure oxidised into oxide at high temperature.
• 2, pitting corrosion: crane contact electrolyte solution and rust (accompanied by current occurs), known as pitting corrosion. Crane pitting corrosion and the working principle of the primary battery is the same. The main component of its steel structure is an alloy of iron and carbon, when in the humid air, its surface is accompanied by a thin film of water, the degree of ionisation of water is small, but it is ultimately an electrolyte, which can produce a very small amount of H + and OH -, not to mention carbon dioxide and sulphur dioxide in the air, especially in the construction of the subsequent units of the power plant, the air contained in the acid, alkali and other erosive media, are able to dissolve in water to generate acids and alkalis gases that increase the H+ in the water. As a result, numerous primary cells are formed on the surface of the steel structure. In this kind of primary cell, iron is the negative pole, carbon is the positive pole, so that iron occurs point chemical corrosion, generating iron hydroxide (Fe (OH) 2), continue to be oxidised and form rust.
• 3, the oxide skin has not been removed cleanly: oxide skin is generally present in the hot rolled steel structure and cutting and welding parts. Because it is tightly attached to the steel structure, extremely difficult to remove, so, before installation or removal of some of the gantry crane operators simply do not remove the trouble, or in addition to the completion. Oxide skin is a hidden danger of damage to the rust layer, under the combined effect of mechanical and atmospheric corrosion, causing anti-rust paint bumps and flaking, so that the crane steel structure to lose the protective layer and lead to corrosion.
• 4, not in time to brush the crane antirust paint: in the crane rust, due to the lack of timely coverage of the protective layer, so that it is in contact with the surrounding erosive substances or gases and corrosion occurs.
• 5, rust has not been removed rust: rust is iron oxide, if the paint is not removed before, the presence of iron oxide under the paint film continues to corrode single girder cranes, and produces expansion and cause cracking of the paint film, accelerating crane rust.
• 6, welding slag is not removed rust: in the removal of cranes, some operators want to save trouble with oxyacetylene flame cut steel structure, installation and then welded, installed and painted without removing the welding slag (welding slag is composed of metal oxides, inorganic salts, pus chloride, zinc chloride. Rosin and other substances), in the process of using the paint film under the steel structure continues to be corroded, Z after the destruction of the paint film.
• 7, oil has not been removed rust: because the crane surface is not removed oil, grease, etc., which will not only affect the adhesion of the coating and drying properties, but also make the paint film is destroyed.
• 8, the old paint is not removed or not clean corrosion: re-painting, such as not removing the paint film has been destroyed, or the old paint film is intact, but the adhesion of the new paint is reduced, the new paint film will still fall off, the old paint will also be bitten off, resulting in crane rust, which is prevalent in large-scale tower crane.
• 9, only coated paint without primer: crane primer is painted directly on the surface of the crane, which contains more powder, less base material, rough film, with strong adhesion to the surface of the steel structure, can play a good purpose of rust prevention. Crane topcoat is painted on the primer paint, which contains less powder, more base material, after the film has a gloss, the main function is to protect the lower layer of primer. Therefore, the single girder crane steel structure in the overall paint, light coating topcoat, not coating primer, can not play a good anti-rust purpose, is bound to reduce the service life of the crane.
• 10, the choice of paint varieties improper rust: crane paint varieties, nature and use of different. In use, due to the primer and topcoat is not properly matched, will lead to bite up the primer film. Such as perchloroethylene can not be used in conjunction with oil-based primer (oil-based red paint), because perchloroethylene paint has a strong solvent, which will bite up the paint film of the primer, so that the crane rust.