When storing QB square pipe， we need to select a suitable place. We need to think about many external factors， such as the corrosivity of steel pipe， etc. Therefore， the place must be clean， dry and ventilated， where harmful gases appear， QB square pipe can not appear， weeds and other sundries should be removed in time， and the outer surface of steel should be kept clean. If there are acid， alkali， salt， etc. in the warehouse， it is easy to react with the steel pipe and corrode the steel pipe， so try to cut it and don"t let it. In addition， if we can think about those higher metal products， we can put them into the warehouse for very good retention. According to geographical conditions， there is a sealed warehouse， such as air cylinder or oil cylinder， which can be seamless pipe or welded pipe， because there is no oxide layer on the inner and outer walls of QB square tube， high finish， flaring and flattening without cracks. The chemical composition of QB square tube includes carbon silicon Si， manganese Mn， sulfur s， phosphorus P and chromium CR.
The reason why it is divided into two types is that chemical cleaning can only clean the surface very thoroughly， and it is difficult to achieve the desired results in some fine cracks.
La luvilleWith the development of economy， there are a lot of demands for project construction， which leads to the continuous increase of square pipe. The of square pipe is more complex. Great efforts should be made in the selection of raw materials， structured treatment and so on.
Purpose of square tube the purpose of square tube includes construction， machinery， steel construction and other projects， shipbuilding， solar power generation support， steel structure engineering， electric products ( pieces)
San RafaelClassification of square tube steel is iron carbon alloy with carbon content of square tube between .% - %. In order to ensure its toughness and plasticity， the carbon content generally does not exceed %. In addition to iron and carbon， manganese， sulfur， phosphorus， etc. There are various classifications of steel and square tubes， mainly including the following: square tubes are classified into ordinary steel according to quality (P & le; .%， S & le; .%)
Strength refers to the performance of metal materials under static load (excessive plastic deformation or fracture). Since the action modes of load include tension， compression， bending and shear， the strength is also divided into tensile strength， compressive strength， flexural strength and shear strength. There is often a certain between various strengths. Generally， tensile strength is used as the basic strength indicator. Appropriate sites and warehouses shall be selected. The sites or warehouses for storing steel pipes shall be in clean and unobstructed places， away from factories and mines that produce harmful gas or dust. Weeds and sundries shall be removed on the site to keep the steel pipe clean; In the warehouse， it is not allowed to stack with acid， alkali， salt， cement and other materials that are corrosive to the steel pipe. Different types of steel pipes shall be stacked separately to prevent confusion and corrosion; Large section steel， rail， steel plate， large-diameter steel pipe， forging， etc. can be stacked in the open air; Small and medium-sized section steel， wire rod， reinforcement， medium diameter steel pipe， steel wire and steel wire rope can be stored in a well ventilated shed， steel sheets， steel strips， silicon steel sheets， or thin-walled steel pipes， all kinds of cold-rolled and cold drawn steel pipes and high and corrosive metal products can be stored in the warehouse; The warehouse shall be selected according to geographical conditions， and generally adopts ordinary closed warehouse， that is， the warehouse with roof， enclosure， tight doors and windows and ventilation devices; The warehouse is required to pay attention to ventilation in sunny days， close and damp proof in rainy days， and often maintain a suitable storage environment. The principle of reasonable stacking and first in first stacking is to stack according to varieties and specifications under the condition of stable stacking and ensuring safety. Materials of different varieties shall be stacked separately to prevent confusion and mutual corrosion; It is forbidden to store articles that have corrosive effect on steel pipes near the stacking position; The bottom of the stack shall be padded high， firm and flat to prevent the material from moisture or deformation; The same kind of materials shall be stacked according to the warehousing order， so as to facilitate the implementation of the principle of first in， first out; The section steel stacked in the open air must be provided with wooden mats or strip stones. The stacking surface is slightly inclined to facilitate drainage. Pay attention to the straightness of the material placement to prevent bending and deformation; The stacking height shall not exceed m for manual operation， m for mechanical operation， and m for stacking width; A fixed channel shall be reserved between stacks， generally .m and the access channel is generally ~ om depending on the size of materials and transportation machinery; The bottom of the stack shall be padded up. If the warehouse is cement floor， it can be padded up by .M; If it is muddy ground， it must be padded . ~ .m high. If it is an open site， the cement ground shall be padded with O & middot; ～O· m， . ~ . m higher than the sand and mud surface， the angle steel and channel steel shall be stacked in the open air， i.e. the mouth shall face down， and the I-beam shall be placed vertically. The i-groove surface of the steel pipe shall not face up to avoid ponding and rust. The packaging and protective layer of the protective materials shall be coated with agent or other plating and packaging before leaving the factory， which is an important measure to prevent material corrosion. Attention shall be paid to protection during transportation， loading and unloading and shall not be damaged， The storage period of materials can be extended， the warehouse shall be kept clean and the maintenance of materials shall be strengthened. Before warehousing materials shall be prevented from being drenched or mixed with impurities. Materials that have been drenched or contaminated shall be wiped according to their properties， such as steel wire brush for high hardness and cloth， cotton and other materials for low hardness; The materials shall be regularly after warehousing. If there is corrosion， the corrosion layer shall be removed; Generally，La luvilleGalvanized steel square pipe， the steel pipe surface does not need to be coated with oil after being cleaned， but for high-quality steel， alloy steel sheet， thin-walled pipe， alloy steel pipe， etc.， the internal and external surfaces need to be coated with anti rust oil before storage; Steel pipes with serious corrosion shall not be kept for a long time after rust removal and shall be used as soon as possible. With the development of economy， all kinds of square tubes，La luvilleGalvanized square pipe 150， rectangular tubes， seamless square tubes， galvanized square tubes and galvanized tubes have been recognized by the majority of customers for a long time. There are more and more counterfeit products on the market. In order to prevent being deceived when you are in square tubes， you need to know some knowledge about how to judge the authenticity of square tubes: & ldquo; We can judge by observing the surface and flatness of the square tube. If the surface of the square tube is relatively flat it can reflect that the square tube is good. On the contrary， if the surface is not good
According to metallographic classification， the annealed state of square tube: A. hypoeutectoid steel (ferrite + pearlite); b. Eutectoid steel (pearlite); c. Steel precipitation through a common square tube (pearlite + cementite); d. Ledeburite steel (pearlite + cementite).
The characteristics of square pipe are as follows: the production process of square pipe is simple， the production efficiency is high， the cost is low and the development is fast. The strength of spiral square pipe is generally higher than that of straight seam square pipe. It can produce square pipe with larger pipe diameter with narrow blank， and square pipe with different pipe diameter with blank of the same width. However， compared with straight seam pipe of the same length， the weld length is increased by ~ which will be oriented to the whole country for a long time Individuals and enterprises provide all kinds of square tubes， square rectangular tubes， seamless square tubes， galvanized square tubes， galvanized tubes， on-site settlement， local offices， long-term cooperation， and low production speed. Therefore， most of the smaller square tubes adopt straight seam welding， and most of the large-diameter square tubes adopt spiral welding.
General square pipes are stacked outdoors， and most of them are buried underground when in use， so they are easy to corrode and rust. In order to ensure the smooth flow of the pipeline， square pipes must have strong corrosion resistance. Once the pipeline is corroded， it will cause oil and gas leakage， which will not only interrupt transportation， but also pollute the environment， and may even lead to fire and cause harm.
Hot dip galvanized square tube is a kind of square tube which is welded after using steel plate or steel strip to curl and form， and on the basis of this square tube， the square tube is placed in the hot dip galvanized pool and formed through a series of chemical reactions; The production process of hot-dip galvanized square pipe is relatively simple， but the production efficiency is very high and there are many specifications and varieties，La luvilleSpecification of rectangular galvanized square pipe， but this kind of square pipe needs little equipment and capital， petrochemical industry， chemical industry， electric power industry， agricultural irrigation and urban construction. It is one of the key products developed.
Square tube is an essential material for the construction and Realization of industrialization. It is widely used and has a wide variety. According to different section shapes， square tube is generally divided into sections， plates， pipes and metal products. In order to facilitate the production， ordering and supply of square tube and do a good job in operation and management， it is also divided into heavy rail， light rail， large section steel， medium section steel， small section steel and square tube cold bending Section steel， high-quality section steel， wire rod， medium and thick steel plate， sheet steel electrical silicon steel sheet， strip steel， seamless steel pipe， square pipe， metal products etc.
Comprehensive classification ordinary steel A. carbon structural steel: (a) Q (b) Q (b); (c) Q( C)； (d) Q( B)； (e) Q.
Welding seamless welding seamless is to make welded elbows. After grinding and pickling， there is no sign of welding on the surface. Even using advanced flaw detection equipment sand blasting， it can not be seen that they are welded elbows.
The cheapestPrinciple of cold drawing strengthening: the lattice defects of steel increase during plastic deformation， and the serious distortion of defect lattice will hinder the progress and slip of lattice， so the yield point of steel increases and the plasticity and toughness decrease. Due to the internal stress in plastic deformation， the modulus of steel decreases. The cold drawn reinforcement is stored at room temperature for ~ d or heated to ~ ℃ and maintained for a fixed time. This process is called aging treatment.
The test can be carried out under cold and hot conditions. If the test temperature is not specified， the test shall be carried out under normal temperature， but not lower than - ℃.
special shaped square pipe is the general name of square pipes with other cross-section shapes except circular pipe. According to the different cross-section shape and size of steel pipe， it can be divided into special-shaped square pipe with equal wall thickness (code D)， special-shaped square pipe with unequal wall thickness (code BD) and special-shaped seamless steel pipe with variable diameter (code D) These special-shaped large-diameter qb square tubes are widely used in various structural parts， tools and mechanical parts. Compared with circular tubes， special-shaped tubes generally have large moment of inertia and section modulus， and have large bending and torsion resistance which can greatly reduce the structural weight and save steel. Square tubes are an indispensable part of construction work
La luvilleCompared with other welding， square pipe welding has many advantages mainly because of the exothermic reaction， the material only needs to be heated below the melting point
Fake and shoddy square tubes are easy to scratch， I"ll give you a detailed introduction to the heating technology of the lower tubes.
