NaranjoIs JDG 
HerediaDN25 gaEffective treatment of square tube coating & ldquo; Surface defense line & rdquo; Surface technology and measures square tube coating is used as the back course & ldquo; Surface defense line & rdquo; The surface treatment technologies and measures can be carried out on the basis of other surface treatment technologies or processes. Here's the & ldquo; Surface treatment before coating & rdquo; It refers to all treatment measures for preparation for coating or joint protection with coating. Therefore, the surface treatment before coating is also called coating surface pretreatment.
Classification of surface treatment square pipe is divided into hot-dip galvanized square pipe, electro galvanized square pipe, oiled square pipe and pickled square pipe according to surface treatment.
San-Ignacio.When storing Q345B 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, Q345B 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,San-IgnacioPrice of galvanized square pipe of 25, we can put them into the warehouse for very good retention. According to geographical conditions, there is a sealed warehouse but the ventilation setting is excellent. The difference between Q345B square tube and seamless steel tube Q345B square tube is a kind of high-precision steel tube material after cold drawing or hot rolling treatment. Q345B square tube is mainly used to produce products of pneumatic or hydraulic components, 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 Q345B square tube no deformation under high pressure, high precision, high finish, cold bending, flaring and flattening without cracks. The chemical composition of Q345B square tube includes carbon silicon Si, manganese Mn,San-IgnacioSteel galvanized square pipe, sulfur s, phosphorus P and chromium CR.
How about the tensile strength of square pipe: square pipe has good tensile strength, tensile strength and sufficient toughness which makes square pipe stand out in the field of steel pipe. The square tube has great advantages in high temperature, high pressure and even high strength environment. What are its characteristics? We analyze it one by one: tensile strength (& sigma; b) the strong force (FB) borne by the sample during tensile breaking, and the unit is nmm2 (MPA).
.Degrease.
The quality of the solid square tube after the square tube formwork removal and curing can be tested according to the requirements and the following ways: use a magnifying glass to observe whether there are non external force cracks on the structural surface of the solid seamless q355b square tube. When non external force cracks appear on the surface of q355b square pipe, and automatic submerged arc welding is adopted for repair welding after rolling into square pipe.
Mechanical property is an important index to ensure the end use performance (mechanical property) of square pipe, which depends on the chemical composition and heat treatment of steel. In the steel pipe standard, according to different service requirements the tensile properties (tensile strength, yield strength or yield point, elongation), hardness and toughness indexes, as well as the high and low temperature properties required by users are specified.
If the surface is not so flat, and the size and thickness are not standardized, it can reflect that this square tube is a poor product& rdquo;
Compared with other traditional pipes, square pipe supply steel pipe has lighter raw materials, high strength, good resistance, can withstand high internal pressure, sensitive application, the inclusions can be fully denatured without generating more high melting point inclusions.
The painting of the square tube has to go through a process, the quality and level of the paint and the relevant technical level deserve our attention. Note that the square tube should not be used immediately after painting, but should be placed for a period of time and wait until the paint is dry!
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.
After the process of polishing, the surface effect of the square tube is quite good. The quality of the polishing process directly affects the external image of the square tube. Therefore, we must choose the appropriate polishing according to the above, and pay more attention to the polishing process of the square tube.
production costs.Electrochemical polishing: long specular gloss, stable process, less pollution and good durability. Suitable for mass production, it is mainly applied to high-grade products, imported products and public service products. Its processing technology is stable and the operation is simple.
Forging square tube: a kind of pressure processing in which the reciprocating impact force of the forging hammer or the pressure of the press changes the blank into the shape and size we need. It is generally divided into forging and die forging. It is often used to produce large-scale materials and materials with large square tube size.
Before square tube forming, the strip steel shall be leveled, trimmed, planed, surface cleaned, transported and pre bent.
San-Ignacio.Square tube flattening test is a kind of test to check the deformation performance of metal tubes (seamless square tubes and rectangular tubes) flattened to the specified size and show their defects. Relevant flattening tests shall be carried out in accordance with relevant provisions of test standards. Requirements for samples samples can be taken from metal pipes with qualified appearance. Generally, sawing is adopted. The inner and outer walls of the pipe shall retain the original surface without any processing. Sample length L & asymp; D (D is the outer diameter of the pipe). When the outer diameter is large, the length l shall not exceed 100mm. When the outer diameter is less than 20mm,San-IgnacioQ235A galvanized pipe, l = 20mm. When cutting the sample the surface of the sample shall not be damaged and the performance of the metal shall not be changed due to heating or cold processing. The edge of the section shall be flattened. The flattening test is a test to check the deformation performance of the metal pipe (seamless square pipe and rectangular pipe) flattened to the specified size and show its defects. Relevant flattening tests shall be carried out in accordance with relevant provisions of test standards.
The first is the influence of external conditions. It mainly depends on the medium characteristics and temperature around the square pipe and whether the medium around the pipe is corrosive. Because the corrosivity of the medium is closely related to the microorganisms contained in the soil. And if it is a long-distance pipeline, the soil environmental properties are more complex. In addition, the corrosion speed will also be accelerated, while if the temperature is low, the corrosion speed will be slowed down.
In & sigma; Expressed in%. The calculation formula is: where: L1 -- gauge length after sample breaking, mm; L0 -- original gauge length of sample, mm. Reduction of area (& psi;) in the tensile test, the percentage between the large reduction of the cross-sectional area at the reduced diameter and the original cross-sectional area after the specimen is broken is called the reduction of area. In & psi; Expressed in%. The calculation formula is as follows: where: S0 -- original cross-sectional area of the sample, mm2; S1 -- small cross-sectional area at the reduced diameter after sample breaking, mm2.