The strength of square tube refers to the function that the data of square tube are destroyed under static load (appropriate plastic deformation or fracture). Because the action forms of load include tension， contraction meandering， shear and so on， compressive strength， flexural strength， shear strength and so on. There is often a definite connection between various strengths. In normal use，Q355d square tube tensile strength is often used as the fundamental strength gauge.
3Therefore，Galvanized square pipe plastic sprayingAchieve the effect of unmanned operation the drawing process of square tube is quite meticulous. For a long time， square tube， rectangular tube， seamless square tube galvanized square tube， galvanized tube and other brand products are provided. The products of designated dealers are complete and the quality is guaranteed. In the process of continuous development square tube has also been processed more rigorously.
nStructural stainless steel square pipe (gbt-) is a hot-rolled (extruded， expanded) and cold drawn (rolled) square pipe made of stainless steel for corrosion-resistant pipes， structural parts and parts widely used in chemical， petroleum， light textile，Q355d square tube food， machinery and other industries.
Square tube failure. When the pipeline is erected， it is necessary to do a good job or directly use the square pipe. The reason for the corrosion of the pipeline is that the layer of the pipeline is damaged. Once the layer is separated from the pipe surface， it will naturally cause failure.
JNewmarkThe cut-off position shall match the construction and site conditions， Standard No.: gbt-. The representative material is Q grade B steel. It is mainly used for straight seam qb square pipe for mine air pressure drainage and shaft gas drainage.
The standard number of spiral square pipe (standard of the Ministry of petroleum) for low pressure transmission is syt-. The representative materials are qbqb and other carbon steel materials. It is mainly used for low-pressure transmission of water， oil， natural gas， heating and other pipelines.
The purpose of heat is to prevent the generation of cold cracks. Cold crack is directly related to carbon equivalent. Therefore， it is necessary to distinguish the carbon equivalent of the qb square tube， and the carbon equivalent of the qb square tube is the same. If the carbon equivalent of Q is less than .%，Q355d square tube it can be said that the weldability is OK. Generally speaking， the cold crack increases when the carbon equivalent is .%.
ySquare tube structural steel A. mechanical steel: (a) quenched and tempered structural steel; (b) Surface hardening structural steel: including carburized steel，Galvanized square pipe plastic sprayingAchieve the effect of unmanned operation ammoniated steel and surface quenching steel; (c) Easy to cut structural steel; (d) Steel for cold plastic forming: including steel for cold stamping and steel for cold heading.
GAfter the square pipes are stacked and stored， the pipe end protector shall be removed to avoid moisture gathering on the surface of the pipe end protector and the square pipe， which is difficult to volatilize.
LJob descriptionSquare tube with complex section: flower shaped square tube， open square tube， corrugated square tube and special-shaped square tube.
uWSquare pipe is a square steel pipe cold drawn from seamless steel pipe， which is not a straight qb square pipe， and qb square pipe， also known as welded pipe，Galvanized pipe_ Galvanized square pipe_ Seamless steel pipe_ Square tube - Wuxi Jiahang is a square pipe welded by steel plate or strip steel after crimping. Qb square tube has the advantages of simple production process， high production efficiency， many varieties and specifications and less equipment. The commonly used materials are QA and QC.
The general delivery length of square pipe is mm-mm， mostly mm and mm. The square tube is allowed to deliver short and non fixed length products not less than mm， or in the form of interface tube， except for the wall thickness of corners and weld areas. The weight of short gauge and non fixed gauge products shall not exceed % of the total delivery. For square tubes with a theoretical weight greater than kgm， it shall not exceed % of the total delivery. We have many different ways in square tubes. Different ways make square tubes have different characteristics. According to these characteristics， we can correctly select the appropriate application field， In this way， the use efficiency of square tube can be improved. Next， we will mainly explain the characteristics of pipe cooling technology below. What are the main characteristics of square tubes? Square tube parts have accurate dimensions and smooth surfaces: the dimensional accuracy of cold parts developed at present can reach grade ~ . If ideal ones are adopted， their accuracy is second only to that of fine polished surfaces. Therefore， cold parts generally do not need to be reprocessed， and a small amount only need finishing (grinding).
When cutting the sample， the surface of the sample shall not be damaged， the properties of the metal shall not be changed due to heating or cold processing， and the edges at the section shall be rounded.
targetyThe 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 - ℃.
ZZinc layer thickness: there is a great difference between cold galvanized square pipe and hot galvanized square pipe in galvanizing process; Cold galvanized square pipes are prone to & ldquo; Electric burning & rdquo; The color of this part is gray and the zinc layer is thick. It is easy to form a current dead angle at the corner， resulting in an under current area. The zinc layer at this part is thin， and there is no zinc layer attached to the cold galvanized square pipe. The cold galvanized square pipe has no zinc lump and caking as a whole but the overall zinc layer is thin， and the thickness of the outer wall zinc layer is μ m-μ m. The and outer walls of the hot-dip galvanized square tube are attached with zinc layer， and there will be water marks and a few zinc tumors， but the overall zinc layer is thick， and the thickness of the zinc layer on the inner and outer walls of the square tube is -mu; M above. The nature of QB square tube!
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 mm. When the outer diameter is less than mm， l = mm.
fAfter the square tube is cut into a single square tube， the head and root of each batch of square tube shall be subject to strict first inspection. The mechanical properties， fusion condition， surface quality of square tube and NDT shall be carried out to ensure that the pipe making process is qualified before it can be officially put into production.
vTDuring the storage of square tubes， pay attention to the stacking layers of square tubes to avoid local stress at the tube end caused by too many layers， resulting in radial plastic deformation and layer damage of square tubes. It is recommended that the stacking layers of smooth pipes refer to apirp l- Recommended Practice for railway transportation of square pipes for pipelines or apirp lw- Recommended Practice for ship and sea vessel transportation of square pipes for pipelines. It can also be determined by test or implemented according to the safe stacking height of square pipes. The stacking layers of pipes shall be implemented according to GBT - polyethylene layer of buried steel pipelines.
The standard quantity of combustible and nonflammable square tubes is gbt- (gbt-). The representative material is l-l pipeline steel. It specializes in selling square tubes， rectangular tubes， seamless square tubes， galvanized square tubes and galvanized tubes， with large quantity， high quality and low price. It is fire-resistant， waterproof， high temperature resistant， durable， safe and reliable. It is mainly used to transport combustible and nonflammable fluids， with high requirements.