steel pipe

 　　Spiral steel pipe(SSAW) is also called spiral welded pipe. It is made by rolling low-carbon structural steel or low-alloy structural steel strip according to the angle of the spiral line (forming angle) into a tube blank, and then welding the tube seam together. It can be made with a narrower The strip steel produces large-diameter steel pipes. 　　How to distinguish inferior spiral steel pipe? 　　1. Inferior spiral tubes are easy to fold. 　　2. From the appearance point of view, there will be numbness and scarring. The reasons for these problems are mostly uneven materials and poor equipment. 　　3. Inferior spiral tubes have no metallic luster, and are light red or similar to pig iron. 　　4. Inferior spiral pipes are easy to scratch. The reason for this problem is that the strength of the steel pipe is not enough. 　　5. The inner diameter of inferior spiral pipe fluctuates greatly. 　　6. The cross-section of the counterfeit spiral tube is elliptical. It is due to the fact that in order...

 　　According to the casting method: it is divided into the continuous ductile iron pipe and centrifugal ductile iron pipe. Centrifugal ductile iron pipe is divided into the sand type and metal type. 　　Centrifugal spheroidal graphite cast iron pipes are cast iron pipes. Cast iron pipes are used for water supply, drainage, and gas transmission pipelines. It includes straight cast iron pipes and pipe fittings. 　　According to the material used: it is divided into the gray iron pipe and high silicon iron pipe. 　　The sand centrifugal cast iron straight pipe is made of gray cast iron, which is suitable for the transportation of pressure fluids such as water and gas. 　　High-silicon cast iron has the advantages of good corrosion resistance, low cost, saving precious metals, etc. It is especially suitable for making to withstand static loads and interact with various strong corrosive media (such as nitric acid, sulfuric acid, chromic acid, organic acid, and A series of salt solutions) contac...

 　　Straight seam steel pipes are steel pipes whose welds are parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on. Longitudinal welded pipe has simple production process, high production efficiency, low cost and rapid development. 　　Spiral steel pipe is a spiral seam steel pipe made of strip steel coils as raw materials, often extruded and formed by automatic double-wire double-sided submerged arc welding. The spiral steel pipe feeds the strip steel into the welded pipe unit. After rolling by multiple rollers, the strip steel is gradually rolled up to form a round tube blank with an open gap. The reduction of the squeeze roll is adjusted to control the weld gap at 1~ 3mm, and make both ends of the welding joint flush. 　　Features of straight seam steel pipe: 　　The LSAW steel pipe adopts double-sided submerged arc welding welding technology, welded und...

 　　When undergoing any construction process, it is crucial to have the correct materials. When that project involves any type of piping, someone will have to make a decision between welded and seamless pipes. That decision is not always a straightforward as it appears. 　　For example, there are many regulations regarding the use of welded pipes. This based on the materials traveling through the pipe and the pressure those materials will travel under. Therefore, it’s important to know about seamless steel pipes before making a decision. 　　Advantages of Seamless Pipe: 　　Welded pipes are more vulnerable to failure at the weld location, even if a seam may not be visible. Despite improvements in welding technology, a welded pipe can handle a maximum pressure 20% less than that of a seamless pipe. 　　There are other advantages to the seamless pipe. A seamless pipe does not require any weld integrity testing and, in most cases, a heat treatment. That’s because seamless pipes harden during t...

 　　Welding residual stress is the temperature difference inside the weldment caused by the heating and cooling process during welding, which leads to inconsistent deformation and internal stress. Welding residual stress causes deformation, cracking and other welding defects. Welding residual stress will break the weld and cause the workpiece. Unallowable deformation is produced, resulting in structural brittle fracture, corrosion resistance and tensile residual stress, reducing fatigue strength and stability limit. 　　How to control welding residual stress? 　　Welding stress is inevitable. After the welding operation, welding deformation will release some welding stress on the one hand, and will exist in the form of residual stress on the other hand, but welded components generally have residual stress and deformation. 　　Methods of controlling welding residual stress: 　　1. Under the premise of ensuring the strength of the weldment, the stamping structure is used to reduce the welding...

 　　As a commonly used steel product, seamless steel pipe has certain defects due to various reasons. The common defects are as follows. 　　1. There are holes in seamless steel pipes, that is, there are round, long, elliptical and various irregular holes inside the steel pipe, and they may also be aggregated into pieces, and the color is black or gray. The shape is mostly irregular, and the crystal grains are also very coarse. There are also some blisters. The so-called blisters refer to the presence of sand-like holes inside the tube. The reason for this situation is generally that air bubbles are mixed in the production process of the steel pipe. 　　2. Metal cracks refer to irregular-shaped cracks or lines on the metal surface, similar to the way the metal is torn. There are many reasons for this situation, mainly due to the insufficient heating temperature of the metal. The hard perforation operation causes the metal to tear. The solution is to control the temperature of the heatin...

 　　Nowadays, welded steel pipes are also used in medium and low pressure boilers, thanks to the rapid improvement of welding technology. For example, the joint microstructure of the pipe butt butt friction welded steel pipe is the same, and after the pipe joints are remelted through the butt joint and the corner joint, it is difficult to observe the clump joint traces with the naked eye. The microstructure of its parts has been The clumps are exactly the same. 　　Common problems in the surface treatment and product processing of seamless steel pipes for high-pressure boilers: 　　1. The surface of seamless steel pipes for high-pressure boilers is inconsistent: only the welds are pickled and passivated, resulting in uneven surfaces and affecting appearance. 　　2. The scratches on seamless steel pipes for high-pressure boilers are difficult to remove: the whole is pickled and passivated, and the various scratches produced during the processing cannot be removed, and the scratches and wel...

 　　Precautions for seamless line pipe production process: 　　1. Raw material inspection and inspection 　　The raw material manufacturer's product quality certificate, the raw material is sampled in batches, and the steel pipe manufacturer will conduct various inspections and issue an inspection report. 　　2. Hydrostatic pressure test 　　Each steel pipe shall be subjected to hydrostatic pressure test without leakage, and the test pressure shall be at least not lower than the requirements in API 5L. The test pressure holding time for seamless steel pipes of various sizes shall be no less than 5 seconds. In order to ensure that each steel pipe can reach the required test pressure, each testing machine should be equipped with a recorder to record the test pressure and holding time of each steel pipe. If there is a representative of the purchaser in the factory for inspection, these records or charts should be available for inspection by the inspector of the purchaser. The test pressure tes...

 　　Preheating refers to heating the workpiece to be welded to above room temperature before or during welding. According to the application standard of the material, the current specification usually requires several preheating temperature levels. 　　The pre-weld and post-weld specifications require preheating. However, under certain conditions, other preheating methods can also be used. Regardless of whether preheating is required, preheating has the following advantages. 　　1. Reduce the shrinkage stress between the weld and the adjacent base metal, which is suitable for welds with high stress values. 　　2. Slow down the cooling rate of the weld in the critical temperature range, prevent excessive hardening, and reduce the ductility of the weld and the heat-affected zone. 　　3. In the temperature range of 400°F, slow down the cooling rate to allow hydrogen to escape from the weld to prevent hydrogen-induced cracking. 　　4. Remove contaminants. 　　The preheating temperature range is usu...

 　　Oil casing drilling is also called percussion drilling. The wire rope is used to send the drill bit to the bottom of the well. The beam mechanism is driven by the driving force to move one end of the beam up and down. The wire rope and the drill bit collide up and down to break the rock. The drilling speed of Dayton rigs is generally relatively slow, and the efficiency is very low, and cannot meet the requirements of increasing well depth and complex formation drilling, so it is gradually replaced by rotary drilling. However, its equipment is relatively simple, low in cost, and will not pollute the oil layer. It can be used in some shallow low pressure oil and gas wells and water loss wells. Downhole power drilling is the use of downhole power drilling tools to drive the drill bit to break the rock. The drill string does not rotate during the drilling process, with less wear and long service life. It is particularly suitable for drilling directional wells. Downhole electric dril...