Comparison Of Spiral Steel Pipe, Straight Seam Steel Pipe And Seamless Steel Pipe

The production process of straight seam welded pipe is relatively simple. The main production processes are high-frequency welded straight seam steel pipe and submerged arc welding straight seam steel pipe. The production efficiency of straight seam pipe is high, the cost is low and the development is fast.The strength of spiral welded pipe is generally higher than that of straight welded pipe, and the main production process is submerged arc welding. Spiral steel pipe can be used to produce different pipe diameters with blank of the same width, and can also be used to produce larger pipe diameters with narrow blank.However, compared with the straight seam pipe of the same length, the weld length increases by 30~100%, and the production speed is lower.Therefore, the smaller diameter welded pipe mostly used straight seam welding, large diameter welded pipe is mostly used spiral welding.They have been used in the industry production of straight steel tube located at a t-shaped welding technology, the short sections of straight seam steel pipe for docking, the length of the connect accords with the need of engineering, t the probability straight seam welded steel defect is greatly improved, and the t-shaped seam welding residual stress is larger, the stress state of the weld metal are often in a three to increase the possibility of a crack.

Straight Seam Steel Pipe

Welding process: from the welding process, the spiral welded pipe and straight seam steel pipe welding method is consistent, but the straight seam welded pipe will inevitably have a lot of t-shaped weld, so the probability of weld defects is also greatly improved, and the t-shaped seam welding residual stress is larger, the stress state of the weld metal are often in a three-way increases the possibility of a crack.In addition, according to the technical regulations of submerged arc welding, every welding seam should have arc initiation and arc quenching, but each straight welded pipe cannot achieve this condition when welding circular seam, so there may be more welding defects at the arc quenching.

Strength characteristics: when the pipe is under internal pressure, there are usually two main stresses on the pipe wall, namely radial stress and axial stress.The resultant stress at the weld is, wherein, is the spiral Angle of the weld of the spiral welded pipe.The helical Angle of spiral welded pipe is usually degree, so the synthetic stress of spiral welded seam is the main stress of straight welded pipe.Under the same working pressure, the wall thickness of spiral welded pipe with the same diameter can be reduced compared with that of straight welded pipe.According to the above characteristics, it can be seen that when the spiral welded pipe is blasted, because the normal stress and synthetic stress of the weld are relatively small, the blasting mouth will not generally originate from the spiral weld, and its safety is higher than that of the straight welded pipe.When there is a defect parallel to the spiral weld, the spiral weld has less stress, so its expansion risk is not as great as that of the straight weld.Since the radial stress is the maximum stress existing on the steel tube, the weld will bear the maximum load when it is in the direction of vertical stress.That is, the straight seam bears the maximum load, the circumferential weld bears the minimum load, and the spiral seam is between the two.Static pressure blasting strength: through relevant comparative tests, it is verified that the yield pressure of spiral welded pipe and straight welded pipe is basically consistent with the measured value and theoretical value of blasting pressure, and the deviation is close.But the spiral welded pipe is lower than the straight welded pipe no matter the yield pressure or the bursting pressure.The test also shows that the annular deformation rate of spiral welded pipe is obviously higher than that of straight welded pipe.It is proved that the plastic deformation capacity of spiral welded pipe is better than that of straight welded pipe, and the blasting hole is generally limited to a screw pitch, which is caused by the strong constraint effect of spiral weld on the expansion of the crack. Toughness and fatigue strength: pipeline development trend is large diameter, high strength.With the increase of the diameter of the steel tube and the grade of steel used, the trend of the ductile fracture tip steady expansion is larger.According to the test of American research institute, spiral welded pipe and straight welded pipe are the same level, but spiral welded pipe has higher impact toughness.Due to the change of the conveying volume, the steel pipe is subjected to random alternating load in the actual operation.Understanding the low cyclic fatigue strength of steel pipe is of great significance to judge the service life of pipeline.

According to the measured results, the fatigue strength of the spiral welded pipe is the same as that of the seamless pipe and the resistance welded pipe.

Quality Customized Construction Pipe

Our company also provides quality customized construction pipes for customers, if you are interested in our products or services, you are welcome to contact us for details.

Do you know the function of our various pipes?

Our company is a professional thermal Insulation pipe factory, we also have produced a lot of gas pipeline spiral steel pipe and spiral pipes. Our products have met with a warm reception in many country. What’s more, our products have obtained favorable comments from customers. Then let me introduce them to you.

 

Thermal insulation pipe is the abbreviation of thermal insulation pipe. Thermal insulation pipe is used for the transportation of liquid, gas and other media. It is used for thermal insulation of pipelines in petroleum, chemical industry, aerospace, hot spring military, central heating, central air conditioning, municipal and other thermal insulation projects. Internal sliding type: thermal insulation structure consists of working steel pipe, aluminum silicate, drag reduction layer, microporous calcium silicate, thermal insulation layer, stainless steel fastening steel belt, aluminum foil reflective layer, polyurethane thermal insulation layer, outer steel pipe and outer anti-corrosion layer. The internal sliding type heat preservation steel pipe is composed of a steel pipe conveying medium, composite silicate or microporous calcium silicate, rigid polyurethane foam plastic, an outer steel pipe and a glass fiber reinforced plastic shell anti-corrosion protective layer structure. All kinds of pipe joints have mature heat preservation technology and reliable quality. External sliding type: thermal insulation structure consists of working steel pipe, glass wool thermal insulation layer, aluminum foil reflective layer, stainless steel fastening steel belt, sliding guide bracket, air thermal insulation layer, external protective steel pipe and external anti-corrosion layer. Spiral steel pipe is a spiral seam steel pipe made of strip steel coiled plate as raw material, which is often extruded and formed at high temperature and welded by automatic double-wire double-sided submerged arc welding process. Using advanced double-sided submerged arc welding technology, welding can be realized at the best position, and defects such as edge misalignment, welding deviation and incomplete penetration are not easy to occur, and welding quality is easy to control.

                  

The standard of spiral steel pipe is divided into 9711 and API. It is necessary to carry out flaw detection tests and ensure flaw detection. Steel pipes at the outlet need to be painted and beveled. It is convenient for steel pipes to be welded and connected during construction. The purpose of painting is a simple anti corrosion procedure. The standard of spiral steel pipe for natural gas pipeline is gb9711 and API. Need to carry out flaw detection tests, enterprises need to ensure flaw detection. Steel pipes at the outlet need to be painted and beveled. It is convenient for steel pipes to be welded and connected during construction. The purpose of painting is a simple anti corrosion procedure. Design and produce steel pipes with new structures, such as double-layer spiral welded pipes, i.e. double-layer pipes welded with strip steel half the thickness of the pipe wall, not only have higher strength than single-layer pipes with the same thickness, but also do not suffer brittle failure. Vigorously developing coated pipes, such as coating the inner wall of the pipe with anticorrosive coating, can not only prolong the service life, but also improve the smoothness of the inner wall, reduce the friction resistance of fluid, reduce wax and dirt accumulation, reduce pigging times and reduce maintenance costs. The development of new steel grades, improvement of smelting technology, production and welding of spiral welded pipe with good quality, extensive use of controlled rolling and residual heat treatment process after rolling, in order to continuously improve the strength and toughness of the pipe body and welding performance.

What are thermal insulation pipe and spiral steel pipe ?

Shall i can introduce something about the thermal insulation pipe ? If yes, now i will begin. Our company is a professional thermal insulation pipe factory. The spiral steel pipe and thermal Insulation Pipe are our company’s main product. But also we are one of the most professional supplier in our country. Because our products are of good quality and excellent price, they have won unanimous praise from people inside and outside the industry.

 

Thermal insulation pipe is the abbreviation of thermal insulation pipe. Thermal insulation pipe is used for the transportation of liquid, gas and other media. It is used for thermal insulation of pipelines in petroleum, chemical industry, aerospace, hot spring ~ military, central heating, central air conditioning, municipal and other thermal insulation projects. Heat preservation pipes are suitable for conveying various media in the range of-50℃-150℃. They are widely used in central heating, cold supply and hot oil transportation, as well as in heat preservation and cold preservation projects in warm rooms, cold storage, coal mines, petroleum, chemical and other industries. The thermal insulation structure of steel sleeve and steel composite thermal insulation pipe can be divided into two categories according to different sliding modes: Firstly is Internal sliding type: the thermal insulation structure consists of working steel pipe, aluminum silicate, drag reduction layer, microporous calcium silicate, thermal insulation layer, stainless steel fastening steel belt, aluminum foil reflective layer, polyurethane thermal insulation layer, outer steel pipe and outer anticorrosive layer. The internal sliding type thermal insulation steel pipe is composed of steel pipe conveying medium composite silicate or microporous calcium silicate+rigid polyurethane foam outer steel pipe+glass fiber reinforced plastic shell anti-corrosion protective layer structure. All kinds of pipe joints have mature heat preservation technology and reliable quality. Second is external sliding type: the thermal insulation structure consists of working steel pipe, glass wool thermal insulation layer, aluminum foil reflective layer, stainless steel fastening steel belt, sliding guide bracket, air thermal insulation layer, external protective steel pipe and external anti-corrosion layer.

 

Spiral steel pipes feed the strip steel into the welded pipe unit, and the strip steel is rolled by multiple rollers, and gradually rolled up to form a round tube blank with an open gap. the reduction of the extrusion roller is adjusted to control the weld gap to 1-3 mm and make both ends of the joint flush. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the weld grain will not be bonded well indirectly, resulting in incomplete fusion or cracking. If the gap is too small, the proximity effect will be increased, and the welding heat will be too large, resulting in welding seam burning. Or the weld seam is extruded and rolled to form a deep pit, which affects the surface quality of the weld seam.  After the two edges of the tube blank are heated to the welding temperature, common metal grains are formed to permeate and crystallize with each other under the extrusion of the extrusion roller, and finally a firm weld is formed. If the extrusion force of spiral steel pipe is too small, the number of common crystals will be small, the strength of weld metal will decrease, and cracking will occur after being stressed. If the extrusion force is too high, molten metal will be extruded out of the weld, which will not only reduce the weld strength, but also produce a large number of internal and external burrs, and even cause defects such as weld overlap.

What Is The Function Of Galvanized Fire Pipe?

Galvanized fire pipes, also known as galvanized steel pipes, are divided into hot galvanizing and electronic galvanizing. Hot galvanizing has a thick galvanized layer and has the advantages of uniform coating, strong adhesion, and long service life. Electronic galvanizing is low in cost, the surface is not very smooth, and its corrosion resistance is much worse than that of galvanized pipes. Hot-dip galvanized pipe is to make molten metal react with an iron matrix to produce an alloy layer, thus combining matrix and plating layer. Hot galvanizing is to pickle the steel pipe first. In order to remove iron oxide on the surface of the steel pipe, after pickling, the steel pipe is washed in an aqueous solution of ammonium chloride or zinc chloride or a mixed aqueous solution of ammonium chloride and zinc chloride and then sent into a hot-dip plating tank. Hot galvanizing has the advantages of uniform coating, strong adhesion, and long service life. Most of the processes in the north adopt a direct coil zinc filling process with a galvanized strip. Cold galvanized pipes are electronic-galvanized. The amount of galvanization is very small, only 10-50g/m2. Its corrosion resistance is much different from that of hot galvanized pipes. Hot-dip galvanized steel pipes have hot dip plated welded steel pipes on their surfaces. Galvanizing can increase the corrosion resistance of steel pipes and prolong their service life. Galvanized pipes have good corrosion resistance, acid and alkali resistance, and generally, do not need surface treatment. So galvanized pipes are used. Galvanized pipes can be welded with carbon dioxide gas shielded welding, and then the welding will not be coated with primer and anticorrosive paint for three times, so as to ensure its reliability and durability.

Galvanized steel construction pipes are made up of galvanized steel tubes, which are unpacked, flattened, crimped and welded to form round tubes, which are then rolled into square tubes and then cut to the required length. Generally, 50 square tubes per package are mostly of large specifications in the spot, ranging from 10*10*0.8-1.5~~500*500*10-25. The square tubes are divided into structural square tubes, decorative square tubes, building square tubes, mechanical square tubes, etc. according to their uses. Square tube is a kind of appellation for square tube, that is, steel tube with equal side and length. It is made by rolling strip steel through technological treatment. Replacing and drawing square tubes: strip steel is usually unpacked, flattened, crimped and welded to form round tubes, which are then rolled into square tubes and then cut to the required length. 

Our company has produced a greet deal of pipes now and our company is the best professional galvanized steel water pipe in China. Because our products are of good quality and excellent price, they have won unanimous praise from people inside and outside the industry