Website large image
Website large image
Website large image
Website large image

Company News

Steel Pipe Knowledge

Blog

Weld Seam Treatment and Process Characteristics of Spiral Welded Steel Pipes

2016/10/11

Weld Seam Treatment and Process Characteristics of Spiral Welded Steel Pipes

Spiral welded steel pipe is produced by feeding strip steel into a welding line. As it passes through multiple sets of rollers, the strip gradually curls up to form a circular tube blank with an open seam. The gap between the weld edges is adjusted by regulating the downward pressure of the squeeze rolls, keeping it within 1–3 mm and ensuring that both ends of the weld are flush. 1. If the gap is too large, the proximity effect diminishes, resulting in insufficient eddy‑current heating and poor intergranular bonding at the weld, which may lead to lack of fusion or cracking. 2. If the gap is too small, the proximity effect intensifies, generating excessive heat and causing burn‑through at the weld; alternatively, the weld may develop deep pits after squeezing and rolling, adversely affecting surface quality. After heating both edges of the tube blank to the welding temperature, the squeeze rolls compress them, promoting mutual penetration and crystallization of the metal grains, ultimately forming a strong, reliable weld. For spiral welded pipes, insufficient squeezing results in fewer shared crystals, reducing weld strength and increasing susceptibility to cracking under load. Conversely, excessive squeezing can force molten metal out of the weld, not only weakening the joint but also producing significant internal and external burrs and even leading to defects such as lap joints. Key features of the spiral welded pipe manufacturing process: 1. Raw materials—including coil steel, welding wire, and flux—are subjected to rigorous physicochemical testing prior to use. 2. Before forming, the strip steel undergoes leveling, edge trimming, edge planing, surface cleaning, conveying, and pre‑bending operations. 3. During forming, the steel plate deforms uniformly, residual stresses remain low, and no surface scratches occur. This process offers greater flexibility in diameter and wall‑thickness dimensions, providing distinct advantages—particularly for high‑grade thick‑walled pipes, especially small and medium diameters—that other methods cannot match, thereby meeting diverse customer requirements for spiral pipe specifications. 4. Advanced double‑sided submerged‑arc welding ensures optimal positioning, minimizing misalignment, weld偏shift, and incomplete penetration, while facilitating precise control over weld quality. 5. A weld‑gap control device guarantees that the weld gap meets specified requirements, with strict oversight of pipe diameter, edge misalignment, and weld‑gap tolerances. 6. Each pipe undergoes 100% quality inspection, ensuring that the entire production process remains under effective monitoring and testing, thus safeguarding product quality. 7. All equipment along the production line is equipped with network connectivity to a computerized data‑acquisition system, enabling real-time data transmission and centralized monitoring of process parameters from the central control room.

View Details >

A 90-degree elbow is a pipe fitting used at pipe bends.

2016/10/11

A 90-degree elbow is a pipe fitting used at pipe bends.

Among all pipe fittings used in piping systems, 90-degree elbows account for the largest share, approximately 80%. Typically, different forming techniques are selected depending on the material and wall thickness of the elbow. Currently, the most commonly employed forming methods for manufacturing 90-degree elbows include hot pushing, stamping, and extrusion. The deformation characteristic of a 90-degree elbow is determined by the principle that the volume of metal remains constant before and after plastic deformation; thus, the diameter of the tube blank is chosen smaller than the elbow’s nominal diameter. A mandrel controls the blank’s deformation, ensuring that the metal compressed along the inner arc flows to compensate for thinning in other regions caused by diameter expansion, thereby producing an elbow with uniform wall thickness. A 90-degree elbow is a type of fitting used at pipe bends. It represents the largest proportion—about 80%—of all fittings in piping systems. Different forming processes are usually selected based on the material and wall thickness of the elbow. Today, common forming techniques for 90-degree elbows include hot pushing, stamping, and extrusion. The cost of a 90-degree elbow is directly proportional to its nominal diameter: the larger the diameter, the higher the cost of the forming process. This is because the steel plate used to fabricate such elbows must first be heated over coal-fired furnaces and then shaped using specialized dies. Moreover, larger diameters require correspondingly larger molds, while orders for large-diameter welded elbows tend to be relatively small. A 90-degree elbow, also known as a reduced‑diameter elbow or seamless elbow, is formed by cold‑drawing seamless tubes made from high‑quality carbon steel, stainless steel, acid‑resistant steel, or low‑alloy steel within specially designed dies. Stamped elbows, or stamped‑welded elbows, are produced by stamping sheet metal of the same material as the pipe into semi‑circular segments, which are then assembled and welded together to form a complete elbow. Among these types, the hot‑pressed 90-degree elbow exhibits superior pressure resistance, excellent temperature and pressure tolerance, good flexibility, and strong heat resistance—outperforming other plastic pipe materials. It is easy to install, has good thermal conductivity, making it suitable for underfloor heating systems, and is recyclable. Furthermore, pressed‑type elbows possess outstanding impact resistance, can be joined via hot‑melt welding or mechanical connections, and offer better thermal conductivity than PB‑PP‑R pipes. In terms of long‑term pressure resistance, considering only design stress levels, pressed‑type elbows demonstrate the best performance. In actual production and manufacturing, 90-degree elbows are fabricated according to specific technical standards and dimensions, ensuring they deliver reliable performance and value in practical applications. By fully leveraging their unique characteristics and advantages, and adhering to standard manufacturing procedures, these products can be exported to various countries and regions, contributing to China’s rapid economic growth and development, and holding significant importance for manufacturing enterprises.

View Details >

The large-diameter spiral steel pipe factory employs numerous protective measures for spiral steel pipes during the winter.

2016/10/11

The large-diameter spiral steel pipe factory employs numerous protective measures for spiral steel pipes during the winter.

Winter protection measures for large-diameter spiral steel pipe plants: Professional pipeline maintenance agents can be used regularly to clean, disinfect, and sterilize sewer pipes, ensuring unobstructed flow and preventing the pipes from becoming breeding grounds for pathogens. When cleaning pipelines, it is essential to use specialized pipeline maintenance products to achieve effective disinfection, odor removal, and prevention of blockages. When selecting maintenance and unclogging products, prioritize safety and choose those with high bactericidal efficacy that have been evaluated by reputable professional authorities. Currently, demagnetization of large‑diameter spiral steel pipes typically employs a DC demagnetizing coil placed after the magnetic particle inspection machine; however, this method often fails to meet customer expectations. The issue lies in the fact that the DC demagnetizing field generates only a reverse half‑cycle magnetic field, which can only partially offset the residual magnetism inside the pipe, leaving the external residual magnetism within acceptable limits—resulting in an unstable effect. Often, the process meets specifications on site, but after relocation or impact, the residual magnetism exceeds allowable levels again. For flaw detection in the welds of large‑diameter spiral steel pipes, pulse‑echo ultrasonic testing is a relatively effective technique. Since the primary concern is determining the presence of defects, we employ a scanning ultrasonic flaw detector. This device exploits the reflection characteristics of ultrasonic waves: on the display screen, the vertical axis represents the amplitude of the reflected echoes, while the horizontal axis indicates the travel time of these echoes. By analyzing the amplitude and timing of defect‑related reflections, the size and location of defects can be accurately determined. In terms of specific manufacturing materials, large‑diameter spiral steel pipes exhibit certain unique properties that distinguish them from conventional piping materials. Their defining feature is the hollow cross‑section; this hollow structure provides a substantial internal surface area, making these pipes highly suitable for widespread application in pipeline transportation. Such pipes offer numerous advantages and, as a specialized material, have earned considerable recognition in the transport sector. During production, edge misalignment frequently occurs, influenced by many factors. In practice, such misalignment often leads to downgrading of the pipe. Therefore, it is crucial to analyze the causes of edge misalignment in small‑diameter spiral steel pipes and develop appropriate preventive measures. All welded joints—whether butt welds or T‑joints intersecting spiral welds—are inspected using X‑ray fluoroscopy or radiographic imaging. Each pipe also undergoes a hydrostatic pressure test, with radial sealing employed as the pressure‑bearing mechanism. Structural steel pipes, including various welded and seamless types, particularly large‑diameter spiral steel pipes, possess an ideal annular cross‑section that confers strong resistance to local buckling, making them among the best lightweight components for withstanding both internal and external radial pressures. Columns, beams, and other basic structural elements fabricated from steel pipes can serve independently or be assembled into diverse structural systems, such as frames, trusses, and space frames.

View Details >

Profit margins across all stages of the stainless steel elbow industry chain have been squeezed.

2016/10/11

Profit margins across all stages of the stainless steel elbow industry chain have been squeezed.

The raw material for stainless steel elbows is steel that resists corrosion from weak corrosive media such as air, steam, and water, as well as from chemically aggressive media like acids, alkalis, and salts. In practical applications, steel resistant to mild corrosive environments is commonly referred to as “stainless steel,” while steel capable of withstanding chemical corrosion is called “acid‑resistant steel.” Due to differences in their chemical compositions, the former does not necessarily resist all chemical media, whereas the latter generally exhibits excellent corrosion resistance. Stainless steel remains one of the highest‑strength metallic materials used in construction. Its outstanding corrosion resistance ensures that structural components maintain their intended integrity over long service lives. Over several decades of development within China, the stainless steel elbow industry has made significant strides in product quality, output volume, technological advancement, durability, and safety. Moreover, its corporate services have aligned with international standards, meeting the demands of the modern era. With the advent of the new century, the industry has progressively shifted toward low‑consumption, high‑efficiency, and intelligent automation, achieving notable results that have greatly enhanced its competitiveness both domestically and internationally. The stainless steel elbow sector has now moved beyond a decade of rapid growth. As competition among companies intensifies, profit margins across all stages of the supply chain have been squeezed, leaving limited room for further price reductions. At the same time, international markets are increasingly raising their expectations for Chinese stainless steel elbow products, demanding higher standards in quality, packaging, and delivery schedules—requirements that are gradually extending even to production processes and product R&D. Stainless steel elbow fabrication is a manufacturing process that employs conventional or specialized stamping equipment to apply forming forces directly to sheet metal within dies, thereby shaping it into parts with specific dimensions, configurations, and functional properties. Sheet metal, dies, and equipment constitute the three essential elements of stamping operations. Thanks to their smooth inner surfaces, low hydraulic resistance, resistance to acids and alkalis, long service life, and ease of installation, stainless steel elbow pipes have seen widespread adoption in heating systems in recent years. National‑standard stamped elbows, as next‑generation piping specifically designed for heating applications, are steadily becoming mainstream in the heating market. Thickening‑wall stainless steel elbows refer to fittings whose wall thickness varies along the pipe’s length, with gradual increases in wall thickness tailored to enhance performance and convenience during use, while also providing assurance of consistent quality. Each of these processing methods possesses distinct characteristics, requires different technical conditions, and entails unique considerations. Pipe fitting fabrication represents an organic integration of machining and metal forming; superior coordination between these processes makes fabrication more rational and better suited to the actual needs of end‑use applications.

View Details >

What is the production process for converting straight-seam steel pipes into bent pipes at Guangxi Canghai Steel Pipe Company?

2016/10/11

What is the production process for converting straight-seam steel pipes into bent pipes at Guangxi Canghai Steel Pipe Company?

As another year draws to a close and the Spring Festival approaches, some rejoice while others grieve. With 2015 now behind us, let’s look ahead to 2016! Today, Guangxi Canghai Steel Pipe Co., Ltd., a company specializing in manufacturing flanges in Guangxi, presents the production process for converting straight-seam steel pipes into bent pipes:

View Details >

How are corrosion‑resistant spiral steel pipes for drainage protected against corrosion?

2016/10/11

How are corrosion‑resistant spiral steel pipes for drainage protected against corrosion?

With the continued development of China’s economy, the state has been vigorously promoting the energy sector. Long-distance oil and gas pipelines are a crucial means of ensuring energy security. During the anti-corrosion construction of oil (and gas) pipelines, the treatment of corrosion‑resistant steel pipes is one of the key factors determining the service life of the pipeline’s protective coating; it is also the prerequisite for achieving a strong bond between the coating and the pipe. Therefore, it is essential to strictly adhere to the specifications governing the surface preparation of steel pipes, continuously explore and refine best practices, and constantly improve the methods used to treat corrosion‑resistant steel pipes. Today, Nanning Canghai Steel Pipe Co., Ltd. will introduce the anti-corrosion treatment procedures for spiral‑welded steel pipes used in drainage applications.

View Details >

Process and Precautions for Steel Support Systems

2016/10/11

Process and Precautions for Steel Support Systems

Steel bracing is typically an inclined connecting member, most commonly configured in a V‑shaped or crossed pattern. Its cross‑section may be made of steel pipe, H‑section steel, angle steel, or other forms, and its primary function is to enhance the structural stability. Below, Guangxi Nanning Canghai Steel Pipe Co., Ltd. will introduce the fabrication process for steel pipe bracing:

View Details >

Spiral steel pipes are manufactured from coiled strip steel.

2016/10/11

Spiral steel pipes are manufactured from coiled strip steel.

Spiral steel pipe is manufactured from coiled strip steel, formed by cold extrusion under pressure, and welded using an automated double-wire, double-sided submerged-arc welding process.

View Details >

< 1...15161718 >

Guangxi Nanning Canghai Steel Co., Ltd. All rights reserved

by:www.300.cn

Skype
WhatsApp

8613768885388
tel

13768885388
wechat
WeChat

WeChat

Link
customize

Sorry, there is currently no content in this section.

You can view other sections.

Business license