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Massive procurement of national-standard large-diameter spiral steel pipes

2018/05/11

Massive procurement of national-standard large-diameter spiral steel pipes

Large-diameter spiral steel pipes refer to spiral steel pipes with a nominal diameter of DN850 or greater. The primary raw material used in their production is strip steel. Spiral steel pipes generally have higher strength than straight-seam welded pipes, allowing for the manufacture of larger‑diameter pipes from narrower billets, and enabling the production of pipes with different diameters from billets of the same width. Large‑diameter spiral steel pipes are manufactured using double‑sided submerged arc welding, which offers advantages such as stable weld quality, high welding productivity, minimal arc radiation, and reduced fumes and dust. Key parameters include outer diameter, wall thickness, and length. Mechanical tests typically encompass hydrostatic pressure testing, bending tests, and flattening tests. The applicable standards include: SY/T 5037-2008 (a ministry standard, also known as spiral seam submerged arc welded steel pipe for general fluid conveyance); GB/T 9711.1-2008 (a national standard, also referred to as steel pipe for oil and gas transportation); API 5L (American Petroleum Institute standard, also called pipeline steel pipe); SY/T 5040-2008 (spiral seam welded steel pipe for pile applications); and SY 5039-2000 (general low‑pressure fluid transport spiral seam high‑frequency welded steel pipe). The main grades used are Q235A, Q235B, 20#, Q345 (16Mn), and pipeline steels ranging from X42 to X70. Their primary applications include: liquid transport—such as water supply and drainage; gas transport—such as coal gas, steam, and liquefied petroleum gas; and structural uses—such as piling tubes, bridge construction, and piping for docks, roads, and building structures. Below is a brief overview of several types of welded pipes and their applications: 1. General welded pipes are used for conveying low‑pressure fluids such as water, coal gas, air, oil, and heating steam. 2. Ordinary carbon steel conduit pipes (GB 3640-88) are steel tubes employed in electrical installation projects—such as industrial and civil buildings and machinery installations—to protect electrical wires. 3. Straight‑seam electric welded pipes (YB 242-63) are steel pipes whose weld seams run parallel to the longitudinal axis of the pipe. They are commonly categorized into metric electric welded pipes, thin‑walled electric welded pipes, transformer cooling oil pipes, and others. 4. Spiral seam submerged arc welded pipes for pressurized fluid conveyance (SY 5036-83) are manufactured by rolling hot‑rolled steel strips into pipe blanks, forming them into spirals at room temperature, and then welding them using double‑sided submerged arc welding. These pipes are designed for transporting pressurized fluids, offering strong pressure resistance, excellent weldability, and proven safety through rigorous scientific inspections and tests. With large diameters and high conveying efficiency, they help reduce capital costs associated with pipeline installation. They are primarily used for oil and natural gas pipelines. 5. Spiral seam high‑frequency welded pipes for pressurized fluid conveyance (SY 5038-83) are produced by rolling hot‑rolled steel strips into pipe blanks, forming them into spirals at room temperature, and welding them using high‑frequency lap welding. These pipes exhibit strong pressure resistance, good ductility, and ease of welding and shaping. After undergoing stringent scientific inspections and tests, they demonstrate reliable performance, large diameters, and high conveying efficiency, while also reducing pipeline installation costs. They are mainly used for laying pipelines that transport oil and natural gas. 6. General low‑pressure fluid transport spiral seam submerged arc welded pipes (SY 5037-83) are manufactured by rolling hot‑rolled steel strips into pipe blanks, forming them into spirals at room temperature, and employing either double‑sided automatic submerged arc welding or single‑sided welding techniques. These pipes are specifically designed for conveying low‑pressure fluids such as water, coal gas, air, and steam.

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Steel prices have risen by more than 1,000 yuan, and steelmakers have generally turned losses into profits.

2017/03/20

Steel prices have risen by more than 1,000 yuan, and steelmakers have generally turned losses into profits.

Since the first half of last year, steel prices have begun to recover, driven by supply-side reforms and measures to phase out outdated production capacity. Taking rebar as an example, its average price on March 9 last year was 2,475 yuan per ton, while on March 9 this year it had risen to 3,852 yuan per ton—a 35% increase. Benefiting from rising steel prices, steel companies’ financial performance improved markedly last year. In 2015, Nangang Co., Ltd., Liugang Co., Ltd., and *ST Shaogang reported losses of 2.432 billion yuan, 1.189 billion yuan, and 2.596 billion yuan, respectively; in 2016, these three companies posted profits of 350 million yuan, 185 million yuan, and 101 million yuan, respectively. According to data from the China Iron and Steel Association, in 2016, large and medium-sized steel enterprises recorded total sales revenue of 2.80 trillion yuan, down 1.81% year-on-year, yet their combined profits reversed from a loss of 84.7 billion yuan in 2015 to a gain of 30.378 billion yuan, marking an overall turnaround for China’s steel industry. Since 2016, the steel sector has also embarked on a capacity‑reduction drive. However, according to the National Bureau of Statistics, China’s crude steel, pig iron, and steel output in 2016 reached 808 million tons, 701 million tons, and 1.139 billion tons, up 1.24%, 0.74%, and 2.30% year-on-year, respectively. China’s share of global crude steel production rose to 49.6%, an increase of 0.2 percentage points over the previous year. Domestic apparent consumption of crude steel stood at 709 million tons, up 2.08% year-on-year. This indicates that capacity cuts have not significantly curtailed steel output, suggesting that the sharp price surge is closely tied to fluctuations in demand. On March 5, the government’s work report for this year explicitly stated: “This year, we will further cut steel capacity by approximately 50 million tons and retire more than 150 million tons of coal‑related capacity. At the same time, we will phase out, suspend construction on, or slow down over 50 million kilowatts of coal‑fired power capacity, aiming to mitigate risks associated with excess coal‑power capacity, enhance industry efficiency, and create room for the development of clean energy.” Although this year’s targets—50 million tons of steel capacity and 290 million tons of coal capacity—are lower than last year’s actual reductions of 65 million tons of steel and 290 million tons of coal—the majority of last year’s cuts targeted inefficient capacity, while overall output continued to hit record highs. Consequently, this year’s supply‑side capacity reduction is expected to move toward more substantive progress, particularly with the complete elimination of “strip steel” capacity in the first half of the year, which will have a tangible impact on market supply. As the market enters the peak consumption season of “Golden March and Silver April,” demand is anticipated to improve further. On the supply side, the National Development and Reform Commission has announced a comprehensive ban on the use of power‑frequency and medium‑frequency induction furnaces for producing construction steel in the first half of the year. Meanwhile, during the Two Sessions, steel mills in North China were subject to a 50% production cut, and the Ministry of Environmental Protection conducted unscheduled environmental inspections—all of which are likely to constrain overall supply, especially for construction steel. Nangang Co., Ltd. On March 10, 2017, Nangang Co., Ltd. issued an announcement forecasting a significant increase in first‑quarter earnings for 2017. The company expects net profit attributable to shareholders of the listed company to reach 400–500 million yuan, representing a substantial year‑on‑year improvement. While strengthening its core steel business, the company is actively pursuing transformation and upgrading, planning to integrate its existing diversified industrial resources and external investment platforms to focus on emerging sectors such as energy conservation, intelligent manufacturing, and Internet Plus. It is also aligning closely with the development plan of Nanjing’s Jiangbei New Area. In 2015, the company established Jin Kai Energy Conservation and Environmental Protection Investment Holding Co., Ltd., consolidating its internal energy‑conservation and environmental‑protection operations into this platform, thereby laying a solid foundation for the growth of these industries. Moving forward, the company intends to adopt a strategy of collaborative partnerships combined with independent integration, concentrating on areas such as solid waste treatment, wastewater treatment, and waste‑heat power generation, with the aim of swiftly bringing relevant projects to fruition. Liugang Co., Ltd. As Guangxi’s sole integrated steel producer, Liugang holds an overwhelming dominant position in the region’s steel market. The company is also expanding into neighboring provinces such as Guangdong and Hainan, dispatching technical personnel to maintain long‑term presence in Guangdong. In 2015, its building‑material products saw a significant rise in market share across Guangxi. In the first half of 2016, the company further reduced rail freight rates for its steel products, making Yunnan, Guizhou, Sichuan, as well as Changsha and Guangzhou, part of a unified regional market with consistent transportation costs. Additionally, the company’s e‑commerce platform has introduced timely trading models—including spot sales, auction sales, and forward contracts—to serve key infrastructure projects and directly supply end users. *ST Shaogang *ST Shaogang released its 2016 annual report, reporting operating revenue of 13.973 billion yuan, up 25.38% year on year; operating costs of 13.326 billion yuan, up 6.40% year on year; and net profit attributable to shareholders of the listed company of 101 million yuan, compared with a loss of 2.596 billion yuan in the same period last year. Earnings per share (EPS) for 2016 stood at 0.04 yuan, versus −1.07 yuan in the prior year. As Guangdong Province’s largest steelmaker, *ST Shaogang’s main products—rebar, wire rod, and shipbuilding plates—command market shares of 13%, 16%, and 10%, respectively, within the province. The company’s successful turnaround in 2016 was primarily driven by a recovery in industry conditions, increased non‑recurring gains, and cost optimization.

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The development of seamless steel pipe manufacturing technology has gone through three major stages.

2016/10/11

The development of seamless steel pipe manufacturing technology has gone through three major stages.

Over the past century and more since the Mannesmann brothers invented the rotary piercing process, the development of seamless steel pipe manufacturing technologies has progressed through three distinct phases: 1. From the 1880s to the 1930s—nearly half a century—seven major pipe‑making processes emerged in succession: the periodic rolling mill (1892), the push‑through mill (1899), the continuous rolling mill (1901), the automatic rolling mill (1903), the Dieser rolling mill (1932), the three‑roll rolling mill (1937), and the extrusion mill. All these processes had reached industrial maturity and gradually became standardized; at the time, the automatic and periodic rolling mills were widely adopted, while pipes produced by the push‑through and three‑roll mills accounted for only a small share. Meanwhile, the continuous rolling mill and the Dieser rolling mill saw little further development. 2. During the roughly four decades from the 1940s to the early 1980s, the fully floating mandrel continuous rolling process experienced significant advancement, as evidenced by the commissioning of two rolling mills in the United States and two continuous rolling mills in Germany. The introduction of the MPM rolling mill at Dalmine’s Bergamo plant in 1978 and the semi‑floating mandrel continuous rolling mill at Yawata in 1983 marked the beginning of a new phase in which three distinct continuous rolling processes coexisted. During this period, developments in seamless steel pipe production also included the evolution of the push‑through process into the CPE process, the widespread adoption of tension‑reduction techniques, and the successful use of continuously cast round billets as raw material for pipe rolling. 3. Since the early 1980s, over the past two decades, both the three‑roll rolling mill and the Dieser rolling mill have undergone improvements, giving rise to new types of three‑roll mills and the Accu‑Roll mill. In addition, the three‑roll planetary rolling mill (1982), the GPS process (1989), and the PQF process (1993) have all been introduced. It is worth noting that the resurgence of the conical‑roller piercing machine represents a major breakthrough in this stage, one that will exert a profound influence on the future evolution of seamless steel pipe manufacturing technology.

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What are the key considerations in manufacturing elbows?

2016/10/11

What are the key considerations in manufacturing elbows?

In piping systems, elbows are fittings used to change the direction of a pipeline. By angle, the most common types are 45°, 90°, and 180°; additional non‑standard angles such as 60° may also be employed depending on project requirements. Elbows can be manufactured from materials including cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non‑ferrous metals, and plastics. Connection methods include direct welding (the most widely used), flanged connections, hot‑melt connections, electrofusion connections, threaded connections, and socket‑and‑spigot joints. Based on manufacturing processes, they are classified as welded elbows, stamped elbows, push‑bent elbows, cast elbows, and butt‑welded elbows, among others. Other names include 90° elbow, right‑angle bend, or “Aer” bend. Elbows are commonly used plumbing fittings for connecting pipes at bends, enabling changes in pipeline direction. Alternative designations include 90° elbow, right‑angle bend, “Aer” bend, stamped elbow, pressed elbow, machined elbow, and welded elbow. They are primarily used to join two pipes of the same or different nominal diameters, allowing turns of 90°, 45°, 180°, or other specified angles. Bends with a radius equal to or less than 1.5 times the pipe diameter are classified as elbows, while those exceeding 1.5 times the pipe diameter are considered bent pipes. So, what are the key considerations in manufacturing elbows? 1. Welding electrodes must be kept dry: titanium‑calcium type electrodes should be dried at 150°C for one hour, whereas low‑hydrogen electrodes require drying at 200–250°C for one hour (avoid repeated re‑drying, as this can cause the coating to crack and peel). Prevent contamination of the electrode coating with oil or other foreign matter, which could increase carbon content in the weld and compromise weld quality. During welding, repeated heating can lead to carbide precipitation, reducing corrosion resistance and mechanical properties. Post‑weld hardening is significant, making cracks more likely. When using similar electrodes, preheating above 300°C and post‑weld slow cooling around 700°C are essential. If post‑weld heat treatment is not feasible, chromium‑nickel stainless steel electrodes should be selected. 2. To enhance the corrosion resistance and weldability of stainless steel elbows, appropriate amounts of stabilizing elements such as Ti, Nb, and Mo may be added. With improved weldability, when using chromium‑based stainless steel electrodes of the same type, preheating above 200°C and post‑weld tempering around 800°C are recommended. If heat treatment is impractical, chromium‑nickel stainless steel electrodes should be chosen.

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The Development of Spiral Welded Steel Pipes

2016/10/11

The Development of Spiral Welded Steel Pipes

Despite the ongoing economic crisis that impacted 2016, Guangxi Nanning Canghai Steel Pipe Co., Ltd. has gradually resumed its growth, paving the way for a brighter future. Spiral steel pipes have played a vital role in gas transmission and transportation. With numerous major pipeline projects planned and under construction both domestically and internationally, this year we successfully delivered large quantities of spiral steel pipes—widely used in Thailand’s Ratchaburi sugar industry—on schedule. High‑value products such as spiral steel pipes, high‑strength hot‑bent bends, and thick‑walled cryogenic pipe fittings have demonstrated strong market competitiveness and robust demand, while domestic companies have been relatively slow in developing these product lines. To accelerate the development of high‑value spiral steel pipes suitable for industrial applications—particularly those used in sugar mills—and to meet growing needs at pipeline stations and facilities, including straight‑seam submerged‑arc welded pipes and spiral‑seam submerged‑arc welded steel pipes, Guangxi Nanning Canghai Spiral Pipe Company is making everything better, driving the vigorous growth of the steel pipe industry.

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Technical Requirements and Construction Safety for Sewer Pipe Installation

2016/10/11

Technical Requirements and Construction Safety for Sewer Pipe Installation

It’s important to note that today, drainage pipes are used in a wide range of applications—on highways, underpasses, tunnels, as well as in wastewater treatment plants, water purification facilities, parks, stadiums, and more. In addition, various earthwork projects involving underground drainage systems also require the installation of drainage pipes of different models and specifications. With so many contractors facing challenges in sewage pipe installation, we’ll briefly outline some key considerations below. 1. The surfaces of the spigot, socket, and rubber gasket must be thoroughly cleaned, removing all adhering substances such as sand, soil, loose coatings, and any foreign matter that could contaminate the water or damage the gasket. 2. When installing the rubber gasket, wear gloves, bend it into a heart shape, and carefully position it within the socket groove, ensuring it lies flat without twisting or warping, and verify that it is properly secured. 3. Clean the exterior surface of the spigot; ensure the end is rounded and slightly tapered to facilitate easy insertion into the socket. Apply a lubricant—such as soapy water or detergent—to both the inner surface of the rubber gasket inside the socket and the outer surface of the spigot. 4. Align the spigot with the socket, using a hand-operated turnbuckle to gently seat the spigot into the socket. The angular deviation at each joint should not exceed 2 degrees. 5. Maintain a minimum gap of at least 3 mm between joints, while ensuring the maximum allowable gap does not exceed the specified limit (typically 5–8 mm), taking into account potential “well‑jumping” of the joint material. During inspection, insert a probe into the socket‑spigot gap to confirm the correct positioning of the rubber gasket. 6. Store rubber gaskets separately, protecting them from heavy pressure, keeping them away from oils and other contaminants, and maintaining a safe distance from heat sources. On site, cover them with canvas to shield them from direct sunlight. 7. During installation, use edge lines or center plumb lines to maintain proper alignment of the pipeline. Ensure the elevation of the bedding layer is accurate to control the final pipe elevation, and verify this using a level. Install four wedge‑shaped concrete pads at 90-degree angles on either side of the pipe, spaced approximately one-fifth of the pipe length from each end. Before lifting, inspect the hoisting hooks and all suspension components for secure attachment, check the pipe for cracks or damage, and assign dedicated personnel to oversee the operation, ensuring gentle handling during lifting and placement to prevent damage. These are the technical precautions to observe during installation. However, when working with steel pipe networks—particularly given their considerable depth and length—special attention must also be paid to the personal safety of construction workers. Sewage network projects often involve deep trenches and long stretches of piping, presenting numerous potential hazards. Even minor oversights can easily result in injuries or fatalities among workers and bystanders. The effectiveness of safety management directly impacts project schedule, quality, and investment. Therefore, safety management is of paramount importance in pipeline installation work. Key measures include: 1. Erecting protective barriers along the entire construction route and displaying clear safety warning signs. 2. Constructing slopes in accordance with applicable standards; where slope construction is not feasible, provide adequate shoring. 3. Avoid piling soil too high along trench edges, and ensure pedestrian walkways at least 0.8 meters wide on both sides of the trench. 4. Provide ladders of sufficient length and structural strength for safe access to and from the trench. 5. Strengthen slope monitoring; if cracks or other anomalies are detected, promptly evacuate personnel and resume work only after eliminating the identified risks. 6. Enhance safety training and briefings, ensuring appropriate personal protective equipment is provided. 7. Reinforce safety management during winter and rainy seasons to prevent accidents such as frozen‑soil collapses or erosion caused by rainwater runoff.

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Spiral pipe market prices reversed slightly earlier.

2016/10/11

Spiral pipe market prices reversed slightly earlier.

Judging from the current performance of pipe manufacturers, the upward trend remains intact, and the price center of gravity in the spiral‑pipe market has been pushed higher. In the capital markets, after a rally that began in early June, prices reached a recent peak in early July before settling into a sideways trading range. With no external catalysts yet to break this consolidation, sentiment among traders is unlikely to face sustained downward pressure. For now, the spiral‑pipe market appears poised for a period of high‑level stalemate and consolidation. Recent developments have heightened risks at the upper end of the market; coupled with continued weak and volatile futures, buying interest has waned while wait-and-see attitudes have grown. Under these constraints, any further price gains are likely to encounter resistance. Nevertheless, producers remain firmly committed to supporting prices: ongoing production cuts, combined with bullish expectations for the “Golden September” season, keep supply tight and reinforce pricing support, making it difficult for prices to fall sharply. Overall, the near‑term outlook points to a phase of oscillating consolidation, punctuated by brief pullbacks as traders adjust positions. Meanwhile, the key driver of steel prices—costs—remains on track for further declines. Whether in iron ore or steel futures, while speculators may be seeking opportunities to go long, the time for strategic bullish positioning has not yet arrived. We recommend sticking to the earlier strategy of selling short on rallies at technical resistance levels. Hot‑rolled coil, though showing some unusual behavior, trades at relatively low volumes. Its underlying dynamics mirror those of rebar: cost factors will ultimately bring its prices back toward fundamentals. Iron‑ore import prices have been declining steadily for several months, falling below $100 per ton last month—down from a year‑end peak of around $140 per ton. This sharp drop stems not only from rapid capacity expansion at mines worldwide this year but also from recent bank audits of ore‑financing risks, which have tightened credit channels and accelerated the downward pressure on iron‑ore prices. Looking ahead, policy signals from the government—particularly its proactive efforts to cut overcapacity in the second half of the year—suggest that the Guoyuan spiral‑pipe market will continue to experience volatility, driven by frequent announcements of production cuts and restrictions. Domestically, local prices are expected to follow broader market trends, with Guoyuan spiral‑pipe prices likely to edge up slightly in the short term.

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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.

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