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Pipeline Material Table: Technical Guide for Classification and Selection Pipeline Material Table: Technical Guide for Classification and Selection I. Introduction 1.1 The Importance of Pipeline Systems In modern industrial and civil buildings, pipeline systems function like blood vessels in the human body, playing a crucial role in transporting fluids such as water, gases, and chemicals. In the industrial sector, pipeline systems serve as the foundation of industrial production, responsible for transporting various fluid substances to ensure the continuity and efficiency of production processes. In industries such as petrochemicals, pipelines carry raw materials and products, playing a crucial role in the smooth progress of production. In civil buildings, systems such as water supply and drainage, heating, and gas distribution all rely on pipes, which provide the necessary infrastructure to support people’s daily lives. The adequacy of the piping system is directly related to the efficiency and quality of industrial production, as well as the convenience and comfort of people’s lives. 1.2 The importance of material selection: The choice of pipeline material is of great significance for the entire pipeline system. In terms of safety, choosing the wrong material can lead to pipe corrosion, leaks, and even serious accidents such as explosions. For example, in the chemical industry where highly corrosive substances are transported, using pipe materials that are not resistant to corrosion can have catastrophic consequences. From an economic perspective, pipes made of different materials vary significantly in price, and their maintenance costs also differ. Choosing the right material can help reduce construction and maintenance costs while ensuring optimal performance. In terms of service life, durable materials reduce the frequency of replacements, minimize production disruptions or interruptions in daily services caused by pipeline problems, and extend the overall operational time of the system, thereby providing more stable support for industrial production and residents’ lives. II. Classification System for Pipe Materials 2.1 Classification by Material Composition Among metal pipes, steel pipes are widely used. Carbon steel pipes are made of carbon structural steel; they have high strength but moderate corrosion resistance, and are commonly used in fields such as industrial fluid transportation. Alloy steel pipes, due to the addition of alloying elements, possess higher strength and corrosion resistance, allowing them to be used in more demanding environments. Stainless steel pipes exhibit excellent corrosion resistance, and are widely used in industries such as chemicals and food processing. Non-ferrous metal pipes should not be overlooked either. Copper and copper alloy pipes play an important role in refrigeration systems and pipelines for chemical instruments; for example, pure copper pipes are suitable for use in refrigeration systems, while brass pipes, with their high pressure resistance, can be used in chemical instrument pipelines. Titanium tubes are lightweight, highly strong, and exhibit excellent low-temperature resistance, giving them significant advantages in fields such as offshore engineering and low-temperature storage tanks. Although aluminum and aluminum alloy pipes have low mechanical strength, they exhibit good corrosion resistance to fatty acids, hydrogen sulfide, etc., and are commonly used for the transportation of low-pressure gases. Regarding cast iron pipes, high-silicon cast iron pipes have a high silicon content and are resistant to strong acid corrosion; they are often used for the discharge of chemical waste liquids. Ordinary cast iron pipes are classified into low-pressure, medium-pressure, and high-pressure types based on pressure, and they play an important role in municipal water supply and drainage systems. There are a wide variety of plastic pipes used in non-metallic pipelines. PVC pipes are resistant to acid and alkali corrosion, have a smooth inner surface, and are suitable for drainage systems. PE pipes have different application areas depending on their density; HDPE pipes, with their high pressure resistance, are used for urban gas pipelines, while MDPE pipes, due to their flexibility, are suitable for underground water supply systems. PP-R pipes have excellent heat resistance, are non-toxic and environmentally friendly, and are widely used in domestic hot water systems. PB pipes have a wide temperature tolerance and excellent flexibility, making them an ideal choice for underfloor heating systems. Composite pipes combine the advantages of different materials; aluminum-plastic composite pipes are pressure-resistant and have a wide temperature range, making them suitable for domestic hot and cold water supply. Steel-plastic composite pipes combine the pressure-bearing capacity of steel pipes with the corrosion resistance of plastics, making them suitable for transporting chemically corrosive media. Special pipes such as glass fiber reinforced plastic pipes have strong corrosion resistance and are used in the treatment of chemical wastewater ； Concrete pipes have limited pressure-bearing capacity and are mainly used in long-distance water transmission projects. 2.2 Classification by pressure rating: The pressure range for low-pressure pipelines is less than or equal to 1.6 MPa. Due to their lower pressure requirements, such pipes are commonly used in applications where high pressure resistance is not necessary. For example, PVC drainage pipes are used in building drainage systems, while low-pressure welded steel pipes can be used to transport fluids under moderate pressure. They find wide application in areas such as municipal water supply and drainage, as well as agricultural irrigation. The pressure range for medium-pressure pipelines is between 1.6 MPa and 10 MPa. Ordinary cast iron pipes, copper pipes, etc., mostly fall into the category of medium-pressure pipelines. Some of the main pipelines in urban water supply systems use medium-pressure pipes to ensure water supply pressure and stability. In some industrial processes, medium-pressure pipelines are used to transport liquid or gaseous media at certain pressures, such as the transportation of chemical raw materials. The pressure range for high-pressure pipelines is greater than 10 MPa. High-pressure pipelines are usually made from high-quality materials, such as high-pressure seamless steel pipes used for fertilizers; these materials require strict specifications and involve complex manufacturing processes. In the petrochemical industry, pipelines used to transport high-temperature and high-pressure media are mostly high-pressure pipelines, such as those for transporting synthetic ammonia in refineries. High-pressure pipelines, due to the high pressures they are subjected to, require extremely high standards in terms of safety; strict standards and regulations apply at all stages such as design, manufacturing, and installation. 2.3 Classification by temperature adaptability: The temperature range for low-temperature pipelines is usually below -20°C. Titanium tubes, LDPE tubes, etc. are common materials for low-temperature pipelines. Titanium tubes maintain good strength and toughness at low temperatures, making them suitable for low-temperature components in offshore engineering. LDPE pipes retain a certain degree of flexibility in low-temperature environments, making them suitable for transporting certain low-temperature liquids. Low-temperature pipelines are widely used in areas such as LNG transportation and low-temperature storage tanks; their materials must possess excellent resistance to embrittlement at low temperatures to prevent brittle fracture in such conditions. The temperature range for pipes at normal temperatures is from -20°C to 100°C; there are many options available for pipe materials within this temperature range, such as PVC pipes and steel-plastic composite pipes. PVC pipes maintain stable performance at room temperature and are suitable for drainage systems and similar applications. Steel-plastic composite pipes combine the advantages of both steel pipes and plastics. They can withstand a certain level of pressure at room temperature while also offering good anti-corrosion properties. They are widely used in applications such as the transportation of corrosive chemicals in the chemical industry. The temperature range of high-temperature pipelines is above 100°C. Stainless steel seamless pipes, PE-X pipes, etc. are typical materials for high-temperature pipelines. Stainless steel seamless pipes exhibit excellent high-temperature resistance, making them suitable for use in high-temperature steam environments such as boiler feed systems in the power industry. Although PE-X pipes do not have as good high-temperature resistance as metal pipes, they are still used in some hot water systems where temperature requirements are not particularly high. High-temperature pipeline materials must possess good high-temperature stability, oxidation resistance, and creep resistance to ensure safe operation over long periods in high-temperature environments. III. Performance parameters and standards of pipe materials 3.1 Key performance indicators Among the key performance indicators of pipe materials, there are significant differences in corrosion resistance. High-silicon cast iron pipes can resist the corrosion of various strong acids, and are suitable for use in environments with strong acids such as those involving chemical waste discharge ； Titanium tubes exhibit excellent resistance to the corrosiveness of media such as seawater, and are commonly used in marine engineering. Plastic pipes such as PVC pipes and PE pipes can resist moderate acid and alkali corrosion, and are widely used in drainage and water supply systems. In terms of pressure resistance, seamless steel pipes perform excellently, capable of withstanding pressures as high as 32 MPa; they are therefore indispensable for transporting high-pressure fluids in industries such as petrochemicals. Concrete pipes have a low pressure resistance, ≤1.0 MPa, and are mainly used in applications such as long-distance water transmission where low pressure requirements apply. In terms of temperature tolerance, PB pipes have the widest range of operating temperatures, from -20°C to 110°C, giving them a significant advantage in underfloor heating systems. PVC pipes are only suitable for normal temperatures, up to ≤60°C, and are mainly used in drainage systems and similar applications. High-temperature pipe materials such as stainless steel seamless pipes and PE-X pipes can withstand temperatures above 100°C, meeting the requirements of high-temperature environments like boiler feedwater systems in the power industry. There is also a significant difference in service life: cast iron pipes can last for a hundred years, stainless steel pipes for 70–100 years, while PVC pipes last around 20–30 years. Choosing the right materials can reduce the frequency of replacements and minimize the impact of pipeline issues. 3.2 Industry standards and specifications for metal pipes: Seamless steel pipes comply with standards such as GB/T 8163-2018 \"Seamless steel pipes for transporting fluids\" and GB/T 6479-2013 \"Seamless steel pipes for high-pressure fertilizer equipment\". GB/T 8163-2018 specifies the dimensions, shape, weight, and technical requirements of seamless steel pipes for fluid transport, and is applicable to general fluid transportation. GB/T 6479-2013 sets more stringent requirements regarding material and mechanical properties for seamless steel tubes used in high-pressure fertilizer equipment. Copper tubes comply with standards such as GB/T 1527-2017 “Drawn copper and copper alloy tubes” and GB/T 18033-2007 “Seamless copper water tubes and copper gas tubes”. These standards specify the dimensions, appearance, mechanical properties, etc., of copper tubes. In the field of plastic pipes, PVC pipes comply with the standard GB/T 10002.1-2006 \"Rigid polyvinyl chloride (PVC-U) pipes for water supply\", which specifies the specifications and properties of PVC-U pipes used for water supply. PE pipes comply with the standard GB/T 13663-2018 \"Polyethylene (PE) pipes for water supply\", which covers the classification and technical requirements of PE pipes used for water supply. In composite pipes, aluminum-plastic composite pipes are governed by the CJ/T 108-2013 standard \"Cross-linked Polyethylene Aluminum-Plastic Composite Pipes\", which specifies the requirements regarding the materials, structure, and performance of such pipes. Steel-plastic composite pipes comply with the standard GB/T 28897-2012 \"Steel-Plastic Composite Pressure Pipes\", which provides detailed specifications for the manufacturing and performance testing of such pipes. These standards and specifications provide important technical basis for the design, manufacturing, installation, and other aspects of pipelines, ensuring the safe and reliable operation of pipeline systems. IV. Application Scenarios and Selection Examples for Pipe Materials 4.1 Applications in the Industrial Sector In the petrochemical industry, the selection of pipe materials is of great importance. In the catalytic cracking units of refineries, seamless steel pipes specified in GB/T 9948-2013 for petroleum cracking are commonly used. These pipes can withstand high pressures of 8.5 MPa and high temperatures of 510°C; they have not leaked after 10 years of use, thus ensuring safe and stable production. In highly corrosive environments such as the chlor-alkali industry, titanium tubes are often used; their excellent corrosion resistance enables them to withstand the corrosion caused by substances like seawater, thus ensuring the long-term operation of equipment. The boiler feedwater systems in the power industry require extremely high heat resistance from the pipeline materials. Thanks to its excellent resistance to high-temperature steam (capable of withstanding temperatures above 540°C), stainless steel seamless pipes are the preferred material for boiler feedwater systems, ensuring their safety and efficiency. For the discharge of waste liquids from pickling lines in the metallurgical industry, high-silicon cast iron pipes are an ideal choice. It has a silicon content of 14.5%, is resistant to strong acid corrosion, and can operate stably in an environment with a pressure of ≤0.25 MPa; this helps to effectively address the corrosion issues associated with waste liquid discharge and ensures the smooth progress of metallurgical production. These cases demonstrate that the proper selection of materials is an important guarantee for the safe and efficient operation of industrial production. 4.2 Applications in municipal engineering: In municipal water supply and drainage projects, there are numerous considerations regarding the suitability of pipe materials and their selection. HDPE pipes are commonly used for the main pipelines in urban water supply systems; they have high pressure resistance, which meets the pressure requirements of urban water supply, and they also possess good flexibility, allowing them to function well in complex underground conditions. For branch pipes, PP-R pipes can be used; they not only meet the water supply requirements but are also non-toxic and environmentally friendly, ensuring water quality safety. In terms of drainage systems, PVC pipes are often used in building drainage systems due to their resistance to acid and alkali corrosion as well as their smooth inner surfaces; these properties help to reduce water flow resistance and improve drainage efficiency. There are also strict regulations regarding the material of gas pipelines in municipal engineering. HDPE pipes are commonly used for urban gas pipelines due to their high pressure resistance, enabling them to withstand the pressures involved in gas transmission. They also possess good airtightness and corrosion resistance, which ensure the safety of gas delivery. PE pipes feature a simple and reliable connection method, which facilitates construction and maintenance; they are widely used in municipal gas projects. Choosing the appropriate materials for water supply, drainage, and gas pipelines is of great significance for ensuring the proper operation of urban infrastructure and improving the quality of life for residents. 4.3 Applications in building water supply and drainage: For the domestic water supply systems in buildings, the material selection for pipes must take into account both safety and health considerations. Stainless steel pipes are commonly used; they have strong corrosion resistance, which helps to prevent secondary pollution of water quality and ensures the safety of drinking water for residents. PP-R pipes are also widely used; they have excellent heat resistance, are non-toxic and environmentally friendly, and are easy to install, making them suitable for domestic hot water systems. There are also various options available for the materials used in building drainage pipes. UPVC drainage pipes are corrosion-resistant, have low fluid resistance, are lightweight and easy to install, and are cost-effective; they are therefore a commonly used material in building drainage systems. Although cast iron pipes are heavy and difficult to install, they have strong corrosion resistance and low noise levels, which allows them to be used in places where noise control is a priority. The selection of materials for building water supply and drainage pipes should take into account factors such as the building’s intended use, water quality requirements, and environmental conditions, in order to ensure the safe and stable operation of the water supply and drainage system and to provide residents with a comfortable living environment. V. Principles and Considerations for Selecting Pipeline Materials 5.1 Core Principles for Selection The selection of pipeline materials requires taking into account factors such as performance, cost, and lifespan. In terms of performance, it is necessary to select materials with the appropriate corrosion resistance, temperature tolerance, and pressure resistance, depending on the properties of the medium being transported, such as its corrosiveness, temperature, and pressure. For transporting highly corrosive media, corrosion-resistant materials such as titanium pipes and high-silicon cast iron pipes should be used, while in high-temperature environments, high-temperature pipes such as stainless steel seamless pipes are required. In terms of cost, it is necessary to consider not only the price of the pipeline itself but also the long-term costs associated with installation, maintenance, and replacement. For example, although stainless steel pipes are more expensive, their strong corrosion resistance and long service life mean that the overall cost may be lower. Regarding lifespan, materials should be selected based on the expected service life of the project to ensure that the pipes can operate safely and stably throughout their entire service life. For long-term operating projects such as municipal water supply and drainage, cast iron pipes and stainless steel pipes with a long service life should be selected. By comprehensively balancing performance, cost, and lifespan, the most suitable pipe material is selected to ensure the economic viability and safety of the project. 5.2 Special considerations and common issues in selection There are special considerations and common issues regarding the selection of pipe materials in different scenarios. In the industrial sector, such as the petrochemical industry, special attention must be paid to the corrosiveness of the media and the process conditions, in order to prevent accidents such as leaks caused by inappropriate material selection. A common issue is insufficient assessment of the corrosion resistance against specific media. In municipal engineering, water supply and drainage pipes must take into account factors such as soil corrosivity and groundwater levels, while gas pipes require attention to their airtightness and tensile strength. A common problem is the neglect of the impact of geological conditions on these pipes, which leads to issues such as pipe settlement and corrosion. In terms of building water supply and drainage, the materials used for domestic water supply pipes must be non-toxic and harmless to prevent water contamination. For drainage pipes, factors such as drainage volume and flow rate need to be taken into account. Common problems include insufficient attention to water quality requirements or an unreasonable design of the drainage system. When making a selection, it is necessary to take into account the specific requirements of different scenarios, consider various factors, avoid common problems, and ensure the safe and reliable operation of the piping system.