Guide and Information
Comprehensive knowledge about pipes,
their manufacturing, and applications.
From ancient origins to modern industrial applications,
discover everything about pipe technology and design.
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids.
It can also be used for structural applications; hollow pipes are stronger than solid shafts or rods of the same mass and wall thickness. Pipes are manufactured from materials such as wood, clay, concrete, glass, fiberglass, brick, stone, lead, steel, aluminum, plastic, and other materials.
Pipes serve numerous industries and purposes. In plumbing, they deliver tap water for irrigation and residential use. Pipelines transport gas or liquid over long distances efficiently. Compressed air systems utilize pipes for industrial and manufacturing applications. In construction, pipes serve as casing for concrete pilings. Manufacturing processes rely on pipes for high-temperature or high-pressure applications. The petroleum industry extensively uses pipes for oil well casing and fluid delivery. Food processing facilities use pipes for bulk solid delivery, and high-pressure storage vessels are constructed using specialized piping.
Beyond fluid conveyance, pipes are fundamental structural elements. Handrails, scaffolding, and support structures are commonly constructed from structural pipes, especially in industrial environments. Pipe is widely used in the fabrication of handrails, guardrails, and railings. Their strength-to-weight ratio makes them ideal for load-bearing applications where material efficiency is essential.
The first known use of pipes dates back to Ancient Egypt. The Pyramid of Sahure, completed around the 25th century BC, included a temple with an elaborate drainage system featuring more than 380 meters (1,247 feet) of copper piping. This remarkable engineering feat demonstrates that pipe technology has ancient roots.
During the Napoleonic Wars, Birmingham gunmakers attempted to use rolling mills to manufacture iron musket barrels. Henry Osborne developed a relatively effective process in 1817, and by 1820, he began manufacturing iron gas tubes. These innovations marked the beginning of modern pipe production, with early applications in gas lighting systems pioneered by Samuel Clegg.
When steel pipes were introduced in the 19th century, they were initially riveted together. Later, they were clamped with H-shaped bars, despite methods for making weldless steel tubes being known since the 1870s. By the early 1930s, welding replaced these traditional joining methods and remains the standard technique today.
Three main processes exist for metallic pipe manufacture. Centrifugal casting of hot alloyed metal is one of the most prominent, commonly used for ductile iron pipes. Each process offers distinct advantages depending on the application requirements and desired pipe characteristics.
Seamless pipe is formed by drawing a solid billet over a piercing rod in a process called rotary piercing, which creates the hollow shell. Because this manufacturing process excludes welding, seamless pipes are perceived as stronger and more reliable. Historically, seamless pipe was regarded as superior for withstanding pressure and was often preferred over welded alternatives.
Since the 1970s, advances in materials, process control, and non-destructive testing have enabled correctly specified welded pipe to replace seamless in many applications. Welded pipe is formed by rolling plate and welding the seam using Electric Resistance Welding (ERW) or Electric Fusion Welding (EFW). The weld flash can be removed from both surfaces using a scarfing blade. Welded pipe often features tighter dimensional tolerances and lower manufacturing costs than seamless types.
In Electric Resistance Welding, electric current passes through surfaces to be welded. The resistance of these components generates heat that forms the weld. Molten metal pools form strong welds that bind abutted components. ERW processes use steel coil as feedstock and create reliable, cost-effective piping solutions.
The High Frequency Induction welding process applies current through an induction coil surrounding the tube. HFI is generally considered technically superior to standard ERW for manufacturing pipes in critical applications, particularly in the energy sector.
Large-diameter pipe (25 centimeters or greater) may be produced through ERW, EFW, or Submerged Arc Welding (SAW) methods. Longitudinal-submerged arc-welded (LSAW) and spiral-submerged arc-welded (SSAW) pipes represent the technologies available for manufacturing pipes larger than those produced by seamless and standard ERW processes.
Steel pipe (black iron pipe) was historically the most popular choice for water and flammable gas supply. Today, steel pipe remains widely used in homes and businesses for natural gas or propane fuel delivery. Its high heat resistance makes it popular in fire sprinkler systems. In commercial buildings, steel pipe conveys heating or cooling water to HVAC equipment including heat exchangers and air handlers.
Steel pipe is joined using threaded connections where tapered threads are cut into tubing ends, sealed with thread sealing compound or PTFE tape, then threaded into fitting. Beyond domestic applications, steel pipe is often joined by welding or mechanical couplings.
Copper tubing is primarily used for hot and cold water supply and as refrigerant lines in HVAC systems. Two basic types exist: soft copper and rigid copper. Copper tubing is joined using flare connections, compression connections, or solder. Copper offers excellent corrosion resistance but has become increasingly expensive.
Soft (ductile) copper tubing bends easily around obstacles in the tubing path. It is carefully annealed to increase flexibility, making it more expensive to produce than rigid copper. It can be joined using any method suitable for rigid copper and is the only copper type suitable for flare connections. Soft copper is the preferred choice for refrigerant lines in split-system air conditioners and heat pumps.
Rigid copper is a popular choice for water lines, joined using sweat, compression, or crimped/pressed connections. Rigid copper cannot bend and requires elbow fittings at corners. When heated and slowly cooled (annealed), rigid copper becomes soft and can be bent without cracking.
Solder fittings are smooth and easily slip onto tubing ends. Male and female ends are cleaned thoroughly and coated with flux to prevent surface oxide and ensure proper solder bonding. The joint is heated with a torch and solder melted into the connection. Solder-connected rigid copper remains the most popular choice for water supply lines in modern buildings.
Compression fittings use a soft metal or thermoplastic ring (ferrule) squeezed onto the pipe by a compression nut. The soft metal conforms to tubing and fitting surfaces, creating a seal. While compression connections don't offer the longevity of sweat connections, they provide ease of installation with basic tools.
Crimped connections use special copper fittings permanently attached to rigid copper tubing with powered crimplers applying thousands of pounds-force per square inch. This pressure deforms the fitting and compresses the sealant against inner tubing, creating watertight seals.
Aluminum is used due to its low cost, corrosion resistance, and ductility. Aluminum tube is preferable to steel for flammable solvent conveyance since it cannot create sparks when manipulated. Aluminum tubing is connected by flare or compression fittings or welded using TIG or heliarc processes.
Tempered glass pipes serve specialized applications including corrosive liquids, medical or laboratory wastes, and pharmaceutical manufacturing. Connections are made using specialized gasket or O-ring fittings.
This comprehensive guide provides educational information about pipe materials, manufacturing methods, and applications across various industries. For specific technical requirements or project consultation, please contact industry specialists and manufacturers for detailed specifications.
Information compiled from industry standards, manufacturing specifications, and established pipe engineering principles. For detailed technical data and current industry standards, consult relevant standards organizations and pipe manufacturers.