Seamless tubes are widely manufactured in industries such as oil and gas, energy, construction and chemical processing due to the strength, reliability and ability to withstand high pressure. They are called seamless pipes as you do not weld the seams or joints, ensuring the same structure and performance throughout the pipe. Riyaarth Overseas provides seamless piping and tubing of the highest quality that are manufactured via state-of-the-art techniques that meet all of an industry’s needs.
Main Characteristics of Seamless Pipes
- Consistent Structure: Seamless pipes are characterized by lack of welds or joints, whereas other types typically have some sets of welds, creating weak points, which allows seamless pipes to demonstrate consistent mechanical properties throughout the length of the pipe.
- Higher Strength: Seamless pipes demonstrate higher tensile strength and greater ability to withstand pressure due to the way they are manufactured which makes it stronger than a welded pipe.
- Dimensional Precision: Precision in controlling dimensions, including wall thickness and roundness, are made possible by the newer rolling process.
- Flexible Application: Seamless pipes can be used in high-pressure situations such as oil pipelines, boiler tubes, heat exchangers, and structural piping.
Manufacturing Processes for Seamless Pipes
The process for manufacturing seamless pipes includes several advanced processes that turn raw steel into high-quality pipes. The most prevalent processes include:
1. Mannesmann Plug Mill Process
Summary: Developed by the Mannesmann brothers in 1885, the process is widely used for the manufacturing of larger diameter seamless pipes (6–16 in in this case).
Steps:
- A steel billet of up to two tons is heated to approximately 2370 degrees Fahrenheit (1300 degrees Celsius). The billet is pierced using a rotary elongator to produce a hollow shell, known as a bloom.
- An internal plug is advanced through the bloom as it travels between conical rolls in the plug mill. This step reduces wall thickness and rounds the tube.
- The tube then goes through reeling mills, and reducing mills to achieve final dimensions, and the tube is limited to heat treatment, straightening
2. Mandrel Mill Process
Overview: This process is typically used for small diameter pipes (1–6 inches), and involves the continuous reduction in wall thickness.
Steps:
- A heated steel billet is pierced by barrel-shaped rolls resulting in a hollow shell.
- The shell is pierced with mandrel bars to control the dimensions of the hollow shell while rolling on the mandrel mill.
- After reheating, stretch-reducing mills complete the final dimensions of the wall thickness and diameter of the pipe.
- The finished pipe is straightened, inspected, hydrostatically tested and heat treated.
3. Extrusion Process
Overview: This process is well suited for a high-strength alloy steel pipe with complicated profiles.
Steps:
- A heated billet is inserted in an extrusion die.
- If the die is split horizontally, a ram on one side forces the heated billet into contact with a piercing mandrel, which helps to pierce the outside of the billet to produce a hollow pipe.
- The die forms the outside profile while the mandrel controls the internal profile.
4. Cold Rolling/Cold Drawing Process
Overview: This process works well for seamless pipe production when high dimensional accuracy and surface finish are desired.
Steps:
- The prepared blank is pickled and lubricated.
- Reduction of dimensions is achieved by cold rolling or drawing through the process while enhancing mechanical properties as well.
- The pipes are then heat-treated to relieve stress before straightening and inspection.
5. Forging Process
Overview: This process is used for the manufacture of large-diameter seamless pipes commonly made into steam headers or pressure vessel shells.
Steps:
- A heated billet is placed inside a forging die which has a diameter that is slightly larger than the finished diameter of the pipe.
- Hydraulic presses then deform the billet into cylindrical forgings.
- The pipe is machined to obtain final desired dimensions and is tested for quality.
Specifications of Seamless Pipes
Seamless pipes come in different shapes, dimensions, and materials that can be used in many industrial applications. The table provided below offers a summary of specifications:
Type | Outer Diameter | Wall Thickness | Weight | Applications |
Square Seamless Pipe | 10×10mm – 400×400mm | 0.6mm – 20mm | 1.39kg/m – 74.55kg/m | Structural systems, frameworks, and heavy-duty applications. |
Round Seamless Pipe | 6mm – 720mm | 0.5mm – 120mm | 0.24kg/m – 120kg/m | Oil pipelines, boiler tubes, heat exchangers. |
Rectangular Seamless Pipe | 20×10mm – 400×300mm | 0.6mm – 20mm | 1.43kg/m – 69.65kg/m | Chemical processing lines, construction. |
Stainless Steel Pipe | Φ6-Φ830mm | 0.5mm – 55mm | Varies based on grade | High-temperature and high-pressure environments. |
Hot-Rolled Pipe | 20mm – 530mm | 2.5mm – 75mm | Weight proportional to dimensions | General-purpose piping systems. |
Material Grades and Standards
Seamless pipes are manufactured using different materials and conform to various international standards:
Material Type | Grade/Standard | Properties |
Carbon Steel | ASTM A333 | Low-temperature toughness for cryogenic applications. |
Stainless Steel | GOST 8732-78 | Corrosion resistance and high strength. |
Copper | ASTM B42 | Suitable for plumbing and boiler feed lines. |
Aluminum Alloy | ASTM B241 | Lightweight and high strength for aviation and machinery. |
Applications of Seamless Pipes
Oil & Gas Industry:
- Seamless pipes are commonly employed in high-pressure pipelines where crude oil and natural gas are transported, as they provide strength and reliability. They help ensure environmental safety by preventing leaks.
- Seamless pipes also perform well under extreme weather conditions and resist acids, making them a reliable means of transporting fluids during offshore drilling operations.
Power Generation:
- Seamless pipes are essential in thermal power plants where tube performance in boiler tubes and heat exchangers must endure extreme high-temperature exposures. Seamless pipes continue to bear the requirements of structural integrity, under thermal stress and high pressure.
- Seamless pipes can also be used in nuclear reactor applications where the transport of radioactive fluids must be managed effectively to ensure the safety and viability of the plant.
Chemical Processing:
- Their uniform structure makes seamless pipes ideal to handle corrosive fluids in reactors and transfer lines. Seamless pipes resist chemical reactions that would cause material failure.
- They allow for the design of piping systems that can resist aggressive chemical environments to maintain efficiency and safety at your facility.
Construction & Structural Systems:
- Seamless pipes are often used in structures like bridges because of their dimensional tolerances and load-bearing qualities. As opposed to welded pipes, seamless pipes provide stability in heavy-duty applications.
- They are also suitable for the design of buildings with earthquake resistant applications to enhance safety and structural integrity.
Quality Assurance Process
Seamless pipes undergo rigorous testing during manufacturing to ensure they meet industry standards:
- Non-Destructive Testing (NDT): Ultrasonic testing is performed to find flaws internally without damaging the product.
- Hydrostatic Testing: Pipes are tested with high-pressure water to reveal leaks.
- Dimensional Inspection: Radiometric gauges are used on the entire length of the pipe to measure wall thickness and roundness.
- Heat Treatment: Pipes are subject to processes like normalizing, quenched, tempered, stress relieved, or heat treated to improve mechanical properties.
- Surface Inspection: Pipes are checked for the surface finishes deemed acceptable.
Environmental Considerations
The production of seamless pipes includes considerations for sustainability:
- Material Efficiency: The latest rolling techniques reduce waste during production.
- Energy Optimization: Latest furnaces utilize energy efficiently while reaching precise heating temperatures.
Quality Assurance & Packaging
Riyaarth Overseas guarantees strict compliance with global standards for its seamless pipes providing reliability and safety in demanding applications:
- Certifications:Compliant to relevant specifications, including ASTM, ASME, EN, and ISO.
- Packaging: Seamless pipes are packed securely with additional protective materials to prevent damage during shipping.
Looking for strong and reliable seamless pipes? Contact Riyaarth Overseas for custom piping solutions for your industry needs! Fill out our inquiry form to ask our team, or call us now!
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- Oil & Gas industries
- Chemical process industries
- Pump and valve in high pressure component
- Food industries
- Pulp and paper industry
- Aerospace industry
- Power plant
- Mechanical component
- Sugar industry
- Cement industry