Quality & Process
Manufacturing Process: Cold Drawn Bench
Before the cold drawing process, tubes are coated with a phosphate layer to prevent metal-to-metal contact and reduce static friction, ensuring smooth drawing and proper lubrication. Approximately 200 mm of the tube’s input end is reduced using the tagging process to facilitate easy insertion into the die.
Cold Drawing is used when tight dimensional tolerances are required for tube diameters. This process not only improves diameter accuracy but also allows for achieving specific mechanical properties. It is especially suitable when there are high surface quality requirements for the internal bore of the tube.
During cold drawing, the tube is pulled through a tungsten carbide die using a fixed or floating plug, which results in a reduction in diameter and wall thickness while simultaneously increasing the overall tube length.
Heat Treatment: Bright Annealing
After each stage of the manufacturing process, tubes and pipes undergo heat treatment in a continuous annealing furnace, set to the specified temperature as per applicable standards. This is followed by either slow air cooling or rapid cooling, depending on the desired material properties. Additional annealing processes are carried out as required.
Heat treatment methods such as Full Annealing, Normalising, and Tempering ensure:
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A homogeneous microstructure and refined grain size
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Elimination of residual stresses developed during cold working
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Enhanced ductility and softness for ease of further processing
These processes are critical to achieving the mechanical strength, stability, and formability needed for demanding industrial applications.
Carbon Steel Seamless Precision Tubes: Manufacturing Process
South India Tubes specializes in the manufacturing of Cold Drawn Seamless Carbon Steel Tubes, which are normalized or annealed in a controlled atmosphere. This process results in tubes that are softer than those annealed under conventional methods. Additionally, the controlled atmosphere prevents oxidation, producing tubes with a bright, semi-bright, or scale-free finish.
Applications of Controlled Atmosphere Annealed Tubes:
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High-Pressure Fuel Injection Tubing
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CNG Piping Systems
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Hydraulic Tubing
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Fuel Pump Lines
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Automotive Industry
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Precision Engineering
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Brake Shoe Lines
These tubes are ideal for industries that demand superior surface quality, consistent mechanical properties, and enhanced formability.
Seamless Tubes Acc. To DIN 2391
Technical Delivery Conditions:
The manufacturing and delivery of tubes follow the technical specifications of DIN 2391 Part 2. Tubes are generally ordered based on outside diameter and wall thickness. However, when ordered based on outside and inside diameter, the specifications must comply with DIN 2391 Grade A or B standards.
High-Pressure Diesel Fuel Injection Tube Specifications:
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Standards: DIN 2391, DIN 73000
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Material Grades: ST 35 AL, ST 35 for Diesel Engine Applications
These tubes are designed to meet the stringent requirements of high-pressure diesel systems, offering superior strength, dimensional accuracy, and leak-proof performance.
