NIPPON STEEL has established a special electric resistance-welded tube factory dedicated to high-grade tubes for boilers and plants in order to conduct the full-scale production of high-grade electric resistance-welded (ERW) steel tubes equivalent to seamless steel tubes. Based on our preeminent steel-making technology and hotrolling equipment, we manufacture electric resistance welded steel tubes for boilers and heat exchangers that rivals or exceeds seamless steel tubes, all by adopting: tubemaking equipment designed for especially high-grade steel tubes, automatic welding control systems, various pieces of extremely highly reliable full-automatic nondestructive test equipment, and large-capacity bright heat treatment furnaces.

Features

NIPPON STEEL ERW steel tubes for boilers and heat exchangers are manufactured consistently, from the raw material process to the tube-making and purification process, and have the following superior features—all through superior manufacturing equipment and thorough quality control.

Extremely favorable welded part quality

• The highest quality killed steel developed especially for boiler tubes is used, and the welded part quality is extremely favorable̶achieved through accurate forming and high-frequency induction welding, adopting an automatic welding control system.
• A string of nondestructive testing facilities centered on state-of-the-art fully automatic ultrasonic inspections are used to ensure quality assurance, and the products are provided with the high quality required by boiler tubes.
• The welded part provides the same metal composition as the base material through bright heat treatment, and it has uniform and superior quality equivalent to seamless steel tubes.
• The specification in (58) in “Note 1 (Remark 1)” in Attached Table 1 of “Interpretation of the Thermal Power House Technical Standard” is satisfied, and the same allowable stress as seamless steel tubes can be applied.

Superior size and shape

• Formed precisely by a state-of-the-art tube-making machine, the product has extremely superior dimensional accuracy and roundness.
• The removal of internal and external surface beads on the welded part from during the steelmaking process is extremely superior. Especially, the removal shape of the internal surface bead is distinguished, and a smooth internal surface property is assumed.
• The product has favorable thickness accuracy, and the tube mass increase rate can be reduced.
• Due to high inside diameter accuracy, steam supply pressure loss can be reduced.

Enhanced management system

• We have established a thorough management system, ranging from technical service to product delivery, in order to respond to every request and offer consultation regarding usage.

Application Examples

• Large utility thermal generation boiler
• Vertical water tube package boiler
• Economizer incorporation
• Air fin cooler steel tube
• Soda recovery boiler
• Furnace wall tube for power boiler