Nakayama Mitsuboshi Steel Products, Ltd.  Nakayama Mitsuboshi Steel Products, Ltd.
 Nakayama Mitsuboshi Steel Products, Ltd.

Carbon steel tubes

Carbon steel tubes (black)

Carbon steel tubes (black)

Carbon steel tubes (plating)

Carbon steel tubes(plating)

Carbon steel tubes (black)
Carbon steel tubes (plating)

Carbon steel tubes

Carbon steel tubes manufactured at our Shimizu, Sakai and Miyakonojo factories is used in farming and gardening greenhouses and temporary construction site, etc. black products and pre-plated (Hot-dip zinc) products are available.

  • Civil engineering, architecture, steel tower, scaffold, column, furniture and other structure.

  • 1. Steel strip used in the products is mainly manufactured by slit coils of Nakayama Steel Works, Ltd.
  • 2. Our pre-plated products with high corrosion resistance become highly effective for white rust prevention if coated by our non-chrome type surfCoat.
Manufacturing facilities Authentication number Authentication date Product name (JIS number)
Shimizu factory QA0508007 May 20, 2008 Carbon steel tubes for general structure
(JIS G 3444)
Sakai factory
Miyakonojo factory

Hot-dip zinc-coated steel strip products

  • POINT01

    Excellent corrosion resistance

    Even if the zinc coating is broken by partly exposing the iron base, the surrounding area is protected from rust by the sacrificial anticorrosion effect of zinc until the area reaches a certain size.

  • POINT02

    Beautifully finished surface

    Zinc is excellent in coating adhesiveness and uniformity. The lubricating effect of zinc makes it easy to mold and provides graceful finished surface.

Minimum coating mass(total mass on both surfaces)
Type of coating Non-alloyed coating Alloyed coating
Coating mass symbol Z12 Z18 Z20 Z22 Z25 Z27 F12 F18
MInimum average coating mass at triple spots 120 180 200 220 250 275 120 180
Minimum coating mass at single spot 102 153 170 187 213 234 102 153
  • 01 Please consult with us in advance as the bolded part in the table are standard products and the others are build-to-order ones.
  • 02 The mInimum average coating mass at triple spots is applied to the average of the measured values of the three specimens taken from sample materials.
  • 03 The following are available as repair paints for processed products such as furring strips and others.
    "74 Aqua repair paint dark gray" JIS K 5674 class 1: Nipponpaint Industrial Coatings Co., Ltd.
  • 04 In response to the customer's request to match the hue of the steel frame body with the dark gray product, the manufacturer has a line-up of the following paints as standard colors.
    "Green bosei quick-drying super-quick drying MK dark gray" JIS K 5674 class 1: Dai Nippon Toryo Co., Ltd.
  • 05 When top coat is required, use of alloyed coating is recommended.


"Surfcoat," a eco- and people-friendly coating agent having surprising effects for white rust prevention on pre-plating products (Carbon steel tubes for general structure) does not come under by the poisonous and deleterious substances control law as it contains no heavy metals such as chromium. It receives a favorable reputation for its amazing coating effect on pre-plating steel pipe used for agricultural facilities in high-temperature and humid environment.

Rest results

"Surfcoat" has also shown good results in laboratory hot water immersion tests and resistance test in humidity of 98% or over, while it has also shown excellent results in long-term field exposure tests.

Long-term exposure test results

10 days later 3 months later 6 months later 12 months later
Other companies' rust prevention products
  • Test Methods: Samples A.B were left outside the user's factory to perform exposure test. Sample A = (1.6 x 38.1 x 5.0 m) 2 bundles of round tube, B = (1.6 x 50 x 50 x 6.0) 2 bundles of square tube
  • Evaluation: ○ = no white rust △ = a little white rust, but no problems in use × = Unusable due to white rust

High-strength carbon steel tubes (EchoStar)

High-strength steel tubes (EchoStar) made of fine grained hot rolled steel sheet (NFG)
of which Nakayama Steel Works, Ltd. succeeded in industrialized production for the first time in the world,

are manufactured at three factories in Sakai, Shimizu and Miyakonojo.
As EchoStar has superior strength, fatigue characteristics, high toughness, and weldability compared to conventional products, it has high demand in various fields.

  • POINT01

    Higher strength and performance than conventional products

    It is superior to conventional products (STK 500) in terms of tensile strength, yield point or bearing capacity, toughness in low temperature environment, workability and weldability.

    Classification Tensile strength (N/mm2) Yield point or proof stress (N/mm2) Elongation(%)
    EcoStar 700N 700 min. 570 min. 10 min.
    STK500 500 min. 355 min. 8 min. (※)
    • ※When the product thickness is 2 mm or more and 3 mm or less
  • POINT02

    Excellent corrosion resistance

    Zinc plating (Staging Z 27), which has excellent resistance to corrosion, is applied on the front and back surfaces, and if necessary, "surfcoat" which is effective in preventing white rust, is applied in pursuit of perfect quality.

     Excellent corrosion resistance

Quality characteristics of fine grain hot-rolled steel sheet (NFG)

Nakayama steel's fine grained hot steel sheet (NFG) has excellent quality characteristics due to its extremely fine ferrite grain size of approximately 1/3 or less compared to conventional hot steel sheets. Furthermore, its manufacuturing technology was awarded the Okochi Memorial Technology Award in 2003.


EchoStar has been adopted as a component of newly developed composite floor slab for bridges due to its superior quality characteristics and unique connection methods.

Application example  Application example
Dimensions, mass and cross-sectional performance
Classification Dimensions
Unit mass
Sectional area
Gemetric moment of inertia
Section modulus
Radius of gyration of cross-section
Outside diameter Wall thickness
EcoStar 700N 48.6 1.8 2.08 2.646 7.26 2.99 1.66
2.3 2.63 3.345 8.99 3.70 1.64
2.4 2.73 3.483 9.32 3.83 1.64
60.5 2.3 3.30 4.205 17.8 5.90 2.06