Aritcle No. 2: Mock-up H-Grade – A Japanese-Standard Product
The 80th anniversary National Achievements Exhibition, which started on August 28th, featured many impressive booths. At the ATAD booth, exhibits of high-rise building steel frames, the “Steel Flower,” the Kura automatic welding robot, a scaled model, and other key projects executed by ATAD attracted a large number of visitors. However, one of the real highlights that captured visitors’ attention was the Mock-up H-Grade at the ATAD booth.
What is the H-Grade Mockup?
The H-Grade Mockup is a fabricated sample manufactured in accordance with the Japanese production standard JASS 6 (Japanese Architectural Standard Specification No. 6 – Steel Work). H-Grade (High Grade) is applied to critical structures subjected to dynamic loads, cyclic loads, or seismic forces, requiring the highest level of welding quality.
What are the standards for H-Grade certification?
To obtain H-Grade certification, the mockup must undergo extremely strict control from material selection, workmanship, to final product quality:
• The main components of the mockup consist of the primary column body fabricated from square hollow section (SHS) 450x450x28 mm, connecting beams from H-shaped steel 500x300x16x32 mm, and a column base plate fabricated from PL 40 mm sheet metal.
• The primary materials are manufactured in compliance with JIS standards (Japanese Industrial Standards) and imported from major reputable Japanese producers.
• Welding consumables used in the fabrication process are produced and certified in accordance with JIS standards.
• Welders must be trained and certified to Japanese standards to meet the stringent requirements for welding parameters, including current, voltage, interpass temperature, and welding sequence.
• 100% of weld in the mockup must be inspected by Ultrasonic Testing (UT) to ensure structural performance, load-bearing capacity, and especially seismic resistance in accordance with Japanese conditions.
• Bolt holes must be machined with high precision. For friction joints with high-strength bolts application, the contact surfaces must be roughened to achieve the required friction coefficient (µ ≥ 0.45 or as specified in JASS 6).
Additionally, the fabrication process is monitored and guided by Level-1 Steel Structure Production Management Engineers under Japanese standards, and by Welding Engineers certified to international standards.
This is not just a product on display, but also a “test” of ATAD’s production capabilities. The fact that all welds must undergo ultrasonic testing (UT) and are performed by professional welders is evidence of a serious investment in quality.
The Mock-up H-Grade tells a story of meticulousness and a commitment to quality. It is ATAD’s strong affirmation of its ability to compete in the international market.
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