[New JSA Standard Issued] Standardization of "Property Class 4.8 Torshear Type Hexagon Bolts" Achieved, Balancing Safety and Efficiency on Construction Sites!

The Japan Standards Association (JSA) (Headquarters: Minato-ku, Tokyo; Director General: Hiroshi Asahi) has issued the JSA standard "JSA-S1028:2026 Set of Torshear Type Hexagon Bolts, Hexagon Nuts, and Plain Washers of Property Class 4.8" on March 24, 2026, for connection components used in civil engineering and construction steel structures.

This JSA standard was primarily developed by Moreshige Kogyo Co., Ltd. The unique feature of this bolt set is its mechanism that controls the breaking torque by the bolt itself. By applying torque to the pintail at the tip of the bolt's screw thread until it torsionally fractures, the bolt maintains the specified tightening force. Furthermore, the fracture of the pintail at the bolt's tip provides a visual confirmation that the bolt tightening is complete. This ensures the safety of fastened structures on Japanese construction sites.

JSA-S1028:2026

"Set of Torshear Type Hexagon Bolts, Hexagon Nuts, and Plain Washers of Property Class 4.8"

(Set of torshear type hexagon bolt of property class 4.8, hexagon nut and plain washer)

Price: ¥5,060 (incl. tax) A4 size, 28 pages

*Standard prices are subject to change. Please note.

Background of Establishment and Expected Effects

Currently, the tightening management of "Hexagonal High-Strength Bolts," widely used on construction sites, relies on the skill and judgment of the workers, making objective confirmation difficult.

To address this issue, the tightening mechanism of "Torshear Type High-Strength Bolts," which have a proven track record in civil engineering and construction sites for many years, was introduced to the highly versatile Property Class 4.8 bolts. The primary goal is the "visualization of construction" by allowing anyone to visually confirm the completion of tightening when the pintail at the bolt tip breaks.

The widespread adoption of this standard is expected to reduce the burden of construction management on-site and ensure uniform quality of structures. Especially in the future construction industry, where a shortage of skilled workers is a concern, a system that provides "consistent quality regardless of who performs the work" without relying on special skills will greatly contribute to economic and social infrastructure maintenance.

Main Provisions

・Terms and Definitions

・Types and Composition of Sets, and Lot Composition

・Mechanical Properties

・Shape and Dimensions

・Threads and Fracture Grooves

・Test and Measurement Methods

・Inspection

What is a JSA Standard? ~Responding to Diverse Development Needs with Rapid Development Schedules~

JSA Standards are private standards issued by the Japan Standards Association. Since the establishment of the system in June 2017, the Japan Standards Association, as a specialized standardization organization, has been receiving consultations and proposals for diverse standard development needs from various stakeholders (companies, organizations, government agencies, academic societies, etc.). It provides efficient project management support for the voluntary standard development initiatives of proposers, developing JSA Standards "rapidly" while ensuring transparency, fairness, and objectivity.

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