Supplying certified bolting assemblies, forged components, and industrial flanges to Ulsan, Geoje, Busan, and industrial hubs across South Korea.
Meeting rigorous quality expectations across South Korea's industrial landscape requires structural integrity, dimensional exactness, and strict metallurgical verification.
Korean industrial conglomerates (Chaebols) and Tier-1 EPC contractors maintain some of the most rigorous technical standards in the world. As global heavy engineering projects evolve, Korean procurement teams frequently source specialized ASME/ASTM and EN standard heavy hex nuts and studs alongside local KS B 1012 requirements. Heavy hex nuts differ substantially from standard hex nuts by having an increased width across flats (AF) and thickness, providing greater thread engagement length and enhanced resistance to high stripping loads.
Our OEM/ODM manufacturing facility specializes in producing ASTM A194 Grades 2H, 7, 8, and 8M, along with ASTM A563 Grades DH and C heavy hex nuts. These components are specifically formulated to handle high preloads and elevated stress environments common in Korean EPC projects executed both domestically and across the Middle East, Southeast Asia, and Europe.
Reliable clamping performance depends on disciplined metallurgical control. We employ precision induction heating and closed-die forging to maintain consistent axial grain flow throughout the hex profile. By ensuring grain continuity around the nut walls and internal tapping zones, our fasteners achieve superior proof-load resistance and reduced notch-sensitivity under fatigue conditions.
In accordance with ASTM A194 and A563, medium-carbon and alloy-grade nuts (such as 2H and Grade 7) undergo continuous liquid quenching followed by precise tempering above 590°C. For sub-zero and cryogenic LNG duty—a key pillar of South Korea's maritime manufacturing sector—we conduct Charpy V-notch impact tests down to -101°C (Grade 7) or -196°C for solution-annealed austenitic stainless grades (Grades 8/8M), preventing catastrophic brittle fracture under thermal contraction.
South Korea's coastal and marine industrial sites demand uncompromising corrosion prevention. As one of the premier hot-dip galvanizing (HDG) exporters, our processing strictly matches ASTM A153 Class C and ISO 10684. Nuts undergo high-speed centrifuging immediately after molten zinc immersion at 450°C, ensuring clean thread clearance without compromising coating density.
To eliminate galling on stainless steel fasteners and ensure steady torque-tension correlation, we provide specialized factory-applied lubricants, fluoropolymer PTFE coatings (Xylan/FluoroKote), and electro-zinc nickel treatments. These coatings maintain predictable friction coefficients (µ = 0.10–0.14) during automated hydraulic bolt tensioning in shipyards and offshore platforms.
Our heavy hex nuts and high-tensile connection components are deployed in safety-critical installations across key Korean industries.
In mega-shipyards across Ulsan, Geoje, and Mokpo, our heavy hex nuts (ASTM A194 Gr. 8M, A194 2H) secure cryogenic fuel tanks, LNG reliquefaction piping, cargo containment systems, and ballast water management modules. High fatigue endurance and resistance to seawater chloride stress-cracking make them indispensable for deep-sea drillships and FLNG vessels.
High-pressure hydrocrackers, ethylene crackers, and high-temperature catalytic reformers demand leak-free flanged joints. Matched with ASTM A193 B7 and B16 stud bolts, our ASTM A194 Grade 2H and Grade 7 heavy hex nuts maintain clamp load under intense thermal cycling, preventing hazardous emissions in downstream operations.
For elevated railway viaducts, transmission towers, and wind turbine anchor rings, joint failure is never an option. We supply structural tension control assemblies, A325/A490 heavy structural bolts, and matching nuts with anti-loosening and micro-vibration resistance, certified to resist decades of cyclic fatigue.
Cross-reference material grades, hardness thresholds, and mating fastener combinations to ensure compliance with project specifications.
| Nut Standard & Grade | Material Chemistry | Proof Load Stress (min) | Hardness Range (Rockwell) | Matching Stud / Bolt | Primary Industrial Sector |
|---|---|---|---|---|---|
| ASTM A194 Gr. 2H | Medium Carbon Steel, Q&T | 175 ksi (≤ 1.5 in) | 24 to 35 HRC | ASTM A193 B7 / B7M | Petrochemical & Pressure Vessels |
| ASTM A194 Gr. 7 | AISI 4140 Cr-Mo Alloy, Q&T | 175 ksi (≤ 1.5 in) | 24 to 35 HRC | ASTM A193 B7 / B16 / L7 | Low-Temp LNG & High Temp Steam |
| ASTM A194 Gr. 8 | AISI 304 Austenitic Stainless | 80 ksi (Standard) | 126 to 223 HBW | ASTM A193 B8 Class 1/2 | Food, Chemical, Cryogenic Service |
| ASTM A194 Gr. 8M | AISI 316 Mo-Bearing Stainless | 80 ksi (Standard) | 126 to 223 HBW | ASTM A193 B8M Class 1/2 | Marine Engineering & Desalination |
| ASTM A563 Gr. DH | Medium Carbon / Carbon Boron | 175 ksi (Plain) | 24 to 38 HRC | ASTM A325 / F3125 / A490 | Structural Steelwork & Bridges |
| KS B 1012 / Class 10 | High-Strength Quenched Alloy | 1040 MPa | 26 to 36 HRC | KS B 1010 / Class 10.9 | Domestic Korean Heavy Machinery |
Combining large-scale capacity with strict quality controls to support overseas procurement contracts.
Certified under the Pressure Equipment Directive (PED 2014/68/EU), our manufacturing operations uphold clear traceability from raw billet to finished bolt. Every batch ships with an EN 10204 3.1 Mill Test Certificate detailing direct optical emission spectroscopy (OES) chemical breakdowns, tensile data, and proof load test records.
We produce both large project runs and specialized custom dimensions up to M100 and 4-inch nominal sizes. From specialized pitch thread rolling (8-UN, UNC, UNF, Metric fine) to customized slotting, counterboring, and custom washer-faced nuts, our internal tooling handles non-standard drawings efficiently.
Export packaging complies with international seaworthy standards. Products are packaged in moisture-barrier bags inside heavy wooden cases or reinforced steel drum pallets. With optimized shipping lanes from Mumbai to Busan, Gwangyang, and Incheon, we maintain dependable lead times for fast-track EPC turnarounds.
Technical answers to procurement, standard cross-matching, and compliance questions common among Korean engineers and purchasing directors.
ASME B18.2.2 Heavy Hex Nuts feature larger across-flat (AF) and thickness dimensions than standard metric KS B 1012 hex nuts. For projects in South Korea designed to US or international codes (such as ASME Section VIII or API 6A), substitution with standard hex nuts is not permitted, as the joint requires the expanded load-bearing area of the heavy hex profile.
Yes. In addition to our internal QA systems and standard EN 10204 3.1 certification, we routinely accommodate third-party inspections (TPI) prior to shipment, including DNV, Lloyd's Register, Bureau Veritas, and Korean Register (KR) witnessed testing for marine piping packages.
Per ASTM A563/A153 guidelines, heavy hex nuts are tapped oversize after hot-dip galvanizing to clean molten zinc from the thread valleys, ensuring smooth hand assembly while preserving galvanic protection via the zinc on the mating bolt threads.
Standard grades (A194 2H, 8, 8M, A563 DH) in common imperial and metric sizes are stocked for rapid dispatch within 7–10 days. Custom forging runs, non-standard diameters (up to M100), and special alloys require 3–5 weeks production before direct ocean transit to Busan or Incheon.
Access comprehensive dimensional tables, certified proof-load ratings, torque calibration datasets, and export pricing schedules tailored to the South Korean market.
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