Our product range includes High Strength Bolts and Nuts, washers, and complete fastening systems, widely used in steel structures, bridges, power towers, wind turbines, oil & gas, rail transit, shipbuilding, and heavy machinery. Made from premium alloy or stainless steels, the products undergo precision forging, heat treatment (quenching & tempering), thread rolling, and surface coating (HDG, Dacromet, etc.), ensuring high tensile strength, shear resistance, fatigue life, and corrosion protection. We offer full fastening solutions including design selection, preload control, installation guidance, and traceability, meeting diverse industrial and environmental requirements.
Key Features
Standards:
Chinese: GB/T 3098.1, 1231, 3632, 5782
International: ISO 898-1/2, ASTM A325/A490, F594, DIN 931/980
Materials:
Carbon/Alloy Steel: 35CrMo, 42CrMo, SCM435
Grades: 8.8, 10.9, 12.9 (bolts); 8, 10, 12 (nuts)
Stainless Steel: A2-70, A4-70, 2205
Special: Low-temp (L7, B7), HIC-resistant (NACE MR0175)
Dimensions:
Bolts: M6–M100, length 10–3000mm
Nuts: M6–M100, hex, flange, lock nuts
Washers: Flat, spring, serrated, high-strength
Assemblies: Complete sets (bolt + nut + washer)
Surface Treatments:
HDG (50–85μm), Dacromet (≥500h salt spray), Mechanical Zn, Electro Zn, Phosphating+Oil
Applications:
Construction, Wind Power, Oil & Gas, Power, Rail, Shipbuilding, Heavy Equipment
Certifications:
Classification Societies: CCS, ABS, DNV, LR, BV, NK (with MTC, test reports)
Owner/Engineering Companies: ISO 9001/14001/45001; Approved by CNPC, Sinopec, State Grid, Shell, ExxonMobil, GE, Siemens, etc.
Common Customer Questions (Q&A Format)
Q: What is the difference between 8.8 and 10.9 grade bolts?
A: 10.9 has higher strength (tensile ≥1040MPa), used for high-load joints; 8.8 (≥800MPa) for general use.
Q: Can high-strength bolts be reused?
A: Twist-off type (Set Screw) is single-use; large hex bolts can be reused if undamaged and re-tensioned properly.
Q: How to ensure proper preload?
A: Use torque wrench, turn-of-nut method, or hydraulic tensioner to achieve specified preload.
Q: Do you provide torque coefficient (K-value) testing?
A: Yes, per GB/T 1231 or ASTM A325, with test reports for each batch.
Q: Can stainless steel bolts be used with carbon steel nuts?
A: Not recommended due to galvanic corrosion; use matching materials (e.g., A4 bolt + A4 nut).
Q: Which bolts for low-temperature service?
A: Use L7, B7 alloy steel bolts tested at -46°C or -101°C, per ASTM A320.
Q: Suitable for H2S (sour) environments?
A: Yes, we offer HIC-resistant bolts per NACE MR0175/ISO 15156, e.g., 316L, 2205.
Q: What is the lead time?
A: Standard: 7–15 days; custom/high-strength: 15–30 days; class-approved: +5–10 days.
Q: Do you provide installation support?
A: Yes, manuals, torque tables, on-site support, and training available.
Q: How to repair damaged galvanized coating?
A: Apply zinc-rich paint or spray zinc to restore protection.
Q: Common causes of bolt failure?
A: Overload, insufficient preload, vibration, corrosion, material defects, improper installation.
Q: Do you support small batch or OEM orders?
A: Yes, custom designs, materials, coatings, and branding (OEM/ODM) supported.
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