Bolts
High-Tensile Structural Bolts (HSFG) Manufacturer, Wholesaler, Supplier & Exporter
Structural steel connections rely on high-strength friction-grip (HSFG) bolt, nut, and washer assemblies rated to precise proof loads. We manufacture and export these to ASTM A325, ASTM A490, and IS 3757 for steel-structure fabricators and EPC contractors.
High-strength friction-grip bolting works on a principle that surprises people outside structural engineering: the joint doesn't primarily rely on the bolt shank resisting shear at all. Instead, the bolt clamps the connected plates together so tightly that friction between the plates themselves transfers the load — which is why installation torque (or the direct-tension method used to verify it) matters as much as the bolt's material grade.
ASTM A325 and A490 aren't simply 'stronger' and 'even stronger' versions of the same bolt; A490 bolts are not permitted for galvanized coating in the same way A325 bolts are in some applications, due to hydrogen embrittlement risk during the galvanizing process. Structural engineers specify one or the other based on more than raw strength alone, and substituting between them without checking the actual specification can create a code-compliance problem even when the substituted bolt is, on paper, 'stronger'.
Minimum Order — Container Quantity (Approx.)
A standard 20ft container (~20 tons) holds approximately 60,000-100,000 sets of high-tensile structural bolt assemblies (bolt, nut, washers) in common sizes (M16-M20). Exact quantity depends on size and grade and is confirmed at quote time.
You don't need a full container to order. Hurain Engitech & Trade — the group Global Fasteners Exports operates under — regularly ships smaller, partial-container (LCL) orders of just a few pallets or boxes for buyers who don't yet need FCL volume, consolidated with other cargo to keep freight cost reasonable.
Specifications
Standards
ASTM A325 (Type 1/3), ASTM A490, IS 3757, EN 14399.
Assembly
Supplied as matched sets — bolt, nut, and hardened washers — to ensure certified proof-load performance.
Size range
M12 to M36 metric; 1/2" to 1 1/2" imperial.
Finish
Plain, hot-dip galvanized, or mechanically galvanized (Type 3 weathering steel on request).
Applications
Structural steel fabrication
Beam, column, and truss connections in buildings and industrial structures.
Bridges & infrastructure
High-load structural connections requiring certified friction-grip assemblies.
Towers & transmission structures
Lattice tower and transmission structure bolting.
Materials Available
Steel
Every assembly is proof-load and hardness tested to ASTM A325/A490 or IS 3757, with mill test certificates supplied for structural sign-off.
How We Manufacture & Export This Product
- 1
Spec confirmation
Confirm standard, grade, size, and galvanizing requirement from structural drawings.
- 2
Forging & heat treatment
Hot forging followed by quench-and-temper heat treatment to reach the required tensile grade.
- 3
Proof-load testing
Batch proof-load and hardness testing with certification traceable to heat number.
- 4
Export packing
Matched bolt/nut/washer sets, boxed and documented for project-based export shipment.
Export Track Record
Supplied as certified bolt-nut-washer assemblies for structural steel fabrication and EPC project shipments.
Real-World Use Cases
High-rise and industrial steel frames
Beam-to-column and truss connections requiring certified friction-grip performance.
Bridge and infrastructure connections
High-load structural joints in bridges and heavy infrastructure.
Lattice towers and transmission structures
Bolted connections in towers subject to significant wind and dynamic loading.
Common Mistakes Buyers Make
Substituting A490 for A325 without checking the spec
A490 bolts have restrictions (including on galvanizing) that don't apply the same way to A325 — check the actual structural specification before substituting.
Under-torquing a friction-grip connection
The joint relies on clamping force generating friction between plates — under-torqued bolts undermine the entire friction-grip design intent, not just the bolt itself.
Mixing bolts from different heat lots without tracking
Structural sign-off typically requires heat-number traceability — mixing lots without recording it can invalidate the QA paper trail.
Glossary of Terms
- Friction-grip connection
- A bolted joint design where clamping force generates friction between plates to transfer load, rather than relying primarily on bolt shear.
- Direct tension indicator (DTI)
- A washer with crushable protrusions used to verify a structural bolt has reached its specified installation tension.
- Hydrogen embrittlement
- A brittleness that can be introduced into high-strength steel during certain plating or galvanizing processes — a key reason A490 bolts restrict some finishing methods.
Quality Inspection We Perform
Dimensional inspection
Thread gauge, length, diameter, and head/drive geometry checked against the specified standard.
Material verification
Grade and material composition confirmed against the order specification, with mill test certificates on request.
Mechanical testing
Tensile strength, hardness, and proof-load testing on sample batches, particularly for structural and high-tensile grades.
Finish & coating check
Plating thickness, galvanizing coverage, or passivation quality inspected before packing.
HS Code & Customs Classification
Most fasteners fall under HS Chapter 73 (articles of iron or steel) or Chapter 74/76 for brass and aluminum items — the exact 8-10 digit subheading depends on the specific product and material. We include the HS code on the commercial invoice; confirm the applicable import duty with your customs broker, since rates vary by country and trade agreement.
Packaging & Export Labeling
Export packing is chosen to survive ocean freight and container loading without corrosion or damage: corrosion-protected paper or oil coating where needed, then cartons, drums, or bulk bags, palletized or crated for the container. We can match specific labeling, barcoding, or carton-marking requirements for OEM and repeat buyers.
Countries We Export High-Tensile Structural Bolts To
View all markets →Buying guide
How to Choose a Reliable High-Tensile Structural Bolts (HSFG) Manufacturer, Wholesaler, Supplier & ExporterWhy structural bolts must be sourced as certified matched assemblies, and the A325/A490 distinction that trips up buyers substituting for cost.
Frequently Asked Questions
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