Large Diameter Bolts: Reliable Supply for Heavy-Duty Applications
If you import or specify large diameter bolts for critical infrastructure, energy, or heavy machinery, you need a supplier that combines factory-direct quality, consistent metallurgy, and China’s supply chain efficiency. At Shijiazhuang TJJ TRADE CO.,LTD., our foundry—operating since before the year 2000—produces high-strength large‑diameter bolts (custom diameters up to 150 mm) with full traceability, ISO 9001 certification, and a track record of serving U.S., European, and African buyers. This page gives you all the technical, commercial, and logistical facts to make an informed sourcing decision. All data are for reference; final specifications confirmed per order.
The Challenge of Sourcing Large Diameter Bolts
Buyers of heavy‑duty fasteners frequently encounter three pain points:
- Inconsistent quality – small workshops lack the control of heat‑treatment and dimensional tolerances, leading to field failures.
- Long lead times – custom large bolts often take 8–12 weeks from conventional sources.
- Inflexible MOQs – many suppliers demand 1,000+ pieces, even when you only need 200 for a pilot project.
In 2026, global project deadlines are tighter than ever. Procurement managers need a partner who can deliver certified large diameter bolts with a short turnaround, without sacrificing metallurgical integrity.
Our Solution – TJJ Precision Large Diameter Bolts
Leveraging over 20 years of foundry and machining experience, TJJ manufactures large diameter bolts through precision casting, forging, and CNC finishing. We serve OEMs, distributors, and contractors who demand repeatability and compliance with ASTM / SAE / ISO standards.
Technical Parameters & Available Specifications
| Parameter | Standard Range | Custom Option |
|---|---|---|
| Diameter | 1″ – 4″ (25 mm – 102 mm) | Up to 6″ (152 mm) |
| Length | 2″ – 36″ (50 mm – 915 mm) | Any length |
| Material | Carbon steel (A36, 1045), Alloy steel (4140, 4340) | Stainless 304/316, duplex, Hastelloy |
| Strength Grade | ASTM A307 Gr.A, SAE J429 Gr.8, ISO 898-1 10.9 | 12.9, custom yield |
| Coating | Black oxide, zinc‑plated, HDG | Dacromet, Xylan, PTFE |
| Thread Type | UNC, UNF, metric coarse/fine | Acme, buttress, custom |
*All specifications can be confirmed during quotation. Minimum tolerances ±0.5 mm on non‑critical dimensions.
Certifications & Compliance
- ISO 9001:2015 – Quality management system (full documentation available for audit).
- CE Marking (EU) – For bolts used in European infrastructure projects.
- RoHS / REACH – Material compliance for surface coatings.
- ASTM / SAE / ISO – Mechanical testing (tensile, yield, hardness) per applicable standards.
- Third‑party inspection – SGS, BV, or Intertek accepted at buyer’s cost.
Application Scenarios for Large Diameter Bolts
- Wind energy – tower flange bolts, pitch bearing bolts (high‑cycle fatigue resistance).
- Bridge construction – structural bolted joints requiring high preload.
- Heavy equipment – bulldozer track bolts, hydraulic cylinder mounting.
- Mining & aggregates – crusher liner bolts, screen deck fasteners.
- Oil & gas – BOP stack bolts, pipeline flanges (special NACE compliance available).
Factory view – precision casting and machining lines for large diameter bolts.
Why Choose TJJ as Your Large Diameter Bolt Supplier?
Factory‑Direct Supply Chain
Our foundry covers an area of 35,000 m² with over 120 experienced workers. We control every step from melt to final inspection. This vertical integration reduces lead times and eliminates middleman markups – important when you buy large diameter bolts in volume.
MOQ & Lead Time
| Order Type | MOQ | Lead Time (FOB Tianjin/Qingdao) |
|---|---|---|
| Standard size stock | 50 pcs | 7–10 days |
| Custom diameter/length | 200 pcs | 20–25 days |
| Special material (e.g., 316SS) | 500 pcs | 30–35 days |
*Lead times are based on current capacity; please confirm with our sales team for your specific order.
OEM / ODM Design Support
We offer full customization: thread forms, head styles (hex, square, socket, eye), hole patterns, and marking. Send your drawing or sample, and our engineers will provide a DFM (Design for Manufacturability) review within 48 hours.
Packaging, Logistics & After‑Sales
- Packaging: Rust‑proof VCI paper, plywood pallets, steel strapping, or export‑grade wooden cases (IPPC heat‑treated).
- Incoterms: FOB, CIF, EXW, DDP (depending on your preference).
- After‑sales: 12‑month defect warranty (excluding abuse). Replacement or credit issued within 10 business days.
- Payment: T/T (30% deposit, 70% against copy of B/L), L/C at sight, or negotiable.
What Our Customers Say
David Keller
Procurement Manager – EnergyWorks, Texas, USA
“We needed 1‑1/4″ diameter, Grade 8 bolts for a wind farm foundation. TJJ delivered 2,800 pieces in 22 days – with full MTRs and third‑party UT reports. The quality exceeded our domestic supplier. We’ve placed three repeat orders.”
Maria Santos
large bolts and nuts large industrial bolts / big nuts and bolts huge bolt
Sourcing Agent – BridgePro Imports, Florida, USA
“I source large diameter bolts from multiple countries. TJJ is the most responsive and transparent. They sent video inspections during casting and heat treatment. The bolts met ASTM F1554 Gr.105 – no issues.”
Robert Lee
Owner – Lee Industrial Fasteners, Ohio, USA
“MOQ flexibility was key for us. TJJ allowed a run of 150 custom 2‑inch bolts with 12.9 grade. Since then we’ve moved all our large bolt imports to them. Very few non‑conformances.”
Andrew Chen
Supply Chain Director – Pacific Mining Corp, Australia
“We tested TJJ’s 3‑inch bolts in our jaw crusher. After 6 months of constant vibration, no loosening or cracking. Their metallurgy report matched exactly. Count on them for heavy loads.”
Author’s Perspective
Hector Ramirez
Senior Sourcing Engineer – 15 years in industrial fastener supply chains
“I’ve visited over 40 fastener factories across China, India, and Europe. TJJ’s foundry stands out for its systematic quality control on large diameter bolts – they actually test every heat lot in their on‑site lab. For U.S. buyers who need CE or ASTM certified parts, they are a reliable mid‑volume supplier. Always request a pre‑shipment inspection if your order exceeds 500 pieces.”
Get a Quote for Your Large Diameter Bolts
Ready to secure a consistent supply of high‑quality large diameter bolts? Contact our export team for a fast response with commercial and technical details.
Shijiazhuang TJJ TRADE CO.,LTD.
Tel / WhatsApp: +86-15511680668
Email: sindyhao2014@163.com
Website: Contact Page
Address: Shijiazhuang, Hebei Province, China
All prices, specifications, and lead times are indicative and may vary. Please refer to the actual order confirmation.
Partial view of TJJ’s export office and finished goods warehouse.
