Our ASTM A307 nuts are workhorses for structural steel connections-built to handle heavy loads without letting you down. Made from low-carbon steel (with no more than 0.29% carbon, just like ASTM A307 requires), they perform reliably in places where rust isn't a big issue, like bridges, transmission towers, and heavy machinery setups.
We offer two finishes: black oxide coated (per ASTM D769) for rust resistance during storage, and zinc-plated (5-8μm layer, ASTM B633) for better protection in damp areas. The zinc plating passed a 300-hour salt spray test (ASTM A307 Nuts) with only light surface rust, making it a solid choice for garages or outdoor sheds.
Our threading is done with precision: UNC threads (ASME B1.1) have a Class 2B fit, so they screw onto bolts smoothly without sticking. We use cold-forging for the nut bodies, which makes them 20% stronger than cast versions, and every nut gets a thread gauge check before shipping. For bulk orders, we pack them in reusable steel crates with dividers to prevent thread damage.
As a Chinese manufacturer with 13 years supplying US construction and hardware stores, we run 8 nut-forming lines and 5 threading machines, churning out 5,500 tons a year. Our raw steel comes from mills with ISO 9001 certification, and each batch gets a chemical check (OES, accurate to 0.001%) to hit ASTM A307 standards.
We keep 800-1000 tons in stock at our Qingdao warehouse, with sizes from ¼" to 2" and styles like hex, square, and wing nuts. Inventory updates in real time on our site, and FOB Qingdao shipments for in-stock nuts leave within 3 days-handy when your customers need to restock fast.
5% discount on orders over 80 tons plus free galvanizing.
We guarantee: If any ASTM A307 nut slips during normal use or does not meet ASME B18.2.2 dimensional standards, we will replace it within 5 days and pay for shipping. We also offer a 25-day price lock on large orders, and returning customers can enjoy an additional 2% discount on reorders within 2 months.
ASTM A307 (covers carbon steel externally threaded fasteners, including matching nuts for A307 bolts and ASTM A307 Nuts)
Carbon steel (low carbon content, typically ≤ 0.29% C; designed to be compatible with A307 bolts for balanced performance)
Companion nuts for ASTM A307 carbon steel bolts, used to secure joints in light to moderate load applications
Mechanical Properties
Tensile Strength: Min. 55 ksi (379 MPa) (to match the strength of A307 bolts and prevent nut failure before bolt)
Hardness: Typically 60–95 HRB (lower than high-strength nuts for ductility)
Thread Standards
Unified National Coarse (UNC) per ASME B1.1 (matching A307 bolt threads)
Sizes: 1/4" to 4" (imperial); compatible with bolt diameters in the same range
Types/Styles
Hex nuts (most common): 6-sided hexagonal shape for wrench tightening
Optional styles: Heavy hex nuts (for greater bearing surface) or slotted hex nuts (for locking with cotter pins in some cases)
Surface Finish
Plain (uncoated): economical for dry, indoor environments
Zinc-plated: for improved corrosion resistance in mild outdoor or humid settings
Hot-dip galvanized: for enhanced protection in harsh environments (e.g., construction sites)
Applications
Paired with A307 bolts in construction (wood/light steel connections, concrete formwork)
Machinery assembly (light equipment, pumps)
Piping systems (non-high-pressure flanges)
General-purpose fastening where moderate strength and cost-efficiency are key
Key Features
Compatibility: Designed to work with A307 bolts for balanced joint strength (nut yields slightly before bolt to prevent sudden failure)
Cost-effective: Low carbon steel construction reduces material costs
Easy installation: Standard hex design for universal wrench use
Frequently Asked Questions
Q: Do you have experience exporting to our country/region?
A: We have exported to over 50 countries, including the US, EU, Southeast Asia, and the Middle East. We're familiar with local import regulations.
Q: Can you arrange door-to-door delivery service?
A: Yes, we can arrange door-to-door delivery through our freight forwarders, covering customs clearance and final transportation to your address.
Q: What materials do your products mainly include?
A: Our products mainly include carbon steel, stainless steel, and alloy steel, with a focus on pipes, flanges, and fittings.
