Structural bolts are high-strength fasteners for heavy-duty steel-to-steel connections, suitable for building beams, long-span bridges, wind turbine towers, petrochemical equipment and other projects. Manufactured to strict American standards, key grades include ASTM A325, A490, A307 and A193. Complying with ASME B18.2.1, these bolts have a 20%-30% wider/thicker head for easy high-torque tightening, partial threading for enhanced shear resistance, and are available in diameters 1/2″-1-1/2″ and lengths 2″-30″+. They must be used with dedicated ASTM A563 nuts and ASTM F436 serrated hardened washers to prevent loosening and protect steel materials. As a reliable structural bolt manufacturer in China, Hangzhou Gmetal supplies the full range of these American standard structural bolts and matching components, providing professional customized solutions and technical support for steel structure projects. If you are looking for a steel structure bolt supplier, please feel free to contact us; our team is ready to meet your needs with professional knowledge and experience.
Heavy Hex Bolts / Structural Bolts / Hex Bolt A325/A325M Specfications
- Material: Medium Carbon Steel, Alloy Steel 40Cr,35CrMo,42CrMo
- Diameter: Metric structural bolts size is M12 to M36, imperial structural bolts size is 1/2” to 1-1/2”
- Grade: A325,A325M,A490,A490M ,8.8,10.9,12.9
- Thread: Half Thread or Full Thread
- Finish: Black Oxide,Hot dipped galvanized ,Plain
- Application: Structural beams and columns, large-span bridges, space trusses, wind turbine towers, and petrochemical equipment frames etc.
- Package: 25kgs/carton,36cartons/pallets or customized package as customer’s requirements.
- Delivery: 30-45days for regular production.
- Standard A325 bolt and nut or Customized hex bolts are available.
- For Heavy Hex bolts dimensions and weight ,please contact us at sales@gmetalparts.com
Hangzhou Gmetal Heavy Hex Bolts/Structural Bolts Production
Gmetal manufacture different types of hex heavy bolts , hex structural bolts ,solar hex bolts ,Ubolts ,Square Ubolts in regular dimentions and sizes ,if you couldnot find the bolts you want in our page ,please contact us directly with your requirements .
Structual Bolt Manufacturing / Bolt China
As a hex structural bolts manufacturer and hex head bolt suppliers, Gmetal produce different types of hex bolts in our production lines, specially Metric & ANSI hex bolt, black hex bolt, HDG hex bolt, Stainless steel hex bolts, structural hex bolts, titanium head bolts etc. Small boxes or standard exporting cartons package are available.
What does Grade A325 mean?
Grade A325 refers to a high-strength heavy hex structural bolt specified by ASTM standards, designed for steel-to-steel connections in structural frameworks. It is quenched and tempered, with a minimum tensile strength of 120 ksi (827 MPa) for sizes ≤1.0 inch and 105 ksi for sizes 1.0-1.5 inches, and is commonly used in construction and bridge projects. Gmetal as a bolt manufacturer which provides grade A325 structural bolts from metric size M12 to M36 and Inch size from 1/2″ to 1-1/2″ with Black or HDG coating .
What is the definition of Grade A490 bolts?
Grade A490 is a high-strength alloy steel structural bolt under ASTM specifications, with higher strength than A325. Its minimum tensile strength is 150 ksi (1034 MPa), and it features a heavy hex head design. It is mainly used for ultra-heavy steel structure connections that require high load-bearing capacity.Hangzhou Gulian Metal Products Co., Ltd. has been manufacturing A490 bolts for steel structure companies . Please contact us directly if you have any needs.
What materials are used to make A325 bolts?
A325 bolts are mainly divided into two types based on their material: Type 1 is made of medium-carbon steel, carbon-boron steel, or medium-carbon alloy steel; Type 3 uses weathering steel, which has better corrosion resistance and is suitable for harsh outdoor environments. 8.8 grade structural bolts and A325 bolts are regular products of Hangzhou Gulian metal products co.,ltd . If you need to purchase them, please feel free to contact us.
What are the size ranges of A325 bolts?
According to ASTM specifications, A325 bolts are available in sizes from 1/2 inch to 1-1/2 inches in diameter, and their length ranges from 2 inches to over 30 inches, covering most structural connection needs.
What is the difference between A325 Type 1 and Type 3?
The main difference is the material and corrosion resistance. Type 1 is medium carbon steel/carbon boron steel, suitable for general environments; Type 3 is weathering steel, which forms a protective oxide layer in the atmosphere, providing better corrosion resistance for outdoor projects like coastal bridges.
What is the key difference in performance between A325 and A490 bolts?
The core difference is load-bearing capacity. A490 bolts have a tensile strength of 150 ksi, 25% higher than A325’s 120 ksi, so they can bear heavier loads. Additionally, A490’s alloy steel material has better toughness and fatigue resistance in harsh conditions.
When should I choose A325 instead of A490 bolts?
Choose A325 bolts for general structural connections such as building beams, columns, and ordinary bridges, where the load requirements are moderate. It balances strength and cost-effectiveness, making it the most widely used structural bolt in construction.So A325 structural bolts is Gmetal best seller products among our higher strength bolts ,which widely used in building ,bridge etc .
Can A325 bolts be used in wind energy projects?
For general wind turbine tower auxiliary connections with moderate loads, A325 bolts can be used. However, for key components bearing high dynamic loads (such as tower base connections), A490 or ASTM A193 (high-temperature and high-pressure resistant) bolts are more recommended. Gmetal can supplied A325 ,A490,or A193 bolts to our Middle East ,American market for customers in construction , building materal and Wind turbine tower industry .
Which main standards do A325 bolts comply with?
A325 bolts mainly comply with two categories of standards: ASTM A325 (specifies material, chemical composition, and mechanical properties) and ASME B18.2.1 (defines dimensional requirements such as head size, thread length, and shank diameter).Hangzhou Gulian metal products co.,ltd strictly adheres to this standard when manufacturing steel structure bolts for our customers.
What nuts are matched with A325 bolts?
A325 bolts must be used with ASTM A563 nuts. It is recommended to match Grade DH nuts, whose strength is compatible with A325, ensuring that the nut does not fail before the bolt during loading, thus guaranteeing connection reliability.
What is the rotational capacity test for A325 bolts?
It is a test to verify the installation reliability of A325 bolts, requiring the bolt to be tightened to the specified tension and then rotated by a certain angle (e.g., 2/3 turn for length ≤4×diameter). After the test, the bolt should reach the required tension without thread shear or torsional failure, and the nut should be manually rotatable.
Can SAE J429 Grade 5 bolts replace A325 bolts?
No. Although their mechanical properties are similar, A325 bolts have a heavy hex head (wider bearing surface) and longer shank (non-threaded portion) than Grade 5 bolts, which can improve shear strength. Grade 5 bolts cannot meet the load distribution requirements of structural connections.
What quality certifications should be requested when purchasing A325 bolts?
You should ask for per-lot manufacturer certifications stating that the bolts meet ASTM A325 and ASME B18.2.1 standards, including information on material composition, tensile strength test results, and heat treatment records, which are required for project quality inspection.Gmetal company will provide these test report to our A325 customers before shipping .Quality is key for us to ensure our relationship with our construction company in these years .
Can Hangzhou Gmetal supply both A325 and A490 bolts with matching components?
Yes. As a professional top 10 structural bolt manufacturer in China, Hangzhou Gulian metal product co.,ltd provides full-series A325 and A490 bolts (including different types and sizes), as well as matching ASTM A563 nuts and ASTM F436 washers, ensuring consistent quality and compatibility. If you have this requirements ,pls contact us at any time by sales@gmetalparts.com
Does Hangzhou Gmetal offer customization for non-standard A325/A490 bolts?
Yes. We can provide customized solutions according to project needs, such as non-standard diameters, lengths, special material modifications, and customized surface treatments, while strictly complying with relevant ASTM and ASME standards to ensure product performance.
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FAQ of Hexagon Head Bolts
1. Are you a hex bolts manufacturer?
Yes, Gmetal is a bolt factory, hex bolts manufacturers and suppliers, as well as leading fasteners manufacturers in china.
We mainly porduce black oxide hex bolts,Hot dipped galvanized hex bolts , Socket head cap screw, metric hex head bolts, stainless steel hex head bolts etc.
2. How long is your delivery time for black hex head bolts?
It takes 7-10 days for stock products. For bulk order, it will be in 30-60 days according to the order quantity.
3. Can we have samples for metric hex head bolts?
Yes, free samples are available, if you have a courier acount like DHL/FEDEX/UPS to collect the samples.
4. Can we use our own head mark or customize package for hex head bolts?
Yes, Gmtal as a hex bolts manufacturers, we can customize headmark and package, please send the requirements when place order.
5. How can we make an order for metric hex head bolts?
Just inquiry on our page or send a email to jenny@gmetalparts.com
For hex head bolt dimensions or weight chart for din 931, din933, iso 4014, iso 4017 ,astm a325 ,as1252 pdf, please feel free to contact us.
