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High-Strength Heavy Hex Cap Screw - ASTM A325/A490 M12-M36
Picture a storm-lashed bridge or a soaring steel frame: at every crucial joint, the High-Strength Heavy Hex Cap Screw stands like a silent guardian. Forged and rated to ASTM A325/A490 standards and offered in sizes M12–M36, its heavy hex head and hardened shank clamp steel with unwavering grip under pressure. Sleek, industrial, and utterly dependable, these cap screws lend your projects the muscle and precision finish that inspires confidence at first glance.
Product advantages
Manufactured to ASTM A325/A490 specifications, these heavy hex cap screws (M12–M36) are forged and heat-treated under strict quality control with full traceability to meet demanding structural requirements. They deliver high tensile and shear capacity—A490 grades offering higher strength than A325—providing secure, fatigue-resistant connections for bridges, buildings and heavy equipment while the standardized hex head ensures consistent torque application. Available with corrosion-resistant finishes such as hot-dip galvanizing or mechanical zinc, the screws reduce fastener count through greater load capacity, extend service life, and simplify installation and maintenance.
Team strength
Our experienced engineering and production team specializes in high-strength heavy hex cap screws (ASTM A325/A490, M12–M36), combining metallurgical expertise, precision machining, and strict quality control. We deliver consistent mechanical properties, dimensional accuracy, and surface finishes through certified processes and in-house testing. Project managers and technical sales provide fast, informed support for specification, customization, and large-volume orders, ensuring on-time delivery and cost-effective logistics. Continuous training, R&D, and lean manufacturing practices enable rapid problem-solving and product improvement. This dedicated team ensures compliance with standards, reliable supply for construction and infrastructure projects, and confident, long-term performance for demanding applications and global delivery capability.
Why choose us
Our seasoned engineering and production team combines deep fastener expertise with rigorous quality control to deliver ASTM A325 and A490 heavy hex cap screws in sizes M12–M36. Core strengths include precision cold-forging, heat-treatment, and thread rolling processes, plus in-house tensile and hardness testing to meet structural specifications. Value comes from reliable supply capacity, certified traceability, and tailored inventory and packaging for construction projects. Dedicated technical support guides specification selection and torque recommendations, while responsive procurement and logistics ensure on-time deliveries. The result: consistent, certified high-strength fasteners that reduce installation risk and support long-term structural performance and exceptional post-sale service guarantee.
Product Introduction
JM Hardware® excels in delivering top-tier fastening solutions, and our Heavy Hex Structural Bolts stand as a testament to our commitment to quality. Crafted with precision from premium materials, these bolts showcase superior strength, resilience, and durability. Engineered for heavy-duty applications, JM Hardware® Heavy Hex Structural Bolts ensure steadfast connections, offering unmatched reliability in diverse industries, from construction to infrastructure projects. Trust in the robust design and exceptional performance of our Heavy Hex Structural Bolts to fortify your projects with the reliability that defines JM Hardware®
Product Parameters
Heavy Hex Structural bolt | |
Size: | 1/2”-1 1/2”,M12-M36 |
Material: | CarbonSteel,AlloySteel |
Grade: | ASTMA325,A490,CL10.9 |
Finish: | Plain, Zinc Plated(Clear/Blue/Yellow/Black), Black oxide, Nickel, Chrome, H.D.G. |
Product Details
Quality Control
JM Hardware conducts product quality control in strict accordance with ISO 9001 standards to ensure that our products meet high quality standards. Below are our five quality control steps:
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Incoming material control
We carry out strict incoming material control by conducting dimensional tests on each batch of raw materials and checking the raw material reports from the steel mills. This ensures that the raw materials we use are within specification and provide a reliable basis for production.
We carry out strict incoming material control by conducting dimensional tests on each batch of raw materials and checking the raw material reports from the steel mills. This ensures that the raw materials we use are within specification and provide a reliable basis for production.
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First part control
After the mold assembly is completed, we conduct a thorough inspection of the first production part and make detailed records. Only qualified first parts can be released to start mass production. This step ensures that the quality of the product meets the standard at the beginning.
After the mold assembly is completed, we conduct a thorough inspection of the first production part and make detailed records. Only qualified first parts can be released to start mass production. This step ensures that the quality of the product meets the standard at the beginning.
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Self-inspection by workers during mass production
In the mass production process, we require the workers of each machine to carry out self-inspection every hour. If any substandard product is found, we will immediately pick or scrap the production within this hour until the problem is solved and meets the standard of conformity, and then we can continue the production. This self-inspection mechanism helps to find and solve problems in time during the production process.
In the mass production process, we require the workers of each machine to carry out self-inspection every hour. If any substandard product is found, we will immediately pick or scrap the production within this hour until the problem is solved and meets the standard of conformity, and then we can continue the production. This self-inspection mechanism helps to find and solve problems in time during the production process.
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QC inspection during mass production
In addition, every two hours, the quality inspection personnel will carry out random inspection on the products of each machine. Only qualified products can continue to flow into the next production stage. If non-conforming products are found, we will take the same selection or scrapping measures and ensure that the problem is properly handled. This helps provide additional quality assurance.
In addition, every two hours, the quality inspection personnel will carry out random inspection on the products of each machine. Only qualified products can continue to flow into the next production stage. If non-conforming products are found, we will take the same selection or scrapping measures and ensure that the problem is properly handled. This helps provide additional quality assurance.
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Finished product control
Finally, after each batch of finished product is made, we conduct random inspections in proportion to the order. Qualified products will be packaged and put into storage, while unqualified products will be returned for further analysis and rectification. We insist on ensuring that the quality of our products meets high standards so that we can provide reliable products to our customers.
Finally, after each batch of finished product is made, we conduct random inspections in proportion to the order. Qualified products will be packaged and put into storage, while unqualified products will be returned for further analysis and rectification. We insist on ensuring that the quality of our products meets high standards so that we can provide reliable products to our customers.
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Non-conforming goods management
According to the process of JMhardware's non-conforming products handling, pick or scrap. And the problem of rectification and tracking reasons to ensure that non-conforming products will not flow into the market.
According to the process of JMhardware's non-conforming products handling, pick or scrap. And the problem of rectification and tracking reasons to ensure that non-conforming products will not flow into the market.
These quality control measures constitute JM Hardware's quality management system, and we are constantly striving to improve the quality of our products and are committed to meeting the needs of our customers. We believe that quality control is the key to our success.
Production equipment
Testing Equipment
Magnetic particle flaw detectorTest report
SGS testing report --310S bolt nut
Third-party testing report-P1
Third-party testing report-P2
JM Hardware® testing report
Packing
Why Choose Us
Strong R&D Capability
Successfully developed 680+ new products in past 16 years
Rich Industry Experience
JM has the rich experience to supply the high quality fasteners to Project contractor
Mature & professional service teams
Provides 24/7 online and offline services for you,70%stuff have 5+ working experience in JM
Rich export experience
15+ years exported to 70+ countries
Supply one-stop service & DDP term
Help clients purchase other products,realize door-to-door service to make international procurement more convenient
Certificate
Valued Partners
JM Hardware @ has exported its hardware parts to over 85 countries around the world.
We will make unremitting efforts to provide hardware parts with high quality and reasonable prices for our customers.
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Contact us
we welcome custom designs and ideas and is able to cater to the specific requirements. for more information, please visit the website or contact us directly with questions or inquiries.
xarella.huang@jm-fastener.comOur address
Add: Rm.27202, No.295 South Lingyan Road, Pudong,Shanghai,P.R.C
Contact person: xarella.huang
Whatsapp: +86 13681923533
Wechat:+86 18621005605
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Since our establishment in 2006, JM has been adhering to the mission of creating maximum value for customers by providing differentiated services, and making a positive contribution to the society.