Top Flange Bolt Supplier in China

As a critical component in any flanged connection, high-quality flange bolts are essential for ensuring a secure, leak-proof joint. Engineered for demanding applications, these specialized fasteners are manufactured from a range of high-strength materials, including alloy and stainless steels, to withstand extreme pressures and temperatures. Each bolt is produced to meet rigorous international standards such as ASTM and ASME, guaranteeing precise dimensions and robust mechanical properties for maximum performance. Our commitment is to provide bolting solutions that offer unparalleled reliability and safety for your most critical piping systems. Secure your connections with flange bolts designed for ultimate strength and durability, providing the foundation for a resilient and long-lasting infrastructure.

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What is a Flange Bolt?

A flange bolt is a specialized fastener engineered to connect two flanges, serving as the essential tensioning component in a bolted flange joint. These bolts work in a set to exert a calculated clamping force, which compresses a gasket between the flange faces to create a secure, leak-free seal. Unlike standard bolts, flange bolts are manufactured from high-strength materials, such as carbon, alloy, and stainless steels, specifically chosen to withstand the high pressures, extreme temperatures, and corrosive environments common in industrial piping. Their production is governed by strict international standards, including ASTM and ASME, which dictate material composition, mechanical properties, and dimensional tolerances to ensure total reliability and safety. The integrity of the entire piping system fundamentally relies on the quality and proper specification of these critical fasteners.

What is a Flange Bolt Used For?

Joint Integrity: Applies Controlled Clamping Force To Compress A Gasket, Creating A High-Pressure, Leak-Proof Seal Between Flanges.
Load Bearing: Carries The Tensile Stresses Within A Piping System, Resisting Both Internal Pressure And External Mechanical Forces.
Assembly & Disassembly: Enables The Secure Mechanical Fastening Of Flange Connections, Allowing For Efficient Installation, Modification, And Removal Of System Components.
High-Stress Environments: Essential For Securing Flanges In Critical Applications, Including High-Temperature, High-Pressure, And Corrosive Service Conditions.

Why Choose Our Flange Bolt?

Our manufacturing philosophy is centered on engineering excellence and reliability. We combine advanced hot forging processes with precision thread rolling to produce flange bolts that consistently exceed strict industry standards for strength, safety, and long-term performance in critical applications.

Superior Material Integrity

Our flange bolts are forged from premium, certified alloy and stainless steels. This process refines the material's grain structure, resulting in superior tensile strength and fatigue resistance to withstand extreme pressure and system vibrations.

Precision Threading & Dimensions

Utilizing state-of-the-art thread-rolling equipment, we guarantee perfectly formed threads and exacting dimensional accuracy on every bolt. This ensures uniform torque application and consistent clamping force, which is essential for a reliable, leak-proof seal.

Exceptional Durability & Coatings

From high-strength carbon steel to corrosion-resistant stainless steel, our bolts are built for maximum service life. We offer a range of specialized coatings (e.g., PTFE, Zinc, HDG) to provide enhanced protection against corrosion, galling, and chemical exposure.

Full Compliance & Customization

We offer fully certified bolting solutions that meet or exceed stringent international standards like ASTM and ASME. We also provide tailored solutions based on your specific requirements, including custom lengths, unique materials, and specialized testing.

What Is The Difference Between a Bolt and a Flange Bolt?

Material Specification: Flange bolts are made from specific, high-strength alloy steels (e.g., ASTM A193 B7) designed for pressure vessels, while standard bolts are often lower-grade carbon steel.
Standards & Certification: Flange bolts must conform to strict industry standards (e.g., ASTM, ASME) and require full material traceability, which is not typical for common commercial bolts.
Design & Purpose: Flange bolts are specifically engineered for generating a high, uniform clamping force in flange joints, whereas general bolts are used for a wide range of less critical fastening tasks.
Thread Specification: Often utilize specific thread series (e.g., 8-UN) to better distribute stress in high-tension applications, unlike the general-purpose threads (UNC/UNF) on standard bolts.

How To Choose The Right Flange Bolt For Your Application?

Assess The Service Conditions: Determine the operating temperature and corrosive nature of the fluid/environment to select the correct bolt material grade (e.g., A193 B7, B8M, B16).
Determine Required Strength: Match the bolt's tensile strength to the flange pressure class and the calculated bolt load required to ensure a secure and reliable joint under pressure.
Consider The Gasket & Flange: Select bolts that can provide the necessary clamping force for the specified gasket type (e.g., spiral wound, RTJ) without damaging the flange faces.
Verify Standards & Dimensions: Ensure the bolt, nut, and washer dimensions and specifications comply with the project requirements and governing standards (e.g., ASME B18.2.1, B1.1).

Explore Our Flange Bolt Types

Hex Flange Bolts

The industry-standard choice, the hex flange bolt features a six-sided head for use with common tools and an integrated washer-like flange. This versatile one-piece design distributes the clamping load evenly, prevents damage to the mating surface, and simplifies assembly, making it ideal for a vast range of construction and mechanical applications.

Serrated Flange Bolts

Engineered for high-vibration environments, these bolts feature sharp locking serrations under the flange. When tightened, the serrations bite into the joint material, creating a powerful anti-loosening effect that eliminates the need for a separate lock washer. They are the ultimate solution for securing components in engines, pumps, and heavy machinery.

12-Point Flange Bolts

Designed for high-torque applications where space is limited, the 12-point (bi-hexagonal) head allows for greater tool contact and higher clamping force without risk of stripping. Its compact head profile is perfectly suited for performance engines, aerospace assemblies, and other critical joints where maximum reliability is essential.

Custom & Specialty Bolts

We provide flange bolts manufactured to your precise specifications, including unique dimensions, special material grades like titanium or high-strength alloys, and protective coatings. Our custom solutions ensure you have the perfect fastener to meet the unique challenges of high-temperature, high-pressure, or corrosive service environments.

NPS (inch)	No. of Bolts	Bolt Diameter (inch)	Stud Bolt Length (mm)	Heavy Hex Nut A/F (mm)
1/2"	4	1/2	65	22.2
1"	4	1/2	70	22.2
2"	4	1/2	75	22.2
3"	4	1/2	90	22.2
4"	8	5/8	90	27
6"	8	3/4	100	31.8
8"	8	3/4	115	31.8
10"	12	7/8	130	36.5
12"	12	7/8	140	36.5

The data above is for reference purposes for standard ASME B16.5 Class 150 Raised Face (RF) flanges. We manufacture a full range of stud bolts and nuts covering all pressure classes (150, 300, 600, 900, 1500, 2500) and various international material standards including ASTM A193 and A194. For complete technical data sheets or custom requirements, please contact our engineering team.

Key Application Industries of Flange Bolt

Marine & Offshore

Applied in structural connections and piping systems on ships, submarines, and offshore rigs. Bolts with superior corrosion resistance are critical for withstanding saltwater exposure, high-stress loads, and constant vibration.

Chemical Processing

Crucial for joining equipment and piping that handles aggressive and corrosive fluids. Stainless steel, nickel alloy, and specially coated bolts are selected to prevent degradation and ensure long-term.

Power Generation

Used to fasten high-temperature steam lines, boiler components, and turbine casings. Specialized heat-resistant bolts are vital for ensuring the safety and reliability of fossil fuel, nuclear, and renewable energy facilities.

Oil & Gas / Petrochemical

Essential for securing critical connections in pipelines, pressure vessels, and processing equipment. High-strength alloy bolts are required to maintain joint integrity under the extreme pressures and temperatures.

Why Choose Our Flange Bolt?

Superior Material Integrity: We source only premium-grade, certified alloys, ensuring our flange bolts offer exceptional tensile strength and corrosion resistance for the most demanding environments.
Precision Engineering For A Perfect Fit: Manufactured to exacting tolerances, our bolts feature precise threading and head geometry, guaranteeing a secure, leak-proof connection every time.
Enhanced Durability & Longevity: Specialized heat treatments and optional protective coatings provide superior resistance to vibration, fatigue, and environmental corrosion, extending the service life of your assembly.
Rigorous Performance Testing: Every batch undergoes strict testing for tensile strength, hardness, and dimensional accuracy, exceeding industry standards to guarantee reliability under pressure.
Extensive Inventory For Rapid Deployment: We maintain a vast stock of standard and specialty flange bolts, enabling us to fulfill orders quickly and minimize project downtime for our clients.

What Our Client Says

Understand from our clients what they say about doing business with us and the unique value addition we provide.

"The reliability of these flange bolts is exceptional. We use them in our high-vibration systems and have seen a significant reduction in maintenance callouts. The product quality gives us complete peace of mind, knowing our critical connections are secure and built to last."

David Kim

MAINTENANCE SUPERVISOR

"For our large-scale projects, quality consistency and on-time delivery are non-negotiable. This company excels at both. Their flange bolts always meet our stringent specifications, and their dependable logistics ensure our production timelines are never compromised."

Sarah Miller

SENIOR PROCUREMENT MANAGER

Comprehensive Guide to Flange Bolt

What is the difference between a flanged bolt and a hex bolt?

The primary difference is the integrated washer, or flange, built directly under the head of a flange bolt. This flange distributes the clamping load over a wider surface area, eliminating the need for a separate washer and simplifying the assembly process compared to a standard hex bolt.

Are flange bolts fully threaded?

Flange bolts are available in both fully threaded and partially threaded configurations. Fully threaded bolts are ideal for clamping force, while partially threaded bolts provide a smooth, unthreaded shank for applications requiring precise alignment or resistance to shear forces.

What are the advantages of flange bolts?

The main advantages include simplified and faster assembly by eliminating the need for a separate washer. The wide flange distributes clamping pressure to prevent damage to the joint surface and can feature serrations that provide excellent resistance to loosening caused by vibration.

How to unscrew flange bolts?

Flange bolts are unscrewed using standard tools like a socket wrench or spanner that fits the hexagonal head. Apply firm, counter-clockwise pressure to loosen it. For stubborn or serrated bolts, a breaker bar may be needed to provide additional leverage for the initial turn.

What are the common flange face types?

The three most common face types are Raised Face (RF), Flat Face (FF), and Ring-Type Joint (RTJ). Raised Face (RF) is the most versatile, featuring a small raised surface for the gasket. Flat Face (FF) requires a full-face gasket and is used for lower-pressure applications. Ring-Type Joint (RTJ) has a groove for a metal ring gasket, designed for high-pressure and high-temperature services.

When to use a flange bolt?

Use a flange bolt in applications where strong clamping force and resistance to vibration are critical, such as in automotive frames, engines, and heavy machinery. They are also ideal for assemblies with oversized holes or soft materials where load distribution is needed to prevent damage.

Can you reuse flange bolts?

For critical applications, it is not recommended to reuse flange bolts. Many are torque-to-yield, meaning they permanently stretch during the initial installation. Reusing them can lead to improper clamping force, and the locking serrations on the flange will be less effective a second time.

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Get the Right Flange Bolts for Your Application

With deep expertise in precision fastening, we are your trusted partner for all flange bolt requirements. From large-volume standard orders to specialized custom designs, our team delivers superior products that ensure safety and performance. Contact us today to get a quote and secure your project’s success.

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Frequently Ask Questions

Q: How does a serrated flange bolt work?

A: A serrated flange bolt features sharp ridges on the underside of its flange. When tightened, these serrations grip the mating surface, creating a locking effect that provides excellent resistance against loosening from vibration, making it ideal for securing components in dynamic machinery.

Q: What is a toilet flange bolt and why is it unique?

A: A toilet flange bolt is specifically designed to anchor a toilet to the floor. Typically made of corrosion-resistant brass, it has a flat, slotted head that slides into the toilet flange. Its unique design and material ensure a secure, long-lasting hold in a moist bathroom environment.

Q: Is it important to use a matching flange bolt and nut?

A:Yes, it is crucial to use a properly matched flange bolt and nut. Pairing components of the same grade, material, and thread type ensures consistent strength, proper thread engagement, and prevents issues like galvanic corrosion, guaranteeing a safe and reliable connection.

Q: Why is the flange bolt pattern critical for a secure seal?

A: The flange bolt pattern—which defines the number of bolts, their spacing, and the bolt circle diameter—is essential for distributing clamping force evenly across a gasket. A correct and uniformly tightened pattern prevents leaks and joint failure, especially in high-pressure systems.

Q: What is typically included in a flange bolt kit?

A: A flange bolt kit is a convenient package containing all the necessary fasteners for a specific application, like an automotive water pump or pipe connection. It usually includes the correct number and size of flange bolts along with matching flange nuts and sometimes gaskets, ensuring compatibility and saving time.

Q: What is the main advantage of a hex flange bolt?

A: The hex flange bolt is the most common type due to its versatility. Its six-sided head is compatible with standard tools, while the built-in flange distributes the clamping load without needing a separate washer. This simplifies assembly, reduces part count, and creates a strong, reliable joint.

Q: When should I use stainless steel flange bolts?

A: Stainless steel flange bolts are the best choice for applications exposed to moisture, chemicals, or corrosive environments. Their excellent resistance to rust makes them essential for marine equipment, food processing machinery, and outdoor structures where durability is paramount.

Q: What is a common flange bolt standard?

A: A common flange bolt standard that governs dimensions and tolerances is DIN 6921 or ISO 4162. For inch-based systems, ASME B18.2.1 is often referenced. Adhering to these standards ensures that the bolts are interchangeable and meet specific performance and quality requirements.

Top Flange Bolt Supplier in China

What is a Flange Bolt?

What is a Flange Bolt Used For?

Why Choose Our Flange Bolt?

Superior Material Integrity

Precision Threading & Dimensions

Exceptional Durability & Coatings

Full Compliance & Customization

What Is The Difference Between a Bolt and a Flange Bolt?

How To Choose The Right Flange Bolt For Your Application?

Explore Our Flange Bolt Types

Hex Flange Bolts

Serrated Flange Bolts

12-Point Flange Bolts

Custom & Specialty Bolts

Flange Bolt Size Specifications Chart

Key Application Industries of Flange Bolt

Marine & Offshore

Chemical Processing

Power Generation

Oil & Gas / Petrochemical

Why Choose Our Flange Bolt?

What Our Client Says

Comprehensive Guide to Flange Bolt

What is the difference between a flanged bolt and a hex bolt?

Are flange bolts fully threaded?

What are the advantages of flange bolts?

How to unscrew flange bolts?

What are the common flange face types?

When to use a flange bolt?

Can you reuse flange bolts?

Latest Blog Posts

Get the Right Flange Bolts for Your Application

Frequently Ask Questions

Q: How does a serrated flange bolt work?

Q: What is a toilet flange bolt and why is it unique?

Q: Is it important to use a matching flange bolt and nut?

Q: Why is the flange bolt pattern critical for a secure seal?

Q: What is typically included in a flange bolt kit?

Q: What is the main advantage of a hex flange bolt?

Q: When should I use stainless steel flange bolts?

Q: What is a common flange bolt standard?

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