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321 Stainless Steel Hex Head Bolts M8 M10 M12 M16, High Temperature Resistant Metric Hex Bolts for Chemical, Boiler and Exhaust Systems

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Product Description

321 Stainless Steel Hex Head Bolts M8 M10 M12 M16

Our 321 Stainless Steel Hex Head Bolts are premium metric fasteners designed for high-temperature, corrosion-resistant, and industrial applications. Compared with 304 stainless steel, 321 stainless steel offers better high-temperature stress rupture performance and improved mechanical stability under elevated temperatures.

These bolts are especially suitable for environments where heat resistance, oxidation resistance, and resistance to intergranular corrosion are required. They are widely used in chemical equipment, petroleum machinery, boilers, heat exchangers, exhaust systems, furnace components, diesel engine mufflers, and other demanding industrial applications.

Available in common metric sizes such as M8, M10, M12, and M16, these hex head bolts provide reliable fastening performance for high-temperature and corrosive working conditions.


Key Features

  • Made from 321 stainless steel for excellent high-temperature performance.
  • Better heat resistance than 304 stainless steel in suitable high-temperature applications.
  • Good resistance to intergranular corrosion due to titanium-stabilized stainless steel structure.
  • Hex head design allows easy installation with standard wrench, spanner, or socket tools.
  • Metric thread sizes available in M8, M10, M12, M16 and other sizes.
  • Suitable for harsh industrial environments, including chemical, petroleum, boiler, and exhaust systems.
  • Strong mechanical properties under elevated temperature conditions.
  • Durable stainless steel finish with good oxidation and corrosion resistance.

Product Specifications

Item Description
Product Name 321 Stainless Steel Hex Head Bolt
Material Stainless Steel 321
Head Type Hex Head
Thread Type Metric Thread
Common Sizes M8, M10, M12, M16
Surface Finish Plain Stainless Steel
Standard Metric / Custom Standard Available
Application High-temperature equipment, chemical machinery, boiler systems, exhaust systems
Customization Size, length, thread pitch, packaging, drawing-based production

Size Chart

Unit: mm

Size Pitch Width Across Flats S Head Thickness K
M8 1.25 13 5.3
M10 1.5 16 6.8
M12 1.75 18 7.5
M16 2.0 24 10

Additional sizes such as M4, M5, M6, M14, M18, M20, M22, M24, M27, M30, M33, and M36 can also be supplied according to customer requirements.


Why Choose 321 Stainless Steel?

321 stainless steel is a titanium-stabilized stainless steel. It is commonly used in applications where parts must maintain good mechanical properties under high-temperature conditions.

Material Main Feature Recommended Use
304 Stainless Steel Good general corrosion resistance General machinery, indoor and outdoor use
316 Stainless Steel Better corrosion resistance, especially in marine environments Marine, coastal, chemical, humid environments
321 Stainless Steel Better high-temperature stability and resistance to intergranular corrosion Heat exchangers, boilers, exhaust pipes, furnace parts

For applications involving heat, exhaust gas, chemical equipment, or thermal cycling, 321 stainless steel bolts are a reliable choice.


Common Industry Applications

Industry / Equipment Typical Use
Chemical Industry Equipment exposed to corrosive and high-temperature environments
Coal Industry Open-air machinery and heat-resistant assemblies
Petroleum Industry Oil and gas equipment, pipelines, combustion systems
Boiler Systems Boiler housing, pressure vessels, and heating components
Heat Exchangers High-temperature fastening and structural connection
Engine Exhaust Systems Exhaust pipes and muffler components
Furnace Equipment Heating furnace components and spiral welded tube assemblies
Diesel Engines Muffler parts and exhaust-related components
Building Materials Industry Heat-resistant equipment parts
Expansion Joints High-temperature pipeline connection systems

Typical Application Examples

These 321 stainless steel hex head bolts are commonly used in:

No. Application
1 Oil exhaust gas combustion pipelines
2 Engine exhaust pipes
3 Boiler housings
4 Heat exchangers
5 Heating furnace components
6 Muffler parts for diesel engines
7 Boiler pressure vessels
8 Chemical trucks
9 Expansion joints
10 Spiral welded tubes for furnace pipes and dryers

Product Advantages

The 321 Stainless Steel Hex Head Bolt is designed for demanding industrial environments where ordinary stainless steel fasteners may not provide enough high-temperature stability.

The hex head structure offers excellent torque transmission and easy installation. The stainless steel body provides corrosion resistance, while the 321 grade material helps improve performance in heat-resistant applications.

These bolts are suitable for manufacturers, maintenance teams, engineering contractors, and industrial equipment suppliers who need reliable fasteners for high-temperature and corrosion-resistant working conditions.


Installation Notes

Before placing an order, please confirm the following details:

Required Information Example
Bolt Size M8, M10, M12, M16
Length 20mm, 30mm, 50mm, 80mm, customized
Thread Type Full thread or partial thread
Material 321 stainless steel
Standard DIN, ISO, GB, ANSI, or custom drawing
Quantity Small quantity or bulk order
Application Environment High temperature, chemical, outdoor, boiler, exhaust system

For high-temperature or pressure-related equipment, please confirm the working temperature, load requirement, and applicable industry standard before use.


Matching Products

For better assembly performance, these bolts can be supplied together with:

Product Function
321 Stainless Steel Hex Nuts Matching threaded fastening
321 Stainless Steel Flat Washers Load distribution and surface protection
321 Stainless Steel Spring Washers Anti-loosening support
Stainless Steel Custom Fasteners Special industrial assembly requirements

FAQ

Q1: What is 321 stainless steel?

321 stainless steel is a titanium-stabilized stainless steel with good high-temperature performance and resistance to intergranular corrosion. It is commonly used in heat-resistant industrial applications.

Q2: What is the difference between 321 and 304 stainless steel bolts?

304 stainless steel is suitable for general corrosion-resistant applications. 321 stainless steel has better high-temperature stability and is more suitable for boilers, exhaust systems, heat exchangers, furnace parts, and chemical equipment.

Q3: What sizes are available?

Common sizes include M8, M10, M12, and M16. Other metric sizes from M4 to M36 can also be supplied according to customer requirements.

Q4: Are these bolts suitable for high-temperature applications?

Yes. 321 stainless steel is commonly used for high-temperature equipment and heat-resistant parts. It performs better than 304 stainless steel in many elevated-temperature environments.

Q5: Can these bolts be used in chemical equipment?

Yes. These bolts are suitable for chemical machinery and equipment requiring corrosion resistance and heat resistance.

Q6: Are these bolts fully threaded or partially threaded?

Both fully threaded and partially threaded versions can be supplied depending on the size, length, and customer requirements.

Q7: Can you customize the length?

Yes. Bolt length can be customized according to drawings, samples, or specific project requirements.

Q8: What tools are used to install these bolts?

They can be installed with standard wrenches, spanners, or socket tools matching the hex head size.

Q9: Can these bolts be used with 304 or 316 stainless steel nuts?

They can be assembled if the thread size and pitch match. However, for high-temperature or special industrial environments, using matching 321 stainless steel nuts and washers is recommended.

Q10: Do you support bulk orders?

Yes. Bulk orders, OEM packaging, customized specifications, and drawing-based production are available.


Short Product Summary

321 Stainless Steel Hex Head Bolts M8 M10 M12 M16 are high-temperature resistant metric fasteners designed for chemical, petroleum, boiler, heat exchanger, exhaust system, furnace, and industrial equipment applications. Compared with 304 stainless steel, 321 stainless steel provides better high-temperature mechanical performance and improved resistance to intergranular corrosion, making it suitable for demanding heat-resistant fastening applications.

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International Standard Certification

Complies with major global standards such as ISO/DIN/GB/ANSI/JIS

Full range of products covered

Standard parts + customized parts, one-stop solution for all your fastening needs

High-precision manufacturing process

Tolerance control far exceeds industry standards, ranging from 4.8 to 12.9 grades.

1-on-1 Customization Service

Customization based on provided drawings/samples/working conditions; rapid prototyping and mass production delivery.

What Our Customers Say

Trusted by global manufacturers for fastener solutions

BrightBuild Hardware Ltd.
BrightBuild Hardware Ltd.
United Kingdom
XZ FASTENER has been a reliable supplier for our construction fastener orders. The bolts and nuts arrived with good surface finish, accurate sizes, and strong packaging. Communication was clear from quotation to shipment.
Andina Industrial Supply S.A.
Andina Industrial Supply S.A.
Colombia
We ordered different sizes of hex bolts, washers, and nuts. XZ FASTENER helped us confirm the specifications and provided a practical shipping solution. The quality was stable and suitable for our local market.
Falcon Engineering Supplies
Falcon Engineering Supplies
United Arab Emirates
XZ FASTENER understands export business very well. They prepared the quotation, packing details, and documents professionally. The products matched our requirements and the delivery was well organized.
Pacific Bolt & Nut Trading
Pacific Bolt & Nut Trading
Philippines
We appreciate their fast response and flexible support. Even though our order included mixed sizes and different surface treatments, XZ FASTENER handled everything carefully. Good partner for wholesale fasteners.
Monterra Hardware Group
Monterra Hardware Group
Mexico
The galvanized fasteners we received were clean, well packed, and consistent in thread quality. XZ FASTENER gave us clear product photos before shipment, which helped us feel confident about the order.
Eastern Mechanical Parts Co.
Eastern Mechanical Parts Co.
Saudi Arabia
We purchased high-strength bolts and nuts for machinery maintenance. The products were strong, accurate, and packed in export cartons. XZ FASTENER is a serious factory supplier.
GlobalFix Distributors
GlobalFix Distributors
South Africa
XZ FASTENER provides competitive pricing without ignoring quality. Their team helped us compare materials, grades, and surface treatments before confirming the order. This saved us time and reduced purchasing risk.
Nova Tools & Fasteners
Nova Tools & Fasteners
Chile
Our customers care about stable quality and good appearance. The fasteners from XZ FASTENER met our expectations. The cartons, labels, and product sorting were also handled professionally.
Delta Construction Supply
Delta Construction Supply
Kenya
We needed fasteners for construction use in several sizes. XZ FASTENER responded quickly and gave practical advice on packing and shipment. The goods arrived in good condition.
Atlas Industrial Trading
Atlas Industrial Trading
Turkey
The product quality was consistent across different batches. Threads were clean, dimensions were accurate, and the surface treatment looked good. We are satisfied with XZ FASTENER’s factory support.
RedRock Hardware Importers
RedRock Hardware Importers
Australia
XZ FASTENER helped us source both standard and customized fasteners. Their team checked drawings carefully and confirmed details before production. This is very important for B2B buyers like us.
PrimeFix
PrimeFix
Canada
We like working with suppliers who communicate clearly. XZ FASTENER gave us photos, weight information, packing details, and shipping suggestions. The whole process was smooth.

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Globally Compliant Standards

All XZ products comply with major global industrial standards and are adaptable to the specifications of different countries and regions.

ISO

International Organization for Standardization (ISO) standards

DIN

German Industrial Standards

GB

Chinese National Standards

ANSI

American National Standards

JIS

Japanese Industrial Standards

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