Stainless Steel Flange

Stainless Steel Flange: A Complete Guide

Stainless steel flanges play a crucial role as connecting components in pipelines, valves, pumps, and other equipment. It’s essential to select the appropriate material, size, and standard of flanges based on specific application environments.

What is a Stainless Steel Flange?

What is a Stainless Steel Flange

A stainless steel flange is a common pipe fitting consisting of two interconnected ring-shaped parts fastened together with bolts. Its primary functions include connecting, sealing, and supporting pipelines. Its structure can be adjusted according to different requirements and is widely used in industries such as petroleum, chemical, food processing, pharmaceuticals, and more.


What are the Technical Characteristics of Stainless Steel Flanges?

What are the Technical Characteristics of Stainless Steel Flanges

Stainless steel flanges are typically made from austenitic stainless steel (such as 304 and 316L), duplex stainless steel (such as 2205), or super austenitic stainless steel (such as 904L). These stainless steel materials exhibit excellent resistance to chemical media corrosion and atmospheric corrosion, as well as high strength and good toughness.

Design Structure: According to international standards such as ASME B16.5 and EN 1092-1, stainless steel flanges come in various types, including flat flanges, butt weld neck flanges, blind flanges, etc., with different pressure ratings and size specifications to adapt to different operating conditions.

Welding Performance: After welding with pipelines, the mechanical properties and corrosion resistance in the weld zone of stainless steel flanges are close to the base metal level, ensuring the safety and reliability of the entire system.


What Types of Connections do Stainless Steel Flanges have?

What Types of Connections do Stainless Steel Flanges have?

Classification by Structural Form:

Stainless steel flanges can be classified into several types based on their structural forms, including slip-on flange, weld neck flange, blind flange, socket weld flange, and threaded pipe flange. Among these, slip-on flanges are suitable for smaller-diameter pipe connections, while weld neck flanges are used for larger-diameter pipe connections. Socket welding flanges are appropriate for connecting cast iron pipes and non-ferrous metal pipes, whereas threaded pipe flanges are ideal for connecting large-diameter pipes.

Classification by Sealing Surface Form:

Stainless steel flanges can be categorized into several types based on the form of their sealing surfaces, including raised face flanges, ring joint flanges, and tongue and groove flanges. Among these, raised face flanges are suitable for connecting pipelines under normal or low pressure, while ring joint flanges are used for high-pressure pipelines. Tongue and groove flanges are ideal for pipeline connections requiring higher levels of sealing.

Classification by Manufacturing Materials:

Stainless steel flanges can be classified into several types based on the manufacturing materials, including 304 stainless steel flanges, 316 stainless steel flanges, and 321 stainless steel flanges. Among these, 304 stainless steel flanges offer good corrosion resistance and machinability, while 316 stainless steel flanges provide even better corrosion resistance and higher strength. 321 stainless steel flanges excel in high-temperature resistance and corrosion resistance.


What are the Advantages of Stainless Steel Flanges?

What are the Advantages of Stainless Steel Flanges

Stainless steel flanges, also known as acid-resistant stainless steel flanges, have an exceptionally smooth surface that resists oxidation and damage from the atmosphere. Here are some main advantages of stainless steel flanges:

Excellent Corrosion Resistance:

Stainless steel flanges boast outstanding resistance to corrosion, making them suitable for various corrosive mediums and reducing the risk of leakage, ensuring reliable performance.

High-Temperature and High-Pressure Resistance:

Stainless steel flanges are capable of withstanding high temperatures and pressures in demanding work environments, ensuring stability and safety at pipeline connections

Long Lifetime:

Stainless steel flanges boast flawlessly smooth surfaces, showcasing remarkable resistance to physical and chemical corrosion, as well as exceptional durability against wear and tear. This results in a long lifespan, ensuring reliable performance over time.


What are the Common Dimensions of Stainless Steel Flanges?

What are the Common Dimensions of Stainless Steel Flanges

The standard dimensions of stainless steel flanges generally include the outer diameter, bore diameter, number, and diameter of holes for bolts. Common international standards include ASME, DIN, and JIS, representing American, German, and Japanese standards, respectively.

Important dimensions of stainless steel flanges include:

Outer Diameter

Ranging from 1/2 inch to 48 inches with various specifications, with the most common sizes being from 1/2 inch to 24 inches for general engineering projects, while sizes exceeding 24 inches are typically used in special projects and equipment.

Bore Diameter

Generally corresponding to the outer diameter of the flange.

Number and Diameter of Bolt Holes: Crucial for flange installation and connection.


What Applications are Stainless Steel Flanges?

What Applications are Stainless Steel Flanges

Petrochemical Industry

Used in pipeline systems for transporting various corrosive fluids, such as material pipelines, reactors, heat exchangers, etc., in refineries and chemical plants.

Power Industry

Applied in critical areas such as boilers, steam pipelines, and cooling water systems, ensuring safe and reliable energy transmission.

Nuclear Energy Industry

Used in the construction of main loop systems, auxiliary systems, and containment systems within nuclear islands.

Food and Pharmaceutical Industry

Due to their good hygiene performance, stainless steel flanges are commonly used in cleanroom pipelines, production equipment, tanks, etc.

Marine Engineering and Shipbuilding

Widely used in ship propulsion systems, compartment piping systems, and offshore platform facilities due to their excellent resistance to seawater corrosion.


What are the Manufacturing Processes of Stainless Steel Flanges?



Material Selection

Material Selection

High-quality stainless steel castings or forgings that meet standards such as ASTM A182 and ASTM A351 are chosen as raw materials.

Production Process

Production Process

Flange bodies are formed through forging, casting, or stamping methods, ensuring uniform internal structure of the material.



Precision machining of the flange surface is conducted to ensure product tolerances and dimensions, meeting strict sealing requirements.

Heat Treatment Process

Heat Treatment Process

Depending on the material of the flange, appropriate solution treatment, stabilization treatment, or aging treatment is carried out to adjust the material’s microstructure and optimize its performance.

Surface Treatment and Inspection

Surface Treatment and Inspection

Surface passivation, polishing, or further corrosion protection is applied to the flange surface to enhance corrosion resistance. Non-destructive testing and mechanical performance testing are strictly conducted to further inspect the flange.




What is the difference between 304 Flange and 316 Flange?

What is the difference between 304 Flange and 316 Flange

304 stainless steel contains 18% chromium and 8% nickel, making it a common stainless steel material with good corrosion resistance and weldability. On the other hand, 316 stainless steel contains 16% chromium, 10% nickel, and 2% molybdenum, providing better corrosion resistance and high-temperature performance.

While 304 stainless steel flanges can meet general usage requirements in most cases, they may encounter corrosion or deformation issues in harsh environments such as strong acids, alkalis, high temperatures, and high pressures. In contrast, 316 stainless steel flanges can better withstand these harsh working conditions and are widely used in chemical, marine, medical, and other fields.


What is the difference between ANSI flanges and DIN flanges?

What is the difference between ANSI flanges and DIN flanges

They are named differently based on pressure: ANSI flanges are designated by class numbers such as class 150, class 300, etc., while DIN flanges are typically labeled with PN1.6MPa, PN2.5MPa, and so on. Additionally, they are named differently based on size: ANSI flanges are referred to in inches (e.g., 1″, 2″, 3″, etc.) while DIN flanges are denoted by DN (e.g., DN100, DN200, DN300).


What are the Causes of flange leakage?

What are the Causes of flange leakage

In industrial production, flanges are subjected to corrosion, erosion from the medium, temperature, pressure, vibration, etc., which can inevitably lead to leakage problems. Factors such as machining errors in sealing surfaces, aging of sealing components, and improper fastening can easily cause leakage in flanges.


What solutions for the flange leakage?

What solutions for the flange leakage

If the flange connection is not properly installed or the pipe fitting is not vertical, it needs to be readjusted and tightened.

Check if there is excessive vibration or impact in the pipeline. After repairing the issue, reinstall the flange connection.

For improperly welded seams, they need to be rewelded or ground and resealed. Replace the gasket.


What kinds of welding methods for stainless steel flanges?

What kinds of welding methods for stainless steel flanges

The commonly used welding methods include manual arc welding, TIG welding, and submerged arc welding. Manual arc welding is suitable for small welded parts, while TIG welding and submerged arc welding are suitable for large welded parts.


What Techniques are requested for welding stainless steel flanges?

What Techniques are requested for welding stainless steel flanges

It’s necessary to understand the chemical composition of the welding material, as well as factors such as thermal deformation and stress deformation during welding. Secondly, it’s important to organize and manage welding work reasonably to ensure welding quality and progress. Finally, it’s essential to master the specific operating techniques of different welding methods to ensure that welding work achieves the desired results.




Stainless steel flanges are widely used across various industries. It’s essential to choose the right flange based on the specific working environment. If you need stainless steel flanges, feel free to contact us.


Scroll to Top