---
title: Custom Stainless Steel Flanges Manufacturer
date: 2025-07-21T17:36:40Z
modified: 2026-08-06T14:59:34Z
permalink: "https://www.longanflange.com/custom-stainless-steel-flanges-manufacturer-china/"
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timestamp: 2026-08-06T14:59:34Z
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---
# Custom Stainless Steel Flanges Manufacturer
Your trusted supplier & factory for high-quality, corrosion-resistant stainless steel flanges. We focus exclusively on stainless steel, delivering globally with certified quality and speed. From standard to 4000mm large-diameter SS flanges, we forge your solution
- API & PED 4.3 Certified
- Comply with ASME, ANSI, DIN, JIS, and GOST standards
- OEM & Drawing-Based Production
- Fast Global Delivery
- Full Traceability
Dapatkan Penawaran Harga Flensa SS Kustom Anda
## View OUR Customization Capability
LONGAN FLANGE specializes in producing non-standard, highly customized forged stainless steel fanges tailored to your specific needs. From concept to creation, we turn unique challenges into practical solutions. Contact us to start your custom large flange project.
## From Your Drawing to a Flawless Forged SS Flange
Our strength lies in turning your unique requirements of stainless steel flanges into reality. As an OEM and drawing-based manufacturer, we collaborate closely with your engineering team to ensure every detail—from material grade to facing finish—is perfectly executed
## Consultation & Drawing Review
Submit your technical drawings or specifications. Our experts review for feasibility and optimization.
## Material Confirmation
We confirm the precise stainless steel grade required for your application and provide material test certificates.
## Precision Forging & Machining
Utilizing advanced equipment to forge and machine your flanges to exact dimensions and tolerances under ASME, DIN, or JIS standards.
## Rigorous Quality Control
Each flange undergoes stringent inspection, ensuring it meets our quality standards and your certification needs (e.g., ISO9001, TS).
## Packaging & Delivery
Professionally packed and delivered to your site with full traceability, meeting your project timeline.
## what’s your Stainless steel flange custom need?
Mulailah Kustomisasi Anda
## Custom Options For SS Flanges
Below are some of the most common parameters and requirements for custom SS flange manufacturing. If you don’t see the specific requirement you’re looking for, don’t hesitate to reach out. With years of experience in custom flange production, we have the expertise to turn your specifications into reality.
### 1. Flange Type:
- **Pressure Vessel Flange:**
Plate Flange, Slip-on Flange, Weld Neck Flange, Socket Weld Flange,
Threaded Flange, Lap Joint Flange, Blind Flange
- **Vacuum Flange**
- **Instrument Flange**
- **Filter Flange**
- **Soft Connection Flange**
- **Large Diameter Flange**
- **Custom Flange (Please specify in notes)**
### 2. Standard
- ASME / ANSI
- DIN
- JIS
- Russian Standard (GOST)
- Other (Please specify)
### 3. Diameter
Flange diameter up to 4000 mm available
### 4. Pressure Class / Rating
LONGAN FLANGE provides custom-forged stainless steel flanges built to your exact specs. No matter how unique or oversized, we deliver practical solutions fast. Start your custom project with us today.
- **ASME/ANSI:** Class 150, Class 300, Class 400, Class 600, Class 900, Class 1500, Class 2500
- **DIN/EN/GOST (PN/Ру):** PN 6, PN 10, PN 16, PN 25, PN 40, PN 63, PN 100
- **JIS:** 5K, 10K, 16K, 20K, 30K
- etc.
### 5. Material Grade
As specialists in stainless steel, we can supply various grades. Select from common options below or specify your requirement. 304 / 304L, 316 / 316L, 321 / 321H, 347 / 347H, etc.
### 6. Required Certifications
API Certificate, PED 4.3 Certificate, TS Certificate, ISO 9001 (Quality Management), ISO 14001 (Environmental Management), ISO 45001 (Occupational Health & Safety), etc.
## Customize Your Stainless Steel Flange Now!
## Expert Material Selection Guide:
Choosing the Optimal Stainless Steel for Your Application
Common Type: 304/304L Stainless Steel Flanges
This is an austenitic chromium-nickel stainless steel, composed of approximately 18% chromium and 8% nickel, making it the most widely used grade. The “L” in the grade stands for **Low Carbon** (less than 0.03%), which significantly improves weldability and effectively prevents the risk of **intergranular corrosion**. We typically supply **dual-certified 304/304L** material, which offers the strength of 304 with the superior weldability of 304L.
- **When to choose 304/304L Stainless Steel Flanges?**
304/304L is the most cost-effective choice when your application does not involve high concentrations of chlorides, strong acids, or extreme temperatures.
- **Typical Applications of 304/304L Stainless Steel Flanges**
General industrial piping, food processing, architectural structures, and some chemical vessels.
- **LONGAN Expert Advice**
If your custom flange requires significant welding, always specify 304L or dual-certified 304/304L to ensure the long-term durability of the welded areas.
Corrosion-Resistant Upgrade Type: 316/316L (UNS S31600 / S31603) Stainless Steel Flanges
316/316L builds upon the 304 base by adding a key element: **Molybdenum**. The addition of approximately 2-3% molybdenum creates a more stable structure, resulting in a quantum leap in corrosion resistance, particularly against **chloride pitting resistance**. Like 304L, the low-carbon nature of 316L is designed to optimize welding performance.
- **When to choose 316/316L Stainless Steel Flanges?**
316/316L is the essential choice when your flange will be used in marine environments, come into contact with chloride-containing fluids, or be used for corrosive media in wastewater treatment and chemical industries.
- **Typical Applications of 316/316L Stainless Steel Flanges**
Marine engineering equipment, chemical pipelines and vessels, wastewater treatment systems, and pharmaceutical equipment.
- **LONGAN Expert Advice:**
Do not take chances. In a chloride environment, using 304/304L may not show immediate problems, but it is highly susceptible to pitting corrosion, which can lead to equipment failure. To ensure safety and long-term reliability, invest in 316/316L.
High-Temperature Solution: Stabilized Stainless Steels (321/321H & 347/347H) Flange
When operating temperatures exceed 425°C (800°F), the carbon in standard stainless steel can combine with chromium to form **chromium carbides**, reducing corrosion resistance. Stabilized stainless steels were developed to solve this.**321 (UNS S32100):** By adding **Titanium (Ti)** as a stabilizing element, the titanium preferentially combines with carbon, protecting the chromium and allowing it to maintain its corrosion resistance at high temperatures.**347 (UNS S34700):** This grade uses **Niobium (Nb)** and **Tantalum (Ta)** for stabilization. Its high-temperature performance and resistance to intergranular corrosion are often superior to 321.
- **When to choose (321/321H & 347/347H) Stainless Steel Flanges**
For high-temperature operating environments, especially for equipment that requires welding and cannot be solution-annealed afterward.
- **Typical Applications of (321/321H & 347/347H) Stainless Steel Flanges**
Petroleum refining equipment, aircraft engine exhaust manifolds, boiler superheaters, and expansion joints.
- **Expert Advice:**
While 321 and 347 are more costly, they are critical for ensuring equipment longevity and safety in high-temperature applications. If you are unsure whether your project requires a stabilized grade, contact our technical team immediately. **Provide your operating temperature, media, and pressure, and we will offer a professional material assessment.**
This is an austenitic chromium-nickel stainless steel, composed of approximately 18% chromium and 8% nickel, making it the most widely used grade. The “L” in the grade stands for **Low Carbon** (less than 0.03%), which significantly improves weldability and effectively prevents the risk of **intergranular corrosion**. We typically supply **dual-certified 304/304L** material, which offers the strength of 304 with the superior weldability of 304L.
- **When to choose 304/304L Stainless Steel Flanges?**
304/304L is the most cost-effective choice when your application does not involve high concentrations of chlorides, strong acids, or extreme temperatures.
- **Typical Applications of 304/304L Stainless Steel Flanges**
General industrial piping, food processing, architectural structures, and some chemical vessels.
- **LONGAN Expert Advice**
If your custom flange requires significant welding, always specify 304L or dual-certified 304/304L to ensure the long-term durability of the welded areas.
316/316L builds upon the 304 base by adding a key element: **Molybdenum**. The addition of approximately 2-3% molybdenum creates a more stable structure, resulting in a quantum leap in corrosion resistance, particularly against **chloride pitting resistance**. Like 304L, the low-carbon nature of 316L is designed to optimize welding performance.
- **When to choose 316/316L Stainless Steel Flanges?**
316/316L is the essential choice when your flange will be used in marine environments, come into contact with chloride-containing fluids, or be used for corrosive media in wastewater treatment and chemical industries.
- **Typical Applications of 316/316L Stainless Steel Flanges**
Marine engineering equipment, chemical pipelines and vessels, wastewater treatment systems, and pharmaceutical equipment.
- **LONGAN Expert Advice:**
Do not take chances. In a chloride environment, using 304/304L may not show immediate problems, but it is highly susceptible to pitting corrosion, which can lead to equipment failure. To ensure safety and long-term reliability, invest in 316/316L.
When operating temperatures exceed 425°C (800°F), the carbon in standard stainless steel can combine with chromium to form **chromium carbides**, reducing corrosion resistance. Stabilized stainless steels were developed to solve this.**321 (UNS S32100):** By adding **Titanium (Ti)** as a stabilizing element, the titanium preferentially combines with carbon, protecting the chromium and allowing it to maintain its corrosion resistance at high temperatures.**347 (UNS S34700):** This grade uses **Niobium (Nb)** and **Tantalum (Ta)** for stabilization. Its high-temperature performance and resistance to intergranular corrosion are often superior to 321.
- **When to choose (321/321H & 347/347H) Stainless Steel Flanges**
For high-temperature operating environments, especially for equipment that requires welding and cannot be solution-annealed afterward.
- **Typical Applications of (321/321H & 347/347H) Stainless Steel Flanges**
Petroleum refining equipment, aircraft engine exhaust manifolds, boiler superheaters, and expansion joints.
- **Expert Advice:**
While 321 and 347 are more costly, they are critical for ensuring equipment longevity and safety in high-temperature applications. If you are unsure whether your project requires a stabilized grade, contact our technical team immediately. **Provide your operating temperature, media, and pressure, and we will offer a professional material assessment.**
### Proven Solutions for Demanding Global Projects
Case Study 1
Case Study 2
Case Study 3
Case Study 4
Case Study 5
### Boiler feedwater piping system for a thermal power plant in Poland
- **Challenge**
The project required flanges that could endure constant high temperatures and pressures while resisting corrosion and creep, with mandatory, fully traceable safety certifications.
- **Our Solution**
We supplied custom **347H stainless steel Weld Neck flanges**, a specialized material ideal for high-temperature service.
- **Key Feature**
The inclusion of **Niobium (Nb)** in the 347H grade provides superior strength and prevents intergranular corrosion at elevated temperatures.
- **Compliance & Safety**
The flanges were delivered in full compliance with **ASME B16.5 standards** and included **EN 10204 3.1 material traceability certificates**, ensuring a fully documented and reliable solution..
### A high-pressure chemical reactor vessel for a client in Turkey
- **Challenge**
The project required a reactor flange capable of withstanding extreme and cyclical high pressures, which had to be manufactured to specific proprietary drawings that standard products could not meet
- **Our Solution**
Leveraging our OEM capabilities, we manufactured a **custom-forged 316L stainless steel pressure vessel flange** precisely to the client’s unique specifications.
- **Certification & Quality**
The flange was produced under **ISO 9001** quality system and certified to the **Pressure Equipment Directive (PED 4.3).**
- **Verification**
Flanges underwent dimensional and material verification, to confirm its absolute integrity and suitability.
### High-pressure pipeline for a chemical processing plant in Vietnam.
- **Challenge**
A chemical plant in Vietnam needed flanges for a high-pressure line. It had to provide superior resistance against aggressive acidic corrosion while also guaranteeing reliable structural integrity under constant high pressure.
- **Our Solution**
We supplied a custom solution of 316L stainless steel Weld Neck flanges that offer excellent defense against corrosion, making it ideal for pipeline’s long-term durability.
- **Compliance & Safety**
The entire batch of flanges was certified to PED 4.3, ensuring full traceability and quality.
- **Guaranteed Performance Outcome**
The result for the client was a fully compliant and documented solution that ensures both leak-free performance and long-term operational integrity.
### Wellhead assembly for a US-based oil extraction project
- **Challenge**
A US-based oil extraction project required wellhead assembly flanges facing a dual challenge: absolute adherence to API standards and a need for rapid delivery to avoid costly operational delays and maintain project momentum.
- **Our Solution**
We responded by supplying high-strength, API-certified forged stainless steel flanges. Ensuring a superior grain structure, enhanced mechanical strength and fatigue resistance.
- **Quality Assurance & Documentation**
Each component was delivered with comprehensive material traceability reports, full history of the material, and verified for API specifications.
### Large-scale water treatment facility in Kazakhstan
- **Challenge**
A large-scale water treatment facility in Kazakhstan required custom flanges of a large diameter for its main pipeline connections, a need that standard suppliers could not meet.
- **Our Solution**
Our direct solution was to manufacture and deliver custom-built 3500mm (3.5-meter) plate flanges, engineered precisely to the project’s unique infrastructure specifications.
- **Manufacturing Capability**
The project leveraged our specialized production capabilities, highlighted our capacity in large diameters stainless steel flange manufacturing.
- **Successful Delivery**
The on-time delivery of flanges demonstrated our proven expertise in major, non-standard manufacturing projects..
### Boiler feedwater piping system for a thermal power plant in Poland
- **Challenge**
The project required flanges that could endure constant high temperatures and pressures while resisting corrosion and creep, with mandatory, fully traceable safety certifications.
- **Our Solution**
We supplied custom **347H stainless steel Weld Neck flanges**, a specialized material ideal for high-temperature service.
- **Key Feature**
The inclusion of **Niobium (Nb)** in the 347H grade provides superior strength and prevents intergranular corrosion at elevated temperatures.
- **Compliance & Safety**
The flanges were delivered in full compliance with **ASME B16.5 standards** and included **EN 10204 3.1 material traceability certificates**, ensuring a fully documented and reliable solution..
### A high-pressure chemical reactor vessel for a client in Turkey
- **Challenge**
The project required a reactor flange capable of withstanding extreme and cyclical high pressures, which had to be manufactured to specific proprietary drawings that standard products could not meet
- **Our Solution**
Leveraging our OEM capabilities, we manufactured a **custom-forged 316L stainless steel pressure vessel flange** precisely to the client’s unique specifications.
- **Certification & Quality**
The flange was produced under **ISO 9001** quality system and certified to the **Pressure Equipment Directive (PED 4.3).**
- **Verification**
Flanges underwent dimensional and material verification, to confirm its absolute integrity and suitability.
### High-pressure pipeline for a chemical processing plant in Vietnam.
- **Challenge**
A chemical plant in Vietnam needed flanges for a high-pressure line. It had to provide superior resistance against aggressive acidic corrosion while also guaranteeing reliable structural integrity under constant high pressure.
- **Our Solution**
We supplied a custom solution of 316L stainless steel Weld Neck flanges that offer excellent defense against corrosion, making it ideal for pipeline’s long-term durability.
- **Compliance & Safety**
The entire batch of flanges was certified to PED 4.3, ensuring full traceability and quality.
- **Guaranteed Performance Outcome**
The result for the client was a fully compliant and documented solution that ensures both leak-free performance and long-term operational integrity.
### Wellhead assembly for a US-based oil extraction project
- **Challenge**
A US-based oil extraction project required wellhead assembly flanges facing a dual challenge: absolute adherence to API standards and a need for rapid delivery to avoid costly operational delays and maintain project momentum.
- **Our Solution**
We responded by supplying high-strength, API-certified forged stainless steel flanges. Ensuring a superior grain structure, enhanced mechanical strength and fatigue resistance.
- **Quality Assurance & Documentation**
Each component was delivered with comprehensive material traceability reports, full history of the material, and verified for API specifications.
### Large-scale water treatment facility in Kazakhstan
- **Challenge**
A large-scale water treatment facility in Kazakhstan required custom flanges of a large diameter for its main pipeline connections, a need that standard suppliers could not meet.
- **Our Solution**
Our direct solution was to manufacture and deliver custom-built 3500mm (3.5-meter) plate flanges, engineered precisely to the project’s unique infrastructure specifications.
- **Manufacturing Capability**
The project leveraged our specialized production capabilities, highlighted our capacity in large diameters stainless steel flange manufacturing.
- **Successful Delivery**
The on-time delivery of flanges demonstrated our proven expertise in major, non-standard manufacturing projects..
## get your custom SS flange solution Right now!
Minta Penawaran Gratis
## About LONGAN – Your Trusted SS Flange Factory
## Expert Pipe Flange Manufacturers: Your Partner for Custom Solutions
https://www.youtube.com/watch?v=hjUaVAy-\_dk&pp=ygUNbG9uZ2FuIGZsYW5nZQ%3D%3D
In a market of generalists, LONGAN stands apart. We are not just another manufacturer; we are dedicated specialists in **ss flanges** and custom stainless steel solutions. This singular focus ensures every **ss pipe flange** we produce benefits from our concentrated expertise, advanced equipment, and commitment to quality.
Our reputation is built on solving complex challenges, especially in manufacturing precision-forged, extra-large **industrial pipe flanges**. With full in-house capabilities, we deliver flanges up to 4 meters in diameter for heavy-duty applications in oil & gas, petrochemical, and power generation. Our commitment to scale and innovation is proven by our factory’s capabilities:
Tell Us Your Project>>>
### 2011
Founded with Decades of expertise
### 160+
High-Precision Machining Centers
### 150+
Advanced Testing Equipment units
### 60+
Technical Patents
- **For Your Engineers:**
We are a reliable extension of your design team, transforming intricate drawings into precision-forged reality. We guarantee every stainless steel flange dimension is perfect for your critical pipework flanges systems.
- **For Your Procurement Managers:**
We provide absolute peace of mind. Our comprehensive suite of globally recognized certifications (API, PED 4.3, ISO) proves our quality and ensures our products meet the strictest project specifications, reducing your risk.
- **For Your Distributors & Timelines:**
We guarantee short product delivery times. Our robust company scale and streamlined logistics network ensure reliable production capacity and schedules you can depend on.
## Exhibition
We actively participate in major industry exhibitions worldwide to connect with engineers, distributors, and project buyers face-to-face. Visit our booth to explore our custom flange solutions and discuss your project needs directly with our team.
CONTACT LONGAN FLANGE
Your Custom Flange Questions, Answered
What is your primary specialization?
At **LONGAN**, our primary specialization is the exclusive manufacturing of stainless steel flanges. This focus on ss flanges, including a wide range of ss pipe flange types, allows us to be true experts in stainless steel properties, applications, and quality control
What is the largest flange diameter you can produce?
**LONGAN** are experts in large-diameter flanges. We can manufacture a heavy-duty industrial pipe flange up to 4000mm in diameter, making us a key supplier for large-scale engineering, mining, and waterworks projects
What information do I need to provide for an accurate quote?
For the most accurate and fastest quote, please provide a technical drawing. If not available, please specify the flange type, required stainless steel flange dimensions (including size and pressure class), standard (e.g., ASME, DIN), stainless steel grade, and any required certifications.
How do you support clients with urgent delivery needs?
We understand that project timelines are critical. Our streamlined production planning and strong logistics partnerships enable **LONGAN** to offer fast delivery and help you avoid costly delays.
Which international standards and certifications can you meet?
As leading pipe flange manufacturers, **LONGAN** manufactures according to all major international standards, including ASME, DIN, and JIS. This ensures every product from **LONGAN** is reliable for critical pipework flanges systems globally and meets the stringent requirements of any engineering project.
At **LONGAN**, our primary specialization is the exclusive manufacturing of stainless steel flanges. This focus on ss flanges, including a wide range of ss pipe flange types, allows us to be true experts in stainless steel properties, applications, and quality control**LONGAN** are experts in large-diameter flanges. We can manufacture a heavy-duty industrial pipe flange up to 4000mm in diameter, making us a key supplier for large-scale engineering, mining, and waterworks projectsFor the most accurate and fastest quote, please provide a technical drawing. If not available, please specify the flange type, required stainless steel flange dimensions (including size and pressure class), standard (e.g., ASME, DIN), stainless steel grade, and any required certifications.We understand that project timelines are critical. Our streamlined production planning and strong logistics partnerships enable **LONGAN** to offer fast delivery and help you avoid costly delays.As leading pipe flange manufacturers, **LONGAN** manufactures according to all major international standards, including ASME, DIN, and JIS. This ensures every product from **LONGAN** is reliable for critical pipework flanges systems globally and meets the stringent requirements of any engineering project.
**Email:** mft@longanflange.com**Phone:** +86-15727821389Ready to Start Your Customization? Partner with LONGAN – Your Trusted Stainless Steel Flange Factory.