Why Stainless Steel Flanges Are Still the Backbone of Industrial Piping in 2026

Author : Riddhi Siddhi | Published On : 13 May 2026

High performance connection components and stainless steel flanges are enjoying a strong and steady increase in industrial piping market demand in 2026. In India and all over the world, engineers and procurement teams are not simply buying flanges; they are selecting them carefully, especially with the major expansion of infrastructure projects that are taking place in the oil & gas, petrochemical, water treatment, and pharmaceutical industries. It is no longer possible to deny corrosion resistance, pressure ratings and compliance certifications.

If you are looking for a trusted stainless steel flange manufacturer in India, Riddhi Siddhi Metal Impex has been supplying quality flanges to industries across the country and overseas. With a strong manufacturing base and a focus on precision, the company offers a wide range, from standard stainless steel flanges to EIL approved flanges for critical project requirements. Explore the range and get in touch to buy now at competitive factory prices.

What Is a Stainless Steel Flange and Why Does It Matter?

A flange is a mechanical component used to connect pipes, valves, pumps, and other equipment in a piping system. It creates a leak-proof joint, usually bolted together with a gasket in between for sealing. Among all materials used in flange manufacturing, stainless steel remains one of the most widely specified and for good reason.

Stainless steel flanges offer a combination of properties that most other materials simply cannot match in demanding industrial environments:

• Corrosion resistance — especially critical in chemical processing, marine applications, and water treatment

• High temperature and pressure tolerance — suitable for steam lines, refineries, and high-pressure systems

• Hygiene compliance — grades like SS 316L are mandatory in food, pharma, and dairy industries

• Long service life — low maintenance, minimal replacement cycles, and better total cost over time

Common Types of Stainless Steel Flanges: A Quick Reference

Understanding which type of flange your project needs is the first step in getting the specification right. Here is a practical overview of the most commonly used types:

 

SS 304 vs SS 316 vs SS 316L — Which Grade Should You Choose?

One of the most common questions buyers ask is which stainless steel grade to specify. Here is a practical breakdown:

If your piping system handles seawater, chlorides, or aggressive chemicals, SS 316 or 316L is almost always the right call over SS 304 Flange. For general utility lines, 304 is cost-effective and perfectly sufficient.

What Is an EIL Approved Flange — and When Do You Need One?

EIL stands for Engineers India Limited — a Government of India enterprise and one of the most respected technical consultancy and engineering organizations in the country. EIL sets material specifications, quality standards, and inspection protocols for large infrastructure and energy projects in India, particularly those in the oil & gas, refinery, and petrochemical sectors.

An EIL approved flange means the product has been manufactured, tested, and certified in accordance with EIL's material specifications and quality requirements. EIL typically mandates these approvals for government-backed projects, PSU (Public Sector Undertaking) contracts, and large EPC (Engineering, Procurement, and Construction) projects.

When is EIL approval mandatory?

• Projects executed by HPCL, BPCL, IOC, ONGC, and similar PSUs

• Refinery expansion and greenfield refinery projects

• Cross-country pipeline projects under EIL's project management

• Petrochemical complexes requiring third-party material inspection

Without proper EIL certification, your materials will not pass the inspection gate at such projects — making it a procurement-critical requirement, not just a preference.

EIL Approved vs Standard Flanges: Key Differences

Pressure Classes and International Standards: What to Know Before Ordering

Flanges are rated by pressure class. The most widely followed standard globally — and in India — is ASME B16.5, which defines the following pressure-temperature classes:

Class 150 → 300 → 600 → 900 → 1500 → 2500

Higher the class number, higher the allowable pressure rating. For most utility and process lines, Class 150 and 300 cover a very wide range of applications. Critical service lines in refineries and high-pressure steam systems often go up to Class 600, 900, or beyond.

Other relevant standards you may encounter:

• ASME B16.47 — large diameter flanges (NPS 26 to 60)

• MSS SP-44 — pipeline flanges

• EN 1092-1 — European standard (PN ratings)

• IS 6392 — Indian Standard for pipe flanges

Always confirm the applicable standard and pressure class with your project engineer before placing an order. A mismatch in pressure class can cause serious safety issues.

Industries That Rely on Stainless Steel Flanges

In 2025, the need for SS flanges spans nearly all the industrial sectors in India:

• Oil & Gas and Refining — May be the biggest consumer segment. Thousands of flanges are installed on each of the refinery and petrochemical plants throughout process lines, utilities and instrumentation connections.

• Pharmaceuticals and Biotech — SS 316L high-purity flange smooth bore finishes and FDA / GMP compliance are critical parameters in the pharmaceutical manufacturing processes. 

• Food and Beverage — Hygienic design, crevice-free connections, and SS 316L material are standard requirements for dairy plants, breweries, and food processing units.

• Power Generation — Flanges for conventional high temperature, high pressure thermal power plants, as well as renewable energy infrastructure (biogas, hydrogen) are rated for high temperatures and pressures.

• Water Treatment and Desalination — SS flanges are more resistant to chloride than carbon steel, and are the preferred material over carbon steel for water infrastructure projects.

• Chemical Processing — A wide variety of media, ranging from mild to aggressive, will require careful material selection and may result in the use of SS 316 or higher alloy flanges.

How to Specify a Flange Correctly: A Practical Checklist

When placing an inquiry or purchase order, make sure you have the following information ready:

1. Material grade — SS 304, 316, 316L, 321, etc.

2. Flange type — Weld neck, slip-on, blind, socket weld, etc.

3. Size (NPS / DN) — Nominal pipe size in inches or DN in mm

4. Pressure class — 150#, 300#, 600#, 900#, 1500#, 2500#

5. Facing type — RF (Raised Face), FF (Flat Face), RTJ (Ring Type Joint)

6. Applicable standard — ASME B16.5, B16.47, EN 1092, IS 6392

7. Special requirements — EIL approval, NACE compliance, IBR approval, TPI, PMI, etc.

8. Quantity and delivery schedule

Having this information ready dramatically speeds up quotation turnaround and reduces the risk of specification errors.

Frequently Asked Questions

Q: What is the difference between a raised face (RF) and a flat face (FF) flange? A raised face flange has a small raised area around the bore where the gasket sits, concentrating the bolt load on a smaller area for a better seal. A flat face flange has no raised section and uses a full-face gasket — typically specified when connecting to cast iron or non-metallic flanges to avoid flange distortion.

Q: Can stainless steel flanges be used in high-temperature applications? Yes. SS 316 retains good mechanical strength up to around 870°C in intermittent service, and SS 321 (titanium-stabilized) is specifically designed for sustained high-temperature use. The exact temperature limits depend on the grade, pressure class, and applicable code.

Final Thoughts

Selecting the right stainless steel flange isn't just about the procurement, it's about the safety of the system, maintenance costs, and regulations. From a standard industrial project to a large EPC contract with EIL approved flanges, if the material grade, pressure class and certification are correct from the beginning, a significant amount of time and money will be saved in the process.

Riddhi Siddhi Metal Impex produces and distributes an extensive collection of stainless steel flanges that comply with the requirements of the project and/or EIL along with proper documentation, traceability, and can be supplied according to the need of the project. Contact the group directly for questions, specifications or bulk orders; they are able to handle technical questions and offer service to your project timeline.