ASA 150 Flange Standard – Dimensions, Pressure Rating & Applications

The ASA 150 flange is one of the most widely used flange standards across industrial piping systems in India and globally. Whether you’re designing water pipelines, HVAC systems, or general process connections — ASA 150 is a go-to standard due to its reliable dimensions, moderate pressure rating, and broad material compatibility.

In this guide, we break down the full ASA 150 flange standard, including dimensions, pressure specs, materials, and real-world usage in Indian industries.

What Is an ASA 150 Flange?

ASA 150 flange stands for “American Standards Association Class 150 flange.” Though the term "ASA" has been replaced by ANSI in modern standards, "ASA 150" is still widely used in engineering drawings and procurement.

ASA 150 Flange Means:

• Pressure Rating: 150 PSI (approx. 10 bar)
• Standard: ANSI/ASME B16.5 (Class 150)
• Connection Type: Weld neck, blind, slip-on, threaded, socket weld
• Face Types: Raised Face (RF), Flat Face (FF)

ASA 150 flanges are suitable for low-pressure, non-critical flow systems across commercial and industrial setups.

ASA 150 Flange Dimensions (Key Parameters)

Standard Dimensional Values for ASA 150 Flanges:

Note: Dimensions may vary slightly by manufacturer. Always cross-check with ANSI B16.5 tables.

Download the standard ASA 150 flange chart (PDF)

ASA 150 = ANSI Class 150: Why the Name Confusion?

The "ASA" designation is legacy terminology. It originally stood for the American Standards Association — the body responsible for early industrial piping standards.

Today, ASA has been replaced by ANSI and the standards are published under ASME B16.5.

Still widely used in India: "ASA 150" and "ANSI 150" are often used interchangeably in procurement and design documents.

Types of ASA 150 Flanges

✅ All these types can conform to ASA 150 pressure rating.

Material Options for ASA 150 Flanges

The standard does not limit material — but pressure ratings depend on temperature and material used.

Most Common Materials:

• Mild Steel (MS)
• Cast Iron
• Stainless Steel (SS 304 / SS 316)
• Carbon Steel
• Forged Steel
• PVC (non-metallic use)

Note: Stainless ASA 150 flanges (304/316) are preferred for chemical and corrosive environments.

Applications of ASA 150 Flanges in India

• Water pipelines (municipal, industrial)
• HVAC systems
• Firefighting networks
• Low-pressure steam lines
• Food, pharma, and dairy plants (SS grade)
• Storage tanks and utility lines

Limitations of ASA 150 Flanges

• Not suitable for high-pressure (above 10 bar) pipelines
• Not ideal for high-temperature or thermal cycling environments
• Can corrode if wrong material (e.g., MS) is used in aggressive media

For such use-cases, consider Class 300, 600 or 900 flanges.

FAQ – ASA 150 Flange

Q1. Is ASA 150 flange same as ANSI 150?

Yes, both refer to the same dimensions and standards. ASA is an older term still used informally.

Q2. What is the pressure rating of ASA 150 flange?

150 PSI, or approx. 10.5 bar at room temperature.

Q3. What is the drilling pattern of ASA 150 flange?

It follows ANSI B16.5 Class 150 drilling — bolt circle, hole count and diameter.

Q4. What size range is available in ASA 150?

Standard sizes range from 1/2 inch to 24 inch NB (DN15–DN600).

Q5. What is the difference between ASA 150 and Class 300?

Class 300 has higher pressure and thickness ratings. ASA 150 is for low-pressure systems.

Conclusion

The ASA 150 flange remains a trusted industry standard in India for low-pressure, general-purpose pipeline connections. With consistent sizing, moderate pressure tolerance, and wide material compatibility — it’s the most frequently used flange type in utility and process systems.

Just remember: check pressure, size, and material compatibility before procurement.

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