Are you familiar with the ASME B16.5 and ASME B16.47 standards for steel pipe flanges? If not, let's delve into these crucial standards that govern the design, dimensions, and materials of flanges used in piping systems.
This article has been refreshed to reflect current ASME flange selection practices commonly followed in petrochemical, power, water, and industrial piping projects.
ASME B16.5: Covering the Basics
The ASME B16.5 standard is your go-to guide for Steel Pipe Flanges and Flanged Fittings ranging from NPS 1/2 through NPS 24, available in pressure classes 150 to 2500. This comprehensive standard addresses everything from pressure-temperature ratings to materials, dimensions, tolerances, marking, testing, and designating openings for pipe flanges and flanged fittings.
ASME B16.5 is one of the most widely used flange standards in industrial piping systems.
Key Components of ASME B16.5:
- Pressure-temperature ratings
- Materials and dimensions
- Tolerances and marking
- Testing procedures
Two essential flange types, weld neck flanges, and blind flanges, find widespread use in piping systems, all within the realm of ASME B16.5.
Check ASME B16.5 compliant steel pipe flanges in our Flanges Collection
ASME B16.47: Extending the Horizon
What about larger sizes beyond NPS 24? That's where ASME B16.47 steps in. While ASME B16.5 covers up to 24 inches, ASME B16.47 takes the baton for sizes ranging from NPS 26 through NPS 60.
Differentiating ASME B16.47 Series A and Series B:
- Series A flanges are thicker, heavier, and stronger, suitable for withstanding greater external loading.
- Series B flanges, on the other hand, are lighter, less expensive, and require more but smaller fasteners.
- Series A includes weld neck, blind, and ring type joint (RTJ) flanges, while Series B primarily focuses on weld neck and blind flanges.
Choosing the Right Flange
The choice between Series A and Series B depends on various factors, including project requirements, budget constraints, and design considerations. Generally, Series A flanges are preferred for new pipelines or critical applications, while Series B flanges are more popular for refurbishments or non-critical designs.
What About API 605 Flanges?
API 605 flanges were historically used for large-diameter piping systems. Today, they have largely been replaced by ASME B16.47 standards. However, API 605 dimensions are still encountered in legacy piping systems, making standard comparison important during maintenance or replacement work.
ASME Flange Standards Comparison
| Standard |
Size Range |
Typical Use |
Notes |
| ASME B16.5 |
NPS 1/2 – 24 |
General piping |
Most widely used |
| ASME B16.47 Series A |
NPS 26 – 60 |
New pipelines |
Heavier, higher strength |
| ASME B16.47 Series B |
NPS 26 – 60 |
Retrofit projects |
Lighter, compact design |
| API 605 |
Large OD |
Legacy systems |
Mostly replaced |
Conclusion: Making Informed Decisions
Understanding the difference between ASME B16.5 and ASME B16.47 is crucial for ensuring the integrity and efficiency of piping systems. Whether you're selecting standard weld neck, slip-on, or blind flanges, knowing the standards empowers you to make informed decisions based on your specific needs.
For a detailed comparison of flange sizes and dimensions, refer to the documents provided below:
- Flange Dimensions as per ASME B16.5 standard
- Flange Dimensions as per ASME B16.47 Series A standard
- Flange Dimensions as per ASME B16.47 Series B standard
In conclusion, ASME B16.5 and ASME B16.47 standards play a vital role in the world of piping, ensuring safety, reliability, and compatibility across various industrial applications.
Frequently Asked Questions
1. What is the main difference between ASME B16.5 and ASME B16.47 flanges?
ASME B16.5 covers flanges up to NPS 24, while ASME B16.47 applies to large-diameter flanges from NPS 26 to 60.
2. What is the difference between ASME B16.47 Series A and Series B?
Series A flanges are heavier and designed for higher loads, while Series B flanges are lighter and used where space or cost constraints apply.
3. Are API 605 flanges still used today?
API 605 flanges are mostly found in older systems. Modern projects typically use ASME B16.47 standards.
4. Can ASME B16.5 and ASME B16.47 flanges be interchanged?
No. Differences in dimensions, bolt patterns, and pressure ratings require careful evaluation before substitution.
