ASME B16.5 vs B16.47 Choosing the Right Flange Standard for Your Project

Understanding ASME Flange Standards

When selecting flanges for piping systems, engineers often face the decision between ASME B16.5 and B16.47 standards. Understanding the key differences ensures proper specification and cost-effective design.

ASME B16.5 Overview

• Size Range: NPS 1/2 to NPS 24
• Pressure Classes: 150, 300, 600, 900, 1500, 2500
• 应用： General process piping, refineries, chemical plants
• Flange Types: Weld neck, slip-on, blind, socket weld, threaded, lap joint

ASME B16.47 Overview

• Size Range: NPS 26 to NPS 60
• Series: A 系列（MSS SP-44）和 B 系列（API 605）
• Pressure Classes: 150, 300, 400, 600, 900
• 应用： Large diameter pipelines, water transmission, oil and gas trunk lines

Key Differences

Feature	B16.5	B16.47
Size Range	Up to 24 inch	26 to 60 inch
Bolt Hole Count	Standard pattern	More bolts for larger sizes
Weight	Lighter	Heavier, reinforced design
Cost	Lower	Higher due to size

When to Use B16.5

• Process piping within refineries and chemical plants
• High-pressure applications requiring Class 1500 or 2500
• Standard industrial applications up to 24 inches
• Systems requiring多种 flange types

When to Use B16.47

• Large diameter water transmission lines
• Oil and gas trunk pipelines
• Pump discharge and suction nozzles over 24 inches
• Low-pressure, high-volume applications

Selection Considerations

1. Pipe size and pressure requirements
2. System design codes (ASME B31.1, B31.3, B31.4, B31.8)
3. Cost implications for large diameter systems
4. Availability and lead time
5. Interchangeability with existing systems

Choosing the correct standard ensures system integrity, regulatory compliance, and optimal project economics.