ASME B16.47
Standard Specification

ASME B16.47 Butterfly Valves

What ASME B16.47 requires for butterfly valves — applicability, key and testing requirements, the alternative standards, and compliant supply with full certification.

What does ASME B16.47 require for butterfly valves?

ASME B16.47 (Large Diameter Steel Flanges NPS 26 Through NPS 60 Metric/Inch Standard, American Society of Mechanical Engineers (ASME)) sets the design, material and testing requirements for butterfly valves in its scope. ASME B16.47 covers large-diameter steel flanges for pipe sizes NPS 26" through NPS 60" in pressure classes 75 through 900, filling the size gap above ASME B16.5 (which only covers up to NPS 24"). The standard provides two distinct flange dimension series: Series A (based on the former MSS SP-44 large pipe flange standard) and Series B (based on the former API 605 standard). The two series have different bolt hole patterns, flange dimensions, and weights, so Series A and Series B flanges are NOT interchangeable - this is critically important for procurement and field installation of large-bore pipeline and industrial valves.

Applicable Pressure Classes

Class 75 (Series A)Class 150Class 300Class 400Class 600Class 900

Key Requirements

  • Two non-interchangeable series: Series A (MSS SP-44 heritage) and Series B (API 605 heritage)
  • Pressure classes covered: Class 75 (Series A only), 150, 300, 400, 600, 900
  • Material groups aligned with ASME B16.5: Groups 1.1 through 2.3 for P-T ratings
  • Flange type: welding neck (most common for large bore), blind, slip-on, ring-type joint
  • Bolt holes: different count and diameter between Series A and B for same class/size - never mix series
  • Maximum size: NPS 60" Class 300 in Series A; NPS 60" Class 150 in Series B
  • All dimensions in both inch and metric (dual dimensioning)
  • Material marking: class, size, material designation, heat number, and standard (B16.47) on flange face

Testing Requirements

  • Dimensional inspection per ASME B16.47 Series A or B tables
  • Hydrostatic shell test at 1.5× rated pressure for flanged valves
  • PMI verification for alloy steel and stainless steel flanges

Alternative Standards for Butterfly Valves

Other standards that also govern butterfly valves — useful for spec cross-acceptance.

API 607Fire Test for Quarter-Turn Valves and Valves Equipped with Nonmetallic SeatsASME B16.34Valves - Flanged, Threaded, and Welding EndAPI 598Valve Inspection and TestingAPI 609Butterfly Valves: Double-Flanged, Lug- and Wafer-TypeISO 15848Measurement, Test, and Qualification Procedures for Fugitive Emissions - Industrial ValvesBS 6755Testing of Valves - Production Pressure Testing and Fire Type Testing RequirementsISO 5208Industrial Valves - Pressure Testing of Metallic ValvesISO 10497Testing of Valves - Fire Type-Testing RequirementsEN 593Industrial Valves - Metallic Butterfly ValvesNACE MR0103Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refinery Environments
Reviewed by Valve Standards Engineering, Vajra Industrial SolutionsDiscipline: Industrial Valve Standards & ComplianceLast reviewed: 20 June 2026

Connected Engineering

Standards
API 6DASME B16.34
Products
Ball ValvesGate ValvesButterfly ValvesCheck Valves
Comparisons
Gate vs Ball ValveBall vs Butterfly Valve
Tools
Pressure Class Converter

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Relevant Products
Vajra Butterfly Valves

Engineering references

ASME B16.47 full standardScope, requirements & documentationVajra Butterfly ValvesFull range, specs & standardsStandards Applicability MatrixWhich standard governs which type