ASME B16.5-2025 PDF

Full title and description

ASME B16.5-2025 — Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24, Metric/Inch Standard. This standard specifies pressure–temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings; it also includes recommendations for flange bolting, gaskets and flange joints for a wide range of pressure classes and flange types.

Abstract

ASME B16.5-2025 provides dimensional, material and performance requirements for flanges and flanged fittings in nominal pipe sizes NPS 1/2 through NPS 24, covering pressure classes commonly used in industry (including 150, 300, 400, 600, 900, 1500 and 2500 where applicable). The standard presents tables of pressure–temperature ratings for materials, detailed flange and gasket dimensional data in both metric and U.S. customary units, and requirements for marking, testing and traceability.

General information

• Status: Current / Active (placed on stabilized maintenance by ASME).
• Publication date: 30 May 2025 (ASME edition year 2025).
• Publisher: American Society of Mechanical Engineers (ASME).
• ICS / categories: Fluid systems and components; piping and pipe fittings — typically classified within ICS 23.040 (pipes, fittings and flanges) and related pressure‑equipment categories.
• Edition / version: ASME B16.5 — 2025 edition (supersedes ASME B16.5:2020).
• Number of pages: 274 pages (typical published length for the 2025 edition).

Scope

Defines standardized dimensions, materials, pressure–temperature ratings, tolerances, marking, testing and methods of designating openings for pipe flanges and flanged fittings in nominal pipe sizes NPS 1/2 through NPS 24 (metric and inch units). Covers flange types such as weld‑neck, slip‑on, socket‑weld, threaded, lap‑joint and blind flanges; includes flanged fittings and guidance on bolting and gasket selection. Flanges larger than NPS 24 are outside the scope (see ASME B16.47).

Key topics and requirements

• Pressure–temperature rating tables for common material groups and pressure classes (150–2500 where applicable).
• Dimensional data and tolerances for flange types (bolt circle, bore, thickness, raised face/RTJ/flat face details).
• Material groups and allowable materials for cast, forged and plate constructions for flanges and blind/reducing flanges.
• Marking, traceability and identification requirements (manufacturer, material spec, size, class, heat number and B16.5 designation).
• Recommendations and requirements for flange bolting, gasket types (including RTJ and spiral‑wound), and flange joint assembly/testing (hydrostatic/pressure tests).
• Tables in both metric and U.S. customary units with bolt diameters and bolt‑hole sizes typically expressed in inches where noted.

Typical use and users

Used by designers, engineers, manufacturers, inspection and QA personnel, procurement/specification writers, and plant operators in oil & gas, petrochemical, power generation, chemical processing, water/wastewater and other industries where pressure‑containing piping and equipment employ standardized flanged connections. Also used by standards bodies and purchasing organizations to define acceptable flange/gasket/bolting combinations.

Related standards

Commonly used alongside other ASME B16 series documents (for example ASME B16.47 for large diameter flanges, ASME B16.20 for metallic gaskets, ASME B16.34 for valves, and applicable ASME B31 piping codes). It is also referenced by industry material and testing standards (ASTM material specifications, bolting standards, and national piping codes).

Keywords

ASME B16.5, pipe flanges, flanged fittings, NPS 1/2–24, pressure–temperature ratings, flange dimensions, gasket types, flange bolting, raised face, RTJ, blind flange, flanged fittings, pressure class 150/300/600/900/1500/2500.

FAQ

Q: What is this standard?

A: ASME B16.5-2025 is the ASME standard that sets dimensional, material and performance requirements for pipe flanges and flanged fittings in nominal pipe sizes NPS 1/2 through NPS 24.

Q: What does it cover?

A: It covers pressure–temperature ratings, flange and fitting dimensions and tolerances, materials, marking and traceability, testing requirements, and guidance on bolting and gasket selection for a range of pressure classes and flange types. Metric and U.S. customary units are provided where appropriate.

Q: Who typically uses it?

A: Mechanical and piping engineers, flange and gasket manufacturers, procurement/specification teams, QA/inspection personnel, and plant maintenance/operations staff in industries such as oil & gas, petrochemical, power, and water/wastewater.

Q: Is it current or superseded?

A: The 2025 edition is current and supersedes the prior ASME B16.5:2020 edition; ASME indicates the product is active and on stabilized maintenance so amendments or reaffirmations will be managed through ASME's maintenance process.

Q: Is it part of a series?

A: Yes — B16.5 is part of the ASME B16 series of dimensional and pressure‑component standards (B16.1–B16.49 etc.), and it is intended to be used alongside other ASME piping and pressure‑equipment codes such as the B31 piping codes and the Boiler & Pressure Vessel Code where applicable.

Q: What are the key keywords?

A: Flange, flanged fitting, NPS, pressure class, gasket, bolting, raised face, ring‑type joint (RTJ), weld‑neck, slip‑on, socket‑weld, threaded, lap‑joint, blind flange, pressure–temperature rating.