ASME B16.5-2020 PDF

Full title and description

ASME B16.5-2020 — 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 (including weld‑neck, slip‑on, socket‑weld, threaded, lap‑joint and blind flanges) for NPS 1/2 through NPS 24, and includes both metric and U.S. customary unit data where applicable.

Abstract

ASME B16.5-2020 provides industry requirements and recommendations for flanges and flanged fittings made from cast or forged materials (with certain blind and reducing flanges allowed from plate). It establishes class/rating designations (150, 300, 400, 600, 900, 1500 and 2500 where applicable), pressure‑temperature ratings, dimensional tolerances, marking and test requirements, and guidance on flange bolting, gaskets and flange joints. The standard is intended to be used with other ASME piping standards (for example the B16 family and B31 piping codes).

General information

• Status: Superseded / placed on stabilized maintenance by a later ASME B16.5 edition (ASME lists B16.5-2025 as the later product edition).
• Publication date: Edition year 2020 (ASME product record / vendor listings show the 2020 edition; some publication records note an ASME product publish date in late January 2021).
• Publisher: American Society of Mechanical Engineers (ASME).
• ICS / categories: Pipeline components and pipelines — ICS 23.040 (metal fittings / flanges are typically classified under 23.040 and subcategories for fittings).
• Edition / version: 2020 edition (commonly cited as ASME B16.5-2020).
• Number of pages: Approximately 250 pages (commonly listed in vendor/product records).

Scope

Limited to flanges and flanged fittings made from cast or forged materials (with blind and certain reducing flanges permitted from cast, forged or plate). Covers rating classes 150–1500 for NPS 1/2–24 and class 2500 for NPS 1/2–12, plus flanged fittings in designated classes and the non‑mandatory appendix for some higher classes; presents both metric and U.S. customary dimensions where applicable, with bolt diameters/bolt‑hole dimensions commonly given in inch units. Intended for use alongside other ASME B16 standards and the ASME Boiler & Pressure Vessel and B31 piping codes.

Key topics and requirements

• Pressure–temperature ratings for flange classes and materials (tables of allowable pressures vs. temperature by class and material).
• Material specifications and allowable materials for cast and forged flanges and fittings.
• Dimensional requirements and tolerances (flange face types, bolt circle, number/size of bolts, raised face/RTJ details, hub dimensions, NPS sizing 1/2–24).
• Marking, identification and material traceability requirements.
• Testing and inspection guidance for flange components and flange joints.
• Recommendations and requirements for flange bolting, gasket selection, joint assembly and joint integrity.
• Non‑mandatory appendices covering additional guidance and acknowledgement of customary‑unit only provisions for certain high‑pressure fittings.

Typical use and users

Used by flange and fitting manufacturers, piping engineers, plant designers, procurement/specification teams, inspection/test personnel, maintenance and reliability engineers, and regulatory bodies. Typical applications include process plants, power generation, petrochemical/refining, oil & gas piping systems, and general industrial piping where standardized flange dimensions, ratings and joint practices are required.

Related standards

Commonly used together with other ASME B16 series standards (for example B16.1, B16.9, B16.11, B16.20) and with ASME B31 piping codes; also references and relates to material and test standards such as ASTM specifications, MSS SP‑55 surface finish/inspection guidance, and ISO/EN flange standards where appropriate (non‑exhaustive examples cited in product notes).

Keywords

ASME B16.5, pipe flanges, flanged fittings, NPS 1/2–24, pressure‑temperature ratings, flange dimensions, flange tolerances, flange bolting, flange gaskets, metric/inch, piping standards, ASME B16 series.

FAQ

Q: What is this standard?

A: ASME B16.5-2020 is the ASME standard that defines dimensional, material, rating, marking and testing requirements for pipe flanges and flanged fittings (NPS 1/2 through NPS 24).

Q: What does it cover?

A: It covers pressure‑temperature ratings, materials, dimensional tolerances, marking, testing and joint-related recommendations (bolting, gaskets, assembly), and specifies flange types and rating classes used in industrial piping systems.

Q: Who typically uses it?

A: Manufacturers, piping and mechanical engineers, procurement/specification teams, inspection/test and maintenance personnel in industries such as petrochemical, power generation, oil & gas, and general process and plant engineering.

Q: Is it current or superseded?

A: The 2020 edition is an official ASME edition (commonly cited as B16.5‑2020) but ASME product records show a later B16.5 edition in the ASME product list (B16.5‑2025). The 2020 edition is therefore placed on stabilized maintenance and industry users should confirm whether their jurisdiction or purchaser requires the 2020 text or the most recent ASME B16.5 edition.

Q: Is it part of a series?

A: Yes — it is part of the ASME B16 series of piping component standards and is intended to be used with related ASME standards (for example the B31 piping codes and other B16 component standards).

Q: What are the key keywords?

A: Flanges, flanged fittings, pressure‑temperature ratings, NPS (nominal pipe size), flange classes (150–2500), dimensions, tolerances, bolting, gaskets, ASME B16.5.