Standard Specification

ASME B16.5 Flange Standard — Covers NPS 1/2 to 24 Pipe Flanges

Complete ASME B16.5 flange standard specification guide: NPS 1/2 to 24, Class 150-2500, pressure-temp ratings, facings (RF, RTJ, FF), materials. Quote in 30 min.

Standard Overview & Scope

ASME B16.5 is the globally dominant standard for steel pipe flanges and flanged fittings from NPS 1/2 through NPS 24. It defines strict dimensional interchangeability, pressure-temperature rating tables across Material Groups 1.1 through 3.17, and face finish standards.

Official Standard Scope

ASME B16.5 covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings in sizes NPS 1/2 through NPS 24 metric/inch standard.

Covered Size RangeNPS 1/2 to NPS 24 (DN 15 to DN 600)
Pressure Ratings / ClassesClass 150, Class 300, Class 400, Class 600, Class 900, Class 1500, Class 2500

ASME vs Metric Specification Conversion

Specification ParameterASME Standard SpecificationEuropean / Metric Equivalent
Size ScopeNPS 1/2" to 24"DN 15 to DN 600
Pressure SystemClass 150 to 2500PN 2.5 to PN 400
Facing StandardRF (1.6mm / 6.3mm), RTJType A, B, C, D, E, F
Gasket StandardASME B16.20 (Spiral Wound / RTJ)EN 1514 / DIN 2690

Related Standard & Material Guides

ASME B16.47 Large DiameterWeld Neck FlangeCarbon Steel Flanges

Standard Specification FAQs

Q: What is the size boundary between ASME B16.5 and ASME B16.47?

A: ASME B16.5 covers pipe sizes up to NPS 24. For flanges NPS 26 and larger, ASME B16.47 Series A (MSS SP-44) or Series B (API 605) applies.

Q: What raised face height is required for Class 150 vs Class 600?

A: For Class 150 and 300, ASME B16.5 specifies a 1.6 mm (0.06 in.) Raised Face. For Class 400, 600, 900, 1500, and 2500, a 6.4 mm (0.25 in.) Raised Face is standard.

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