Standards by Component

Flange

Flange dimension, rating, and face standards for process and waterworks piping.

Primary Standards
ASME B16.5ASME B16.47ASME B16.36EN 1092-1JIS B2220

ASME B16.5

ASME

Pipe Flanges and Flanged Fittings

ASME B16.5 is the foundational standard for pipe flanges and flanged fittings globally. It establishes the comprehensive dimensional and pressure-temperature rating system for flanges up to 24 inches. This standard ensures that flanges from different manufacturers are completely interchangeable, facilitating safe and modular construction of high-pressure piping systems.

FlangeDimensionPressure-Temperature RatingMaterial

ASME B16.47 Series A

ASME

Large Diameter Steel Flanges — Series A (MSS SP-44 basis)

ASME B16.47 Series A specifies the dimensions and ratings for large diameter steel flanges (NPS 26 to NPS 60). Originally based on the MSS SP-44 standard, Series A flanges are heavier, thicker, and designed for rigorous pipeline and heavy industrial applications.

FlangeNPS 26–60Class 75–900Dimension

ASME B16.47 Series B

ASME

Large Diameter Steel Flanges — Series B (API 605 basis)

ASME B16.47 Series B specifies dimensions and ratings for large diameter flanges (NPS 26 to NPS 60). Originally based on API 605, Series B flanges are engineered to be lighter and more compact, requiring more bolts of smaller diameter to maintain the gasket seal.

FlangeNPS 26–60Lighter SeriesDimension

ASME B16.36

ASME

Orifice Flanges

ASME B16.36 specifies dimensions and tolerances for orifice flanges. These are specialized flanges equipped with pressure tap holes used in conjunction with orifice plates to measure the flow rate of liquids and gases in piping systems.

FlangeOrifice TapsClass 300–2500Dimension

ASME B16.1

ASME

Cast Iron Pipe Flanges and Flanged Fittings

ASME B16.1 covers the dimensional and pressure-temperature rating requirements for gray cast iron pipe flanges and flanged fittings. It is predominantly used in low-pressure, ambient-temperature services like municipal water, wastewater, and HVAC systems.

FlangeClass 25/125/250Cast IronDimension

ASME B16.24

ASME

Cast Copper Alloy Pipe Flanges and Flanged Fittings

ASME B16.24 specifies requirements for cast copper alloy (brass and bronze) flanges. These are used primarily in marine environments, seawater cooling systems, and specialized oxygen or potable water services where corrosion resistance and non-sparking properties are required.

FlangeCopper AlloyClass 150/300Dimension

API 6A

API

Wellhead and Christmas Tree Equipment

API 6A is the primary standard for wellhead and christmas tree equipment used in upstream oil and gas production. It includes specifications for extremely high-pressure flanges (up to 20,000 psi) designed to contain subterranean reservoir pressures at the wellbore.

FlangeWellhead6B / 6BX FlangesMaterial Class

API 605

API

Large Diameter Carbon Steel Flanges (historical)

API 605 was the historical standard developed by the American Petroleum Institute for large diameter, compact flanges used in refineries. It has been officially withdrawn and incorporated into ASME B16.47 as "Series B".

FlangeLarge DiameterHistoricalSeries B basis

EN 1092-1

EN

Circular Flanges for Pipes, Valves and Fittings (PN designated)

EN 1092-1 is the European standard for steel flanges. Instead of the American "Class" system (e.g., Class 150), it uses the Nominal Pressure (PN) designation system (e.g., PN16, PN40), which roughly corresponds to the allowable pressure in bars at room temperature.

FlangePN RatingsType CodesDimension

JIS B2220

JIS

Steel Pipe Flanges

JIS B2220 specifies steel pipe flanges for the Japanese industrial system. It utilizes the "K" rating system (e.g., 5K, 10K, 20K) to designate pressure classes, representing the working pressure in kgf/cm² at ambient temperature.

FlangeK RatingsFlange TypesDimension

AWWA C207

AWWA

Steel Pipe Flanges for Waterworks Service

AWWA C207 is the American Water Works Association standard for steel ring and blind flanges intended for water and wastewater service. It is designed to be a highly cost-effective, lighter alternative to ASME B16.5 for massive water pipelines operating at ambient temperatures and low pressures.

FlangeClasses B/D/E/FWaterworksDimension

ASME B16.48

ASME

Line Blanks

Dimensions, ratings, materials, marking, and tolerances for spectacle blinds, spades, and spacers installed between flanges.

FlangeSpectacle blindsSpades and spacersPressure classes

ASTM A694

ASTM

Carbon and Alloy Steel Forgings for High-Pressure Transmission-Service Components

Material requirements for forged flanges, fittings, valves, and parts for high-pressure transmission service.

MaterialHigh-strength forging gradesHeat treatmentMechanical properties

ASME B16.47

ASME

Large Diameter Steel Flanges

Family reference for large-diameter steel flanges covering Series A and Series B dimensional systems.

FlangeScope and applicabilityMaterials or componentsQuality and acceptance requirements

MSS SP-44

MSS

Steel Pipeline Flanges

Pressure-temperature ratings, materials, dimensions, tolerances, and marking for steel pipeline flanges.

FlangeScope and applicabilityMaterials or componentsQuality and acceptance requirements
Disclaimer: Disclaimer: This page provides a simplified engineering reference only. It is not a replacement for the official standard. For design, inspection, procurement, and construction, always refer to the latest official standard and the applicable project specification.