In the petroleum, chemical, electric power and other industrial fields, the safety and reliability of the pipeline system are of vital importance, and the standardized design of flanges, as the core components of pipeline connections, is directly related to the operating efficiency and safety of the entire system. The ASME B16.5 and ASME B16.47 standards formulated by the American Society of Mechanical Engineers (ASME) are globally recognized flange design and manufacturing specifications, but there are significant differences between the two in terms of scope of application, technical requirements and application scenarios.
ZIZI specializes in the generation of flanges in various materials and types, in strict compliance with international standards (e.g. EN 1092-1, ASME B16.5, etc.), and provides high-quality piping connection solutions to customers all over the world.
Overview of the Standards System：
ASME B16.5 Standards System：
This Standard covers pressure–temperature ratings, materials, dimensions, tolerances, marking,testing, and methods of designating openings for pipe flanges and flanged fittings. Flanges with rating class designations 150, 300,400,600, 900, and 1500 in sizes NPS 1/2 through NPS 24 and flanges with rating class designation 2500 in sizes NPS 1/2 through NPS 12, with requirements given in both metric and U.S. Customary units with diameter of bolts and flange bolt holes expressed in inch units.
ASME B16.47 Standards System：
This Standard covers pressure–temperature ratings,materials, dimensions, tolerances, marking, and testing for pipe flanges in sizes NPS 26 through NPS 60.Included are flanges with rating class designations 75,150, 300, 400, 600, and 900 with requirements given in both SI (Metric) and U.S. Customary units, with diameter of bolts and flange bolt holes expressed in inch units.
ASME B16.5 and ASME B16.47 Material Options：
| Carbon Steel | ASTM A105, 20# |
| low Temperature Steel | ASTM A350 LF2, 16Mn |
| Pipeline Steel | ASTM A694 F42 / 46 / 56 / 60 / 65 |
| Alloy Steel | ASTM A182 F11 / 12 / 5 / 9 / 91 / 92 |
| Stainless Steel | ASTM A182 F304/304L/304H, 316/316L, 310S, 317,347,904L |
| Duplex Stainless Steel | ASTM A182 F44,F51, F53, F55,F60 |
Flange Design Requirements：
ASME B16.5:
ASME B16.5 applies to small and medium diameter flanges from NPS ½”-24” and is designed to emphasize interchangeability and standardization. The geometry of the flanges (e.g., outside diameter, center distance of bolt holes, sealing surface tolerances) is strictly defined by the standard to ensure interchangeability between products of different manufacturers. Pressure classes (Class 150-2500) correspond to different maximum allowable working pressures and decrease with increasing temperature.
ASME B16.47:
ASME B16.47 for large-diameter flanges from NPS 26”-60” is designed with emphasis on deformation resistance and structural strength. The standard is divided into Series A (metric) and Series B (inch), which are not compatible in terms of bolt hole layout and flange thickness. Due to the higher bending moments and axial forces experienced by large-diameter flanges, the thickness tolerances are relaxed with the dimensions to accommodate manufacturing tolerances. In addition, the tolerance of the pitch circle diameter of the ring joint groove is ±0.13 mm to ensure sealing reliability under high pressure conditions.
ASME B16.5 VS ASME B16.47:
| Item | ASME B16.5 | ASME B16.47 |
| Size Range | 1/2 inch to 24 inches | 24 inches to 60 inches |
| Application | Medium-sized pipes, oil, chemical, etc. | Large industrial pipes, oil and gas, etc. |
| Pressure Ratings | 150, 300, 600, 900, etc. | 150, 300, 600, etc. |
| Flange Design | Simple design, moderate pressure environment | Complex design, high pressure, large flow environment |
| Material Requirements | Carbon steel, stainless steel, moderate pressure | High-strength alloy steel, high-pressure environment |
| Installation Requirements | Simple installation, standard welding methods | Complex installation, requires special equipment |
Application Areas:
ASME B16.5 Flange Application Areas:
✅Oil and gas: small and medium diameter pipeline connection, such as wellhead unit, refinery internal pipeline.
✅Chemical: corrosive media transportation, suitable for reactor, heat exchanger, pump valve connection.
✅Electric power: boiler, steam piping (≤24″), high temperature and high pressure resistance.
✅ Nuclear energy: auxiliary piping system for nuclear power plants, materials need to meet strict non-destructive testing requirements.
✅ Shipbuilding: nacelle piping, fuel system, with emphasis on interchangeability and standardization.
ASME B16.47 Flange Application Areas:
✅Oil and gas long-distance pipeline: NPS 26“-60” high-pressure trunk line, such as cross-regional gas pipeline.
✅Large chemical plant: reaction tower, distillation tower and other large-diameter high-pressure connections.
✅Power (steam piping): main steam piping (>24″) with high temperature creep resistance requirements.
✅ Offshore engineering: offshore platform risers, submarine pipelines, corrosion and external load resistance required.
✅Refineries: high pressure reactor flange connections such as hydrocracking units.
We are professional in manufacturing and exporting flanges in various materials.
