Pipe flanges

There are many different flange standards to be found worldwide. To allow easy functionality and inter-changeability, these are designed to have standardised dimensions. Common world standards include ASA/ANSI (USA), PN/DIN (European),[1] BS10 (British/Australian),[2] and JIS/KS (Japanese/Korean).

In most cases these are not interchangeable (e.g. an ANSI flange will not mate against a JIS flange). Further, many of the flanges in each standard are divided into “pressure classes”, allowing flanges to be capable of taking different pressure ratings. Again these are not generally interchangeable (e.g. an ANSI 150 will not mate with an ANSI 300). These pressure classes also have differing pressure and temperature ratings for different materials. Unique pressure classes for piping can also be developed for a process plant or power generating station; these may be specific to the corporation, engineering procurement and construction (EPC) contractor, or the process plant owner.

The flange faces are also made to standardized dimensions and are typically “flat face”, “raised face”, “tongue and groove”, or “ring joint” styles, although other obscure styles are possible.

Flange designs are available as “welding neck”, “slip-on”, “boss”, “lap joint”, “socket weld”, “threaded“, and also “blind”.

ASME standards (U.S.)

ASME type flange on a gas pipeline

Pipe flanges that are made to standards called out by ASME B16.5 or ASME B16.47 are typically made from forged materials and have machined surfaces. B16.5 refers to nominal pipe sizes (NPS) from ½” to 24″. B16.47 covers NPSs from 26″ to 60″. Each specification further delineates flanges into pressure classes: 150, 300, 400, 600, 900, 1500 and 2500 for B16.5; B16.47 delineates its flanges into pressure classes 75, 150, 300, 400, 600, 900.

The gasket type and bolt type are generally specified by the standard(s); however, sometimes the standards refer to the ASME Boiler and Pressure Vessel Code (B&PVC) for details (see ASME Code Section VIII Division 1 – Appendix 2). These flanges are recognized by ASME Pipe Codes such as ASME B31.1 Power Piping, and ASME B31.3 Process Piping.

Materials for flanges are usually under ASME designation: SA-105 (Specification for Carbon Steel Forgings for Piping Applications), SA-266 (Specification for Carbon Steel Forgings for Pressure Vessel Components), or SA-182 (Specification for Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service). In addition, there are many “industry standard” flanges that in some circumstance may be used on ASME work.

Other countries

Flanges in other countries also are manufactured according to the standards for materials, pressure ratings, etc. Such standards include DIN, BS,[3] and/or ISO standards.

Pipe-to-pipe connections between different joint types

Molded raised faces for swaged PP-lined pipe are shown in many connections illustrated here, however, reinforced flared faces (PVDF and PTFE) may be used in most of the same connections.

Note: Normally no gaskets are required between plastic lined piping components. When lined piping is connected to a flange face of another material, a gasket shall be installed. 

Figure 1 – Connection of molded raised face to gasket plastic-lined pipe

  Figure 2 – Connection of reinforced flared face to gasket plastic-lined pipe

Figure 3 – Providing low-angle bend using tapered face spacer

New Produce Season Start – Supply Forged Carbon Steel Flanges and Pipe Elbows

Season’s greeting to everyone.

Today our factory open again, from February 11 we will return to normal production, welcome to contact us for forged flanges and pipe elbows, tees, reducers etc, we supply ANSI/ASME/ASTM/ASA B16.5 flanges, DIN flanges, UNI flanges, EN1092-1 flanges, BS10 flanges, BS4504 flanges, GOST12820/12821 flanges, SABS/SANS 1123 flanges.

Jinan Hyupshin Flanges Co., Ltd want to be your cooperation partners, real friends in this field.

The CEO Mr. Guo Zhaoji welcome customers from anywhere to contact us, build long business relations.


2011. 02. 10