A Comprehensive Analysis of Flange Sealing Surface Types and Selection Principles

I. Overview of Flanges

Flanges are essential components in piping systems used to connect pipes to each other or to equipment, enabling detachable connections through bolt tightening and gasket sealing. Flanges can be classified into various types based on the form of their sealing surfaces, with different sealing surfaces suitable for different pressure, temperature, and medium conditions.

II. Common Types of Sealing Surfaces

1. Raised Face (RF): The most commonly used sealing surface type. The sealing surface is flat, making it simple to machine and cost-effective. It is suitable for medium and low-pressure conditions (PN≤4.0MPa).

2. Male-Female (MFM): Consists of a male face and a female face, with the gasket placed in the female face. It offers accurate positioning and good sealing performance, suitable for medium-to-high pressure conditions.

3. Tongue and Groove (TG): Formed by the mating of the tongue and groove surfaces, with the gasket placed inside the groove, offering excellent sealing performance. Suitable for high-pressure, flammable and explosive, and toxic media conditions.

4. Full Face (FF): The sealing surface is flush with the flange face, suitable for low-pressure conditions (PN≤1.0MPa), and is commonly used for cast iron flanges and FRP flanges.

5. Ring Joint (RJ): Uses a metal ring gasket, offering excellent sealing performance. It is suitable for high-temperature and high-pressure conditions (PN ≥ 10.0 MPa) and is commonly used in high-temperature and high-pressure pipelines in the petrochemical industry.

III. Selection Principles

1. For low-pressure, non-toxic media, raised face (RF) flanges are preferred due to their cost-effectiveness;

2. For medium pressure and general media, male-female (MFM) flanges may be selected;

3. For high-pressure, flammable and explosive, or toxic media, flanges with tongue-and-groove (TG) or ring joint (RJ) faces shall be selected;

4. For high-temperature and high-pressure conditions, prioritize the use of ring joint face (RJ) flanges with metal ring gaskets;

5. The sealing surface forms of the mating flanges must be identical and shall not be mixed.

IV. Flange Types

Plate flat welding flange (PL), necked flat welding flange (SO), necked butt welding flange (WN), integral flange (IF), socket welding flange (SW), threaded flange (Th), loose flange (PJ/SE), blind flange (BL).

V. Execution Standards

GB/T 9119, HG/T 20592, ANSI/ASME B16.5, DIN 2573/2576, JIS B2220, SH/T 3406, etc.

Cangzhou Kairuifeng Pipeline Equipment Co., Ltd. specializes in the production of various flange products, offering a complete range of sealing surface types and supporting customization. We welcome your inquiries and purchases.