Standards for selecting takeover flanges

For reference: 1. First, select according to the pressure class specified in the standards, with the flange’s pressure class being one level higher than the design pressure of the equipment. 2. Choose a flange face structure and sealing type that meet the requirements based on the pressure class. 3. Select the flange material depending on the corrosiveness of the medium. 4. Choose a flange standard.

A connection flange generally refers to the flange that connects the fittings on a device to pipelines, or between different pipelines; the commonly used standards for such flanges are HG20592, HG20615, JB82.1(2)-94, and so on； The equipment flanges generally refer to those used for connecting the cylinder of a pressure vessel with other cylinders, and the JB4701~03 standard is commonly applied

HG20592 is a standard issued by the Ministry of Chemical Industry; there are also standards from the Ministry of Machinery that start with JB – it seems to be JB/T 81-94

b. Selection of structural type: Flat welding flanges are commonly used in situations with relatively mild medium conditions, such as low-pressure, unpurified compressed air or low-pressure circulating water; their advantage is their relatively low cost； Butt weld flanges: The most commonly used type, as they are connected to pipes by butt welding; the quality of the welded joint is good. Moreover, the neck portion of the flange features a tapered design, allowing it to withstand harsh conditions ； Socket weld flanges: commonly used in pipelines with PN≤10.0MPa and DN≤40 ； Loose-flange: It is commonly used in situations where the temperature and pressure of the medium are not high, but the medium has strong corrosiveness. When the medium is highly corrosive, the part of the flange that comes into contact with the medium (the flanged stub) is made of corrosion-resistant high-grade materials such as stainless steel, while the outer portion is secured using lower-grade materials such as carbon steel flange rings to achieve sealing ； Integral flange: The flange is often integrated with equipment, pipes, fittings, valves, etc.; this type is commonly used on equipment and valves. b. Selection of seal surface type: Full-flat seal surface: Often used in combination with the butt-welding style to suit operating conditions that are relatively mild (PNg1.0) ； Commonly used for cast iron flanges or steel flanges connected to cast iron ； Raised face seal surface: This is the most widely used type; it is often used in combination with butt welding and socket welding methods. In \"American flanges\", it is commonly employed for pressure ratings of PN2.0, PN5.0, and some PN10.0 MPa grades ； In \"European flanges\", it is commonly used for pressure grades of PN1.6 and PN2.5 MPa ； Rough and smooth sealing surfaces: Often used in combination with butt-welding and socket-type connections; not commonly used in \"American flanges\", but are frequently employed in \"European flanges\" for PN4.0 and PN6.4 MPa pressure classes. But it is not convenient for replacing the gasket ； Tenon-and-socket face sealing surface: Same application as male-and-female flanges ； Ring groove face seal surface: It is commonly used in conjunction with butt welding connections (not with socket welding), and is primarily applied in conditions of high temperature, high pressure, or both. In \"American flanges\", they are commonly used in pressure grades of PN10.0 (in some cases), PN15.0, PN25.0, and PN42.0 MPa. In \"European flanges\", PN10.0, PN16.0, PN25.0, PN32.0, and PN42.0 are commonly used.

1. The nominal pressure of the flange shall meet the process requirements； 2. The flange material should be suitable for the design temperature and pressure ； 3. The flange connection type, seal surface type, and medium must be compatible ； 4. The nominal flange series complies with the temperature and pressure rating table. 　　Currently, the main flange standards include the Ministry of Chemical Industry standard HG20592 \"Steel Pipe Flanges, Gaskets, and Fasteners\" ； **Standards GB/9112~9124 \"Steel Pipe Flanges\" ； GB/T13402-92 \"Large-diameter carbon steel flanges\" ； Sinopec Standard SY/T3406-1996 \"Steel Pipe Flanges and Flanged Fittings\" ； Mechanical industry standard JB/T74~90-94 \"Piping flanges and gaskets\". 　　Among several standards, HG20592 is the standard recommended by the tolerance regulations.

First, it is necessary to ensure that the pressure-temperature rating meets the requirements; thereafter, the flange type and appropriate gaskets must be selected

Generally, for desulfurization processes, GB/T 9119-200 is used for diameters below DN600, while GB/T 9113-200 is used for diameters above DN600

　　Currently, the common flange standards are: the Ministry of Chemical Industry standard HG20592 \"Steel Pipe Flanges, Gaskets, and Fasteners\"； There are also JB/T81.2 and others. When selecting flanges, note the following: 1. The nominal pressure of the flange should meet the process requirements ； 2. The flange material should be suitable for the design temperature and pressure ； 3. The flange connection type, seal surface type, and medium must be compatible ； 4. The nominal flange series complies with the temperature and pressure rating table.

First, select the standard for the equipment connection flanges based on the flange standards used in the piping system. Then, determine the flange type, pressure rating, and seal face type according to the design requirements

In addition, the effect of temperature must also be taken into account! ! This is also very important!

We deal in equipment, and the selection of flange types is based on the pipeline specifications provided by the design institute; HG20592 is commonly used, while standards from the Ministry of Machinery are rarely utilized； After the standard is selected, the specific flange model is chosen based on pressure and temperature

In practical applications, the selection of the connection flanges for equipment is determined by the piping system; the equipment simply needs to meet the requirements specified by the piping specialists

“First, it is necessary to select according to the pressure class specified in the standards, and the flange’s pressure class should be one level higher than the design pressure of the equipment. Do you not know where this requirement comes from?

This question is too general; it’s difficult to explain. When choosing flanges, I take the following aspects into consideration. 1. First, the appropriate sealing surface and flange type should be selected based on the characteristics of the medium. 2. Select the appropriate flange pressure class based on the temperature and pressure of the medium. 3. Select the appropriate flange material based on temperature and pressure. 4. Stress verification: If standard flanges are used, either the mechanical or chemical engineering departments can take a shortcut by referring to the classification and technical specifications for flanges, which contain this information (otherwise, stress calculations must be performed).

For the nozzle flanges of pressure vessels, the \"Regulations on Pressure Vessels\" recommend the use of standards from the HG20592~HG20635 series. But in reality, it seems that adoption is required; this seems to stem from requirements set by the Accreditation Committee during certain training sessions. This post was last edited by lsswyb01 on 2009-3-12 09:56.]