How to measure the dimensions of a flange?

The edges of the flange usually have markings on them, including pressure, dimensions, standard numbers, and so on; take a close look

Flanges are divided into butt-welded flanges and socket weld flanges. There are also many different types of sealing surfaces for flanges, and the number of bolt holes varies depending on the grade of the flange. The center-to-center distance of the bolt holes also varies. They are classified according to the welding method of the flange and the type of sealing surface, while grades are determined based on the bolt hole spacing and the thickness of the flange. For specific details, refer to series 20592

First, determine the type of flange. Common types of flanges include slip-on flanges, butt-welded flanges, socket weld flanges, plate-type slip-on flanges, and loose-ring flanges； Secondly, determine the flange end shape, which mainly includes RF face, concave face, convex face, and RJ torus face. tenon and mortise surface ； After determining the flange type, the main parameters to be measured include the bolt hole center distance, the inner diameter of the flange, the flange thickness, and the diameter at the flange connection point ； By then comparing the measured data with the standards, it is possible to determine the specific model of the flange. Measuring flanges is actually quite simple; just go back and read the relevant standards carefully. HG20592 and HG20615 provide detailed explanations on this topic (with HG20592 being part of the PN series of standards, while HG20615 belongs to the CLASS series of standards)

First, you need to check whether the flange has a serial number; if it does, things are simple. National standards require such a number to be present, including information on the standard code, welding method, pressure rating, and sealing type. Different manufacturers use different notation formats, for example: hg20592-2009 SW 4.0 DN80 M