What is the difference between a flange and a blind flange

As we all know, pipes are usually connected by some kind of fitting, which we call a "flange". However, in real life, many of us are not clear about the difference between a flange and a blind flange, and often confuse them. The differences between a flange and a blind flange are explained in detail below:

First, flanges and blind flanges have different characteristics.
(1) The normal name for a blind flange is a flange cover, and it is also sometimes called a blind flange or a pipe block. It is a flange without a hole in the middle, mainly used at the front end of the pipe seal for sealing. Its function is the same as that of the end cap and pipe cover, except that the blind flange seal is a detachable sealing device. The seal of the end cap is not intended to be opened again. The materials of the blind flange include carbon steel, alloy, stainless steel, plastic, etc. The blind flange has the same functions as the end cap and pipe cover. Because of its good sealing performance, it is generally used as a constant isolation means for systems that need to be completely separated. The blind flange is a solid with a handle. It is generally used for the general state of the isolation system. It is more convenient to use the blind flange. When separation is required, the end of the blind flange is used. When normal operation is required, the throttling ring is used. It can also be used to fill the installation gap of the blind flange on the pipeline.
(2) Flange, also known as flange or raised edge, is a component for connecting pipelines. Usually, at the end of the pipeline, the flange has a hole. When connecting, the two flanges need to be tightened with bolts. The flange uses a gasket seal to play a sealing role, or to play a temporary role in the test. The flange is a common disc part in pipeline engineering. Generally, flanges are used one-to-one. Depending on the connection method, flanges are divided into threaded flanges, welded flanges, and clamping flanges. Low-pressure pipelines can use threaded flanges and welded flanges, with pressures exceeding 4 kg.

Second, the applications of flanges and flange blind flanges differ.
(1) Flanges, due to their excellent performance characteristics, are widely used in basic engineering projects such as chemical, construction, petroleum, sanitation, pipeline, and fire protection.
(2) During pipeline strength tests or sealing tests, blind flanges installed during the initial startup preparation phase cannot be used simultaneously with connected equipment (such as turbines, compressors, gasifiers, reactors, etc.). Blind flanges must be installed at the connection points between the equipment and the pipeline. All process material pipes are connected to the boundary area outside the boundary area. When the equipment stops operating, blind flanges should be installed at the shut-off valves.