Blind flange (BL)

A flange blind plate, also known as a blind flange, is actually called a blind plate. It is a type of connection for flanges. One of its functions is to seal the end of a pipeline, and another is to facilitate the removal of debris from the pipeline during maintenance. In terms of sealing function, it serves the same purpose as heads and pipe caps. However, heads cannot be disassembled, whereas flange blind plates are fixed with bolts and can be easily removed. Flange blind plates are available in various materials, including carbon steel, alloy steel, stainless steel, plastic, and others.

A flange blind plate is a connecting device for two large-diameter pipelines, usually consisting of two flange pieces and several fastening bolts. A large flange is a flange made of steel. Mild steel has good plasticity but low strength; when an appropriate amount of carbon is added, it becomes hard, with reduced plasticity and increased strength.

With the rapid development of long-distance pipeline construction at home and abroad, pipeline pressure testing has become an essential and important procedure. Before and after pressure testing, each pipeline section must undergo pigging and cleaning, generally 4 to 5 times. Especially after pressure testing, the residual water inside the pipeline is difficult to clean completely, requiring more cleaning passes.