1.During the initial start-up preparation stage, when the strength test or tightness test of the pipeline cannot be performed simultaneously with the connected equipment (such as turbine, compressor, gasifier, reactor, etc.), the equipment Set a blind flange at the connection with the pipeline.
2. Various process material pipelines connected to the boundary area outside the boundary area. When the device is stopped, if the pipeline is still in operation, set a blind flange at the cut-off valve.
3. When the device is of multiple series, the total pipeline from the boundary area is divided into thousands of pipelines to enter each series, and a blind flange is set at the cut-off valve of each branch pipeline.

4. When the device is to be regularly maintained, inspected or switched over, and the equipment involved needs to be completely isolated, set a blind flange at the shut-off valve.
5. When pressurized pipelines, replacement gas pipelines (such as nitrogen pipelines, compressed air pipelines) process pipelines are connected to the equipment, set the blind flange at the shut-off valve.
6. The low point of the equipment and pipelines are drained. If the process medium needs to be concentrated into a unified collection system, a blind flange is set after the valve is cut off.
7. The exhaust pipe, drain pipe and sampling pipe of the equipment and pipeline shall be provided with blind flange or wire plugs behind the valve. Except for non-toxic, non-healthy and non-explosive materials.
8. When the device is constructed in stages, the interconnected pipelines are provided with cut-off blind flange at the cut-off valve for subsequent construction.
9. When the device is in normal production, some auxiliary pipelines that need to be completely cut off should generally be equipped with blind flanges.