ASTM A105N Blind Flange, RF End, ASME B16.5, Forged, 24 Inch, Class 300, Pipe Connection.

Introduction
Blind plate is mainly used to completely isolate the production medium and prevent accidents due to the lax closure of the cut-off valve. Blind plate should be set in the required isolation, such as the equipment nozzle, before and after the cut-off valve or between the two flanges, often recommended to use 8-word blind plate; for pressure, blowing and other one-time use of the part can also use the insert plate (round blind plate).

Role and Classification of Blind Boards
Blind board from the appearance, generally divided into plate plate plate blind board ,8-word blind board, insert board, and pad ring (insert board and pad ring blind to each other). The blind plate acts as isolation, cutting off, and the same as the head, pipe cap, welding plug. Because of its good sealing performance, it is generally used as a reliable isolation method for systems that need complete isolation. Plate plate blind plate is a solid circle with handle, which is used in isolated system. The 8-character blind plate, with a shape of 8 characters, one end is a blind plate and the other end is a throttle ring, but the diameter is the same as the diameter of the pipe and does not act as a throttle. The 8-word blind board is easy to use, when it needs isolation, it uses the blind board end, when it needs normal operation, it uses the throttle ring end, and can also be used to fill the installation gap of the blind board on the pipeline. Another feature is that the logo is obvious and easy to identify the installation status.

Production process
Generally divided into four types: forging, casting, medium plate cutting, casting. Among them forging product price is highest, medium plate is second, cast forging is lowest. And casting is the most secondary process. And the quality is forging and medium plate good, casting and forging should be slightly worse.

Application of folding blind plate
1. the original start-up preparation stage, when the strength test or tightness test of the pipeline can not be carried out at the same time as the connected equipment (such as turbine, compressor, gasifier, reactor, etc.), a blind plate should be arranged at the connection between the equipment and the pipeline.

2. various process material pipes connected to the boundary area outside the boundary area, when the device stops, if the pipeline is still in operation, a blind plate is arranged at the cut-off valve.
3. the device is multi-series, the main pipeline from the boundary area is divided into thousands of pipes into each series, and the blind plate is set at the cut-off valve of each branch pipe.
4. the device is to be regularly repaired, checked or switched to each other, when the equipment involved needs to be completely isolated, a blind plate is arranged at the cut-off valve.
A blind plate is arranged at the cut-off valve when the process pipe is connected to the equipment 5. the charging pipe, the air exchange pipe (such as nitrogen pipe, compressed air pipe) is installed.
6. the low point of equipment and pipeline, if the process medium needs to be concentrated in a unified collection system, the blind plate is set after the valve is cut off.
7. exhaust pipe, drain pipe and sampling pipe of the equipment and pipeline shall be provided with blind plate or wire plug after the valve. Except for non-toxic, non-hazardous and non-explosive materials.
8. the installation is built by stages, the connected pipeline is equipped with blind plate at the cut-off valve for subsequent construction.
9. the normal production of the device, some auxiliary pipes that need to be completely cut off should also be provided with blind plates.

Notes
1. in the premise of meeting the process requirements, as little blind board as possible.
2. the blind board must indicate normal opening or normal closing.
3. the blind plate is located upstream or downstream of the cut-off valve, it should be determined according to the cutting effect, safety and process requirements.

National standards
Steel pipe flange GB/T 9123-2010
Steel flange GB/T4450-1995 for marine blind plate

essential information