Rules for the use of blind plates
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Both the extraction and post-treatment processes in the hydrogen peroxide production plant operate at atmospheric pressure. Can polytetrafluoroethylene blank plates be used as blind plates during the operation of inserting drill towers into the tanks? Our new head of safety said that our way of using blind flanges does not meet the requirements, but we have always used them in this manner before. Is it really true that our use of blind flanges is not proper?
Blind plates are generally used to isolate materials; your safety officer might think that blind plates made of polytetrafluoroethylene are non-conductive, and therefore consider their use to be unacceptable.
You can ask your safety officer what the specific safety hazards are What good suggestions does he have, such as what materials and types of blind flanges should be used to meet safety standards and requirements? My personal opinion is: 1. White boards are not suitable for use as blind plates; blind plates are usually designed in an 8-shaped format ； 2. PTFE does not have sufficient hardness; it is generally used as a lining or gasket, and is not suitable for use as a blind flange. For the guidelines on the use of blind plates, one can refer to the previous safety procedures issued by the Ministry of Chemical Industry regarding blind plates.
Refer to the various provisions on safety requirements for blind plate removal and installation operations outlined in the \"Safety Regulations for Blind Plate Removal and Installation Operations in Plant Areas\" (Chemical Industry Standard of the People’s Republic of China, HG 23013-1999). Facilities that meet the requirements should establish a dedicated ledger for blind flanges in order to manage the blind flanges in use within their production areas in a centralized manner.
It’s a matter of the strength of polytetrafluoroethylene white boards; when using them, it’s impossible to rule out the possibility of accidents occurring.
Reply 1# tczxs: There are requirements for both thickness and pressure rating.
Reply 1# tczxs AQ3027—2008 Safety Specifications for Blind Plug/Remove Operations in Chemical Production Units 4 Requirements for Blind Plugs The blind plugs and gaskets shall meet the following requirements: 4.1 Blind plugs should be made of materials suitable for the nature, pressure, and temperature of the medium inside the pipeline. High-pressure blind flanges shall be designed and manufactured in accordance with design specifications and must pass ultrasonic testing. 4.2 The diameter of the blind plate shall be determined based on the diameter of the pipeline flange sealing surface, and its thickness shall be calculated according to strength requirements. 4.3 Generally, blind plates should have one or two handles to facilitate identification and removal, although 8-shaped blind plates may not require handles. 4.4 Appropriate materials should be selected for blind flange gaskets based on the properties, pressure, and temperature of the medium in the pipeline. Our company stipulates that metal sheets, asbestos rubber sheets, Bakelite sheets, etc. cannot be used as substitutes for blind flanges.
14.4 Blind Flanges 14.4.1 When the unit is shut down for maintenance, on those pipelines that may need to continue operating outside the unit, in addition to installing shut-off valves at the unit’s boundaries, blind flanges should also be installed at the flange on the side of the valve that is closest to the unit. .14.4.2 During operation, when some equipment needs to be shut down for maintenance, a blind flange should be installed at the flange joint between the valve and the equipment. For pipelines carrying Class B fluids, if a small vent valve is installed between the valve and the blind flange, the pipeline downstream of that vent valve should be led to a safe location. 14.4.3 Blind plates shall be installed at the locations to be isolated for pressure testing and airtightness testing. 14.4.4 When the fluid temperature is below -5°C or in environments with severe atmospheric corrosion, a separate blind plate is recommended; plug plates and gaskets should not be used, and L-shaped blind plates are not suitable. 14.4.5 The plug plates and gaskets shall have identification marks, and the marking area shall extend beyond the flange. In accordance with the requirements regarding blind plates in Chapter 14 \"Safety Provisions for Pipeline Systems\" of the \"Code for Design of Industrial Metal Piping\" (GB50316-2000)
Polyvinyl chloride cannot be used for blind flanges, as it is highly brittle and lacks flexibility; it may crack when used for isolation, leading to accidents.