A ‌blind flange‌ is a solid disc-shaped flange used to seal the end of a piping system or pressure vessel, preventing fluid flow.  

1. ‌Design & Structure‌

• ‌No Central Bore‌: Unlike standard flanges, blind flanges lack a center hole, creating a complete seal when bolted to a pipe or vessel opening‌.

• ‌Sealing Surfaces‌: One side has a flange face (e.g., raised face/RF) with bolt holes, while the other is smooth for gasket placement‌.

2. ‌Key Functions‌

• ‌Isolation/Testing‌: Temporarily blocks pipelines during maintenance, inspections, or pressure tests‌.
• ‌Permanent Closure‌: Seals unused pipe ends or equipment nozzles permanently‌.

3. ‌Materials & Standards‌

• ‌Materials‌: Carbon steel (A105), stainless steel (304/316), and alloys (A182 F304)‌.

• ‌Standards‌: ANSI B16.5, ASME B16.47, and JB/T86.1-94 (China)‌.

4. ‌Advantages vs. Alternatives‌

• ‌Removability‌: Unlike welded caps/plugs, blind flanges allow easy disassembly with bolts‌.
• ‌Pressure Handling‌: Suitable for high-pressure systems (e.g., Class 150–2500)‌.

5. ‌Common Applications‌

• ‌Oil/Gas‌: Isolates pipeline sections for safety during repairs‌.

• ‌Chemical Plants‌: Seals reactors or tanks during cleaning‌