A paddle blind (also called a spade or paddle spacer) is a flat, solid steel disc inserted between two flanges to provide positive isolation of a piping section. It has a protruding handle that extends beyond the flange OD, serving as a visual indicator that the line is blinded. Paddle blinds are covered under ASME B16.48 and are one of the simplest yet most reliable methods of mechanical isolation in process piping.
Key Specifications
| Property | Detail |
|---|
| Standard | ASME B16.48 |
| Size range | NPS 1/2 to NPS 24 |
| Pressure classes | 150 through 2500 |
| Materials | A105 (CS), A182 F304/F316 (SS), A182 F11 (alloy) |
| Disc | Solid (no bore) |
| Handle | Extended tab for identification and removal |
| Gaskets required | Two per installation (one each side of blind) |
| Companion piece | Spacer ring (bored disc) for flow-through position |
Paddle Blind Thickness (ASME B16.48)
| NPS | Class 150 (mm) | Class 300 (mm) | Class 600 (mm) | Class 900 (mm) |
|---|
| 4 | 6.4 | 9.5 | 15.9 | 22.2 |
| 6 | 7.9 | 12.7 | 20.6 | 28.6 |
| 8 | 9.5 | 14.3 | 23.8 | 33.3 |
| 12 | 12.7 | 19.1 | 31.8 | 44.5 |
| 16 | 15.9 | 22.2 | 38.1 | 53.8 |
Minimum thickness values from ASME B16.48 for A105 carbon steel.
Paddle Blind vs Spectacle Blind
| Feature | Paddle Blind (Spade) | Spectacle Blind |
|---|
| Shape | Single solid disc with handle | Figure-8 (blind + spacer connected) |
| Installation | Inserted between flanges | Permanently installed; rotated |
| Switching | Remove blind, insert spacer ring | Rotate 180 degrees |
| Storage | Must store blind or spacer when not in use | No separate storage—both discs always present |
| Weight | Lighter (single disc) | Heavier (two discs + bridge) |
| Best for | Infrequent isolation (annual turnarounds) | Frequent switching (regular maintenance) |
Installation Sequence
- Depressurize and drain the line
- Unbolt the flange joint
- Spread the flanges using a flange spreader
- Insert new gaskets on both sides of the paddle blind
- Position the blind with handle pointing outward
- Install longer stud bolts and torque per bolt torque procedure
Read the full guide to flanges
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