PLSteel Pipe FlangesPlate Flange (PL)
Flat-type flange with simple structure, light weight and low cost — ideal for low-pressure pipeline systems.
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Spectacle Blind (SB)
Figure-8 blank for positive pipeline isolation — switch between open spacer and closed blind by rotation.
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SBSteel Pipe Flanges
Overview
A spectacle blind flange (figure-8 blank) is a pressure-retaining fitting used for positive isolation and flow control. Shaped like the number 8, it consists of a solid disc (blind end) and an open ring (spacer end) connected by a web. Installed between two flanges, it rotates 180° to switch between open flow and closed isolation.
Size Range
½" – 48"
Pressure Class
Class 150 – 2500
Key Features
- Positive visual isolation — superior to valves alone
- Interlocked design prevents loss of blind or spacer
- Manufactured per ASME B16.48
- Carbon, stainless and alloy grades
- Sizes ½" to 48" (DN15 – DN1200)
Benefits
- Physical barrier with visible open/closed state
- No separate loose parts to misplace
- Critical for safety shutdown procedures
Specifications
| Standard | ASME B16.48 |
| Pressure Ratings | Class 150 – 2500 |
| Nominal Diameter | NPS ½" – 48" (DN15 – DN1200) |
| Types | Paddle blank, spacer ring, figure-8 |
| Operation | Manual 180° rotation between flanges |
Applications
Oil and gas pipeline isolationRefinery maintenance shutdownsPetrochemical turnaround safetyPower plant steam line isolation
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Standards
- • ASME B16.48
- • ASME B16.5
Materials
- • Carbon Steel: A105, 20#, Q235B, A234 WPB
- • Stainless Steel: 304, 304L, 316, 316L, 321
- • Alloy Steel: 16Mn, F11, F22, 15CrMo
- • Duplex & Super Duplex: F51, F53, 2205
- • Special alloys: Monel, Hastelloy, Titanium (on request)
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