The Essential Guide to Line Blanks in Pipeline Systems
2025-08-06
Introduction to Line Blanks
Line blanks (also called spectacle blinds or paddle blanks) are critical safety components in pipeline systems that provide positive isolation during maintenance or process changes. At SN Valve, we manufacture high-performance line blanks that meet stringent industry standards for oil & gas, chemical, and power generation applications.
This comprehensive guide covers:
✔ Function and types of line blanks
✔ Material selection and design considerations
✔ SN Valve product specifications
✔ Proper installation procedures
✔ FAQ addressing common technical questions
Line Blank Fundamentals
Primary Functions
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Positive isolation of pipeline sections
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Safety barrier during maintenance
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Process separation for system modifications
Common Types
| Type | Description | Applications |
|---|---|---|
| Spectacle Blind | Rotatable spool with blind/flow sections | Frequent isolation needs |
| Paddle Blank | Single solid disk | Permanent/temporary isolation |
| Spacer Ring | Empty ring for flow | System testing configuration |
SN Valve Line Blank Product Specifications
Material Options
| Material | Temperature Range | Pressure Rating | Corrosion Resistance |
|---|---|---|---|
| Carbon Steel | -29°C to 425°C | ASME 150-2500 | Moderate |
| Stainless 316 | -196°C to 800°C | ASME 150-1500 | Excellent |
| Duplex 2205 | -50°C to 300°C | ASME 150-900 | Superior |
| Nickel Alloy | -100°C to 1000°C | ASME 150-600 | Extreme |
Standard Dimensions
| Size Range | Thickness | Face Finish | ASME Compliance |
|---|---|---|---|
| 1/2"-24" | 3-50mm | RF, FF, RTJ | B16.48, B16.5 |
| 26"-60" | 5-80mm | RF, FF | B16.47 Series A/B |
Proper Installation Procedures
Step-by-Step Guide
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System depressurization - Verify zero energy state
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Gasket inspection - Replace if damaged
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Alignment check - Ensure proper flange face contact
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Bolt tightening - Follow crisscross pattern (SN-VLB torque specs)
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Pressure testing - Hydrotest at 1.5x working pressure
Safety Considerations
✔ Use lifting lugs for heavy blanks (>50kg)
✔ Apply alignment pins for large diameters
✔ Install warning tags on spectacle blinds
Industry Applications
Oil & Gas
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Pipeline maintenance isolation
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Refinery turnaround safety
Chemical Plants
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Batch process separation
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Reactor servicing
Power Generation
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Boiler feedwater systems
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Steam line isolation
FAQ: Line Blank Essentials
Q: How to select between spectacle blinds and paddle blanks?
A: Consider these factors:
| Factor | Spectacle Blind | Paddle Blank |
|---|---|---|
| Frequency of Use | Frequent changes | One-time use |
| Space Requirements | Needs swing clearance | Compact |
| Cost | Higher initial cost | Lower cost |
| Visual Indication | Clear position status | No indication |
SN Valve recommends spectacle blinds for processes requiring regular isolation changes and paddle blanks for permanent installations.
Why Choose SN Valve Line Blanks?
✔ Precision CNC machining (±0.1mm tolerance)
✔ Full material traceability with MTCs
✔ Non-stick coatings available
✔ 24/7 emergency delivery service
Get Your Pipeline Isolation Solutions
For technical drawings or urgent requirements:
📞 Phone: +86-577-85886898
📱 Mobile: +86-13306772198
📧 Email: [email protected]
With 30+ years manufacturing experience, I personally guarantee SN Valve line blanks provide leak-proof isolation under the most demanding conditions. Contact us today for your pipeline safety needs!