PTFE-Lined Spectacle Blinds | Corrosion-Resistant Piping Isolation

Product Overview & Engineering Excellence

Designed for positive, visual line isolation in aggressive chemical piping systems, our PTFE-Lined Spectacle Blinds (Figure-8 Blinds) combine high structural pressure capability with complete internal chemical protection. Manufactured with a heavy-duty carbon steel or stainless steel core encapsulated in thick virgin PTFE or molded PFA, these blinds allow plant operators to safely switch between open flow and full blank isolation.

The figure-8 steel body consists of a solid paddle blind on one side and an open spacer ring on the other, connected by a central tie bar. The seamless fluoropolymer coating encapsulates both functional faces and inner flow diameters, providing continuous corrosion isolation without metallic exposure to process media.

Key Performance Benefits

• Positive Line Isolation: Provides absolute physical shut-off during equipment maintenance, line cleaning, or process changeovers.

• Universal Chemical Resistance: Chemically inert PTFE/PFA boundary protects the structural metal core against aggressive acids, alkalis, and reactive solvents across the entire pH range.

• Clear Visual Status Indication: External tie bar clearly indicates whether the line is set to open flow or blank isolation.

• Integral Flange Sealing: Extended fluoropolymer lining faces function as self-sealing gaskets, preventing leakage at flange connection joints.

• High Structural Integrity: Rigid steel core absorbs pipeline bolting loads and pressure stresses without face warping.

Technical Specifications

• Steel Core Material: Carbon Steel (ASTM A105 / A516 Gr. 70) or Stainless Steel (304 / 316L)

• Lining Material: 100% Virgin PTFE, Modified PTFE, or Molded PFA

• Size Range: DN15 to DN600 (1/2" to 24") nominal pipe sizes

• Pressure Class: ASME B16.5 Class 150 / Class 300, DIN PN10 / PN16 flange drillings

• Operating Temperature: -29°C to +200°C (-20°F to +392°F)

• Standards Compliance: Manufactured to ASME B16.48 and ASTM F1545 specifications

Primary Applications

• Chemical Processing Plants: Positive boundary isolation for reactor feed lines, acid distribution manifolds, and storage tank nozzles.

• Petrochemical Refineries: Line breaking safety isolation for maintenance on corrosive hydrocarbon lines.

• Pharmaceutical & Fine Chemical Facilities: Sterile process isolation preventing cross-contamination during batch changeovers.

• Industrial Wastewater Treatment: Blanking off aggressive effluent transfer piping and chemical neutralization loops.

Quality Assurance, Testing & Packaging

• 100% High-Voltage Spark Testing: Every spectacle blind undergoes holiday spark testing to guarantee zero pinholes or micro-porosity in the lining.

• Dimensional Alignment Verification: Thickness and parallelism across both the open and blind faces are verified using precision instruments.

• Protective Export Packaging: Coated faces are fitted with protective covers, wrapped in plastic film, and packed in reinforced wooden crates to protect the sealing faces during transit.

Contact our technical sales team for dimensional datasheets, custom pressure ratings, or project quotations.