Pfa Lined Tube Sight Glass Material Characteristics And Selection

A PFA lined straight sight glass isolates process fluid from the metal housing with a fluoropolymer liner. Install by checking liner faces, fitting the gasket, tightening bolts in a cross pattern, and pressurizing slowly. The flanged connection covers PN10, PN16, and 150LBS, with a range of -29°C to 200°C. This ptfe lined pipe component allows visual flow checks on corrosive lines.

How the Liner Isolates the Flow Path

The liner forms a continuous barrier over the body bore and the glass sealing face. Process fluid contacts only the fluoropolymer surface, so metal parts stay out of the wetted path.

• Liner covers body bore and glass seat

• Process fluid touches fluoropolymer only

• Metal housing stays outside the wetted path

• No exposed metal in the flow path

A pfa lined pipe section uses the same isolation principle. The liner thickness and molding method set service life under thermal cycling.

Liner Materials and Temperature Limits

PFA handles strong acids and bases across a wide temperature band. PTFE covers similar chemistry at lower cost. ETFE offers mechanical toughness where abrasion is a concern.

An etfe lined pipe liner resists impact and thermal shock better than PTFE in some duties. The choice follows the medium, temperature, and flow conditions.

A carbon steel ptfe lined pipe body carries the pressure load. The liner handles chemical isolation, so the steel shell provides structural strength.

Sight Glass Construction and Sealing

The glass sits between two lined flange faces. A gasket seats against the liner, not the metal body. Bolt torque compresses the gasket and glass into a sealed stack. The glass is tempered borosilicate, rated for the working pressure and temperature. A guard ring reduces impact risk on exposed installations.

Gasket material matches the liner compound. A mismatch lets the medium attack the gasket before the liner sees service. Even bolt torque around the circle keeps the glass seated.

Installation and Maintenance

1. Confirm the flange rating and face-to-face length.

2. Align the sight glass with pipe flanges and check liner faces.

3. Fit the gasket and tighten bolts in a cross pattern.

4. Pressurize slowly and check for weeping at the glass seat.

5. Inspect the liner and gasket at scheduled intervals.

A damaged liner face leaks at the flange joint. Replace the gasket and inspect the liner when cuts, swelling, or discoloration appear. Check the glass for scratches that obscure the view.

Common Applications

Lined sight glasses serve lines that need visual checks on corrosive media. The liner protects the body where bare metal corrodes.

• Chemical dosing and transfer lines

• Acid and caustic service

• Pharmaceutical solvent handling

• Water treatment chemical feed

• Petrochemical corrosive streams

A PFA lined sight glass suits lines where the medium would etch glass or attack metal. The fluoropolymer barrier keeps the wetted path inert.

Field Notes

• Store spare gaskets flat and away from direct sunlight.

• Match gasket compound to the liner material before assembly.

• Re-torque flange bolts after the first thermal cycle.

• Protect the glass from impact during handling and installation.

• Record liner and gasket replacement dates to track service life.

These steps extend service life and reduce unplanned downtime. A small stock of gaskets and glass keeps the line running when a part reaches the end of its service.

FVF PFA Lined Tubular Sight Glass

• FVF lined sight glass provides reliable and safe visual indication of fluid flow on any corrosive service. Safe and shatter-proof,each window consists of two glasses,cemented together by a proprietary adhesive.
• Fluid flow can be viewed from either top or bottom.No product retention when it is installed vertically.
• It is widely used in corrosive services in chemical and petrochemical plants, pharmaceutical plants and food and beverage processing. 

Product Parameter

Materials of Main Parts

Technical Specification