Thermoseal C4400 Flange Isolation Gasket Kit - Ensuring Efficient and Reliable Flange Sealing

Every flanged joint in a process plant is a potential leak path and a potential galvanic cell. The Thermoseal C4400 flange isolation gasket kit — a PTFE-based gasket with sleeves, washers and nuts — seals the joint and breaks the electrical path in one assembly, which ordinary flange gaskets cannot do.

What the C4400 Kit Is

The kit is built for the flanged joints that hold process lines together, where a leak or a stray current can idle a whole unit. Its gasket, insulating sleeves and washers isolate the two flange faces while holding pressure at the joint.

A complete kit contains four element groups.

• The gasket — premium-grade PTFE-based material that seals against corrosive fluids and chemicals.
• Insulating sleeves — they line the bolt holes so the fasteners never touch flange metal.
• Insulating washers — they break the electrical path under the nut and bolt head.
• Nuts — matched to the stud bolts for even clamping across the joint.

That combination delivers physical sealing and electrical isolation at once: no metal-to-metal path survives across the joint, cathodic currents stop at the flange, and galvanic corrosion never starts.

Where the Kit Works

One kit fits raised face (RF), flat face (FF) and ring-type joint (RTJ) flanges, which covers most process duty.

• Oil and gas — pipeline systems, offshore platforms, refineries and storage depots, where salt air and corrosive media attack flange faces.
• Petrochemical — plants running aggressive chemicals that demand tight corrosion protection at every joint.
• Power generation — nuclear, thermal and renewable plants that need leak-free flange sealing to keep units running.
• Water treatment — municipal and industrial plants, where sealing keeps treated water free of contamination.

In cathodically protected lines the kit does double duty: it seals against the medium and blocks the cathodic current that would otherwise drive galvanic corrosion on the faces of the pipe flanges in the circuit.

Selection, Installation and Care

Four details decide whether an isolation kit performs as promised.

• Flange face match — order the gasket cut for RF, FF or RTJ faces; the wrong profile will not seal.
• Bolt isolation — check that every bolt runs through a sleeve and sits on washers, or the electrical path stays closed.
• Assembly — tighten bolts in a cross pattern to even pressure so the gasket seats without extruding.
• Service checks — inspect the joint for leakage and rust staining, and confirm isolation still reads open-circuit after maintenance.

Because the gasket, sleeves and washers work as one system, fit a full new kit on reassembly instead of mixing old and new parts. Regular inspection of the joints keeps the system leak-free and extends the life of both the gasket and the flanges it protects.

Frequently Asked Questions

What does the C4400 kit contain?

One gasket, insulating sleeves, insulating washers and nuts — everything needed to seal and electrically isolate a flanged joint in a single assembly.

Which flange faces does the kit fit?

Raised face (RF), flat face (FF) and ring-type joint (RTJ) flanges. Order the gasket profile that matches the face on the line.

How does the kit stop galvanic corrosion?

The sleeves and washers break the metal-to-metal path across the joint, so cathodic currents cannot cross the flange and drive galvanic attack.

What media can the PTFE-based gasket handle?

It resists corrosive fluids and chemicals found in oil and gas, petrochemical and water treatment service, and it tolerates high process temperatures.

Can I reuse the kit after unbolting the joint?

No — fit a full new kit on reassembly. Reused gaskets and sleeves lose their set and can leak or fail to isolate.