Different Types of Gaskets Used in Pipeline Flanges in the Oil and Gas Industry

In the oil and gas sector, reliable sealing protects safety, prevents leaks, keeps pressure integrity and supports long stable operation. Gaskets do the quiet work in a flanged joint, closing the gap between two machined faces as pressure and temperature swing. The six flange gaskets families below cover most duties; each one is chosen against the operating conditions, the flange design and the process requirement.

Gasket Types Used in Oil and Gas Service

Picking the wrong gasket shows up as leaks, unplanned shutdowns and safety hazards, so the type list is the first reference for both engineers and purchasing.

• Spiral-wound gasket — for high-pressure and high-temperature duties. The winding gives excellent resilience and sealing, especially on critical process piping.
• Non-asbestos sheet gasket — for medium and low pressure. A safe replacement for asbestos gaskets, widely used with water, steam, oil and gas media.
• Spiral-wound gasket without inner ring — for less demanding services where bore protection is not needed and cost control matters.
• Rubber sheet gasket — for low-pressure systems such as water lines, utility services and non-hazardous fluid circuits.
• PTFE envelope gasket — for corrosive and aggressive chemical media. The PTFE envelope delivers chemical resistance while the filler core keeps mechanical strength.
• Ring-type-joint (RTJ) gasket — for extremely high pressure and temperature, for example upstream oil and gas lines. It needs specially machined RTJ grooves.

Table 1. Common gasket types for oil and gas service, with the service level and media each one is built for.

Matching the Gasket to the Joint

Pressure, temperature, fluid type, flange face finish and bolt loading all take part in the decision. A gasket rated far above the duty wastes money; a gasket rated below it fails early.

• Pressure and temperature — spiral-wound and RTJ gaskets cover the top of the range, sheet and rubber types the bottom.
• Fluid compatibility — PTFE envelopes resist aggressive chemicals; hydrocarbon service is fine for spiral-wound and non-asbestos sheet types.
• Flange facing — RTJ gaskets only seat in machined RTJ grooves; spiral-wound and sheet types need flat or raised faces in good condition.
• Bolt loading — even bolt load keeps the gasket compressed as designed; the joint on pipe flanges only seals when the studs are tightened in a proper pattern.
• Cost control — non-standard sizes and winding materials are quoted individually, so simplifying a spec often cuts price more than haggling.

Installation and Handling Rules

Most gasket failures are handling failures. A short routine covers the risk.

• Store gaskets flat, dry and protected from impact; a dented spiral winding or a nicked PTFE envelope leaks from day one.
• Inspect flange faces before assembly: no scratches, no old gasket residue, correct surface finish for the gasket type.
• Tighten bolts in stages and in a cross pattern so the gasket loads evenly around the circumference.
• Reuse is rarely acceptable — most gaskets take a permanent set after one service cycle and must be replaced at every opening.

With the type selected and the handling routine in place, a flanged joint keeps its pressure integrity through the whole operating cycle.

Frequently Asked Questions

When is a spiral-wound gasket the right choice?

When pressure and temperature are high and the joint is critical, such as main process piping. The metal-and-filler winding resists blowout and recovers after thermal cycles.

What is the difference between a spiral-wound gasket with and without an inner ring?

The inner ring protects the bore and stabilises the winding. Without it, the gasket is cheaper and suits less demanding services where bore protection is not needed.

Can a PTFE envelope gasket handle hydrocarbon service?

Yes, but it is chosen mainly for corrosive chemical media. For plain hydrocarbons at high pressure, a spiral-wound or RTJ gasket is usually the better match.

Why must RTJ gaskets use matching RTJ flanges?

The metal ring seals against the machined groove of the flange. On a flat or raised face there is no groove to bite into, so the gasket cannot seal.