Spiral Wound vs Sheet Gaskets

author: Qishine Industry

2025-01-04

One-Minute Overview

Natural rubber seals mild, low-temperature water and air lines at the lowest cost.
Above 100°C or with oils present, use EPDM, silicone, or neoprene synthetics.
PTFE and aramid fiber gaskets resist chemicals and creep for high-pressure duty.
Match the gasket to flange type, temperature, and pressure class before bolting.

Minute Read: Rubber vs Fiber Gaskets at a Glance

Not all rubber and fiber gaskets are equal. For low-pressure, low-temperature water or air lines, natural rubber is an economical seal. Above 100°C, or wherever oils are present, switch to heat-resistant synthetics such as EPDM or silicone. For aggressive chemicals, steam, or high-pressure flanges, artificial fiber gaskets (PTFE or aramid-reinforced) give better creep resistance and dimensional stability. This guide compares material properties, pressure-temperature limits, and installation torque so you pick the right gasket the first time and avoid leaks and downtime.

Natural Rubber Gaskets - The Economical Workhorse for Mild Service

Natural rubber (polyisoprene) remains a top choice for sealing potable water, dilute acids, and alkaline solutions up to 70°C. Its high resilience (elastic recovery above 85%) lets it conform to minor flange imperfections without excessive bolt torque. However, natural rubber degrades quickly in petroleum oils, hydrocarbons, and UV. In practice we specify natural rubber gaskets for HVAC systems, irrigation pumps, and food-processing washdown stations, provided the temperature stays below 80°C and no mineral oils contact the seal. Cost per unit is typically 30-50% lower than silicone, which suits high-volume, low-risk duty. Check compression set: a good compound should show under 25% set at 70°C for 22 hours.

Heat-Resistant Rubber Gaskets for High-Temperature Service

When temperatures exceed 100°C, natural rubber fails. Heat-resistant elastomers take over:

Silicone rubber (VMQ): continuous service from -50°C to +230°C. Good for dry heat, electrical enclosures, and oven doors. Not for steam or high-pressure hydrocarbons because of poor tear strength.
EPDM: -40°C to +150°C, with strong resistance to weather, ozone, and hot water or steam up to 120°C. Common in automotive cooling and outdoor pipe flanges.
Neoprene (CR): moderate heat resistance up to 120°C with good oil and flame resistance. Used in refrigeration and hydraulic return lines.

A key engineering note: heat-resistant rubber gaskets lose bolt torque over time through thermal relaxation. Above 200°C, switch to spiral-wound or metal-jacketed gaskets—rubber sheet gaskets are unreliable in cyclic thermal service above 180°C.

Artificial Fiber Gaskets for Chemical Attack and High Bolt Loads

Artificial fiber gaskets are composite materials made from aramid, carbon, glass, or PTFE fibers bound with nitrile (NBR) or SBR. Their advantage is dimensional stability under load: they resist cold flow (creep relaxation) far better than pure elastomers.

PTFE-fiber gaskets: inert to almost all chemicals except molten alkali and fluorine. Range -200°C to +260°C. Fit aggressive acids, chlorine, and pharmaceutical lines.
Aramid-fiber gaskets (Kevlar-reinforced): high tensile strength and abrasion resistance. Used in high-pressure water jets, pulp and paper mills, and compressor valves.
Carbon-fiber reinforced: strong thermal conductivity and resistance to superheated steam (up to 450°C in low-oxygen environments).

Installation warning: fiber gaskets need higher bolt torque than rubber to compress properly (typically 30-40 MPa gasket stress). Use a torque wrench and follow the ASME PCC-1 tightening sequence to avoid flange distortion.

Rubber vs Fiber vs Spiral Wound: Match the Gasket to Flange Type and Pressure Class

Use this comparison to shortlist a material, then confirm it against the flange type and pressure class.

Parameter	Natural Rubber	Heat-Resistant Rubber (EPDM/Silicone)	Artificial Fiber (PTFE/Aramid)
Max Continuous Temp.	80°C	150-230°C (by type)	260-450°C (with filler)
Oil/Chemical Resistance	Poor	Moderate to Good	Excellent (PTFE) / Good (Aramid)
Bolt Torque Requirement	Low	Medium	High
Creep Relaxation	High (bolt loosening)	Medium	Low (stable seal)
Typical Cost	$	$$	$$$
Best Application	Water, air, weak acids	Outdoor, cooling, dry heat	Chemical, steam, high-pressure

Practical rule from the field: for flange pressures above 5 MPa (50 bar) or temperatures above 180°C, drop rubber sheet gaskets and use fiber-reinforced or metallic gaskets. For ambient, low-stress service, natural rubber gives the best return. Match the gasket to your flange type and pressure class before you bolt it down.

FAQ

Can natural rubber gaskets handle steam?

No. Steam at 100°C rapidly degrades natural rubber. Use EPDM or PTFE-fiber instead.

What is the maximum temperature for silicone rubber gaskets?

Continuous use up to 230°C; intermittent peaks up to 280°C, but only in dry, non-pressurized applications.

Are artificial fiber gaskets reusable?

Generally no. Once compressed, the fibers take a permanent set, so replace them after each flange opening.

How tight should I bolt a fiber gasket?

Target 30-40 MPa gasket stress. Use a calibrated torque wrench and tighten in three passes (30% to 60% to 100% torque).

Which gasket is best for outdoor piping in sunny climates?

EPDM rubber, for its excellent ozone and UV resistance. Neoprene also works, but EPDM is more cost-effective.

Can PTFE-fiber gaskets be used with oxygen service?

Yes, but only if cleaned for oxygen service (ASTM G93) and the PTFE compound is hydrocarbon-free. Never use oil-based binders.

How do I store rubber gaskets long-term?

Keep them in cool, dark, dry conditions, away from electric motors (ozone). Shelf life: natural rubber about 3 years; EPDM and silicone about 5 years.