Skip to Content

Deciding on a Replacement Gasket Material

0 Comments

KEY POINTS

  • Comprehensive list of materials for making custom DIY gaskets for hard-to-find gaskets for older equipment
  • For thin rubber-fiber sheets (1/32″ thick) use a low-temp iron setting to flatten out the sheet

Table of Contents

What is a Gasket

Sometimes commonly referred to as an O-ring or washer, a gasket seals the gap between two mating surfaces.

Gaskets are found in outdoor power equipment with small engines and made from a diverse materials such plastic, metal, fiber and rubber and the material selection depending on operating conditions.

If your outdoor equipment is exposed to harsh environment for a long time, gaskets will deteriorate quicker.

When equipment gets older, you will find that replacement gasket parts will be more difficult to buy (the idea to create this post came to me when I could NOT find a replacement gasket for my Generac Wheelhouse 5550 portable generator).

Gasket or Seal

The word “gasket” and “seal” are frequently used interchangeably to describe a method to provide a barrier between two surfaces to keep them from leaking.

Simply put, a gasket is a physical piece installed between two, static or non-moving parts to prevent leaks (i.e. mounting a carburetor to an air inlet).

A “seal” is a generic category that includes many types of sealing products that are engineered as well as to describe joining together “dynamic joints”.

^ Return to top

Leak-Proofing Methods

Gaskets

  • Used to seals between two connecting surfaces to create a a static seal
  • In order to maintain the leak proof sealing, during different types of operating conditions, various gasket materials are used
  • Such materials can be graphite, PTFE, Silicone, Vermiculite, neoprene, aramid/SBR rubber gaskets and other materials.
  • Ultra high temperature gaskets materials can withstand up to 1800 degrees in Fahrenheit

Gasketing Adhesives

  • Used to hold gaskets in place during assembly
  • May not be sold to any regions that has local regulatory limits of VOC (volatile organic compounds)
  • Can handle temperatures from -30 F to 300 F
  • Oil-Resistance Gasketing Adhesive, such as Loctite 30540, will not degrade in the presence of oils and fuels but can only handle temperatures from -20 F to 170 F

Gasket Maker Sealants

  • Used to INSTEAD of a rubber, cork and other traditional gasket materials to form irregular-shaped gaskets
  • Two primary products are Loctite 587 and Permatex 80022. sealants. Both products are RTV (Room Temperature Vulcanizing) sealants and can handle temperatures from -65 F to 400 F. They can be used on aluminum, brass, bronze, copper, steel, stainless steel, cast iron and titanium surface. Permatex can also be used on various plastic/polymerized materials
  • For higher temperature settings (-65 F to 600 F), use Loctite 5920 or Permatex 8116

^ Return to top

History of Gasket Materials

In the old days, it was common to find a piece of paper used as gaskets.

However, the standard paper material cannot withstand to heat, moisture and pressure. That is why gaskets that are in areas like oil cooler and engine block usually have a small thin sealer bead on it to help with high heat / high pressure areas.

During 1940s and 1950s, asbestos was used heavily as a gasket material but due to health hazard issues, this practice was mostly discontinued.

Please note that more than 60 countries have completely banned the use of asbestos. However, asbestos can still be used in the United States and some building products such as gaskets and roofing materials can have asbestos.

For more information, please visit the US Center for Disease Control website (click here)

^ Return to top

Gasket Materials for Specific Applications

  • Chemical-Resistant
    • Compressible PTFE Pipe gaskets – Also known as Gore GR, this gasket is ultra resistant to chemicals
    • Compressible PTFE Pipe gaskets for Cast Iron Flanges – specifically formulated for use with cast iron pipe flanges; also referred to as Gore UPG ring gaskets
    • Compressible Rinforced PTFE Pipe gaskets – made from soft expanded PTE, these stainless steel reinforced gaskets can retain their shape
    • PTFE Pipe gaskets – pure PTFE gaskets (i.e. slippery) that prevent sticking between two surfaces
    • Viton Fluro-elastomer Pipe gasket: resistant to boric and citric acid, isopropyl (rubbing) alcohol, fuel, oil and transmission fluid
  • High-Temperature / High-Pressure
    • Graphite Gaskets – able to withstand temperatures up to 750 F; contains stainless steel inset for strength to handle up to 1000 psi
    • Graphite/Buna-N Gasket = blend of graphite and Buna-N rubber to withstand temperatures up to 650 F
    • Silicone Gasket: Withstand temperatures up to 450 F; resists water and salts
    • Oil-Resistant Carbon/Buna-N Gaskets: This mixture is unaffected by oil and can handle temperatures up to 650 F
  • Oil-Resistant
    • Aramid/Buna-N Gaskets: resists oil, water and aliphatic hydrocarbons (i.e. ethylene)
    • Compressible Buna-N gaskets: this rubber gasket ensure a tight seal and resists water and salts
  • Ultra-High-Temperature
    • Vermiculite Gaskets which can withstand temperatures up to 18000 F
  • Water and Steam-Resistant
    • EPDM gaskets; resistant to salt water
    • Neoprene gaskets; resist salts
    • Aramid/SBR rubber gaskets; resists water, inert gases and abrasion
    • SBR rubber gaskets; higher abrasion resistance than Aramid/SBR mixture gaskets

^ Return to top

Different Types of Gasket Materials

Cork Gaskets

  • Cork is natural and lightweight that comes from a bark of the Cork tree found in the Mediterranean
  • When used in making gaskets, the cork is ground down and bound together using a “binder” which can be a simple glue or resin, or can incorporate rubber, carbon or other materials
  • Cork is very extremely compressible and resilient (it can be compressed on one direction while maintaining dimension in the other direction)
  • Fire retardant / high resistance to abrasion
  • Low conductivity to hear / absorb noise and vibration
  • Most modern gaskets are no longer made from cork only

Cork-Rubber Gaskets

  • Rubber makes cork denser, providing better resistance to leaks by eliminating pathways that can cause leaks
  • Can handle swelling better than a Cork gasket for better seal
  • Nitrile is the most common rubber used in this mixture, followed by neoprene and a blend of various rubbers

Rubber-Fiber Gaskets (felt)

  • These rubber-fiber sheets are commonly referred to as fabric-reinforced, multipurpose neoprene rubber sheets
  • Has a cotton/polyester fabric for every 1/16″ of thickness to maintain size and shape under heavy compression
  • In high-strength fabric-reinforced multipurpose neoprene rubber sheets, there is one layer of nylon fabric for every 1/16″ of thickness
  • Most often used as flange gaskets, this material can better handle heavy compression which would normally squeeze non-reinforced neoprene out of place

Rubber-Cellulose Gaskets (fiber)

  • Cellulose can be categorized as fibers that are in nature and are not petroleum-based, such as plant and animal fibers
  • Thicker than other materials, a rubber-cellulose gaskets are traditionally 3/64″ thick and are commonly used for sealing water (i.e. water pump) or coolant
  • Ideal to be used for water and oil sealing applications
  • Aramid and Cellulose Gasket – For irregular flange surface; Latent cure styrene butadiene rubber binder; Used for oil and water sealing

Gasket Material – Brand or Trade Names

Compressed Non-Asbestos

  • Garlock Blue-Gard
  • Thermoseal (Klingersil)
  • Frenzelit Novapress
  • JM Clipper
  • Teadit
  • Armstrong

Cork / Cork-Rubber

  • Composition Cork
  • Cork / Fiber
  • Cork / Neoprene Blend
  • Cork / Nitrile Blend

Felt

  • Acoustic Grade
  • Felt Stripping
  • Polyester Felt
  • SAE Grades
  • Sheet Felt
  • Wool Felt
  • Woven Wool Felt

Fiber

  • Cellulose Fiber Beater Ad
  • Cellulose/Synthetic Rubber Beater Ad
  • Cellulose/Nitrile Rubber Beater Ad
  • Cellulose Fiber Paper
  • Compressed Fiber Sheet
  • Fibercork
  • Fiberflex
  • Fish Paper
  • Non-Asbestos NBR Aramid Fiber
  • Tan Fiber
  • Vegetable Fiber (Detroiter)
  • Vellumoid
  • Vulcanized Fiber

Fiberglass

  • Braided FG Tape
  • Drop Warp Tape
  • High Temp Cloth
  • Plain FG Tape
  • Braided Rope
  • Twisted Rope
  • Vermiculite Coated FG Tape

Foam

  • Closed Cell EVA Foam
  • Polyester Foam
  • Polyether Foam
  • Polyethylene Foam
  • Polyurethane Foam
  • Cross-linked Polyethylene Foam
  • Volara
  • Poron Foam
  • Ensolite Foam
  • Silicone Foam

Graphite

  • Garlock
  • Grafoil
  • Frenzelit Novatec
  • Thermoseal (Klinger)

High Temperature

  • Compressed Non-Asbestos
  • Fiberfrax Ceramic Fiber
  • Flurosilicone
  • Frenzelit Novatec
  • Graphite
  • PTFE
  • Silicone
  • Silicone Sponge and Foam
  • Viton

Rubber Materials

  • Cloth-Inserted (CI)
  • Diaphragm
  • EPDM
  • EPDM Nylon Inserted
  • Peroxide Cure EPDM
  • FDA Approved (food grade)
  • Flourosilicone
  • Hypalon
  • Natural (gum) Rubber
  • Neoprene
  • Nitrile Buna-N
  • Polyurethane
  • Santoprene
  • SBR (red rubber)
  • Silicone
  • Skirtboard
  • Sponge Rubber
  • Urethane
  • Viton
  • White FDA Neo/Buna
  • Fiberfrax Ceramic Fiber
  • Flurosilicone
  • Frenzelit Novatec
  • Graphite
  • PTFE
  • Silicone
  • Silicone Sponge and Foam
  • Viton

Closed-Cell Sponge Rubber

  • Cross-lined Polyurethane
  • EPDM Sponge
  • Epichlorochydrin (ECH) Sponge
  • Neoprene/EPDM/SBR Sponge Blend
  • PVC-Nitrile Sponge
  • Silicone Sponge
  • Viton Sponge

Open-Cell Sponge Rubber

  • Neoprene Open Cell Sponge

^ Return to top

Commonly Used Gasket Materials by Sector

Automotive Industry

  • The most common gasket materials used in the automotive industry are nitrile and viton based polymers which are fuel and oil resistant
  • For use with combustion engine parts, non-asbestos fiber and graphite materials, which are fuel/oil resistant as well as high tolerance for heat, are used
  • Cork composite materials, which are natural cork blended with nitrile, can also used as a less expensive alternative option to pure nitrile rubber gaskets

Drinking Water / Water Industry

  • Gaskets used in the potable water industry must follow a strict health guidelines to prevent contamination
  • Neoprene and graphite gaskets used in this industry which are highly resistant to UV and can handle steam under high pressure

Electrical Industry

  • Primary purpose of gaskets in this industry are used as weather so the material must be able to handle a wide range of temperature swings and harsh weather elements
  • Cork, rubberized cork, Neoprene, nitrile foams and rubbers are commonly used under these applications

Oil and Gas Industry

  • O&G industry requires gaskets must be able to withstand high temperatures and harsh environments
  • Most gaskets are made from composite materials including graphite and clay -based materials

Petrochemical Industry

  • The flange gaskets commonly used in the petrochemical industry ae made with non-asbestos gasket materials
  • In addition to graphite and non-asbestos materials, nitrile, silicone and PTFE in foam can also be used which are all resistant to fuel, oil and corrosion

Where to Buy

  • FEL-PRO 3046
    • Material Type: Rubber-Cellulose
  • FEL-PRO 3046
    • Material Type: Karropak
    • Sheet dimension: 36″ length x 12″ width (9.14 cm x 30.5 cm)
    • Thickness: 1/32″ (0.8 cm)
    • Application: Good for sealing oil in auto; smaller places (i.e. carburetor, Idle Air Control (IAC), sealing oil, coolant, gearbox and gasoline/diesel; for larger applications, like replacing a valve cover, consider using a thicker material like cork-rubber
    • Tips: Use a clothing iron to flatten the cutout before installing
    • Notes – Unknown durability when used with E85 gasoline mixture
    • Where to buy: Local automotive parts store may have this item; You can also purchase it from online retailers (Click here to check the latest price)
  • FEL-PRO 3022
    • Material Type = Karropak
    • Sheet dimension = 36″ length x 18″ wide x 1/64″ thick (0.015″ thick)
    • Application = automotive only
    • NOTE A – Very thin material designed to be used in gasoline and diesel environment to seal oil, coolant and other fluids (gearbox, idle air control box, carburetor, etc.)
    • NOTE B – For larger applications (i.e. replacing a valve cover) consider using a thicker material like cork-rubber along with a good sealant
    • Where to buy – Click here to check the latest price
  • FEL-PRO 3157
    • Material Type = Rubber-fiber
    • Sheet dimension = 36″ length x 18″ wide x 1/64″ thick (0.015″ thick)
    • Application = automotive only
    • NOTE A – Very thin material designed to be used in gasoline and diesel environment to seal oil, coolant and other fluids (gearbox, idle air control box, carburetor, etc.)
    • NOTE B – For larger applications (i.e. replacing a valve cover) consider using a thicker material like cork-rubber along with a good sealant
    • Where to buy – Click here to check the latest price

^ Return to top

Ensuring Material Quality

Current US industry standard is concerned about flame retardancy for consumer and environment safety.

The main international governing bodies are::

  • ISO (International Standards Organization)
    • A European organization tasked to verify quality control, continuing the work of the BSI Group and Germany’s VDMA (German Engineering Federation)
  • BSI (British Standard Institution) Group
    • UK-standards organization to ensure standard quality and manufacture of parts and products across many sectors
  • JIS (Japanese Industrial Standards)
    • All Japanese products are certified by JIS
  • UL (Underwriters Laboratories)
    • American worldwide consulting and certification company, certifying, validating, testing, inspecting, auditing and advising

^ Return to top

Gasket Installation Tips

  • If possible, choose a thinnest material as possible
  • Thoroughly clean the flange surfaces/studs/bolts/nuts
  • Make sure to NOT gouge or scratch the mating surfaces
  • Lubricate the bolts and nuts using molybdenum disulfide, copper or PTFE to ensure that matting surface receives even force
  • Tighten bolts in the sequence outlined in the manual

^ Return to top

Frequently Asked Questions

  • Should I use a gasket sealant along with a gasket for better seal?
    • In most cases, no. The primary reason for using a gasketing adhesive is to hold a large (cumbersome) gasket in place during installation. Gasket sealant, on the other hand, is designed to used in place of a gasket.
  • Do gaskets have to certified to work in certain temperature?
    • The main flammability test for rubber materials is UL94, UL94V-0, UL94-1, UL94HBF and UL94HF-1
  • What happens when gaskets are exposed to extreme low temperatures?
    • Rubber based gaskets gets very brittle and can crack at low temperatures
  • What happens when gaskets are exposed to extreme low temperatures?
    • When exposed to extreme high temperatures, rubber gaskets can melt, shrink, de-form or even ignite
  • Are thin gaskets better than thick gaskets?
    • Thinner is generally better because it will cause less leakage, higher resistance to blow-out, stronger compression strength and less expensive
  • Should I use a supplementary sealing product with a gasket?
    • In unique situations, you can either use the Indian Head shellac or Threebond 1194. Indian Head shellac can also be applied to the outer edge to seal. It should not be used when the product will come in contact with rubber parts.
  • What is Karropak?
    • Karropak is a chemically treated fibrous sheet designed for use on oil, water, gasoline
  • What kinds of substitute gasket substitute materials can I use to make emergency repairs?

^ Return to top