Thermoseal C4401: An (Almost) Universal Gasket Material

Gaskets seal everything from pipe flanges to manways but there’s no single gasket material that can do everything. However, Thermoseal C4401, (also known as Klingersil C-4401,) comes close. Here’s a quick review of how to select gasket material and an introduction to this versatile choice.

Factors to Consider

For every sealing application, a first step is to work out what material to use. This entails considering the temperature, environment, media, and pressure that the gasket will experience. (The mnemonic “TEMP” might help you remember this list.) Once those are known a gasket material can be chosen.

TEMP Compatibility Challenges

All gasket materials have a limited temperature range. Environmental concerns relate to things like exposure to ozone, UV light, and water. The media is the fluid being sealed in the pipe or outside the enclosure or man-way. And the pressure is the force the gasket will be exposed to.

Of these factors, media may pose the biggest sealing challenge. Every gasket material resists attack by some chemicals but is susceptible to others. EPDM for example is acetone-resistant but vulnerable to many fuels and oils. (Those examples are taken from “Gasket Material Compatibility Chart for Chemicals”.)

Meet Thermoseal/Klingersil C-4401

Thermoseal C4401 is one of a family of compressed fiber-reinforced gasket materials produced by KLINGER Thermoseal. These are made by mixing fibers into a rubber-like binder and then rolling it into a sheet. The fibers provide strength while compressibility and recovery come from the binder.

In Thermoseal C4401 the binder is a nitrile rubber and the fibers are aramid. Aramid is a light and strong synthetic fiber that resists abrasion and solvents. Nitrile is a form of synthetic rubber with excellent elastic behavior and good oil resistance. When combined the result is a gasket material that withstands temperatures as high as 750 °F (399 °C), and withstands a long list of chemicals.

Ask About Thermoseal/Klingersil C-4401

If you’re unsure about the media you’re sealing or just looking for a universal gasket material, C4401 is an excellent choice. Specialists at Hennig Gasket & Seals will be happy to tell you more.

Flexible Graphite Gasket Material – When to Use

If you need an alternative to PTFE gasket material, how about graphite? Produced as sheet material, flexible graphite gasket material withstands high temperatures while deforming easily enough to take up imperfections in flange surfaces.

Chemistry and Production

Graphite is a form of carbon. It’s used in pencils because it’s easy to slide the layers apart and spread them on paper. To produce a useful gasket material the graphite is first expanded and then passed through a machine called a sheeter.

Expanding entails exposing small pieces of graphite to sulfuric or nucleic acid. These force the atomic layers apart, making the graphite expand dramatically and forming what look like tiny worms. These “worms” are then fed into a sheeter that compacts them into a sheet of flexible graphite material.

For added strength, the graphite can be laminated onto either a thin stainless steel foil or a stainless tang.

Properties of Flexible Graphite Gasket Material

The practical upper-temperature limit is around 750 °F (399 °C) although some grades will go to 900 °F (482 °C). You may see claims that graphite can withstand temperatures as high as 5,400 °F (2,982 °C) but this is in an oxygen-free atmosphere, which few gaskets ever experience.

A limitation of sheet form expanded graphite is low tensile strength. Laminating onto 316 stainless raises this from around 700 psi to a much more useful 5,000psi. In terms of gasket applications, this means pure graphite sheet has very low resistance to pressure: foil and tang forms of graphite sheet are far more useful.

The downside of combining graphite with stainless is that this slightly reduces both compressibility and recovery behavior.

Graphite has excellent resistance to water, steam, hydrocarbons, and many acids and alkalies. However, sulfuric or nucleic acids will cause rapid decomposition. Note that graphite is not suitable for food, medical or pharmaceutical applications because there’s a possibility of releasing carbon particles into the fluid.

Flexible Graphite Gaskets Cut to Size

Hennig Gasket & Seals carries flexible graphite gasket material in a range of thicknesses. Gaskets can be cut to sizes up to 48” in diameter. Contact us for more information.

What’s Special About Food Grade Silicone Gasket Material?

Silicone makes excellent gaskets. It works over a wide temperature range, has a low compression set, high elongation, and is resistant to water, ozone, many acids, and UV light. If you’ve shopped for silicone gaskets or gasket material you probably noticed some formulations are specified as “food grade.” Here’s what that food-grade silicone gasket material means and why it might matter in your application.

Composition, Properties and Forms of Silicone Gasket Material

Silicone is an elastomeric polymer made from silica, (which is silicon dioxide, or sand), water and methanol. Silica is chemically inert and very stable, even at temperatures as high as 550 °F. It’s also an electrical insulator.

As a gasket material silicone has two weaknesses. First, it’s not oil-resistant and should not be used where it might be exposed to oil-based greases and lubricants. Second, it has poor wear and abrasion resistance so is best used as a static gasket rather than in applications where there’s sliding or dynamic contact.

Silicone gasket material is produced as a solid sheet in a range of thicknesses. It’s also available in foam and sponge form.

Food Grade and Non-Food Grade Silicone

Pure silicone is white. If it has no additives and is not ink-marked it will probably be suitable for use with foods. However, it’s important to check that it complies with 21CFR Part 177.2600 before using it in food or beverage-related applications. This is the FDA regulation that governs the purity of materials classed as food grade.

Some silicones are formulated with fillers, coloring, or both. This is to provide a particular appearance, improve wear behavior or reduce compression. However, some of these can leach out into the liquids or solids they come into contact with. If you need food-grade silicone gasket material with additives, check it meets FDA standards.

Ask Your Silicone Gasket Material Supplier

If you’re installing or replacing gaskets on food processing and preparation equipment they should be food grade, as defined by the FDA. Silicone is a good choice for food-grade gasket material.  Contact Hennig Gasket & Seals for various silicone gasket material options for your application.

When to Use a Full Face Flange Gasket

When you’re installing or replacing a gasket between pipe flanges correct alignment is important. If it’s misaligned, the part will protrude into the fluid flow while on the opposite side there’ll be a cavity. On both sides, there will be less gasket material trapped between the flange faces.

A full-face flange gasket avoids this problem because it’s located by the flange bolts. However, this design isn’t necessary for every application. Read on to learn more.

Full Face Flange Gasket vs. Ring Gasket

Flange Gaskets: Full-Face or Ring” explains the difference between the two types. Choosing which to use is largely a matter of clamping force needed and flange design.

A gasket prevents leaks by taking up imperfections between mating surfaces. This is achieved by firmly compressing the material so it conforms to both faces. This compression also helps the gasket resist the internal pressure within the pipe. The higher the pressure the greater the compression needed, (and it helps to keep the gasket as thin as possible.)

Ring-type flanges seal over a smaller area than full-face designs and apply higher compressive loads for a given bolt tightness. This needs to be considered when selecting a gasket material. Elastomeric gaskets can be crushed if over-tightened.

Because they seal over a larger area, full face flanges can’t achieve the same compressive load without tightening the bolts more than would be done for a ring face flange. Thus full face flanges, and also full face flange gaskets, are reserved for lower pressure and less critical applications. Conversely, most process plant piping systems use ring face flanges and gaskets.

Full Face Flange Gasket Versatility

A full-face flange gasket can be used in a ring face application. The material outside the faces won’t contribute to sealing but the bolt holes make it easier to position. Just be sure to get the right material properties and thickness for the task. However, don’t use a ring-type gasket in a full face application. You’ll be sealing over a smaller area and there’s a risk of bending or cracking the flange.

Contact us for a free full-face gasket quote.

When To Use Garlock Blue-Gard 3000

Garlock is one of the best-known brands in gasket materials and they have an extensive range of products. Here we’ll take a look at one of their materials that’s suitable for a wide variety of applications: Garlock Blue-Gard 3000.

Garlock Blue-Gard® 3000 Composition

The spec sheet tells us Blue-Gard 3000 is composed of aramid in an NBR binder. Here’s what that means.

The word “aramid” is a contraction of the chemists’ term, aromatic polyamide. It’s a generic term for high strength fibers produced from PPTA (poly-p-phenylene terephthalamide) polymer. You may recognize one of the widely used brand names: Kevlar.

In gasket material, these fibers need holding together. That’s the job of the NBR or nitrile rubber. NBR also provides the elasticity and compressibility we look for in a good gasket material.

Properties of Blue-Gard® 3000 Gasket Material

Aramid is very strong with excellent abrasion and creep resistance. It doesn’t melt or burn, even at very high temperatures, and it resists attack by solvents and oils. It will however degrade with prolonged exposure to UV light.

NBR is limited in the maximum temperature it can tolerate and is attacked by ozone as well as ketones, esters, aldehydes, and chlorinated hydrocarbons. Two examples of chemicals it should not be exposed to are acetone and benzene.

Where NBR excels is in resistance to oils, including those used in hydraulic systems, as well as fats and greases. When exposed to these oils it will swell. It also has good elasticity but will creep under load.

Garlock 3000 combines the most useful properties of aramid and NBR. It can tolerate 400°F (205°C) and has excellent creep resistance, which makes for good torque retention. Good strength means it withstands high internal pressures and it also resists attack from a wide range of oils.

When (And When Not) To Use Blue-Gard® 3000

Good uses are for sealing water, oils, and greases, even those being moved at high temperatures. Applications involving thermal cycling will benefit from high creep resistance. Applications to avoid are those with exposure to ozone, (such as high voltage electricity,) as well as perfumes and foodstuffs.

Hennig Gasket & Seals is the preferred vendor of Garlock Blue-Gard® 3000 and all other Garlock gasket material.  Contact us today for a quote on custom cut Blue-Gard® gaskets or sheets of Garlock gasket material.

Gasket Materials for Washdown Environment

Cleaning is important in many industries, but pharma and food and beverage have it down to a fine art. For those sectors frequent intensive washdowns are a way of life and equipment gaskets must be up to the task. Silicone gasket material and neoprene gasket material are, open-cell foams are not. Here’s some detail.

The Washdown Process

Water heated to 170°F is blasted at 1,500psi of pressure to remove every trace of dirt and contamination. For extra-thorough cleaning caustic chemicals might also be added, creating an even more challenging sealing environment.

NEMA and IP Ratings

Enclosures are rated for the “ingress protection” they provide. NEMA is the US system while elsewhere they like the “IP” categories. A NEMA 4 rating, broadly equivalent to IP66, means an enclosure is designed to resist jets of high-pressure water from a hose. In other words, washdown. A step up in protection is NEMA 4x or IP69k. NEMA 4x protects against aggressive chemicals while IP69k is a rating for steam jet cleaning.

Gasket Materials for Washdown Environments : EPDM, Silicone, Neoprene

First, note that equipment and enclosures should be designed in a way that prevents water jets from directly impinging on the gasket material. Even with that though, the gasket outer surface is still going to get soaked.

This is why open-cell foam is not appropriate. It’s going to let water soak through to the interior. Closed-cell foam is better and solid better still, (though not as soft or compressible.)

Second, the gasket material must resist attack by hot water, possibly incorporating caustic chemicals. Good candidates are EPDM, silicone, and neoprene. Some points to note about each of these are:

  • EPDM gasket material is also UV-resistant. That makes it a good choice outdoors and wherever UV light is used.
  • Silicone gasket material is flexible from –100 to 500°F.
  • Neoprene gasket material works over a range from -40 to 250°F. It also has good oil resistance but is attacked by ozone.

Ask the Experts

You should know the strengths and limitations of the gasket materials you’re considering. The specialists at Hennig Gasket have a lot of knowledge and experience. Call them or reach out by email.

SBR Sheet – 7 Uses

Natural rubber is an imperfect material for gaskets. While soft and compressible at room temperature it hardens in the cold and has poor weather resistance. Styrene Butadiene Rubber (SBR) is a manmade alternative that comes in mainly in extruded and sheet form. For gaskets, SBR sheet is inexpensive and performs well in a range of applications. Here’s a closer look.

Properties of SBR Sheet

SBR is an abrasion-resistant elastomer manufactured in hardnesses ranging from 50 to 80 Shore A. (50 is firmer than a pencil eraser while 80 feels like a leather belt.) It’s also less variable than natural rubber.

SBR has good impact strength and tensile strength from 400 to 1,000 psi. Consider fabric-reinforced grades for applications needing higher strength.

For gasket applications, SBR sheet has high resilience and low compression set. It resists acids, brake fluid, and moisture but is attacked by oils and hydrocarbons. Useful temperature range is -40°F to 180°F (-40°C to 82°C) though limits vary by grade.

SBR Sheet Availability

SBR is available in sheet and roll form up to 36” wide. Thicknesses are from 1/64” to 1/4” with wider and thicker sheet available for special order. SBR sheet comes mainly in black, red and gray. For other colors please ask.

Applications for SBR Sheet

SBR is a good choice for applications needing flexibility and abrasion resistance. Examples include:

  1. Flaps (access doors and panels, seals around doors.)
  2. Scrapers and wipers (especially those used in low-temperature environments.)
  3. Lining rubber (Placed over workbenches and in drawers, SBR sheet absorbs impacts and prevents damage to tools and workpieces.)
  4. Conveyor Belting
  5. Skirtboards (Rubber strips at the base of walls in high-traffic and washdown environments.)

High resilience and low compression set make it a good two choice for two other types of application:

  1. Brake system seals
  2. Gaskets

The Manmade Alternative

Natural rubber would make an excellent gasket material if it didn’t stiffen in low temperatures and had better weather resistance. SBR sheet has similar useful properties – abrasion resistance, resilience, and strength – without the weaknesses. If you’d like to learn more, specialists at Hennig Gasket can help.

How to Install a Gasket

The costs of gasket failure are far greater than the price of the gasket itself. A leaking joint means wasted gas or liquid, and that can have safety and environmental implications. Unplanned downtime cuts into production, reducing output and perhaps needing expensive overtime working to make good the shortfall. Then there’s the actual time and effort involved in opening up the joint, cleaning the faces and installing a new gasket.

Bottom line: you only want to do the job once, so do it right. Here’s what and what not to do.

Don’t reuse an old gasket. It’s a false economy. The material has been compressed and creep has taken place. It won’t have the recovery of a new gasket so it won’t seal as well.

Do clean the mating faces thoroughly. Residual gasket material or adhesives will reduce the ability of the new gasket to make a good seal.

Don’t use a gasket that’s thicker than what the flanges need. Remember, the purpose of the gasket is just to take up surface imperfections and misalignment and to handle expansion and contraction. An unnecessarily thick gasket is more likely to fail.

Do choose a gasket that’s appropriate for the joint TEMP – that’s Temperature, Environment, Media and Pressure. Soft gaskets – those made from materials like neoprene, graphite, fiber or cork – should not be used in high-pressure applications. Ask your gasket material supplier if they can provide pressure-versus-temperature (PxT) charts for your preferred material.

Don’t overtighten a soft gasket joint. Once the gasket has been crushed the material loses its ability to recover as the joint opens up. That leads to leaks.

Do follow the correct bolt tightening procedure. See “How To Bolt Flanges” for details.

Don’t glue thin gaskets together to make one thick enough for the joint. It won’t behave like a gasket of the right thickness and will almost certainly fail prematurely.

Do it right

Replacing a gasket outside of scheduled maintenance periods is often awkward and expensive. Achieving a long life is a function of gasket selection and installation, and these dos and don’ts will help.

White Nitrile Rubber

Gaskets made from white nitrile rubber won’t impart any taste to food. That’s one reason they’re used in food and beverage production but it’s not the material’s only useful property. Here’s a look.

Understanding White Nitrile Rubber

White nitrile rubber chemical name Acrylonitrile Butadiene carries the ASTM designation NBR and is sometimes referred to as white Buna-N. A blend of neoprene and SBR, white nitrile rubber is an abrasion-resistant elastomer. Shore hardness is around 60, putting it somewhere between tire tread and a pencil eraser, making it firm yet flexible.

White nitrile is usable over temperatures from around -40°F to 220°F (-40 to 105°C.) It resists attack by oils, fats, greases and hydraulic fluids although it is vulnerable to ozone, ketones, esters and aldehydes. (These were explained in a previous blog post, “Ketones and Gasket Materials”.)

Nitrile rubber is produced in a range of colors, but white nitrile is, as the name suggests, white. This gives it some useful applications.

Applications for White Nitrile Rubber Gaskets

As it doesn’t mark surfaces or impart a taint, white nitrile is available in grades approved by the FDA for food use. It’s also non-allergenic. Consequently, white nitrile gaskets are common in food and beverage production as well as pharmaceuticals.

White nitrile rubber is also used in applications where appearance matters. The smooth white finish is often desirable, especially in medical applications, and has a secondary benefit: it shows up leaks that would be unseen against dark materials.

In addition to sealing and gasketing applications, white nitrile is used for cushioning and protection. You may see it as liner in food processing equipment and also as bumper protection strips. A less obvious, though still common application, is for food grade rubber scrapers.

Talk to Hennig Gaskets & Seals

Gaskets for food and pharma use must comply with FDA requirements. White nitrile is often a good choice for such applications, although it has other uses too. As an attractive, non-marking material it works well in situations where appearance matters. Learn more by talking to our specialists.

Spiral Wound Gasket Manufacturers

Spiral Wound Gasket Manufacturers and Suppliers are your best resource for understanding the selection process.  When choosing a gasket material recovery and compression set should be important considerations. That’s because joints flex and move under changing temperature and pressure. If the gasket material can’t adapt to a varying distance between flanges the joint is certain to leak.

Rather than rely on the inherent material properties, spiral-wound gaskets seal by acting like a spring, expanding and contracting to fill the space available. Spiral-wound gaskets aren’t the solution to every gasketing problem, but for flanged joints, and especially those in petrochemical industries, they can be an excellent solution.

Spiral-wound gasket construction

Spiral-wound gaskets are made from a flat metal strip coiled into a shape rather like a clock spring. Interleaved with the steel is a good sealing material like PTFE or graphite. The metal is given a bend as these are coiled so that in profile it has a ‘U’ or ‘V’ form.

This profile gives the gasket its excellent recovery. Imagine the flange faces pressing against the legs of the ‘V’: closing the gap compresses this shape while opening it lets the ‘V’ spread further apart. In this way, the gasket stays in contact with each flange and maintains a good seal.

Most spiral-wound gaskets have a solid metal outer ring. This prevents over-tightening which would damage the gasket. Some also have an inner ring to protect against chemical attack or high pressure.

When to use a spiral-wound gasket

Spiral-wound gaskets excel in flange applications that see big swings in temperature and pressure. (The kind of environment that makes bolts lengthen and clamping pressure drop.) In addition, when the non-metallic element is PTFE or graphite these gaskets provide excellent resistance to chemical attack. This is why spiral-wound gaskets are the gasket of choice in refinery and related petrochemical applications.

Spiral Wound Gasket Manufacturers and Suppliers

It takes specialized equipment to manufacture spiral-wound gaskets. The leading producers are Flexitallic and Garlock. At Hennig we stock gaskets from both, and if you need something non-standard we can get that for you too. If you have an application you think needs a spiral-wound gasket, call or email and we’ll be happy to help.