The Top 5 Things to Remember When Working with Gaskets for Service Applications

Not all gaskets go into brand new applications straight off the production line. There are many gaskets used across the aftermarket, in service operations and in engine rebuilding. Do the same rules and considerations apply to the seal points and gaskets in service applications as they do in OEM manufacturing?

We have put together a list of considerations for those working with gaskets in situations where a gasket is being replaced.

 

Things to Remember

1. Flange surfaces will change – Over time and repeated heat cycles, flange surfaces can warp and become distorted, become pitted or corroded, or otherwise become less than ideal. When replacing a gasket, you’ll either need to spend both time and money machining the flanges back to their original state, or use a gasket that can compensate for the irregularities now present. Often, thicker, more compressible gaskets are used in service applications to not only save cost in flange prep, but to make up for material lost in the flange resurfacing process.

2. Replacement products vary greatly – Service parts are available across an entire spectrum of price and quality. Customers typically are in control of choosing the cost and quality of the parts used in the repair. Parts are available from OEM quality (or better) down to low cost/low quality choices. How long do you want the gasket to last?

3. There are alternatives to the OEM gasket – While marketing experts will want you to believe that you can only replace a gasket with the same OEM gasket, there are actually quite a few OEM-quality replacements on the market. You can usually save some money and sometimes get better performance.

4. Multiple factors to consider – There are many factors to consider in the process of replacing gaskets. One of which is the installation process itself. What is the torque? What is the sequence? What is the process? Should I include a sealant? Should I retorque it? Is it possible it might be upside down? Are the flanges clean and prepped? The answers to these questions will ultimately help you to settle on the proper replacement gasket, as well as ensure it will perform as expected in your application.

5. Materials / Construction – Have you explored and considered the various material choices for service applications? Which one is best? There are often different constructions of gaskets. Some are single layer materials, some are embossed metal, some are composite laminates. Which is best? Often, the composite designs are the best choice in replacement parts as they best compensate for the factors mentioned throughout this post.

 

Plenty of Options

Although there are a few extra considerations when choosing a gasket or gasket material for a service application, you may actually find that you have a little more latitude. There are materials out there that have characteristics that excel in these markets. Talk to your trusted gasket material supplier to  figure out which materials will be best suited for your application.

What differences do you find between sealing OEM and service applications?

Metal Tech offers the HT337, which works well in many service applications.

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Jacketed Gaskets: Here’s Why & Where You’d Use One.

Have you ever dealt with applications that require jacketed (or sometimes called double jacketed) gaskets? While the technology may not be as commonly used as others, it is one that definitely has its place in the sealing world.

In today’s post, we’re going to address what they are, as well as why and where you would use one.

 

The Details

What is a jacketed gasket? – A jacketed gasket has a construction composed of a soft filler material, wrapped by a metal outer layer. Often, this is a two-piece metal construction with a flat layer against the soft facing and a wrap layer that wraps at both sides to form a complete enclosure to encapsulate the filler.

Why would I need a jacketed gasket? – High pressure/high temperature applications often need a rigid shield to resist blowout. Also, the jacketing feature protects the core layer from the conditions.

Where would I use a jacketed gasket? – These gaskets are used in high pressure and high temperature applications where flange areas are limited, but a rigid construction is needed. They are also used in high load exhaust applications, heat exchangers, and pipe flange gasket connections.

Does material selection matter? – Of course it does! The metal layer must be chosen for the environment, with stainless being preferred. Also, the filler material can come from a variety of choices. Often a tanged core graphite or fiber layer is chosen for it’s compressibility yet rigidity in handling and durability for long-term performance.

 

Meeting Your Needs

It is important to continue to educate yourself on the various gasket technologies available in order to make the smartest choice for your particular needs. As always, your trusted gasket material supplier(s) will often be a great resource for you when it comes time to narrow down your choices. Understanding jacketed gaskets and the applications that they are suited for will make it that much easier to make your decision.

How often do you work with jacketed gaskets?

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Losing Load in a Gasketed Joint? Here’s What You Can Do About It.

There are many reasons why load can be lost in a gasketed joint. Maintaining the desired load can be a challenge at times for a variety of reasons. Today we’re going to cover some of these reasons.

Before we get into it, we want to make sure all of our readers are on the same page and understand what we mean by ‘losing load’. Load is the amount of force (pressure) placed on flanges by applying torque (tightening the bolts) to create the proper seal with the gasket. When you ‘lose load’, your bolts do not retain the torque values applied to them and the gasket will no longer seal properly.

 

Losing Load

Here are a couple of reasons why you could be losing load, which may help you troubleshoot any issues.

1. Material has creep/relaxation. Most compressible materials have some level of this which should be considered in the assembly.

2. Improper material selection. Materials exhibit different characteristics in assembled conditions. Be sure to understand the parameters to select the proper choice.

3. Insufficient load – bolts are not torqued sufficiently.

4. Bolt incorrect – bolts may be undersized or an improper grade for the load required.

5. Environmental exposure or thermal cycles can cause materials and hardware to lose load due to compression/recovery, creep/relaxation, bolt stretch/yield, etc.

 

Find Something That Works

The inability to achieve a proper seal due to loading issues can be a very frustrating issue to resolve. Using some of the information provided above can be a good starting point for you to resolve any of these issues. If troubleshooting seems to point back to a poor gasket material selection or a design flaw that cannot be fixed, talk to your trusted gasket material supplier. They should be able to offer a few suggestions on materials that may be better suited for your application.

What is the root cause of most of your loading issues?

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The Top 6 Applications Where Composite Gaskets Excel

There are a handful of gasket materials and technologies that are acceptable for a variety of conditions within an application. However, as you venture into specific conditions, those options start to narrow – especially as you get into higher temperature and higher pressure applications.

As an experienced materials manufacturer, when we hear a customer or potential customer start talking about gasketing needs, there are certain applications where we know immediately that metal reinforced composite laminates are a great option. To help you in your planning process, we decided to put together a list of the top applications where these types of gaskets excel (in no particular order).

 

Look to Composites

1. Exhaust system gaskets – Composite laminates work well in exhaust systems because they tolerate heat and distortion of the flanges. They can also be made with a stainless steel core to resist corrosion and provide long term performance.

2. Aftertreatment system gaskets (DPR, EGR, etc.) – Composite materials perform well here with the rigidity of the steel core for strength and the sealability of the facing material in aftertreatment joints.

3. Manifold gaskets (exhaust/intake) – Graphite laminates are one example of a composite laminate that works well in exhaust manifold gaskets. The material helps to manage heat flow while maintaining a seal.

 4. Collector gaskets – Collector gaskets are generally high temperature flanged joints that require a compressible material to seal the joint. Often, composite materials are the first choice here due to their economic advantage and compressible nature.

5. Cylinder head gaskets – Head gaskets have been successfully made from graphite composite laminates since the mid 1980’s. These gaskets perform well as they seal a variety of surfaces while managing heat and providing long-term service.

6. Aftermarket/replacement gaskets (head, exhaust, and intake applications) – Composite laminates are by far the best choice in aftermarket/replacement applications. They provide additional compressibility and conformance to seal against less-than-ideal flange surfaces while compensating for removed material such as surfaces that are refinished. Composites also provide lasting service with their ability to compress and recover in these applications.

 

Materials that Survive

If you’re dealing with applications that meet any of these conditions, it is important to be aware of the types of materials that are known for successfully sealing them. Once you have an awareness of the general direction you should be going in, talk to a gasket material supplier that specializes in that type of material. Then, you can narrow down your choices to the one material that is best suited for the conditions it will need to withstand.

What are the other applications where you prefer metal reinforced composites?

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Re-torque?!? We don’t need to re-torque! Or do we??

Do you understand when and why a re-torque would be needed to maintain an optimal seal in your joint? Is a re-torque ever not necessary? All of these burning questions and more are addressed in this week’s post.

 

Re-torque or Not to Re-torque?

1. Typically, when and why do a majority of re-torques need to happen? The best scenario is to re-torque all gaskets after they have seen their first heat cycle. This will provide sufficient loading after the initial relaxation of the part due to heat exposure. Gaskets that NEED to be re-torqued are typically softer construction, with low recovery values and can benefit by being reloaded or re-torqued.

2. Under what conditions would a re-torque not be needed? Stiff gasket materials with good recovery and low creep-relaxation properties such as metal gaskets or high density graphite gaskets would be an example of such items.

3. Are any re-torques ever required beyond the initial one? Typically, no. Further re-torquing will result in crushing of the material beyond it’s designed loading. Most OEM gaskets are designed to be used without re-torquing, as this is not an option on a new engine. Aftermarket parts, however, can often be re-torqued, depending on the application, allowing a more cost-effective material selection to perform adequately.

4. Can multiple re-torques be a sign of a design flaw or gasket issue? It is normally not necessary to re-torque more than once. Ongoing leaks or gasket failure indicate that a better material should be selected in that joint.

5. What are some of the conditions you might observe when it is time for a re-torque? Bolts may be loose or have low retained torque. Also, the gasket may exhibit slight leakage or failure to seal.

 

Now You Know

We hope this helped clarify any misunderstanding that might be out there regarding re-torquing and its standard practices. It really is very straightforward when it does and does not need to occur, and a lot of it really is material-dependent. If you have any questions or concerns about a specific material, talk to your trusted gasket material supplier.

Until next time!

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