Thermal Cycling Effects on Valve Operation

Jan 21, 2021

By: Bruce Ellis, Inside Sales Consultant at Triangle Fluid Controls Ltd.


What is Thermal Cycling?

Thermal Cycling is the process of alternately cooling & heating material and is often used in manufacturing environments to enhance the material’s properties.

Wafer Check Valves

When a wafer valve is placed in an application that has a wide range of thermal cycling or is exposed to prolonged periods of high temperatures, other system components may be affected. Exposed studs that span from the outside of the flanges on either side of a standard wafer valve, will elongate and can lead to a decrease in bolt load on the gaskets. This will cause the gaskets to leak.

One of the most recent products offering from DFT® is the TLW® (Tapped Lug Wafer valve). This valve is based on the proven wafer designs of the ALC® and WLC® and has many of the same trusted benefits and features, just in a lug style valve.

The TLW® axial flow spring assisted check valve has a one-piece body design that is lightweight and compact. It meets the API 594 face to face dimensions and can be installed in both horizontal and vertical flow applications. The big difference between the standard wafer style valve and the TLW is the tapped design doesn’t have exposed studs which protects the studs from the negative effects of thermal cycling and reduces the opportunities for gasket failure due to stud elongation and relaxation. This style of valve is also suited to fire-safe applications where there is a need to protect bolt exposures as each end of the valve is bolted to the flange similar to the way a flanged valve is.


So, when thinking about valve applications involving high temperature or with a wide range of thermal cycling it is important to consider the valve type itself. The DFT® TLW® might be just the valve you want to use.
See the line-up of DFT® Silent Check Valves here.
Bruce Ellis is an Inside Sales Consultant at Triangle Fluid Controls Ltd. He may be reached at [email protected] or 613-968-1100.

Samantha Harrison promoted to QA/Applications Specialist

January 14, 2021


Samantha Harrison has been promoted to the position of QA/Applications Specialist effective January 18, 2021.

Samantha has been with TFC since April 2019 in the role of Lab Technician and has demonstrated a keen interest in the gasket technical side of our business. Samantha has shown great initiative in R&D Projects, ISO Administration, and learning gasket technical aspects to name just a few. Samantha is an excellent team player with a “can-do” attitude and has already begun to deal with distributor and end-user application questions in order to provide solutions.

Please join us in congratulating Samantha on her new role at TFC!




Chett Norton Appointed to the Role of General Manager, Durabla Canada Ltd.

December 28, 2020

Chett Norton


Chett Norton Appointed to the Role of General Manager, Durabla Canada Ltd.

“Chett first started with Durabla Canada in 2002 on Inside Sales. After a couple of years, he explored other opportunities in the USA, but eventually came back to Canada about 8 years later. I stayed in touch with Chett through that whole time as I always said that he would eventually replace me as the Durlon gasketing technical expert. Lucky for us, I convinced Chett to come to Triangle Fluid Controls in 2012 as an Applications Engineer and then in 2015, he was promoted to Engineering and QA Manager. Chett is probably one of the most hands-on team players that I’ve ever had the privilege of working with and to that extent, Chett has been involved in a vast array of projects and activity at TFC since 2012. With his enthusiasm, drive, professionalism, and ability to develop and grow, this next challenge as General Manager is the perfect fit for Chett, our companies, and Durabla Canada’s long-term stability.”

“Durabla is the name that started everything for us and Durabla will continue to be the name that stands the test of time. Durabla Canada will continue to play an integral role in the health and viability of our global gasket brands and under Chett’s leadership, we’ll get there together.” Mike Shorts, President, Triangle Fluid Controls Ltd.

Welcome Chett to the Durabla team!




Check Valves – Back to the Basics – Part 2

Dec 3, 2020

By: Bruce Ellis, Inside Sales Consultant at Triangle Fluid Controls Ltd.

What is meant by check valve sizing?

Sizing a centre guided valve is not difficult. Along with the pipe size, pressure class, and type of valve required (flanged, wafer, etc.), users need the actual working pressure, flow rate, media type, temperature, and the specific gravity of the media. It may be as simple as building the valve with a lighter spring to allow the valve to fully open. In order for the valve to reach the full open position, it may need a lift limiter to reduce how far the disc travels. When the valve is 100% open, it will be stable in the flow and will result in reduced premature wear and failure by eliminating the effects of chatter. It is very important to remember; these valves are designed to the actual flow values and not to the line size. A properly sized valve will be in either the full open, or closed positions.

Why size a valve?

Benefits of using a properly sized and positioned silent check valve:

  • It can protect a system from costly failures and down-time of a production facility.
  • The valve life span can be greatly increased by reducing the risk of parts breaking off and damaging equipment downstream.
  • It protects the pumps that are upstream by not allowing backflow which can severely damage the pump as it can spin in the reverse direction.
  • It leads to better pump and compressor protection.
  • It results in less piping vibration.
  • There is a reduction in Water Hammer issues.
  • It will work in the vertical down flow direction.


Return on investment

Initial “sticker shock” for a sized valve, in many cases can be scary, so we need to ask ourselves a few questions:

  • How long does the off-the-shelf valve last?
  • What does it cost to change it?
  • How much revenue is lost while it is being replaced?

Replacing a valve can be quite costly based on the effects of lost revenue, wages, and the cost of the replacement valve. The price of an off-the-shelf valve may be attractive, but what is the real cost of ownership? If a sized valve costs five times as much but lasts five times as long, consider how these affect your financial balance given maintenance costs and lost production.


While there are applications where double-door and swing check valves operate properly and are required, it is not true that these and other off-the-shelf valves are the only solutions. In any application where check valves are being used, having the correct valve installed could enhance the performance and extend the lifespan of the piping system, affecting the financial balance when adding maintenance costs and lost production. This translates into more value and overall, long term cost savings.
See the line-up of DFT® Silent Check Valves here.
Bruce Ellis is an Inside Sales Consultant at Triangle Fluid Controls Ltd. He may be reached at [email protected] or 613-968-1100.

The 5 W’s of Isolation Gaskets

Oct 8, 2020

By Chett Norton, C.E.T.


Isolation gaskets may seem to be a complicated subject when trying to determine what is required and whether you require them at all. When looking at possible isolation gasket application requirements I like to put on my “Sherlock Holmes” hat and asks myself the following 5 W’s – What, Why, Where, When, and Who.


Let’s begin with what are isolation gaskets? Isolation gaskets are exactly as they sound, they isolate flanges from the flow of electrostatic charges through the pipeline and or can separate dissimilar metals which can cause galvanic corrosion. For galvanic corrosion to occur you need an anode (metal 1), cathode (metal 2), and an electrolyte or carrier such as water to help allow the transfer between the two metals. The anode will be the sacrificial material and will corrode at a much higher rate than the cathode; in some cases, the cathode material may even stop corroding completely. The further the two metals are apart on the galvanic corrosion chart (Most Noble – Cathodic to Least Noble Anodic), the higher the potential for corrosion (See Figure 1 – Dissimilar Metals Chart below).



Durlon® iGuard isolation gaskets are commonly sold in kits that are composed of a gasket, a set of insulating sleeves for the bolts, 2 sets of insulating washers, and two additional sets of steel washers. (See Figure 2 – Isolation Gasket Kit Components). The gaskets themselves can be either full face (Type E), ring style (Type F) or RTJ (Type D) and are offered as a carrier ring such as phenolic, neoprene faced phenolic, Silicone Glass G-7 or Epoxy Glass G-10 or G-11 and comes standard with a Viton sealing element but has other sealing element options such as PTFE, nitrile or EPDM. Additionally, the gaskets can also be composed of sheet material such as Durlon® 8400, 8500, or 9000 (1/8” thickness recommended) which have excellent dielectric breakdown properties (371 – 406v/mil). The standard offering for isolating sleeves is mylar, Phenolic for the isolating washers, and zinc-plated steel washers. Additional materials for the isolating sleeves and washers are available upon request. See Durlon® iGuard technical datasheet here.




Galvanic corrosion is a big problem because it can lead to a rapid metal loss in piping systems and tanks. It can cause leaks or even failures which can have catastrophic consequences for plant personnel safety and the environment.


Isolation gaskets are found anywhere that you have flanges that consist of dissimilar metals such as cast iron to carbon steel or even aluminum to stainless steel for instance. The isolation gasket kits create a dielectric break which generates cathodic protection for both above and underground piping where metal components that are in contact which each other in the bolted flange joint assembly. Isolation gaskets are commonly used in the petrochemical industry, oil & gas, and marine/offshore applications that deal with high chlorides such as seawater.


Whenever galvanic corrosion or electrical isolation is a concern in the piping system. It should also be noted that there are additional benefits to using isolation gaskets (carrier ring with sealing element) such as:

  • Isolation gaskets seal at very low stress, perfect for low torque requirements
  • Installations that have frequent assembly and disassembly, such as pressure test stands. These can be reused multiple times due to their resilient double-ogee sealing element (normally it is not recommended to reusing gaskets).


    Engineers, plant & maintenance managers, pipefitters, and installers can all use the benefits of Durlon® iGuard isolation gaskets for plant piping protection in both new design and existing piping systems.
    So, if you are wondering if you need an isolation gasket for your application, there is a good chance you do, but if you are still not sure……give us a call and we can help guide you through the isolation gasket material selection process.
    Click here to learn more about Durlon® iGuard Isolation gaskets kits.

    Check Valves – Back to the Basics – Part 1

    September 25, 2020

    By: Bruce Ellis, Inside Sales Consultant at Triangle Fluid Controls Ltd.

    Many informative articles have been written about check valves in the past… with that being said, let’s take this discussion “Back to the Basics”. Check valves, or one-way valves, are designed to stop backflow and ultimately, to protect pumps & compressors. They are available in several styles and sizes; from 1/8” to as large as may be required.

    Check valves are found in many industries, and with various types of media, ranging from municipal water to mining and natural gas.

    The 3 most common types are Swing Check Valves, Double-Door Check Valves, and Silent Spring-Assisted Axial Flow:

    1. Swing Check Valves

    Generally speaking, this is probably the most common check valve in use today and is a full-port design, meaning the disc, when fully open, is out of the flow stream. This style of check valve is a good choice in applications that have a high percentage of solids and a lower on/off cycle count. Due to the travel distance of the disc, swing check valves close slowly. This causes the last push of reverse flow to slam the disc closed, resulting in a huge pressure spike, causing Water Hammer*.
    *A pressure surge when a fluid, in motion is forced to stop or change direction suddenly, causing a pressure wave in the pipe. This pressure wave can cause major problems, from noise and vibration to pipe collapse.


    2. Double-Door Check Valve

    This valve is similar to the swing check and a little better in terms of closing because of the coiled springs that assist the two cantilevered doors in closing more quickly. It has been proven time and time again that this is not the best choice when faced with Water Hammer though they will perform better than a swing check valve. Generally, this style of valve is considered an off-the-shelf commodity valve with little customization available.


    3. Silent Spring Assisted Axial Flow Check Valve

    These full flow valves typically incorporate a centre guided stem-disc assembly along with a compression spring. This means the disc stays in the flow stream and the media flows around it and doesn’t require manual or automated assistance to operate. When the pump is running, the valve is open; when the pump shuts off, the valve closes slightly before the reversal of fluid flow, due to the compression spring force acting on the disc, which nearly eliminates Water Hammer.

    See the line-up of DFT® Silent Check Valves here.
    Most requests for check valves take into consideration the line size and pressure class alone, as media pressure and flow can vary dramatically where pipe designs are oversized for future concerns or undersized due to lack of or incorrect information. This is not always the best way when deciding which style of valve to use in a system. Other things to consider are: working pressure, flow rate, the specific gravity of the media, and temperature. An analysis of the system design is highly recommended.
    It is necessary to understand why valves fail, and the root causes. The most common failure is due to excessive wear of the internal parts of the valve. Springs, discs, and stems wear prematurely by not being held steady during operation. When the disc is not stable due to insufficient flow to hold it in the full-open position, chattering can occur.
    Bruce Ellis is an Inside Sales Consultant at Triangle Fluid Controls Ltd. He may be reached at [email protected] or 613-968-1100.
    Watch for Part 2 “Check Valve Sizing” coming in December!

    Choosing the Right Gaskets for FDA Applications

    Aug 28, 2020

    By: Samantha Harrison, Lab Testing Technician/QA Assistant

    The Food and Drug administration (FDA) comprises of a very broad and complex area of regulations. While there is no specific required certificate for FDA approval, it is up to the manufacturer to read and review the regulations to ensure their material/product meet that particular criteria.

    There are multiple ways a gasket can conform to FDA regulations.

    • GRAS (Generally Recognized As Safe) – Materials adequately shown to be safe under the conditions of its intended use, or unless the use of the substance is otherwise excepted from the definition of a food additive. Eg. PTFE or 316SS.
    • Existing FDA Regulations – Material ingredients that are listed as compliant in the applicable FDA regulations.
    • FDA FCN (Food Control Notification)– These are new materials that are not covered by either of the above but can be submitted to the FDA under a FCN.

    PTFE and Virgin PTFE gaskets are commonly used in FDA applications. Filled PTFE gaskets can conform to FDA regulations if the filler or fillers, colouring agents, etc., are considered as GRAS or if the fillers and colouring agents are complying with another regulation. If PSA (Pressure Sensitive Adhesive) is used, it will also need to conform to FDA regulations.

    Elastomer gaskets are another gasket material that will conform to FDA regulations (For eg. Durlon® 8500). This gasket material is commonly used in both raised-face and flat-faced flanges (in which the available compressive load is low).

    If any adhesives are used to perform a sealing function, they will need to meet the requirements mandated by the FDA (21 CFR 175.105).

    When inks are used to mark gasket material, it must follow the same FDA (21 CFR 175.105) criteria and all ingredients used in the branding ink must be acceptable for direct contact with food and pharmaceutical products.

    Some applications are more complex/difficult and require the use of systems that are over and above the FDA regulations, such as the National Sanitary Foundation (NSF), U.S. Pharmacopeias (USP) and 3A.

    It is always important to contact your gasket manufacturer to confirm your gasket conforms to FDA regulations.

    Board of Directors Appoint Mike Boyd, Vice President & General Manager of TFC

    June 9, 2020


    Board of Directors Appoint Mike Boyd, Vice President & General Manager

    Triangle Fluid Controls’ (TFC) Board of Directors is pleased to announce the appointment of Mike Boyd as Vice President & General Manager of the company. Mike started with TFC as an Operations Manager in January 2009 for the PTFE gasket manufacturing operations and was promoted to General Manager in October 2016 for the entire company. Under Mike’s leadership and guidance, TFC has continued a prosperous track of top-line and bottom-line growth with improvements in efficiencies, cost control, market expansion and diversity, sales depth, supplier strength, marketing penetration, employee development, and community engagement.

    Triangle Fluid Controls is the global manufacturing center of the Durlon® brand of fluid sealing products recognized around the world to solve tough fugitive emissions sealing applications. “Under Mike’s keen eye for operational efficiency improvements and his continuous improvement approach to the business and his professional skills, TFC and Durlon® will continue to be global market contenders for many years to come.” Mike Shorts, President, Triangle Fluid Controls Ltd.

    Congratulations Mike on your achievement, your leadership strength, and your dedication to making us a better company!




    A Moment with Mike Shorts – Industrial Processes and Emissions Control

    June 9, 2020

    “I think a manufacturer’s position on sustainability needs to be twofold. It’s not just about the years of product design and improvement, it is also about what they are doing on the frontline to reduce their own environmental impact.” – Mike Shorts, President, Triangle Fluid Controls

    Spend a moment with Mike and read about his thoughts on industrial processes and emission control in this month’s Fugitive Emissions Journal.




    Considerations When Upgrading or Changing Pre-Specified Gaskets

    May 13, 2020

    By: Samantha Harrison, Lab Testing Technician/QA Assistant

    With on-going global changes, most industries in turn, have reflectively looked at making improvements in their choice of gaskets for their particular application needs.


    Here is a list of factors that can contribute to changing and/or upgrading a gasket:

    • Change in the process or application
    • Change in environmental regulations (lower emissions)
    • Changes effecting long- or short-term gasket spending
    • Change to a supplier that can provide better service and technical support


    Using the ASTM F104 line callout chart can assist with cross-referencing and/or comparing existing gaskets thus improving the material selection process and the transitioning towards the gasket replacement. Most manufactures will complete F104 callout numbers for their products to promote easy comparison. It should be noted that in some cases, the line callout will use the digit ‘9’ which denotes as specified, meaning you will still need to look up the value from the product technical data sheet.


    Some gasket properties such as creep relaxation, maximum compression and even material thickness selection can cause a change in the installation procedure and/or required torque value. Each product type is based independently on different equipment and processes using different formulations. Depending on the gasket type selected, the installation parameters can vary, requiring more/less minimum loading in order to establish a leak-free seal. A determination will be established depending on the application changes that have occurred within the system. For example, the addition of new equipment or process changes/improvements. In most cases, this is a factor that is commonly overlooked and not planned. A change in the operating pressure or temperature can affect gasket performance requirements but if properly selected based on design (not operation) the gasket can still fit into existing parameters, and save a lot of headaches down the road.


    Here are parameters that need to be considered when changing and/or upgrading a gasket:

    • Temperature
    • Pressure
    • Process fluid
    • Operating conditions (process cycling or vibration)
    • Flange Conditions
    • Service life


    It is recommended to always review the published data sheets regarding new gaskets. This will help ensure that the gasket will be able to withstand the conditions where it is intended to be used. Reviewing the pressure-temperature charts will ensure that the gasket will be operating in the safety zone when there is a change in conditions over time.

    The following in an example of our Durlon® 9000 PTFE gasket material PxT Chart

    “So as you can see, there is a lot more to gasket selection when considering a change or an upgrade…and not as simple as choosing a specific colour!” If you have questions or are unsure, please be sure to contact the manufacturer of the material.

    Learn more about our product line of Durlon Gaskets.

    More Gasket Guru Video Training Videos to come!

    May 1, 2020

    By: Sylvia Flegg, TFC Marketing Manager

    Finding a reliable sealing solution has never been easier!

    With the past success of our 2019 release of 4 SEALutions videos, we are happy to announce that more will be coming later this year!

    This past year we presented a brand new video series, SEALutions, that answers basic fluid sealing questions in 1-2 minute videos. Topics we covered were: Re-Torquing a Bolted Flange, Quality Control Testing for SWG’s, Handling & Shipping of SWG’s and, Gasket Failure Analysis. They can all be viewed here.

    SEALution’s stars TFC’s Gasket Guru – QA & Engineering Manager, Chett Norton, a hands-on, tech guy with a plethora of fluid sealing knowledge to share. Chett has over 15 years of experience in fluid sealing and industrial process and is a certified member with the Ontario Association of Certified Engineering Technicians and Technologists (Mechanical Discipline) as well as an active participating member of the Fluid Sealing Association’s Gasket Technical Committee.

    Stay up to date with SEALutions by subscribing on our YouTube Channel. In the meantime, you can reach the Guru by e-mailing [email protected] for your fluid sealing needs or if you have any suggestions of topics for future videos.

    Press Release – TFC Producing PPE Face Shields for QHC

    April 22, 2020

    Triangle Fluid Controls Ltd. in production of more than 1,000 face shields to be delivered to front-line health care workers at Quinte Health Care (QHC).

    Triangle Fluid Controls Ltd., proudly announced their plan to start production of more than 1,000 Medically Approved Face Shields for QHC, the regional health care
    sector. Quinte Health Care provides a wide range of high-quality health care services to 160,000 people living in the 7,000 square kilometer region of Prince Edward and Hastings Counties and the southeast portion of Northumberland County.

    Using our manufacturing capabilities and employee involvement, we will be producing the main components for these medically approved Face Shields. Along with TFC’s contributions, we were able to source other required materials from a couple of our suppliers as donations for this combined accomplishment. The cost of the main material; PETG Plastic, is being funded by the employees of Triangle Fluid Controls Ltd. through donations.

    “We heard the call for PPE, and as proud Canadians, we knew we had to help. Through donations from our employees and generous partners, we are proud to be able to do our part for front-line health care professionals in our local region.” Mike Boyd, General Manager

    Triangle Fluid Controls Ltd. is a market-driven, technology-based company, serving customers throughout the world with innovative sealing products. Based in Belleville, Ontario, we manufacture and distribute filled-PTFE, compressed non-asbestos sheets/gaskets, metallic and semi-metallic gaskets.

    Along with TFC’s contributions, we would like to thank Joe Mathew of AM Rubber & Foam for donating the rubber inserts and John Hume of Hume Media Inc for donating the printing of the labels. The cost of the main material; PETG Plastic, is being funded by the employees of Triangle Fluid Controls Ltd. through donations.

    Using the ingenuity and collaboration of some of our staff members design skills, we are also going to provide these mask mates – an alternative to attach surgical masks behind the head, protecting ears from the elastic.

    Download the Press Release here.

    Read article from Quinte News here.

    A 360° Look at Check Valve Flow Orientation

    April 16, 2020

    By: Bruce Ellis, Inside Sales Consultant

    Check Valve Flow Orientation and Position Explained

    As we know, not all styles of check valves are suitable for different flow directions. Pump design or space limitation are important considerations when designing a system that specifies the correct check valve to be used.

    Given correct information, DFT axial flow centre guided check valves can be customized to most applications, thus increasing the performance and life span of the components in your system. If we know the media, its specific gravity and system design specifications, pressure, flow rate, temperature etc.; the correct valve can be customized to suit your application.


    Horizontal Flow

    This is the most common of the flow directions and all check valves. The question then becomes: “How do you choose one valve style over another?” It may be as simple as initial cost or lead-time. This can easily be offset by the advantages centre guided valves have over swing check and dual door designs:

    • virtual elimination of water hammer
    • reliable and less troublesome
    • elimination of costly maintenance and downtime


    Vertical Flow (Up)

    This installation is commonly used in mine de-watering and sump applications, or where space is at a premium. It is important to remember any foreign matter introduced into the system, such as sand, can settle on the closed valve causing it to not open or close properly. If you are aware of this, modifications can be made to help prevent the problem. Again, since spring assisted axial flow valves don’t require backflow to aid in closing, water hammer is not an issue and the system will work smoother.


    Vertical Flow (Down)

    This is the most difficult flow direction for check valves to function. This orientation can be found in boiler supply lines and occasionally skid designs that are very space-limited. Some designs, such as swing checks, cannot be used in this situation, as they will open but not close. The spring assisted centre guided valves can be made to operate in this orientation. Given the static head pressure the valve is subjected to, the added spring will allow for proper operation.


    In closing, it is important to note that the greater the amount of information given, the easier it is to make an educated buying decision. DFT Check Valves come in different styles, wafer, flanged and NPT (National Pipe Thread), to satisfy most requirements. They are also available in exotic alloys and can be customized to suit most applications.


    As the Canadian master distributor for DFT® silent check valves, TFC proudly stands behind these product offerings and it shows from the beginning of our process, to the care taken in packaging and shipping to your door.


    For more information please see the helpful resources below from We are here to help, so please contact us for any information you require.


    You May Also Be Interested In:

    E-Book: Design for Flexibility: Key Considerations to Make When Designing Fluid or Gas Flow Systems


    DFT Check Valve Catalogue

    DFT Valve Data Sheet

    DFT Installation & Maintenance Manual

    Should I stay? Or should I go?

    April 14, 2020

    By: Sylvia Flegg, TFC Marketing Manager

    Gasket Shelf Life

    The shelf life for Durlon® gaskets vary, depending on the material and the length of time it has been stored. All full-sized sheets and rolls of Durlon® materials are fully lot traceable and have the applicable batch number and cure date printed on each sheet. Each material, however, ages differently so here are a few standards we recommend under normal storage conditions:


    5 Year Shelf Life

    Durlon® Compressed Non-Asbestos (CNA) sheet materials

    6 Year Shelf Life

    Durlon® HT1000

    Unlimited Shelf Life

    Durlon® PTFE sheets, Flexible Graphite, Durtec®, Kammprofiles and SWG’s


    Storage Conditions

    • Gasket material should be stored in a cool, dry location.
    • Avoid storage of material in direct sunlight or near heaters.
    • Avoid contact with water, oil or chemicals.
    • Gaskets should not be stored so that they become too tightly packed and damaged.


    Other Recommendations

    • All dust producing processes such as drilling, grinding and sawing should not be used near gasket materials.
    • Avoid hanging gaskets on pegs or nails as this may cause distortion of the gasket.
    • When stocking the shelves or bins where gasket materials are stored, the material should be rotated by placing the older material first or on top with the newer material behind or under it.
    • All gasket material should be properly identified to guard against misapplication.
    • Consider consolidating materials to 1 or 2 if possible, to prevent using the incorrect gasket usage – for example, Durlon® 9000 or 8500 both feature multi-application usage.


    So, referring to some of the above, I like to describe ideal gasket storage similar to how some of us like to vacation – clean of sand, in the shade (out of UV) and laying down…and perhaps with drink in your hand!

    What is Ideal Gasket Stress?

    March 26, 2020

    By: Samantha Harrison, Lab Testing Technician/QA Assistant

    Gasket stress is a very important parameter that describes the unit load of a bolted joint surface because each type of gasket material responds differently to gasket stress. Soft and conformable gaskets may seal at low gasket stress where hard metal gasket may require much higher stress. It is always important to contact gasket manufacturers to determine the recommended gasket stress and/or how the gasket will react with the load that is available.

    There are 4 aspects to gasket stress


    1. Conforming to flange surface

    A flange surface will never be perfect. There could be pitting or corrosion that affects the surface, requiring the gasket to have enough compression to form and fill the voids.

    2. Block the gaskets material permeability

    The gasket needs to be able to block any permeability in the gasket body. The permeability through gaskets are different for each material. The rate of leakage decreases as the compressible load increases. The required stress is dependent on the permissible leakage requirements determine by the end user, such as a T3 tightness level (0.00002 mg/sec/mm-dia).

    3. Withstand internal pressure

    The gasket needs to be able to withstand internal pressures acting upon it. The minimum compressive stress needs to be high enough to maintain the friction that is needed to keep a gasket from blowing out. This is more common for non-metallic gaskets that has internal pressures that are dependent on friction.

    4. Temperature

    Temperature is an important factor when determining gasket stress. When temperature is elevated it will cause gasket relaxation and relaxation in the bolt load. When installing the gasket, it needs to have a high enough stress that will compensate for this. Therefore, it is always important to retorque the gasket 4 to 24 hours at ambient temperature after installation.

    There are different types of stresses that occur in a system; minimum seating stress, ideal operating stress, minimum operating stress and maximum operating stress specific to a given gasket material. The values for these stresses can be found in ASME PCC-1.

    • Minimum Seating Stress
      Occurs when there is an assumption of little or no pressure for the gasket to be able to conform to the flange.
    • Minimum Operating Stress
      This is dependent on the design pressure of the assembly.
    • Maximum Assembly Gasket Stress
      Is the stress that could damage the integrity of the gasket to affect the ability to maintain a seal.

    The target stress to be used will allow for optimal performance and sealability. This will be at a value that is not too high to cause damage to the gasket but at the same time, allow enough load to the gasket.

    It is always important to properly install a gasket. If done correctly, with adequate gasket stress and proper procedures, be assured that the gasket is given the best chance for a leak free service life.

    Learn more about Gasket Installation Procedures.