Designing Cryogenic Seals for High and Low Temperature Sealing

cryogenic

When designing for low temperature sealing, the first step is to define the temperature range that the seal will be operating in.

Typically, cryogenic as seals are those that are operating below -65 Fahrenheit. Gallagher’s partner, Eclipse, chooses this benchmark because they currently have elastomers that have a usable TR10 value at this temperature.

When designing at this level — with high temperatures around 300 Fahrenheit — an understanding of what level of leakage control is required on the low temp end. Seals that operate in aircrafts must function within this range.

However, there may be an allowable leakage rate which allows for reduced drag. When requiring zero leak, the drag in the system is often increased to support some elastomeric contact with a dynamic surface. In the case of static seals, elastomers span this range although increased squeeze may be necessary.

Eclipse Engineering routinely designs in the range indicated above.

While -65 Fahrenheit is extreme cold, it’s not considered cryogenic. Liquid nitrogen at -320° Fahrenheit (-195°Celsius) requires special hardware and seal material consideration.

To begin, many projects and applications don’t utilize lubricant in dynamic applications. To improve sealability, a better-than-average surface finish is required.

Surface finish often holds lubricity. But without this, a smooth finish reduces friction, improves life, lowers drag, and improves sealability.

Static seals are often required to have leak rates approaching zero; meaning hardware considerations and surface can be even more important. This may mean polishing the groove, which in some applications can be very challenging.

Cryogenic Seal Materials

The next criteria are the seal materials. Elastomeric materials lose their flexibility at these extreme temperatures, so Eclipse relies on polymer-type materials to bridge the gap. When we experience temperatures below -180° Fahrenheit ( -195° Celsius), that’s when it becomes wise to move away from basic PTFE to modified fluoropolymers such as PCTFE, known for operating down to -460 Fahrenheit. Continue reading Designing Cryogenic Seals for High and Low Temperature Sealing

Metal Detectable O-Rings, A Must Have in the Food & Beverage Industry to Avoid Product Recalls

Metal Detectable O-Rings are a Must-Have in the Food & Beverage Industry

Metal Detectable O-Rings are used in equipment that produce and package food. During service, o-rings are exposed to temperature variations and corrosive clean-in-place (CIP) chemicals used during equipment sterilization.

picture of food and beverageOver time, o-ring materials can break down and fail during operation causing material fragments from the o-ring to break off and enter the food stream. Without a way to find material fragments quickly, machine operators must shut down equipment to locate the contaminate source resulting in lost production time and loss of revenue.

Metal detectable o-rings from DICHTOMATIK are formulated with the specific rubber and metal combination that allows for easy detection using metal detection machines that locate and remove contaminated product quickly or by using metal separators. Having an efficient inspection process to monitor product consistency and quality allows for worn o-rings to be found and replaced quickly to avoid product recalls further downstream once the product is placed on the shelf.

DICHTOMATIK O-Rings & Sealing Solutions That Meet FDA Standards

The DICHTOMATIK complete catalog of food grade rubber seals meet FDA and food safety standards outlined under the Food Safety Modernization Act (2011).

Available Materials

  • Blue – FKM
    • [Best Use Running Condition] *Where  high acid and temperature resistance is critical
  • Yellow – EPDM
    • [Best Use Running Condition] *Offers very good water and steam resistance
  • Green – NBR
    • [Best Use Running Condition] *Use when working with oil and animal fats
  • Orange – Silicone
    • [Best Use Running Condition] *Operate within a wide temperature range

The original blog article was written by the marketing team at DICHTOMATIK and can be found here.

Gallagher Fluid seals is an authorized distributor of DICHTOMATIK seals. For more information about their products or to find a solution that works for you, contact our engineering team.

Gore’s Gasket Tape Makes Installation Easy

Attention: When installing GORE Gasket Tape Series 1000 in joints with multiple (2 or more) gaskets compressed with a single set of bolts or clamps, see the installation supplement “Installation on Joints with Multiple Gaskets,” for additional mandatory instructions.


1. Select the size

picture of select sizeGASKET WIDTH

Select the gasket width that provides enough material to align the gasket tape flush with the inner and outer diameter. Ensure full coverage of the glass surface. Excess material may exceed the outer diameter.

GASKET THICKNESS

Most applications require a base layer of 6 mm (1/4″) tape, which can accommodate deviation up to 1.5 mm (1/16″) without shimming. Applications with deviation up to 2.3 mm (0.090″) can utilize 9 mm (3/8″) tape without shimming.

SHIMMING

To effectively seal flanges with deviations beyond the maximum for the base layer, a shimming process is recommended. Use of 3 mm (1/8″) GORE® Series 1000 shim tape as a shim layer will accommodate an additional 1.5 mm ( 1/16″) of flange deviation. Ensure the shim layer has the same width as the base layer.


2. Determine a Torque Value

To achieve a reliable seal, adequate gasket stress must be applied during installation.

Typical minimum stress to seal values for GORE Gasket Tape Series 1000 are:

  • 6 mm (1/4″): 14 MPa (2,030 psi)
  • 9 mm (3/8″): 18 MPa (2,610 psi)

Perform an engineering calculation to determine the torque value for your specific application.

Industry guidance is available, for example in ASME PCC-1 Guidelines for Pressure Boundary Bolted Flange Joint Assembly, and EN 1591-1 Flanges and their Joints – Design Rules for Gasketed Circular Flange Connections – Part 1: Calculation.

However, ASME PCC-1 does not include glass-lined steel specialties. Therefore, it is advised to contact the equipment manufacturer for an adequate torque recommendation.

Continue reading Gore’s Gasket Tape Makes Installation Easy

Selecting Seal Materials for Medical Ventilators

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.

Original content can be found on Parker’s website and was written by Dan Ewing, senior chemical engineer, Parker Hannifin O-Ring & Engineered Seals Division.


In the rush to massively increase the number of medical ventilators available to treat patients with severe cases of Covid-19, using the correct seal materials for those ventilators should never take a back seat to expediency.

Medical ventilators are mechanical devices that essentially breathe for a patient with damaged lungs. They force air into the lungs and draw it out, augmenting or even replacing the natural functions provided by the movement of the diaphragm and the inflation/deflation of the lungs themselves. These devices can supply room air, pure oxygen, or nearly any ratio of the two to the patient, depending on health needs.

What makes a good seal selection in this environment?

First, seals within the device must be compatible with air and pure oxygen. They should not harden or crack, nor should they contain a significant amount of volatile matter that can evaporate out of the seal where it could be inhaled by the patient or potentially catch fire in a concentrated oxygen environment. Further, it should be assumed that any air that contacts the seals will likely end up in the patient’s lungs. As a result, it’s strongly recommended using seal materials that have passed USP <87> Class VI testing for any seals used in a medical ventilator.

Parker O-Ring & Engineered Seals Division has already helped several customers ramp up production of critical medical equipment with supplying the right materials and O-rings for the application.

These application requirements limit the recommended compounds to only a small handful.

Recommended compounds suitable for use in ventilators

Continue reading Selecting Seal Materials for Medical Ventilators

Coal-Fired Power Vacuum – The Importance of Flexible Piping Products

It’s no news that coal-fired generation is going by the way-side.  Despite a recent resurgence in political support, coal is fighting an uphill battle on two major fronts: economically and environmentally.  After the shale gas boom in the 2000’s, plummeting natural gas prices and rising environmental concerns have continued to make operating aging coal-fired plants less and less attractive – for owners and consumers alike. The recent slowdown issues with the pandemic are only exacerbating the conditions – as industrial and commercial sectors are the greatest consumers of electricity.  With only the cleanest and most efficient plants left in operation (in 2010 coal generated 45% of the nation’s electricity, compared to 24% by the end of 2019) and the rest quickly moving towards eventual closure, we are witnessing a tremendous shift take place.  So how is this shift going to resolve and what should we expect?

picture of cooling towers

Long-Term Changes

Fortunately for us in 2020 – the shift away from coal has been happening long enough that new generation capacity has already been under construction and is coming online just in time to replace the retiring coal plants.  The economic downturn effecting industry has showed an acceleration in these trends – but natural gas and renewable outputs have been rising to pick up the slack for over a decade.  In fact, the U.S. has been somewhat lagging behind in terms of progress towards renewables with some European countries already shutting down the last of their coal-fired plants.  Though domestic renewables are indeed growing significantly – having nearly doubled in power production in the past ten years, and are expected to double-over again and overtake natural gas by 2050. Continue reading Coal-Fired Power Vacuum – The Importance of Flexible Piping Products

Kalrez PV8070 Parts in Reactors

High Performance Seals for Polycrystalline Silicon Process Equipment

The Challenge

To meet growing demand in solar cells, the Siemens* process is used to produce highly purified polycrystalline silicon by thermally decomposing tri-chloro-silane (TCS). The reactors employed require three kinds of high-performance seals in the following locations: A) bell jar seals; B) electrode seals between the electrode and ceramic inlet; and C) a gasket for the view port seal (see schematic).

pv8070 seals in Polycrystalline Silicon Process Equipment

Application Details

The process involves a very hot, dry environment with temperatures up to 1200°C (2100°F). Sealing components see up to 300°C (572°F). Process media include TCS and aggressive by-products of its decomposition, such as HCl gas. Superior compression set performance is needed for effective sealing and extended seal life. Very low outgassing is a key requirement for preventing contamination of the process environment.

The presence of harsh chemicals in high temperature conditions often require an upgrade from standard sealing materials to PTFE or fluoroelastomers (FKM) to improve thermal stability and chemical resistance. However, PTFE can deform and creep “hot flow” in the bell jar seal increasing the risk of product loss. FKM, with its high temperature rating of 200°C (392°F), also has deficiencies in this 300°C (572°F) environment.

The Solution and Key Advantages of Kalrez PV8070

Kalrez PV8070 perfluoroelastomer parts installed as washers and gaskets in reactors for the Siemens CVD process have demonstrated outstanding performance in this demanding application. Kalrez® PV8070 parts are effective seals that provide: Continue reading Kalrez PV8070 Parts in Reactors

THE KLINGER-SAVER – Eliminating Hand Injuries During Installation

picture of klinger-saver

In addition to KLINGER’s complete Sheet Gasketing Product Line which now includes the new major change in construction of their PTFE Products TC 1003, TC 1005, and TC1006, they have added a great new product to cover additional applications during day-to-day operation.


The KLINGER SAVER

A new product we are featuring on our blog is THE KLINGER-SAVER – a tool to eliminate hand injuries.

Bolt tightening or loosening activities, or using slug wrenches and hammers can often the cause of serious finger or hand injuries.

 The KLINGER-SAVER is a safety device that allows an assembly technician to remove his hand from the potential danger of being struck by the hammer.

klinger-saver


How The KLINGER-SAVER Works

The wrench is held securely in place on the nut with webbing attached to a strong rubber cord, which is tensioned and locked within a plastic distance tube.

how the klinger-saver works


What comes with the KLINGER-SAVER?

The KLINGER-SAVER is supplied as a complete kit, including an extension tube. The extension tube allows further separation from the strike zone, particularly when helpers are involved, or for hard to reach bolts.
Materials
  • Supplied in a highly visible bright yellow color.
  • The distance and extension pieces are molded from high impact resistant polypropylene.
  • The cord is molded nitrile rubber with a 60 Shore hardness.

KLINGER-Saver is a product of Thermoseal.

For more information about this product, contact Gallagher Fluid Seals‘ engineering department.

What’s the Difference Between EPR and EPDM?

EPR vs EPDM – How do they differ?

What’s the difference between EPR and EPDM? What do the different abbreviations (EPR, EPM, EPDM, EPT, etc.) mean? These questions pop up from time to time in the seal industry, and here are basic answers to these questions.

EPDM MaterialsIn the range of ethylene-propylene (EP) rubber there are two lightly different branches: EPR (EP copolymer) and EPDM (EP terpolymer.) The differences are subtle, and a basic knowledge of polymers and rubber compounding is necessary to grasp the differences.

First of all, polymers (derived from the Greek for “many units”) are long  chemical chains that can be thought of as behaving like long pieces of cooked spaghetti. Each chain is made of one or more monomers (Greek “single unit”) linked together end-to-end. A copolymer (Greek “two units”) is composed of two monomers, while a terpolymer (Greek “three units”) is composed of three monomers. EPR (aka EPM, EP copolymer) contains only ethylene and propylene monomers. EPDM (aka EPT, EP terpolymer) is composed of ethylene, propylene, and a third monomer called a diene (three different dienes are in common use today, but discussing their differences gets extremely dry and technical.)

To make a rubber material rubbery, we essentially have to “glue” the polymer chains together. We do this through a process called vulcanization or curing. This is where the subtle difference between EPR and EPDM is found. Because of the chemistry of the polymer chain, EPR can only be vulcanized with a peroxide-based cure system. On EPDM, the additional diene monomer provides a specialized cure site that allows the polymer to be vulcanized with peroxide- or sulfur-based chemistries. Because of this added flexibility, most EP compounds in the seal industry today use EPDM terpolymer instead of EPR copolymer. In other industries (hose, roofing products, etc.) EPRs may still be the material of choice.

From a functional standpoint, there are very few performance differences between EPR and EPDM. Both swell dramatically in petroleum products, and both are excellent in water, steam, and polar solvents like MEK and acetone. There are some notable performance differences in extremely demanding applications: EPRs or very tightly cured EPDMs are suited for the nuclear industry (E0740-75 is recommend), and for applications involving concentrated acetic acid, some EPDM compounds (like E0692-75) show superior performance to most EPRs. In other applications, the performance difference is difficult (if not impossible) to identify.


The original article was written by our partners at Parker and can be found on their website here.

For more information about which material(s) might be the best fit for your specific application, contact Gallagher Fluid Seals’ engineering department.

The Role of Seals in the Quest for Medical Cures

The coronavirus has prompted all of us to do everything we can to protect ourselves from catching and spreading the virus. We are all taking important safety measures to maintain a clean and uncontaminated home environment, and limiting our exposure to a potentially hazardous outdoor environment.

picture of coronavirus medicalIn this blog, our partners at Eclipse will be examining the role that seals play throughout a pandemic. The very role of seals is to keep a certain environment in, and certain environment out, similar to how we are living these days.

In Eclipse’s last blog, they wrote about boundary seals in aircraft and how seals allow the aircraft to be pressurized. In the research lab, a different style of boundary seal is required to keep the outside environment out.

Labs all over the world are working toward preventing the spread of coronavirus. Scientists are working with test equipment to find a cure and a vaccine to prevent not just the spread of this virus, but other viruses which we’ve not yet seen.

When we design seals, we must consider keeping something as small as a single cell from entering a test chamber. Last week, Eclipse received a call directly from a customer building a prototype ventilator to be built in volume to help support patients suffering from coronavirus.

The client requested that Eclipse’s engineering and manufacturing team turn an 8-inch (203mm) seal around from concept, design, and finally produced and shipped in less than 4 hours — and they made it happen.

Keep reading to explore the important role that seals play in research equipment as scientists seek to find the cure for coronavirus and beyond. Continue reading The Role of Seals in the Quest for Medical Cures

Curing Chronic Pipe Leakage

How the raised surface profile of PTFE sheet gasket helped a midstream oil and gas processor address leaky pipes

Bolted flange-gasket connections in process piping systems are common and given little thought – unless they start to leak.

Chronic leakage proved to be an issue for one of Garlock’s clients, a midstream oil and gas processor and services provider. The site processes, stores, and transports natural gas, liquefied natural gas and petroleum products. Garlock was brought in to provide a solution to the problem.

Successful connections are dependent on a variety of things, including the state of the flange surfaces, alignment, bolt and nut grade and strength, bolt and nut thread condition, lubrication, bolt tightening process, service conditions, and choice of gasket.

When a flange-gasket joint is assembled, the gasket must first be compressed to fill the gaps between the flange surfaces, creating a seal when system pressure is applied. Secondly, it must maintain that seal as the system is brought on-line and temperature and pressure escalate.

As the temperature increases, a gasket made of non-metallic materials such as rubber, fibre, PTFE and inorganic fillers is prone to lose thickness, that is, creep. And the thicker the gasket is, the
more it is prone to creep (1/8-inch thick gaskets creep more than 1/16-inch).

The two most important performance qualities of a gasket are its ability to seal and its ability maintain that seal. These can be indicated by industry standard tests for sealability and creep.

On the surface, this particular case study would seem to be an application of little complexity. However, the details of the joint gave rise to several issues that caused the user chronic leakage problems. Here are the service conditions and background of this particular case:

  • Temperature: 100°F to 120°F (38°C to 49°C)
  • Flanges and use: 18-inch Class 150 raised face flanges used in the pipe systems of cooling tower water pumps. Multiple gaskets are on either side of spool piece
  • Media: Water
  • Pressure: 100 psig to 150 psig (7 bar-g to 10.3 bar-g)

Continue reading Curing Chronic Pipe Leakage