Benefits of Replacing a Swing Check with a Non-Slam Check Valve

July 3, 2019

By: John Anderson, Regional Sales Manager, Western Canada


Recently, while calling on an oil and gas customer, I was illustrating the perils of using a swing check on liquid pump discharge where reverse flow and water hammer can be an issue. Part way through our conversation, the customer’s eyes lit up, and he said, “oh, that’s why I found the disk of the check valve in my sump!”. That is one of the risks that designers and maintenance people run into, when a swing check valve is misapplied on pump discharge where reverse flow and water hammer can be a problem.

When a pump trips, (due to a power failure as an example), backflow can get into the pump discharge, spinning the impellor of the pump the wrong way, and potentially damaging the pump. A check valve is typically applied to the pump discharge, to prevent this from occurring.

In a situation, that I term “light duty”, meaning that the pump is not cycling often, and there is not a large volume of media at play, (water as an example), a swing check would likely be fine in that application. However, in a situation where the pump is cycling often, and is dealing with a large volume of fluid (horizontal orientation), several things can happen, if a swing check is misapplied in this case.

Due to a phenomenon known as column separation, an inordinate amount of head comes back onto the pump when it trips. In this case, a swing check does not close quickly enough to prevent backflow from getting past the valve, and when it closes, it slams shut, and backflow behind the valve hits the disk, the energy has to dissipate somehow, and it does so in the form of water hammer. This occurs because a swing check largely depends on back flow for it to close. A non-slam check valve does not. It utilizes a coiled spring, downstream from the valve disk, that moves the disk toward the seat as soon as the flow velocity slows down. This valve is designed to be closed, just before zero flow is reached, thereby eliminating backflow. With no backflow, the cause of the water hammer disappears.

In addition, if a misapplied swing check sees a number of slamming incidents, it is possible for the hinge pin (holding the valve disk in place), to crack, and break off, thereby sending bits of metal downstream, potentially damaging components downstream of the check valve. It is also possible for the entire disk to break off, sending it downstream, leaving nothing but a spool piece.

Designers and maintenance personnel should be aware of situations where backflow and water hammer can be a problem on pump discharge and consider the use of a non-slam check valve in these cases, thereby eliminating the chance that you to may find a disk in your sump!

As the Canadian distributor of DFT® silent check valves, Triangle Fluid Controls Ltd. is proud to represent a company that is known around the world as the valve to use for preventing or eliminating Water Hammer problems – DFT® Check Valves, Serious performance, Superior reliability.

Gasket Joint Safety

June 24, 2019

By: Samantha Harrison, Lab Testing Technician/QA Assistant

Safety First

Being safe on the job includes maintaining and correctly installing gaskets. The number one safety procedure when installing a gasket into a bolted flange joint is to have an assembler who has been qualified in reference to ASME PCC-1. When installing a gasket, make sure proper PPE (personal protective equipment) is worn. This can include safety glasses, hard hats, steel toed shoes/boots, gloves, etc. Proper lockout and tag-out procedures also need to be followed. And it is critical to check that there is no debris, or foreign material on the sealing surface in order to avoid leaking of fluid and gases. Choosing the right gasket is imperative for safety. If a gasket is not the right size or material it can result in leaks, serious damages and ultimately, injury.

Considerations for Bolted Flange Connections:

  • temperature and pressure of the fluid
  • chemical nature of the fluid
  • mechanical loading
  • variations of operating conditions

Different stress variables need to be analyzed when choosing a gasket. This includes minimum seating stress, ideal operating stress, minimum operating stress and maximum operating stress. All these variables need to be understood and taken into consideration. It is always advised to purchase gaskets from a reputable supplier whose priority is to sell quality products and back it up with technical support.

Always make sure that the material of the gasket is compatible with your application. If a gasket is deteriorating it most likely means the material is incompatible with the fluid and temperature. When a gasket deteriorates it can cause leakage which can lead to damages and injuries.

You should never re-use a gasket because it will affect its mechanical properties. As a system expands and contracts, the gasket should move with the piping. If it doesn’t and there isn’t enough load on the gasket you will get a leak which can lead to serious injuries.

When installing a gasket, it is imperative that proper bolting procedure is followed, such as the modified legacy method (star pattern) mentioned in ASME PCC-1. Without proper bolt tightening, leaks can occur resulting in damages and serious injuries. The operating temperature should never be exceeded above the maximum allowable temperature. If the temperature is exceeded it can cause heat cracks and blistering which can inevitably cause leakage.

When disassembling a joint it is important that proper plant procedures are in place. The procedure should include lockout and tag-out to depressurize the system, removal of liquid head from the system. Always loosen the joint away from yourself in case of accidental release.

Here are important questions to ask yourself before disassembling:

  • Is the flange still under pressure?
  • Is there still gas or fluid in the line?
  • What if the piping springs up on release?
  • What if the load swings in my direction?

Knowing when a leak is happening is important to help keep employees safe. Gasket unloading is the most common reason for leaks. This is caused from a joint not able to generate enough seating stress on the gasket material. When gasket seating stress is low it can be from applying the wrong load to the gasket or the inability to transfer the correct load to the gasket from friction that is unaccounted for during tightening. To prevent these issues, a good bolting procedure should be in effect ASME PCC-1.

For other specific applications or general procedures, please contact the TFC applications engineer at [email protected] and read our Bolt Tightening Worksheet here.

Low Temperature Gaskets – How Low Can You Go?

June 6, 2019

By: Michael Pawlowski and Sylvia Flegg

Modern technology often requires rare or ultra-pure materials that can only be handled or obtained within extreme environmental conditions. These same conditions present unique and hazardous difficulties when transporting or utilizing these resources. Resources such as liquid oxygen, nitrogen, or argon; all of which are classified as “industrial gases” are handled well below the normal temperature ranges that every-day liquids exist; ranging as low as -195.8°C (-320.4°F).

As an example, let’s look at argon; an important gas used in Welding, Neon Lights, 3D Printing, and Metal Production, just to name a few. It is far more economical to house and transport argon in its liquid state. However, it must be held at an astonishingly low -185.9°C. Fitting the pipes together and maintaining a seal in a cryogenically engineered system that the liquid argon is housed presents unique difficulties. Argon gas is colourless, odourless, tasteless and can irritate the skin and the eyes on contact, and in its liquid form it can cause frostbite.

 

Proper Gasket Installation

Many gasket materials can become brittle, crack, shrink, and blow out when exposed to extreme cold – not something you want to happen at any time let alone with a liquid that can freeze you into a meatsicle. So, proper installation is also key! During installation, it is important that all parts are dry, the installation is done at ambient temperature and then re-adjusted with changes in temperature.

 

Cryogenics

Any mechanical seal that is sealing a product with a temperature below 0 degrees Celsius is given the name “Cryogenic”. Liquefied gases (LNG), such as liquid nitrogen and liquid helium, are used in many cryogenic applications, as well as hydrocarbons with low freezing points, refrigerants and coolants.

When selecting a gasket or sealing material to be used in cryogenic service then it is important that the material can withstand cryogenic temperatures.

Low temperature applications are found across many industries, these include:

  • Chemical
  • Food
  • Pharmaceutical
  • Refrigeration
  • Petroleum
  • Automotive

 

Durlon® PTFE Gasket Material

A good material that can withstand the frigid cold and remain ductile is required to maintain the seal, and the standard go-to is polytetrafluoroethylene (PTFE). Durlon-9000’s low temperature threshold of -212 degrees centigrade makes it capable of withstanding the hostile environment demanded from handling ultra-cold and this glass filled PTFE is capable of resisting thermal contraction which otherwise might compromise the integrity of the seal.

 

Conclusion

As with all gasket applications, environmental conditions should be considered in conjunction with the functional requirements of the device. Learn more about our various Durlon PTFE products.

Understanding Gasket Temperature and Pressure Limits

May 14, 2019

By Chett Norton, C.E.T.

When choosing the correct gasket material for a specific application, there are 3 minimum fields that you must understand in order to properly select the correct gasket:

  1. Pressure
  2. Temperature
  3. Media

All 3 of these items are straight forward on their own, however, most gasket applications are not based on 20°C or ambient test conditions in a lab so I will talk about each topic and how they interact with each other. The pressure is normally stated on the technical data sheet and refers to the pressure that the gasket is rated to at ambient temperature, so, for instance, Durlon® 8500 is rated for 1500psig at 20°C. Since soft gaskets are only recommended for both Class 150# & 300#, 1500psi seems adequate, right? Well if at ambient temperature, the max working pressure for a class 300# flange is 740psi for WCB piping/flanges and we used 1.5x this working pressure to cover system pressure tests, it would still only be 1140psig – still below the max allowable for the material. Unfortunately, it is not this simple.

What we sometimes fail to realize is that as the application temperature increases, the materials ability to withstand pressure decreases. Based on this, using a material’s Pressure vs. Temperature chart or referencing the materials PxT number are both quick tools that can be used to help verify if the material you have selected will work for the pressure and temperature conditions of your application. Many material tech sheets feature a “straight-forward” and easy-to-use PxT chart. The chart has a line that shows you a ‘go’ or ‘no-go’ area based on the pressure and temperature of the application for the material. Normally the pressure is listed on the Y-axis and the temperature is listed on the X-axis of the chart. Plotting the point at which these two values intersect will advise whether it is safe to use the material or not. If the point is inside the recommended line, it is generally safe to use, while being outside the line indicates not safe to use or recommends you contact engineering for more information. See the chart below for reference.

 

A second way to quickly check if the material is suitable for the application, is the PxT number. In some cases, the material-technical data sheet for the gasket material will give you a unit-less PxT number. For instance, Durlon 8500 material has a PxT (Psi x °F) value of 250,000 for 1/8″. Now what you can do is divide this number by either the working pressure or temperature (the number used to divide cannot exceed the max allowable temperature or pressure allowed for the material) and it will give you the maximum allowable of the variable not used. Allow me to give you an example:

Durlon 8500, PxT = 250,000

What is the maximum allowable pressure that the gasket can handle at 400°F?

250,000 / 400°F = 625 psi

Therefore, the maximum pressure the material can be used at 400°F is 625psi.

Additionally, media reactivity is also dependent on temperature. In a lot of cases, a materials chemical resistance at ambient temperature is good; however, at elevated temperature, the chemical is much more reactive and/or aggressive and renders the material not chemically compatible anymore. Therefore, it is very important when verifying chemical resistance, the temperature of the material needs to be taken into consideration besides the concentration of the media itself.

So, remember to verify these 3 items (Pressure, temperature, and media) and you can simplify it further by using the Durlon® iGasketPlus app to help recommend the correct material. So, play it safe, use the app and remember to always “Keep the fluid between the pipes”.

8 Steps to Properly Installing a Gasket

April 11, 2019

By Chett Norton, C.E.T. and Sylvia Flegg

 

 

 

 

Visually examine and clean flanges, bolts, nuts and washers and make sure to replace any defective components, if necessary.

 

 

 

 

Lubricate bolt threads, nut threads & facing, and washers.

 

 

 

 

Install new gasket (Do not reuse old gaskets or use multiple gaskets).

 

 

 

 

Number the bolts in a “cross pattern” sequence according to this diagram. Important: hand-tighten then pre-tighten bolts to 20 ft/lb torque but do not exceed 20% of target torque.

 

 

 

 

 

Check gap uniformity using a gap tool, feely gauge or Vernier calipers.

 

 

 

 

Target torque round #1 – 30% of target torque, Round #2 – 60% of target torque and round #3 – 100% of target torque. It is very important that you check the flange gap around the circumference in several spots between each of these tightening rounds. If the gap is not reasonably uniform, make the appropriate adjustments by selective bolt tightening before proceeding.

 

 

 

 

Rotational round: to reach 100% of the target torque, use a rotational clockwise tightening sequence starting with bolt 1 for one complete round and continue until no further nut rotation occurs at 100% of the target torque value for any nut.

 

 

 

 

Final-round: Re-torque within 4-24 hrs at ambient temperature if possible. Consult TFC technical department for hot-torquing procedures, repeat round 4 followed by a rotational round. A large percentage of short-term preload loss occurs within 24 hours after initial tightening this re-torquing round covers this loss and is especially important for PTFE gaskets.

 

We recommend the use of an installation assembly worksheet with the details of the assembly and installation including the installers signature and date for verification. You can use the TFC worksheet for easy adoption into your bolting installation verification program.

 

For other specific applications or general procedures, please contact the TFC applications engineer at [email protected] and you can read more about our Gasket Installation Procedures here.

Blaming the Valve

March 4, 2019

By: Bruce Ellis

In many situations where a system starts to suddenly fail, the valve is the first suspect. This may or may not be true, depending on the issue. If a swing check valve is being used it is important to remember they are inherently noisy, so a quiet swing check is a problem. Whereas a non-slam check valve is designed to operate quietly, so if it becomes noisy, there is a problem.

Here are 3 questions to ask to help diagnose the issue causing system failure:

  1. Did the systems components change?

Simply put, is your pump or compressor working at the same efficiency (flow rate and pressure) as when it was new? Or did something change? It’s a good idea to have a pressure gauge and flow meter installed to monitor the conditions.

  1. Did something foreign enter the system?

Foreign objects sometimes find their way into a system causing damaged components, such as impellers and pistons. These objects can possibly get jammed in a valve, causing it to become stuck in the “open” or “closed” position. This can occur when intake screens become dislodged after repairs have been done, or on new installations. There have been documented occurrences where rocks, pieces of wood and even hand tools have been stuck in valves.

  1. Has there been a change in process conditions?

The media in a process can change. Is it more acidic? Does it contain more particulate? Did the specific gravity change? Any or all of the these will change how a valve operates. Increased acidity can cause failure of the spring and corrosion of the wetted parts. Increased particulate will cause faster wear of all parts and can lead to leaks and failure of a valve and other components in the system. A thicker than normal media will put strain on a pump and can slow the “close time” of a valve.

To help save money and down time, it is highly important to have an inspection and maintenance schedule to keep your system working properly and safely.

It’s all about efficiency!

Download the DFT® Silent Check Valve 6-page Brochure now!

Material Spotlight – PTFE (Polytetrafluoroethylene)

Feb 14, 2019

By: Michael Pawlowski

From interplanetary deep space missions to sealing the fittings between the faucets and pipes in your kitchen sink, Polytetrafluoroethylene (PTFE) can be found being used in almost every aspect of our daily lives. It was discovered accidentally April 6, 1938 by Dr. Roy J. Plunkett while running experiments utilizing gasses for freon refrigeration. The white waxy substance that had spontaneously polymerised was found to have some remarkable properties. PTFE turned out to be a resin impervious to almost every known solvent with a near frictionless surface which no substance would stick to.

The unique properties of PTFE lend itself well for use in a variety of industrial, manufacturing, and engineering facilities. The superb chemical resistance and tolerance to vast temperature gradients has not only improved the efficiency of many industries but the safety for the employees that work around those conditions as well.

12 ADVANTAGES OF USING PTFE FILLED COMPOUNDS

  • Excellent chemical resistance
  • Wide range of service temperature
  • Excellent dielectric properties
  • Non-stick, low friction
  • No embrittlement or ageing
  • Smooth surface finish can be achieved
  • Non wetting
  • Outstanding corrosion protection
  • Electrical insulation
  • High thermal stability and flame resistance
  • Resistance to weathering
  • Food grade compliancy

5 COMMON GRADES OF PTFE

Virgin PTFE
“Virgin PTFE” (PTFE without a filler) is one of the most chemically inert materials known and is used in many different applications and industries.

Glass Filled PTFE
Virgin PTFE with 25% Glass fiber filler which dramatically increases compressive strength and lowers deformation under load.

Bronze Filled PTFE
The addition of Bronze to PTFE gives better dimensional stability and lowers creep, cold flow and wear.

Carbon Filled PTFE
The addition of Carbon Fibre to PTFE increases the compressive strength and wear resistance. It provides good thermal conductivity and low permeability.

Stainless Steel Filled PTFE
The material is extremely hard wearing, has excellent strength and stability under extreme loads and elevated temperatures whilst still retaining the low coefficient of friction of conventional PTFE.

PROCESSING PTFE

Because PTFE is a thermoplastic and due to its high viscosity, it cannot be processed using conventional polymer processing techniques. PTFE is processed by cold shaping and followed by heat treatment (sintering) during which polymer particles fuse to form a solid moulding.

PTFE is highly resistant to corrosion due to its chemical inertness. Unfortunately, that same chemical inertness prevents PTFE from being cross-linked like elastomers and is subject to the phenomenon of cold-flow – otherwise known as “creep”. To reduce and diminish cold-flow, additives are introduced during the preparation of PTFE compounds. Fillers, such as glass fiber found in Durlon® 9000 and 9000N gaskets, not only reduce creep but also maintain chemical inertness against aggressive and caustic chemicals but are still considered safe for use by food, drug and medical services.

Durlon® 9000 & 9000N PTFE SHEETS & GASKETS

Various shapes of inorganic fillers have been homogeneously blended with pure PTFE resins to give Durlon® 9000 its physical and mechanical properties. It is suitable for use in steel flanges and will not exhibit the cold flow problems associated with virgin PTFE or the hardness problems of some other filled PTFE products. It cuts easily and separates cleanly from flanges after use.

Certifications
Durlon® 9000 – API Standard 6FA Fire Test, TA-Luft (VDI 2440), BAM, Pamphlet 95 (Chlorine Institute), FDA Compiant, USP Class VI Certified, ABS-PDA Certified, EC 1935/2004 Compliant, DNV-GL Accreditation, RoHS Reach Declaration

Durlon® 9000NFDA compliant, ABS-PDA Certified, USP Class VI Certified, RoHS Reach Declaration

 

Durlon® 9000 is made with Teflon™ fluoroplastic. Teflon™ is a trademark of The Chemours Company FC, LLC used under license by Triangle Fluid Controls Ltd.

It’s not me…it’s you!

Jan 31, 2019

By: Chett Norton, C.E.T.

I have had many conversations over the years with end users and installers, and the majority of the time, we realize that it wasn’t the gaskets fault for blowing. I often chuckle to myself wondering how the conversation would go if a gasket could talk to its end user? I think it would be very similar to the stereotypical relationship break-up line, “It’s me…it’s not you” but just the opposite, “It’s not me…it’s you” ‑ gasket talking to the end user.

Gasket failures are far too common and in a lot of cases can be categorized into 4 main categories – as this poll explains that was conducted by the FSA on 100 gasket failures. They determined the root cause of the failure causes as:

  • Under Compression (68%)
  • Over Compression (14%)
  • Wrong Product Used (14%)
  • Other (4%)

Under Compression can be caused by not tightening the bolt enough to apply the correct load on the gasket due to manual tightening or friction that is unaccounted for or possibly due to gasket relaxation. As you begin to tighten the material it will start to “creep” due to the compressive load being applied. As the gasket thickness decreases, the originally applied load on the bolts will lessen. This is due to the thickness change resulting in a lower gasket stress or compression and can cause a leak due to permeation through the gasket or tangential between the gasket and the flange sealing surface. Additionally, unloading of the gasket can occur due to temperature or pressure cycling which can have the same effect.

Over Compression is caused by too much load on the gasket. This can be caused by not using the correct torque value or perhaps using a tightening tool that you cannot measure the torque, for example an impact gun or cheater bar extension. Over compression reduces the contact area of the gasket and crushes the gasket towards the ID allowing fluid to penetrate the gasket ID thus leading to deterioration of the gasket, damaged flanges and can result in leakage or gasket failure ‑ a huge problem.

When Wrong Product is used, it can become a serious safety issue. The material selected must be capable for the temperature, pressure and media that it is being installed into. If the gasket material is not rated for either the pressure or temperature of the application, this can cause very serious issues such as worker injury or plant down time. Additionally, the gasket must be chemically compatible with the media or the chemical can attack the gasket; causing it to prematurely break down which may cause leakage or even failure.

And lastly, the Other category could be several things, such as using the incorrect gasket size, poor method of cutting, or quite simply, it is somewhat of anomaly and couldn’t be grouped into one of the three categories above.

The good news is, 96% of the above listed failures can be eliminated as they are in YOUR control! By following these few points, you can ensure that your gasket doesn’t have to give you “The Talk”.

  • Pick the correct material, verify the pressure, temperature and media that you will be installing the gasket into.
  • Use the proper tightening procedure noted in ASME PCCC-1.
  • Lubrication is key, friction is robbing and can account from more than 50% of the required torque.
  • Always use the manufacturers recommended torque values. If you are unsure, give them a call as they will be happy you did.
  • Use a proper tightening tool, such as torque wrench.
  • Gasket creep and bolt relaxation happens, be sure to eliminate this by always remembering to re-torque within 4-24 hrs.

So, the next time you have a gasket related issue, check to make sure it wasn’t due to one of the reasons mentioned above and remember to think to yourself WWTGGDWhat Would The Gasket Guru Do?

Until next time, keep the fluid between the pipes!

At Triangle Fluid Controls Ltd., we provide Gasket Installation Training to help prevent lost production time, to decrease maintenance costs, eliminate fines and to help ease your health and safety concerns.

2017 Randy McKay Sales Award goes to…..

Triangle Fluid Controls (TFC) is pleased to award the 2017 Randy McKay Sales Award of Merit to Ryan Kelly in recognition for his outstanding sales performance with TFC. The award is given to TFC’s Regional Sales Manager (RSM) whose territory had the largest year-over-year sales increase from 2016 – 2017 and was presented August 23rd, 2018 at TFC’s headquarters in Belleville, Ontario. “I am extremely proud to present this award to Ryan Kelly for the second time in 3 years.” said TFC’s General Manager, Mike Boyd. “Ryan joined TFC in 2015 and has demonstrated a high level of energy and commitment to drive sales growth in Ontario and Manitoba. Given Ryan’s passion for his work, I am very excited to see what the future holds for Ryan and his sales territory”.

The award, created in memory of the late Randy McKay, TFC’s Central Canada RSM, was created by TFC President Mike Shorts, as a means of paying homage to the former TFC employee. “Randy did a lot for TFC, was a stand-up individual, and somebody that I personally, learned a lot about sales from. After Randy’s passing in 2015, I knew I wanted to create an award in his memory.”

The award includes two pieces: an engraved glass plaque and hand-blown glass sculpture made in a similar shape, style, and colouring to TFC’s company logo. The glass plaque will hang in TFC’s lobby with each year’s winner added to it. The making of the pieces, commissioned by a local glass blower in Wellington, Prince Edward County, and was completely documented and can be found posted online on TFC’s social media channels or by clicking here.

Sealing for Extreme Cold: Best Practices for Static Seals

As published in Pumps & Systems Magazine, July 2018

Co-written By: Chett Norton, C.E.T.

 

Flexible graphite and PTFE are commonly used in cryogenic sealing. Natural gas popularity is growing exponentially because of its low cost, low risk to transport and store, and its status as one of the cleanest burning fossil fuels. With increasing global pressure to reduce greenhouse gas emissions, the need to meet growing energy demands while reducing these emissions is more important than ever.

Click here to read entire article.

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