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Vibration, dynamics and noise

formerly BETA Machinery and SVT


Pipe support performance – ask the expert

Q&A from our pipe support evaluation webinar "Shake, rattle and grow (part III)"

By Jordan Grose and Timothy Bootsveld

Watch the recording Download the technical paper

The answers below were given in the context of the webinar and do not address all aspects of the issues discussed.
For more comprehensive information or application support, we strongly encourage you to contact the experts directly.

1 Videos

Videos shown in the webinar:

2 Definition of anti-vibration support

We define ‘anti-vibration supports' as follows:

Supports that (when installed on an adequately stiff base) are capable of forcing the vibration nodes of a gas-filled pipe’s fundamental bending mode to manifest at the support location, for all vibrating modes up to 15 Hz, and for pipe wall thicknesses up to Sch. XS.

3 Classification of pipe supports
For pipe supports to dynamically restrain piping, (= vibratory node is enforced at the support location) the support must restrain the pipe with a sufficiently high stiffness

For pipe supports to dynamically restrain piping, (= vibratory node is enforced at the support location), the support must restrain the pipe with a sufficiently high stiffness.

Stiffness, ‘K’, is the measure of the force require to achieve a unit displacement (lb/in, N/m)

How can I know if a pipe support has nodality?

For most pipe supports out there, we don't know if it will provide nodality or not. This is a reason why we do the testing, so that's part of the problem of what we're trying to address: there’s a gap in the industry in how we categorize these supports.

Testing can determine if there is nodality or not, and we do provide a testing methodology in the GMRC paper we've referenced.

On the anti-vibration support definition, why does it use a gas-filled pipe?

The definition was indexed to the gas-filled pipe because the mass of gas is negligible compared to the mass of the pipe.

For liquid systems, the mass of the fluid is not negligible compared to the mass of the pipe. The nodal frequency/minimum stiffness can be corrected for this using the density of the fluid particular to your application.

Can you confirm, the discussed definition for ‘anti-vibration,’ is it from Wood, and where did the Hertz come from?

Yes. This definition was put forward by Wood. I would recommend you look up the paper that we wrote for the Gas Machinery Conference, “Shake rattle and grow – empirical data on the effectiveness of vibration supports in a thermal growth environment.”

We go through a very in-depth discussion as to how we came to the Hertz. The Hertz is high enough that it avoids a lot of the low-frequency flow-induced turbulence-based broadband energy that you typically see in liquid and even gas systems. I've seen some companies use seven Hertz. It’s a good number to keep you away from low-frequency vibration problems.

Have you reviewed I-Rod/u-bolt pipe supports? How would you evaluate them?

Yes, we included 'Nu-bolts' in our testing and found that they are classified as 'flexible' supports because they do not have the minimum stiffness in all three directions (decision point #1 of the flow chart). So, they have their place, but they are not anti-vibration.

Please refer to our paper Shake rattle and grow, which includes more results than shown in the webinar, and we're continuing to do more research and testing even up to today.

Pipe support classification chart - flexible, rigid and dual-purpose supports
 Classification flow chart for pipe supports – flexible, rigid and dual-purpose supports
4 Applications

In what environments can DamperX clamps be used?

The current DamperX products can be used for temperatures between -17°C to 204°C (1°F to 400°F).

Can Wood's anti-vibration supports be used on high-speed and multiple-speed-range machines, for example, compressors around 1000 RPM?

Wood ThermaGlide anti-vibration clamp for thermal growth environments

Wood ThermaGlide anti-vibration clamp for thermal growth environments

We recommend selecting a support that can maintain nodality for these frequencies. You'd want to space your supports appropriately. If you can't find a support that can maintain nodality up to that Hertz, you might consider using a support that has a higher amount of damping.

How will these anti-vibration supports work in areas with winter conditions?

Our clamps have a temperature range from -17°C to 204°C (1°F to 400°F), depending on the lining that you select. The same applies to the shoes. For conditions outside this range, please contact us directly.

Can Wood’s anti-vibration clamps be used in hazardous areas?

Generally, yes. It depends on what type of hazard, but they can be used in most petroleum, chemical and natural gas type facilities.

Do these supports work with liquid pipes too?

Yes, our clamps work on liquid systems, too.

5 Effects of support types

If you restrain the pipe to prevent vibration, will this increase the stress in your system? How do you balance both these requirements of holding down the pipe and remit static stresses?

Yes, if you hold down the pipe with an anti-vibration support, you will create stress problems unless the pipe and support are allowed to slide. That's why we have introduced both:

  1. ThermaGlide anti-vibration sliding supports that both control vibration, while also having sliding capability to reduce pipe stress in the system, and;
  2. The concept of a bilinear pipe support, to allow for accurate modeling of anti-vibration pipe supports in a pipe stress model

We discuss this in-depth in Shake rattle and grow part I, where you can learn how to accurately model these types of pipe supports in your pipe stress model, and how to account for the sliding capability of these anti-vibration dual-purpose supports.

Can we use spring washers with adequate stiffness as a damper spring washer?

We don't recommend it. We've seen people try, but you'd have to implement it in a way that the stiffness is always in contact with the pipe. It can be problematic ensuring the spring washer stiffness exceeds the stiffness minimums. We have seen installations in the past that failed because the pipe lifts off from the support, thus removing the vertical stiffness from the supporting structure.

We prefer the clamp design and do not supply spring washers due to these implementation issues. We provide calibrated torque specifications that we find is a simpler solution to maintain the hold-down friction force you need. We don't recommend using the spring washer method.

Would the rigid support (contestant 2) break away with steel on steel friction?

If we continued to increase the pulling load on the pipe, the pipe would eventually be pulled through the clamp. However, we only pulled up to a load equal to the maximum allowable load given by the manufacturer and did not observe sliding up to that load level.

6 How to model supports

How do you model the sliding support in Caesar II?

Please find out how to model sliding supports or other anti-vibration supports in Caesar II accurately by watching part I of this webinar, where this topic is covered extensively.

7 Support features and details
Pipe support performance test results - damping and vibration

Pipe support performance test results – damping and vibration control

Do Wood supports use Fabreeka?

Fabreeka is a material that is often used in lining clamps. It is very popular in North America.

The answer is no; we do not use Fabreeka in our supports. We have tested numerous materials as liners for our clamps, including Fabreeka, and have found that very few lining materials provide any damping benefit at all. The DamperX materials we use in our products provide the most damping on the market, while also having good properties for industrial environments.

Is ThermaGlide a trademark?

Yes, it is. It's one of the ways we use to categorize our anti-vibration products that have the thermal sliding capabilities.

Do you supply data sheets on how to apply DamperX clamps?

Yes, we provide data on where and how they can be used. Please contact us directly for detailed specs.

8 Video: damping liner test
  • Transcript

    Note: This transcript is auto-generated and may contain errors.

    Hello everyone. Thank you for joining us to today's webinar “Shake Rattle and Grow part 3”. Hi. My name is Jordan, and I'm your facilitator and part speaker today. Today, we're going to talk about how to quantify the performance of pipe supports for vibration service. Just a few things before we get started. If a couple of housekeeping items, if you have any questions during the webinar, you can type them in in the Gotowebinar question box.

    So, before I get started, I'd like to give you a little bit of background on Wood.

    Wood is global leader in technical engineering and project services, generating success for our customers and communities all around the world. Our core values are care commitment and courage which we use in our work to push the boundaries to create smarter more sustainable solutions every day. So within Wood, the panel today is part of the vibration dynamics and noise group, which is a consultancy within Wood. This vibration dynamics and noise consultancy looks after piping and structural vibration compressor pump and rotating equipment dynamic studies machinery monitoring reliability. So, for operating equipment damping clamping solutions, let's anti-vibration products, which all three of the panelists are form today, and noise management and also field troubleshooting.

    So that's a bit of a snapshot of what the VDN team looks after every day. We're a global team that function out of several offices around the world. So, today's our speakers are myself. My name is Jordan Grose. I have a lot of experience in vibration and dynamic design analysis and troubleshooting. I currently lead our anti-vibration product team which researches and develops solutions to mitigate vibration and I've authored many numerous papers at different industry conferences around the world.

    Also, we have Starr Dalton here, who works for the anti-vibration project team and has past experiences project engineer capital projects. She works with our operator and EPC clients to help integrate anti-vibration solutions into their projects. She's presented in numerous training courses in technical conferences around North America. We also have Timothy Bootsveld who is one of our engineers specializing in pipe stress and vibration and product design.

    He has a strong background in pulsation and finite element modeling and is one of the developers of our anti-vibration products. He also famously instructed our compressor pulsation mechanical simulation training courses. And so that's your panel for today.

    So, in today's agenda, we're going to look at a few different things. Number one. We want to teach you about a new methodology to qualify pipe supports vibrating systems. Want to help you gain more confidence in your pipe support selection and also help you solve real problems in your piping designs. We're going to do that by discussing a few different items specifically competing requirements between both pipes dress and vibration design considerations.

    We want to walk through a few different design phase activities for vibration talk about anti-vibration support categorization and performance and show you some empirical data on real pipe supports. So that's the agenda and we're going to dive right into it now.

    All right, so we're going to pass it off to stars going to talk about conflicting requirements between the vibration design and pipe stress Design Star. Thank you, Jordan.

    So, let's get started. The first one we're going to look at is vibration engineers and vibration Engineers love clamping down pipe. So, they say hey, we need to support here there, you know, basically everywhere. However, pipe stress engineers love keeping pipe flexible. They come in and say, you know, we don't really need this clamp or that clamp. Okay, really any clamps, but we'll leave to keep the vibration guys happy and then we'll throw pipe shoes everywhere else.

    And this can lead to some problems in vibration if these standards aren't balanced early in a project. It could look something like this.

    So, we're about to play a video. Give us just a second here while it loads.

    Here it goes.

    So, a rest in a guided shoe would be required as you can see there's still some pretty severe vibration happening in this system both in the pipe in the forefront and then as it turns up in the back now, this is a yard piping that's shaking quite a bit. You can see it's got a couple of u-bolts on it, but the supports aren't spaced adequately for a vibratory service.

    See it’s really bouncing a lot in the middle there.

    And then the last one is sometimes you can't see vibration without additional help.

    So, this is shot with the motion amplification technology to show how much So we'll switch back to the presentation here.

    And this might lead you to the question. Okay.

    And we'll be showing that screen here in just a second. There it is. So now when we look at balancing the requirements, we will still have some anti-vibration clamps.

    But we'll also have anti-vibration ThermaGlide lateral side clamps anti-vibration ThermaGlide axial slide clamps and even a couple of anti-vibration DamperX ThermaGlide axial slide clamps. So, when the pipe stress and vibration requirements are balanced during the design phase of a project it produces a more Optimum design earlier in the project and eliminates the need to modify the piping layout later to accommodate one or the other design practices.

    So, let's look at the design phase and some common vibration activities and their limitations. So, this is a gas compressor installation where you can do the following studies per the API standards for machinery dynamics, pulsation analysis, piping dynamic analysis, torsional analysis, foundation and small-bore connections. Now, if we look at a different system a liquid pumping station, perhaps we can now do the following studies. Foundation and piping dynamic analysis, piping stress analysis, small-bore connections transients and even fluid dynamics.

    But how do you know when to be worried? So, in this particular case an operating staff was out on site and was able to see a vibration problem on the PSV line up on the screen. They called us out to do an analysis of the system and find the root cause and make recommendations.

    But sometimes you can't see vibration problems and in a large facility, it might be hard to pinpoint where the problem areas might be.

    And of course, this gets even harder if there's multiple units within the same facility. So, the question remains, where should you be worried about vibration induced fatigue failure?

    Well, there are design standards on the meth on the market that can help. So, some of the industry standards for piping design such as ASME BE and the Energy Institute standard could be helpful.

    And of course, industry standards for rotating Machinery are more extensive but to name a few we've got API for pumps API for gas turbines and vibration is covered in most of these industry standards and some of these standards are fairly effective at reducing the vibratory response.

    But as we saw in some of those previous videos, the vibration can still be a problem in the piping system, even if we design and build / these industry standards for Example how many pipe supports are needed for vibration service? And where should they be located?

    And vibration can manifest away from the rotating piece of equipment and maybe it shows up in a small-bore connection failure.

    So, coming next year, we’ll be giving a webinar talking about these very problems. It'll be all around how to define vibration service in the piping system. So be on the lookout for that next year.

    And with that I'm going to pass it off to Tim to talk about the anti-vibration supports both the support categorization and the performance. Okay. Thank you, sir. So, before you hear from me, I would like to hear from you. I'm going to send out a poll. The question is: have you ever used anti-vibration supports in your systems? Have you ever used antibodies vibrations Sports in your systems?

    So, I've launched that it should be showing up on your screens.

    As you answer that I want to remind you that we will be taking questions. And if you have a question during the presentation, feel free to enter it in the question box and we'll be addressing a few of them at the end.

    There is a No-No and say they're not involved in that, but this is interesting because the question I have for you is how do you know that what you've used is anti-vibration? Perhaps you've relied on a manufacturer to let you know that what you are using is anti-vibration, but the funny thing is that there are no standards currently available that that dictate appropriate use and we were approached by quite a few different people after our first two webinars about this question. Our first two webinars had to deal with the first one was Shake Rattle and Roll Part One how to model anti-vibration supports and pipes dress software.

    The part was how to apply anti-vibration supports effectively during design phase in a way that can balance both vibration and pipe stress requirements, but we kept on getting questions about that. Does this support meet the qualifications for anti-vibration? And the question is a good question. What is an anti-vibration support? What qualities should we be looking for in a support that that makes it appropriate for use in vibratory service?

    A common place you'd look for an answer to this question would be the design documents that you have when you're doing a pipe stress design job, right? There's two of them. Typically, two of them. They might be Immaculate Amalgamated into a single document or the information might be spread out in multiple documents. But typically, I've seen them in two different documents.

    There's the first one is a pipe stress design philosophy document or selection practice document this document references codes and standards that That apply to the pipe support use and they give guidance on which support should be used where the second document is a pipe support standard, or a pipe support catalog and they give drawings of each of the supports. They give guidance on how to spec it and they give application notes like allowable loads.

    Typically, though these documents don't give you an answer as to what anti-vibration supports are and how to identify them not because the authors are negligent but simply because there is no industry standard that gives a robust definition as to what an anti-vibration support is.

    They acknowledge that there's a difference between, for example, says you want to use your pipe supports to avoid resonance.

    It acknowledges that there's that difference between pipe supports that can do that, but it doesn't tell you how to identify that.

    So perhaps you could take your quest so as an example most catalogs, whether their company internal or manufacturer also do not indicate whether your support is appropriate for vibratory service the plot you see on the right-hand side is from DSP standard which gives a whole bunch of different types of pipe supports. Some of them are appropriate for vibratory service.

    Some of them aren't. The point is that they don't indicate for you, which ones are and are not.

    So, you could go to Google and ask Google: show me what anti-vibration supports are and Google will come back. He was Million results very helpfully. And one of the funny things about Google is that what we've observed from the results that from the search is we've done is that there are some types of ports that show up they are labeled as anti-vibration. They have titles such as vibration isolating or vibration control.

    When in our experience these supports are not appropriate for vibratory service, they should not be used but because there is no standard these labels can be applied to a product.

    at the manufacturers will so what are anti-vibration sports industry acknowledges that there is a difference between pipe supports that are appropriate for using vibratory service and those that are not but there is no proper method of categorization as it stands today piping designers use their intuition and experience in using supports the five pictures. You should see at the bottom of the screen or pipe supports which word selected by piping designers for use in vibratory service.

    some of them are some of them are appropriate for use in vibratory service. Some of them are not.

    The point is that the piping designer in using their intuition and experience selected those supports for use in vibratory service.

    So, we would like to say that there's a better way we recently wrote a paper for the GMRC titled Shake Rattle and grow, and it had to deal with this question. What are anti-vibration supports and in it, we gave a definition and a methodology to categorize supports as to whether or not they are appropriate for use in vibratory service.

    The definition we came up with is the one that you are seeing on your screen the definition of an anti-vibration support.

    Is a support that wouldn't installed on an adequately synth bass is capable of forcing a vibration node of a gas Fields pipes fundamental bending mode to manifest at the support location for all vibrating modes up to Hertz and for pipe wall thicknesses up to schedule Xs.

    So that I understand that as being a bit opaque, but let's walk through the components of this definition. You can see why we've made the decisions we have in making this the definition the first thing let's address is nodality .

    What is nodality? Why is it important for anti-vibration support?

    Well a vibration node is a point on a vibrating system that has zero displacement, right? You should be seeing an animation on the bottom left-hand side of your screen. It's a pipe segment that we've put together a put in a finite element software and we've supported it at seven locations, and this is the vibrating mode that shows up first.

    For this piping segment, you can see at the support locations. There is zero translation going on. There's zero displacement. The supports are acting notably. There's no displacement at the supports that the supports are restraining the pipe and the supports themselves are not participating in vibration.

    That's what we'd want to see out of our anti-vibration supports and as an example of a support that does not do that job. Here is the same pipe but we've used supports. We install supports on this pipe that are not appropriate for use in vibratory service. And this is the mode that shows up right the pipes the pipe is dragging the supports along with them.

    What we see is that the supports are not acting notably. They are not restraining the pipe these supports are not appropriate for use. They are participating in the vibration.

    So as a real-world example, we have we've done some motion amplification video of pipes supported by two resting style shoes. There's a Shaker at mid-span and we're exciting this piping spool to find out where the vibration nodes are in this case. Hopefully you can see it in this case.

    The vibration modes the points of no displacement on this pipe manifest not at the support locations where we Them to be for an antiviral import they manifest somewhere in the middle. There's two of them. You can see that they are the points on the pipe where there is zero displacement the support itself. The support itself is not nodal. It is participating in the vibration.

    If we take the same piping spool the same Shaker and we simply replace the supports these two clamps unlike the shoes are producing nodality. There is zero displacement at the support and the supports are not participating in the vibration. They are not translating. That's the situation would want for and anti-vibration support the support produces nodality at the support location. Now, how do you produce nodality? What quality does a support need to do that? Well for a pipe support to dynamically restrained piping that is to produce a vibratory node at the support location. The support has to restrain the pipe with a sufficiently high stiffness is it's not we're not using a special definition here. This is the same definition you get in your mechanics class that it's the measure.

    Of the force required to achieve a unit displacement.

    As an example, and we're going to create a force displacement chart that you're going to see a lot of these in the remaining part of the presentation. I have a spring. I haven't applied a load to it, and I have no displacement. I can plot that point.

    If I if I apply a force that spring, I get a certain amount of displacement I can plot that point.

    If I apply double the force, I get double the displacement. I can plot that point what we find is that on your Force displacement chart the slope of that line is your stiffness.

    So, let's take that to our real-world examples where we had our clamp to clamp was able to dynamically restrain the piping right? The vibratory node manifested at the support location. The clamp was acting to restrain the pipe. It had a sufficiently high stiffness to do so and we can map that onto our Force displacement turn.

    Our other example of the resting shoe the vibration. So, the vibration nodes did not manifest at the support location. It did not have a sufficiently high stiffness to generate vibratory nodes.

    It had a very shallow stiffness now between those two there's a stiffness value at which We start generating modality right above that stiffness value your support sack node Ali below that stiffness value your supports do not act knowingly what we've done and then again, I'd reference you to the paper that we've written.

    It gives a full explanation of how we did this, but we went and calculated the stiffness is you'd need for your support to generate that nodal condition the supports you see in the table on the right-hand side give you the stiffnesses. You need per pipe size and for a pipe support to be considered an anti-vibration support. You'd have to have these stiffnesses in all three directions to even be possibly considered an anti-vibration support. Now. Remember the rest of the definition we linked these stiffnesses to certain conditions. That's that those minimums are calculated such that the support maintains nodality for the Hertz minimum that we wanted for schedule extra strong pipe.

    And for gas field pipe now for the extra strong piping you if you have a thicker wall thickness, you can correct for that. If you have a fluid-filled instead of gas-filled piping you can correct for that, but these differences are indexed to Hertz, but you can imagine your support might have more stiffness than those minimums. We just gave in the table.

    And you can think of stiffness as being correlated to the frequency at which the support can maintain nodality. Right? And this gives us an easy way to compare supports across different sizes and it gives you the ability to do a quick check on the support performance for your project.

    This is going to be we're going to call this our first performance factor for anti-vibration supports.

    As an example. I'm going to fill out this table as we go but for our two and three and four-inch pipe we're taking those as an example. The stiffness is required to maintain nodality, which I've taken from the table in the previous slide are thousand and eleven thousand seven hundred pounds per inch.

    Those although they are all different stiffnesses. Those all generate vibration nodes at Hertz. But if your support has different stiffness values than that such as the example stiffnesses I give here it's difficult to correlate those and given that they're all different.

    They're not very useful, but we can correlate them to the frequency at which they can maintain nodality so in this example as the stiffness increases you can hold your pipe nodal for higher frequencies.

    There's a conversion you can do from changing from your support to your maximum nodal frequency using this as a performance metric is helpful because this allows you to add a glance see if the anti-vibration support that you've selected. It is appropriate for your project say, you know that you have dynamic energy in your system up to a maximum of Hertz. Well, what you need to do is Select an anti-vibration support that can maintain nodality to greater than Hertz.

    So, this is the first of all performance factors we're going to talk about anti-vibration sports. The second is damping, right your support has a certain amount of stiffness and that's important because it allows the pipe to create a vibratory node. But the damping is that the damping that the support provides to the pipe is that which determines the magnitude of the vibration at resonance. We're going to revisit this chart at the bottom of the screen later on in the presentation, but this is the vibration response.

    Since that we have gotten out of testing three different styles of supports, when we excite a pipe to resonance supported by these supports support x with very low damping gives us inches per second. But as we test different supports with different amounts of damping, we get less and less vibration using damping as a way to qualify.

    Your supports are helpful in as much as if you know, you have a situation where there's Hi excitation High dynamic excitation or if you have Broadband energy selecting us an anti-vibration support that has more dampening would be helpful to you.

    You'd want to select a Support that can generate a node for a higher frequency than your dynamic energy. Also consider your span damping that determines the magnitude of your vibration at resonance. If you know that you have high excitation or if you have Broadband energy, you might consider moving to an anti-vibration support that has more damping.

    There is a feature also about that some anti-vibration supports have that allow the support to move under a static load move under a thermal growth condition. Now up to this point. We've been talking about Force displacement relationships that have a single line. They are linear right? No matter how much you push on it. It resists with the same stiffness.

    No matter the magnitude of the force that you use but there are supports that act in a by linear fashion. These supports have a base stiffness. And then there's a sliding segment. Once the static load reaches the Breakaway friction Force value sliding occurs. No additional reaction at the support is sustained and the displacement continue so long as your load equals the Breakaway friction Force.

    So as an example for that, I have a video for you.

    What we have here is the pipe in yellow clamped down to a supporting structure and it's being pulled Along by a screw Jack we can pull the loads that the screw Jack is applying to the pipe off of transducer and we can measure the displacement what we'll see is that The screw Drive slowly loads up the support with force and we get a little bit of deflection out of the support itself. But once we reach the Breakaway friction Force the support itself starts to slide. We don't see any additional load on the screw Jack at that point for two sliding as so long as we keep that same load applied.

    Well that begs the question how much how much Breakaway friction Force do you need in order for it to still be considered an anti-vibration support? Well at your support location A well-designed system can have static loads upwards of , pounds even more but your dynamic forces at your pipe support location are typically less than a thousand pounds and even smaller for Less sizes of pipe and the disparity we can we can leverage that in as much as if we put our minimum friction.

    Enforce value for an anti-vibration support above the dynamic forces. We'd otherwise experience expect to see if your dynamic forces are less than your friction Force. Then there will be no dynamic sliding. There'd be no vibration. This still allows a static Force to overcome the friction and allow static sliding and we have a prescribed value of friction Force for which we'd say that an anti-vibration support needs to maintain in order to be considered an anti-vibration support.

    So, given those three metrics the stiffness of a support the sliding characteristics of support and the Breakaway friction Factor, we can classify supports as to their appropriate use will start at the beginning. It's a good place to start the first question. You have to ask yourself.

    The first decision point is the support stiffness does your support Meet or exceed the minimums that we've given in all three directions.

    If your answer is no what you have is a flexible support.

    An example of that would be a spring support with low stiffness. That would not meet the minimums and it would be flexible support.

    But if you meet those stiffnesses in all three directions, you have to ask the second decision point on the flowchart is does one or more Direction allow for sliding. Is it a bilinear forced displacement relationship if your answer is no to that question what you have is a rigid support an example of this would be a bolt down shoe. It doesn't allow either dynamic nor static.

    displacements However, if your support does allow sliding the third question you asked your scalp you have to ask yourself is my Breakaway friction force in that sliding Direction greater than the minimum.

    If it is not then again, you have a flexible support an example of that would be resting style shoe the shoe may have enough stiffness to exceed the minimums. But if your friction force is too low, you'd expect to see dynamic movement of the pipe at the support location.

    However, if your answer to that question is yes, what you have is a dual-purpose support Dual Purpose supports our supports which resist dynamic movement resist vibration and yet they allow static deflection. They can move under a thermal load those two categories that do purpose support in the rigid support. Our that which we classify as anti-vibration supports. Those are the supports appropriate for use in vibratory service.

    So, to conclude this section categorization of supports helps piping designers in a few ways how you can select supports appropriate for your application. You can model them accurately. You can make informed decisions during the design phase as to how you are supporting your pipe and we've proposed three categories of supports flexible supports, they allow static and dynamic movement. They are useful in non-vibratory service only and then anti-vibration supports which come in two flavors rigid supports, which prevent both static and dynamic.

    Movement of the bike and do a purpose supports which prevent dynamic movement of the pipe prevent vibration, but they allow a static movement of the pipe.

    Anti-vibration supports are appropriate for both laboratory and non-vibratory service.

    And not all anti-vibration supports are created equally you have to consider the part performance factors associated with your anti-vibration support the two that we recommend considering the maximum nodal frequency. You want to use a nodal frequency appropriate for your system. Make sure that you're maintaining separation away from your dynamic Force.

    And damping if you have a system with high or Broadband excitation, you might consider using a higher depth support and key locations to mitigate anti-vibration in your system.

    I'm going to hand over the presentation to Star again. She's going to walk through some examples of some pipe supports that you can visually categorize start. Thank you, Tim. Alright, let's get started.

    So, for this section as Tim mentioned we're going to visually categorize these different supports. So, measuring the stiffness in the Breakaway friction forces of a support may not always be possible. However, some features help to immediately categorize a support. So, the three cases we're going to look at is a resting shoe support a guide wedge clamp and then a castle hold down.

    So, the example one is the resting pipe shoes. Now as we've kind of been talking about resting pipe shoes provide zero or next to zero stiffness. They have no vibration control and they tend to lift off of the support.

    We're going to pull up a video here to show you exactly what we're talking about so this video is taken with the motion amplification camera, but as you can see that pipes move quite a bit.

    So, if we move back into the presentation and we look at the flow chart to figure out if the pipe shoe is suitable for vibration service. We know that the support stiffness is not greater than the dynamically fixed minimum in all three directions. So therefore, the pipes you see is considered a flexible support.

    Moving on to example a wedge clamp and the question of is this suitable for vibration service? Well, the first thing you should notice is the gap between the pipe and the pipe clamp in both the vertical and horizontal directions.

    So once again if we follow through on our flow chart Due to the Gap in the vertical and the horizontal, we know we do not have a fixed minimum in all three directions. So, this is considered a flexible support.

    Now let's look at a couple other problem areas. We've already talked about the gap between the pipe and the support and this not being acceptable and vibration service. Another area to look is there's no locking mechanism on the wedge because it's actually vibrated itself off. You can see the nut sitting there on close to the short bolt.

    So again, not suitable for vibration service and then finally the short bolt now, we do not suggest using short bolts and vibratory service because you can't get enough bolt stretch in order for to stay in place in a vibration service. So overall the wedge clamp in this case is not suitable for vibration service. Let's move on to example castle hold down. And again, our question. Is this suitable for vibration service? Well, if you were paying attention in the last example, you see there's a gap in the horizontal between the pipe and the support now the pipe is touching the support in the vertical Direction. So, we do have some stiffness in the vertical but none in the horizontal.

    So, if we look at our flowchart, you should easily be able to tell no this is considered a flexible support.

    Once again, let's look at those problem areas. So, the Gap means it's not suitable for vibration support. We've also got multiple shims. So while it is a good idea to shim up, so you have contact between your pipe in the support and this case those shims aren't adhered to anything in the work themselves out over time, which means you no longer have that vertical stiffness, so not acceptable and then finally just like the last case they're short bolts once again and short bolt should not be used in vibration service.

    And with that I'm going to pass it back to Jordan for the pipe support game show.

    All right, folks who said a webinar isn't Fun you get to play a way a game show today. So, what we want you to do we're going to basically come forward with five different pipe support contestants in our game show. And what you need to do is you need to evaluate the features that are marketed by that each contestant and choose the pipe support category. You think that'll fit so to give you a little bit of background on this what we did to Duke with these five.

    Words, we did a standardized test to compare them all according to the categorization methodology. We've been talking about if you want more details of this testing procedure. You can refer to the gym or see paper. We've been talking about Shake Rattle growth, but to give you an idea what the testing involved we install the pipe support on a pipe segment and a structural component as per manufacturer specs.

    We applied a known force on the pipe at the support and as result we measured the Displacement accordingly and we plotted that deflection versus force and created the plot similar to what Tim was showing earlier. So, we've done that for each of our five contestants and we'll show you that data, but first you need to vote so contestant number one. You can see it on the screen. This is a you boa coated u-bolt who they claimed to reduce has a reduction of we're due to fretting they also show this is a polymer coating.

    On the u-bolt. There is the claim to have reduction of vibration and Noise with using of this u-bolt and there's also a under pipe liner that provides some damping benefit. So, given all those features and what you see on the screen. Let's see what you think. The category is for this this particular pipe supports. I'm launching the voting buttons right now. So, you need to tell us do you think it's flexible dual-purpose rigid?

    Are you not sure?

    Give you some time to vote here.

    All right. So, thank you everyone for voting keep them coming in will give another few seconds here. All right, we're going to close the poll and show you what people think.

    So, if you what most people think that this will be a flexible support % percent will think it's going to be a dual-purpose % considered to be rigid and % Archer. So, let's look at the data find out.

    Okay. So, this this data we've got should be popping up on your screen here. This is testing if we look at the top right-hand corner of Tim's flow chart with the first thing, we evaluate is the stiffness test is the pipe is the support stiff enough for vibration service. So, what do we find? Well, we've tested this in two directions what we find in the axial direction is the stiffness is , pounds Force per inch.

    And in the lateral the stiffness is a little bit less the lateral Direction. So, what that's good. We got some stiffness out of it, but the minimum stiffness for this size of fight is , pounds-force per inch minimum. So, these values fall below that, so we go back to our flow chart. Once again, we find that our support stiffness does not meet our minimum in all three directions. Therefore, this this support is considered a flexible support. So those of you who guessed flexible you are correct.

    We're showing you a grantor a video here of hopefully it's coming through on your side of the supports and action. So, what you can see is similar to actually the pipe shoe video.

    We showed earlier these supports the vibration nodes are not at the supports where we want them, but there's somewhere else I shown in red here and if it's coming through the if the video is coming through on your end what it does show, is that the supports are going along for the ride in this vibratory system and they aren't providing a nodal response. Like we'd like so that that gives you an idea of how these things might look in the real world. The other part of this testing was a slide testing and what we found with these supports was when the pipes slide through them.

    They grip the pipe adequately are they grip the pipes of subscribe substantially such that even the coating doesn't let the pipe slider actually rolls around the and gets damaged and as you can see down here this damping under pipes or actually gets dragged along with the thermal growth of the pipe as well. But it was adequate thermal growth. This would probably get ripped off. So that's some of these flexibles Ford's do have their limits All Right contestant number two. This is a clamp with all steel construction. No liners it has that extra bolt stretch. So, with these long bolts and these are the main features of the clam.

    Your job now is to vote on what you think of contestant number two.

    Is it flexible dual-purpose rigid? Not sure.

    Okay, the votes are pouring in thank you for voting quickly and often we're going to close the poll. They can check it out the results here. So, percent of people think it's going to be a rigid support % think it's going to be Dual Purpose % Thank you can be flexible and five or not quite sure. So, let's check out the data and find out.

    If you guessed right, so here's the data for the stiffness test. Again, that's Point number one on our on our flowchart. Is it stiff enough? Well, we find in the axial that the stiffness is around a hundred thirty-three thousand pounds Force per inch and in the lateral hundred forty thousand. So quite High stiffness and for this size of pipe, the minimum is . So, what does that mean? These two stiffnesses are greater than the minimum. Which is a good thing so that gets us answering the question yes. The next question we ask are these do these clamps allow sliding what you find if we look at the data here that the stiffness type is linear and it does not break away and produce a Lena by linear portion after the fact so that that means is these this contestant number two does not produce sliding in any direction.

    Ian So we go back to our categorization flow chart. We passed gate. Number one, which led us to gate number two, but did we pass the sliding criteria? We did not so this support is considered a rigid support. So those of you that voted rigid congratulations, you are correct contestant number three, this is again another steel strap clamp. It has a proprietary damping liner in it.

    This damping liner is backed up with some Fiber backed PTFE or Teflon. So, it provides a low-friction contact between the pipe and the clam. So, let's vote again. What do you think?

    Is there a contestant number three flexible dual-purpose rigid or not? Sure.

    The votes are coming in getting very good and fast at this is great two more seconds.

    Four three, okay, we're going to close the poll now and share it. We've got % of people thinking dual-purpose % flexible % rigid. So, let's look at the data find out once again.

    so, when we look at the data for this contestant number three, we apply our stiffness test. So, what we find is these are stiffness points in the axial and a hundred forty-seven in the lateral that is greater than our minimum of eleven thousand pounds for four-inch pipe. So, we do we pass the stiffness criteria. Let's go on to Sliding. Well, what we find with sliding is that in the axial direction. We have a bi-linear stiffness type.

    We're at this level here where my cursor is the - changes and start sliding whereas in the lateral. It's a linear stiffness site. So, we get sliding in the axial Direction only so that's good news. We can carry on to number three number three is our Breakaway friction force test. So, what is our Breakaway friction Force well in the axial it breaks away at about , pounds load and start sliding laterally, it does not slide.

    It just keeps going so this , pounds in the axial means that it's greater than our pound minimum for a four-inch pipe. This means this clamp under dynamic loads under , pounds, which are we expect to be most of them it can restrain the pipe and not slide if for loads greater than that, it will slide for static loads. So that's good news. We can we meet the support stiffness.

    We do allow sliding in One Direction and if we come down to decision point three, we meet Mm, um friction Breakaway friction Force criteria. Those of you guessed a dual-purpose support you are correct.

    Okay contestant number for two more this this support has the features of a stiff steel construction has a low friction liner as a captive where plate to prevent the under pipe where plate from migrating off to support onto the ground and it also includes some low friction slotted hardware for the bolts. Please vote once again for contestant number . Tell us what you think flexible dual-purpose rigid.

    Or not sure.

    Okay, we got about  % of the people. We're going to close the poll. Thank you very much for voting. And what we find is % think dual-purpose % think flexible meaning not suitable for vibration service and consider it rigid. Let's hide the pool and see what the data shows us.

    Okay. So, for this clamp what we find in the axial direction, we do perform our stiffness test. We find thousand pounds in the axial hundred thirty-six thousand pounds per inch in the lateral which is greater than or , pounds for an inch pipe clamp. We've passed gate number one this these clamps are stiff enough. Does it allow sliding what we find in the axial Direction? You see this by linear stiffness type and in the lateral, we get the same thing.

    I linear stiffness type. So that means it slides after it gets to the Breakaway friction load. So, we get sliding in both axial and lateral directions for contestant number four.

    And if we go down to the friction force and understand is that friction force greater than our expected dynamic loads and the answer is yes.

    So, we meet all three criteria if we follow our flowchart through, we find it's a dual-purpose support So percent of the people We're correct.

    Last one contestant number five. This is a tricky one. It's got a stiff steel construction vibration proof washers low-friction slotted bold Hardware a damping liner with a low-friction liner of in addition to that and also as a captive where plate please vote and tell us what do you think this support?

    Where does it land in the categorization process?

    Okay, so we're getting lots of votes pouring in and get about % It will close the polls and share. So % people consider. This support will be flexible and non-suitable for vibration service % Say it'll be Dual Purpose % will settle be rigid and we still have four percent who aren't sure so let's go check the data and become sure.

    Okay, you should see the data popping up on your screen here. So, for this contestant number five the stiffness test, we find thousand pounds in the axial hundred thirty-three thousand pounds per inch in the lateral. This meets our stiffness criteria. This is stiff enough for an anti-vibration support. Does it slide?

    Well, we see in the axial we get a by linear relationship and in the lateral by linear relationship, so the answer is yes, it does slide in to those both of those directions for the friction Force visit greater than our expected dynamic force in the answer is yes, we've got , pound Breakaway friction force in the axial and little higher , pounds in the lateral Direction. So those who has dual purpose support or correct? Okay, that's that talks about, you know, our categorization are these supports suitable for vibration or not?

    About those performance factors came introduced us to earlier.

    Now the first one introduces the maximum nodal frequency. What is the free magazine frequency at which this support can maintain? No doubt e well when we put our anti-vibration contestants and plot them on this spectrum here is Continuum. What we find is contestant number three was a dual-purpose support, but it's only adequate up to Hertz.

    If you have a vibration say a faster machine or a higher-order vibration above hordes This support would not be able to maintain modality contestant number does a bit better, it gets up to about Hertz and contestants to and for can maintain about nodality for vibrations up to Hertz. So, this is a this is where performance factors begin to start differentiating those anti-vibration support out there. The second performance Factor was damping Tim introduced us to that.

    So, if we plot the damping of each of these contestants, Tents online we see contestant number as the lowest amount of damping like point six or eight point seven or eight contestant. Number two is a little bit more you can test number four is about % damn thing. Whereas contestant number five has three times that % damping.

    So, let's see you can see as far as the damping will where does how does that affect us in real life? Well, let's go and plot a vibrant do a vibration test on those supports and see what kind of vibration we get. We have a standardized vibration. We have a standardized input dynamic force on the standardized pipe, and we have the vibration response for that. So, what we find is contestant number three has the lowest amount of damping the small narrow bar.

    Are in the bar chart and it produces about almost inches per second vibration for those metric folks. It's over millimeters per second. So, it’s quite high vibration; a little bit more damping maybe a bit more stiffness and it reduces that vibration by half. It's about four inches per second.

    So, damping can affect our vibration performance quite significantly.

    Higher damping lower vibration. All right. So, let's summarize the game show here. We've got a table that says, okay what vibration service categorization do we get? We give a little clue about what these products were, and we also include performance factors in it. So, contestant number one was this so-called anti-vibration u-bolt what we found was that its stiffness, then meet the category the categorization at all. It is a flexible support not suitable for vibration service.

    Contestant number two was a Wood anti-vibration clamp on line clamp. It met the stiffness categorization but did not have any sliding capabilities. So, this can support was considered rigid. You can see no sliding in either direction.

    The damping was ., but it has a strong nodal frequency performance factor of Hertz contestant number three was a flat bar clamp with a damping liner now this met the stiffness sliding in from Friction Breakaway friction criteria and categorize itself as a dual purpose support it did provide axial sliding in One Direction, which is great but it didn't exactly provide any damping it even has less damping that an unlined steel clamp. So that didn't isn't going well for it. But it does have an okay nodal frequency performance test number four was a Wood ThermaGlide anti-vibration clamp with axial lateral sliding capability.

    Meets the stiffness. It meets the sliding and meet the friction Force criteria and considered a dual-purpose support. We got sliding it in both axial and lateral directions. There's a little bit more damping. We're quite a high nodal frequency capability contestant number five was a Wood DamperX ThermaGlide PTFE line daddy vibration clamp. We have axial lateral sliding capability.

    We need to step in as we meet those sliding, we meet the friction and it considered a dual-purpose support it has as the axial and lateral sliding capability, which is very handy in certain High stripe stress consider a are situations as % damping and quite High nodal frequency of Hertz. So that kind of summarizes all these contestants. We hope you found that useful and informative.

    But if we look back at the five supports that Tim introduced us to earlier one of the questions was, we don't wear any of these suitable for vibration we have Tested any of these as per this criterion, but we can we did do the we were called out for field troubleshooting in order to solve these problems. We know what this what the support scattered how they function and how they performed. This one here on the far left did not as does not meet an anti-vibration support qualification why it doesn't have adequate stiffness in the lateral and axial directions.

    You can see this threaded Rod doesn't provide much support in Those directions this one on the next one in the in the in from left to right. This was a hold down clamp, but it was not touching there was a gap between the hold-down portion of the clamp and the pipe therefore. There's no stiffest doesn't meet the criteria number here. This was considered an anti-vibration support, but it doesn't have good stiffness in the axial or lateral Direction. So, it doesn't qualify either this support here did meet the quiet.

    Asians it has good axial lateral and vertical support stiffness and also has a damping as well. The final one from left to right is a spring can support this one is a mixed bag. It could be good. If the spring can is set up with adequate stiffness to provide this friction that it can withstand our dynamic loads, but if it doesn't that this dynamic load are going to force this shoe to slide on the spring can it won't be affected so we're not sure.

    Bout that one. It could go either way.

    So just to summarize the webinar, we're just about to wrap it up here. Not all some pipe supports are suitable for vibration service. We presented you a new categorization methodology that's available to qualify supports for vibration service. We've also shown you some important performance factors to Aid piping designers and selecting the right support for the job and some of that data we show with this latest table. It showed that Woods anti-vibration products do provide some of the best performance on the market.

    And so just to give you an example of what some of those products look like. These are our lineup of anti-vibration clamps. Some of them have ThermaGlide axial slide lateral slide capabilities. This axial lateral slide and lateral sliding is a patent-pending design. We also have a DamperX clamp lineup, which allows for axial lateral sliding for your thermal pipe stress concerns.

    Well, adding a significant amount of damping, so green clamps, and we do have some ThermaGlide axial lateral sliding capability. All the red clamp are for higher temperatures and the blue clamp is for lower temperatures. All of these options are available in our wedge clamp lineup. So, these wedge clamps the benefit is they have a certain amount of variable height capability for especially in yard piping where you might need an inch here or there. They also you can pull out the wedges to inspect for corrosion. So that's why many clients like these types of clamps.

    We also want to introduce a product line that we're going to be introducing in early 2020. This is a pipe shoe with anti-vibration supports that require piping insulation.

    You can insulate around the products that we've had I showed you earlier, but it's a bit difficult. So, what we're coming out with is a new design that will accommodate anti-vibration and insulated pipe. So, if you have any situations or projects where you need support for insulated pipe, give us a call. Even if it's before we launched this product, we can help you out.

    We do have some disclaimers here. This information is based on various standards join industry research and our own would experience simulations and field measurements. It's not intended to be an exhaustive guide for all pipe supports.

    We've shown you a few we've shown you data for there are many more out there and we didn't discuss a lot of important issues that can contribute to vibration like the clap supporting structure operating deflection shapes resonance damping, well details and in terms of elements and All these kinds of things. So, there are there the vibration world is complicated but we're giving you a few more tools in your toolbox to help deal with some of these issues. We provide some references. If you want to contact our vibration dynamics and noise team, you can contact Starr Dalton in Houston or myself or Tim as well. And we provide some phone numbers here for contacts all around the world that can help in from the vibration of dynamics and moist team.

    We do I would refer you to our website www.woodplc.com/vdn. We do have a lot of training and webinars and online tools that you can use the parts and of the shake rattle grow series. This is part three. One and two are available on the website and you can watch a recording for those for those who are interested.

    And now we're going to open up to questions. Yeah, I've been answering questions as they come in but some of them, I've saved to the end. So, if you haven't had your question answered yet.

    First one is, do Wood supports use Fabreeka?

    That's a good question. Fabreeka is a material that is often used in lining clamps. It is very popular in North America. And the answer is no, we do not use Fabreeka in our supports in the reason. Why is the damping what we found with testing of Fabreeka line clamps is that they claim to have damping but we in our measurements in our testing we don't find it as much damping at all.

    And so, we have our DamperX products that provide a significant amount of damping and we use those instead of Fabreeka. If Fabreeka does have some merits, it is a very stiff material.

    It shouldn't hurt you too much, but it definitely won't give you a damping benefit like people think.

    Next question is, if you restrain the pipe to prevent vibration, aren't you increasing the stress in your system? How do you balance both these requirements of holding down the pipe and remit static stresses?

    Yes, if you hold down the pipe with an anti-vibration support, you will create stress problems unless the Type is allowed to slide. And so that's why we introduced this idea of a bilinear pipe support and we teach a lot about that and go into an quite depth in depth in Shake Rattle and Grow Part 1, and you can see how to accurately model these type of pipe supports in your pipe stress model which in by what do we mean by accurate is how to account for the sliding capability of these anti-vibration dual-purpose supports so you can do it.

    It can be done accurately. We show you and shake rattle grow part 1.

    We have a question asking to confirm the definition that has been put forward for anti-vibration supports is from Wood and the second part of that question is, where did the Hertz come from to answer the question?

    Yes. This definition was put forward by Wood.

    I would recommend you look up the paper that we wrote shake rattle and grow. we go through a very in-depth discussion as to how we came to the Hertz very quickly. Hertz is high enough that it avoids a lot of the low frequency flow induced turbulence based Broadband energy that you typically see in liquid and even gas systems and it also, is it still low enough that it keeps the low-speed the low-speed machinery guys happy I've seen some companies have seven Hertz. Some have had we'd advocate for because it we've seen problems that with people who use ten or seven before is a good number to keep you away from problem low-frequency vibration.

    Now we've got a question here from Christopher. He's asking you the supports can be used on high-speed multiple speed range machines for example compressors from to a thousand RPM and the piping systems attached to them yet. Which one to look for is you have a compressor running to a thousand RPM your API standard says keep your mechanical natural frequencies above that.

    Around Hertz to piping guideline is around Hertz. What you'd want to do is select a support which can maintain nodality for above Hertz. You'd want to space your supports appropriately. If you can't find a support that can maintain no doubt be up to Hertz, you might consider using a support which has a higher amount of damping.

    You say have you reviewed i-rod or u-bolt pipe supports and what is your comment on that? Yes, we have again in the paper. We have more results than the ones that were shown today. We've only shown there we did in the paper and we're continuing to do more research and testing even up to today.

    We did review I rods and what we found is that they have No, I'd have to make sure that I'm speaking correctly by God reference to the paper again. But my recollection is that they were found to be flexible. They could not maintain nodality in the lateral direction. We saw excessive vibration in that sat in that case and in when we tried to pull the pipe through them, we found that a single pull of the pipe damage the coating.

    So, they have their place they have their place, but they are not anti-vibration.

    We have another question asking for the new CL supports for thermally expanding systems. How will those work in areas with winter conditions? How will they work? Well, we supplied a limited set already to a client who was excited about our sliding features on our clamps, but they needed pipe shoes. So, we've developed one.

    It’s a limited series for them and they put them into service which have a very wide temperature range that they wanted to protect against, and they are happy with the supports we supplied. Our clamps have a particular temperature range which we would recommend their application and depending on how much winter you're talking, our clamps can go down to zero.

    Zero degrees Fahrenheit depending on the lining that you would select the same would be for the shoes. I think we're getting to the end here. We've got a question from Iran. He says can we use spring washers with adequate stiffness as a damper spring washers?

    Could you we've seen people try what you'd have to implement it in a way that the stiffness is always in contact with the pipe. It's possibly yes. It's possible.

    I'd be interested to see the implementation because we've seen some people try to do that and it's failed because the pipe lifts off from the support and we don't have vertical stiffness from the supporting structure anymore, but I could say, without knowing any other details, it's possible you'd have to run through the procedure that we prescribed making sure that your stiffnesses exceed the minimums. You have to apply it correctly to your system.

    We prefer the clamp design. We don't supply those for a good reason because of implementation issues. What we do is we provide it with a calibrated torque specification and that we find is adequate enough and much simpler of a solution to maintain the hold-down friction force you need. We don't recommend using the spring washer method.

    Is ThermaGlide a trademark?

    Yes, it is. It's one of the ways we use to categorize our anti-vibration products that have the thermal sliding capabilities.

    We hope you got something out of this webinar. We really enjoyed putting together. Thank you for the excellent questions, and we'll be following up with what we talked about earlier. Thanks so much and have a nice day.

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Related Pages

Webinar: Shake, rattle and grow I (2022 update)  •   Webinar: Shake, rattle and grow – part II  •   Webinar: Shake, rattle and grow – part III  •   Shake, rattle and grow – empirical data on the effectiveness of vibration supports  •   Pipe Clamps, incl. DamperX™ and ThermaGlide™  •  

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