When you need to adhere two or more surfaces together, it is not always easy as grabbing whatever type of glue you have close by. Different materials require vastly different adhesives, and using the wrong one could cause serious problems. Rubber is one material that is notably difficult to bond. It comes in many different types and is used in a wide range of applications requiring diverse electrical, thermal, chemical and physical properties. The adhesives you use, of course, must also satisfy these requirements. There are several things you need to know and do when bonding rubber. Let&#;s take a closer look.

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Types of Rubber

There are numerous types of rubber on the market, and some are more common than others. Some of the ones that you are most likely to encounter include nitrile rubber, butyl rubber, polyurethane rubber, silicone rubber, EPDM rubber, and natural rubber. There are countless others, too, but these are the ones we see most often in our daily lives in the form of things like hoses, gaskets, inner tubes, seals, etc.

Preparing Rubber for Bonding

No matter what type of rubber you are working with, properly preparing it is the first step to a successful bond. Start by performing a thorough solvent degrease to remove things like slip additives, mold release, and other processing lubricants. A quick wipe with isopropanol is usually your best bet, as acetone may be too strong for certain types of rubber.

What Type of Adhesive to Use

In general, cyanoacrylate instant adhesive is the best choice for bonding rubbers. More commonly known as super glue, this product cures in just seconds and lets you know quickly whether or not the bond will hold. When applying cyanoacrylate, apply only a tiny drop and make sure both surfaces are squeezed together tightly. If the bond fails quickly, you may be dealing with one of the more challenging types of rubber, such as silicone rubber or natural rubber.

For natural rubber or EPDM, try using a specialist cyanoacrylate adhesive, such as ASI RP Series Cyanoacrylate Super Glue. This product provides strong adhesion for most substrates, but it is especially effective for rubber and plastic. If you are working with silicone rubber, you will need to use a primer, such as Permabond POP, before applying the adhesive. If flexibility is desired, Permabond cyanoacrylate works well.

Bonding Rubber to Other Substrates

Bonding two rubber surfaces together can be challenging enough, but, when you need to bond rubber to another substrate, the challenge can become even greater. When you need to glue rubber to plastic, metal, glass, or any other substrate, you need to consider the properties of each and your ultimate goal. While cyanoacrylate is the ultimate choice for many applications, it cannot be used on many plastics, as it can eat through the material.

When working with multiple substrates, an epoxy adhesive is often the best solution. While epoxies are not the best choice for bonding rubber to rubber, they do effectively allow you to bond rubber to other materials, including metal and glass. Fast-curing silicone compounds are also an option, especially for small projects.

Conclusion

When bonding rubber, it is important to use the right type of adhesive. Using the wrong type could result in damage to your substrates or prevent them from adhering together. Cyanoacrylate is one of the products of choice for bonding rubber to rubber, but it is not always effective.

Properly cleaning the surfaces to remove things like mold releasers and lubricants increases your chance of a successful bond, but sometimes a different product is needed. At Glue Gun, we stock numerous adhesives for a wide range of projects. Whether you are in need of a high-quality cyanoacrylate super glue, an epoxy, or a silicone adhesive, we have you covered. Contact us today or browse our website for the adhesive products you need for bonding rubber.

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Rubber Bellows vs Metal Bellows Expansion Joints

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Rubber Bellows vs Metal Bellows Expansion Joints

Rubber Bellows vs Metal Bellows Expansion Joints

simon17

(Structural)

(OP)

2 Apr 15 15:18

Good morning.

I haven't had much luck recently in finding information on when to use rubber expansion joints and when to use metal. My expansion joint experience is limited. If either can be used, what information is critical to choose which to use? How do they differ?

Thanks,
D

RE: Rubber Bellows vs Metal Bellows Expansion Joints

btrueblood

(Mechanical)

2 Apr 15 15:21

Rubber is more flexible, cheaper. But has limitations on chemical compatibility, service temperature (both high and low).

Metal bellows are more expensive to produce, and have more limitations on the amount of flex allowed, cycles to failure (fatigue life).

RE: Rubber Bellows vs Metal Bellows Expansion Joints

pennpiper

(Mechanical)

Additional reading:
Polyurethane vs Rubber Hose- Which one to choose?
Cleaner Salt Brine Manufacturing
The Ultimate Guide to Choosing Metal Corrugated Compensator
How To Choose The Right/best Hydraulic Hose Manufacturer
Exploring the Diversity of Rubber Stoppers in Pharmaceuticals
Revolutionizing Safety: Is Chemical Rubber Hose Essential?
What are the benefits of PTFE lined hoses?

For more China Oil Sealinformation, please contact us. We will provide professional answers.

2 Apr 15 15:34
Do you have a specific purpose or use for an expansion joint?

dso88,Do you have a specific purpose or use for an expansion joint?

Sometimes its possible to do all the right things and still get bad results

RE: Rubber Bellows vs Metal Bellows Expansion Joints

simon17

(Structural)

(OP)

2 Apr 15 15:43

To relieve nozzle loads due to thermal expansion of my piping system. I'm doing stress analysis. The system is low pressure and fairly low temperature (<200F) with brine service.

Thank you btrueblood for the response. This was the type of information I was looking for.

RE: Rubber Bellows vs Metal Bellows Expansion Joints

XL83NL

(Mechanical)

2 Apr 15 16:05

What line size and configuration/routing do you have? Thats not a fairly high temp.

RE: Rubber Bellows vs Metal Bellows Expansion Joints

simon17

(Structural)

(OP)

2 Apr 15 17:58

Line size is 30", 15psig & 160F. Line routing travels down out of a flat bottom tank and bends 90deg to pump suction. Line size reduces to 18" prior to pump nozzle. There is plenty of space for an expansion joint in either the horizontal or vertical portion of the line. It just depends which nozzle I choose to relieve using the expansion joint. The flat roof/bottom tank nozzles are especially sensitive to loads, but so are pump nozzles.

RE: Rubber Bellows vs Metal Bellows Expansion Joints

XL83NL

(Mechanical)

2 Apr 15 18:36

Can you solve the problem with an expansion loop? Expansion joints are more prone to failure and sensitive to damage, and should be used as a last resort.

RE: Rubber Bellows vs Metal Bellows Expansion Joints

3

pennpiper

(Mechanical)

2 Apr 15 19:10
What is your plan for when your expansion joint springs a leak?

Both rubber and metallic expansion joints can and will fail. The best insurance against a catastrophic expansion joint leak is don't use expansion joints.

OH! you say but I need to reduce the loading on the nozzles. Expansion joints do not reduce nozzle loading. In order to work an expansion joint needs an anchor on each side of the joint & pipe run. The nozzles just become the anchors, so they are taking the loading and force of any expansion.

Whats the answer? Place a fixed anchor a minimum distance from the Pump Nozzle (at or near the suction reducer). Place another anchor a minimum distance from the elbow for the vertical drop from the tank nozzle. Allow vertical growth down but no horizontal movement. Place the expansion joint any place along the 30" pipe run. The long horizontal leg of 30" pipe with the expansion joint needs to be guided so the expansion joint does not 'snake' on you. Place one guide a minimum distance upstream and down stream of the expansion joint (2 guides required).

You did not define any lengths for the two legs of the pipe run so we cannot tell you where to place the expansion joint (or Loop). Place it in a location that is easily accessible for visual inspection and maintenance.

dso88,What is your plan for when your expansion joint springs a leak?Both rubber and metallic expansion joints can and will fail. The best insurance against a catastrophic expansion joint leak is don't use expansion joints.OH! you say but I need to reduce the loading on the nozzles. Expansion joints do not reduce nozzle loading. In order to work an expansion joint needs an anchor on each side of the joint & pipe run. The nozzles just become the anchors, so they are taking the loading and force of any expansion.Whats the answer? Place a fixed anchor a minimum distance from the Pump Nozzle (at or near the suction reducer). Place another anchor a minimum distance from the elbow for the vertical drop from the tank nozzle. Allow vertical growth down but no horizontal movement. Place the expansion joint any place along the 30" pipe run. The long horizontal leg of 30" pipe with the expansion joint needs to be guided so the expansion joint does not 'snake' on you. Place one guide a minimum distance upstream and down stream of the expansion joint (2 guides required).You did not define any lengths for the two legs of the pipe run so we cannot tell you where to place the expansion joint (or Loop). Place it in a location that is easily accessible for visual inspection and maintenance.

Sometimes its possible to do all the right things and still get bad results

RE: Rubber Bellows vs Metal Bellows Expansion Joints

StressGuy

(Mechanical)

6 Apr 15 18:14

You may get some relief considering the local flexibility of the tank nozzle in your piping system, but probably not enough to qualify. Based on the fluid conditions you are describing, a non-metallic joint will probably be suitable for your application. The joint will most likely need to have control rods to restrain pressure thrust - meaning that it will not give you any flexibility in the axial direction of the joint, only in some lateral bending. A pair of joints acting as a "universal" would be needed if you had a large amount of lateral deflection to take across the joints, but I don't expect that will be your case.

Based on your description, I'm assuming that both the vertical leg out of the tank and the horizontal leg to the pump are fairly short, but that the vertical leg is much shorter than the horizontal. In such a case, I would put the joint in the vertical leg so that the growth of the horizontal leg deflects the joint and filtering it's impact on the tank nozzle. This joint won't directly help your flexibility with regard to the pump nozzle, however, you would discount any thermal growth across the joint itself as the control rods (also known as tie-rods, particularly in metal bellows speak) force any expansion across the joint into compressing the bellows slightly. That reduction in expansion in the vertical will reduce the loads imparted on the pump nozzle.

Of course expansion joints reduce loads on nozzles - provided they are properly designed along with the piping system. You don't have a lot of thermal expansion given that temperature, but the large line size is going to make for a stiff system.You may get some relief considering the local flexibility of the tank nozzle in your piping system, but probably not enough to qualify. Based on the fluid conditions you are describing, a non-metallic joint will probably be suitable for your application. The joint will most likely need to have control rods to restrain pressure thrust - meaning that it will not give you any flexibility in the axial direction of the joint, only in some lateral bending. A pair of joints acting as a "universal" would be needed if you had a large amount of lateral deflection to take across the joints, but I don't expect that will be your case.Based on your description, I'm assuming that both the vertical leg out of the tank and the horizontal leg to the pump are fairly short, but that the vertical leg is much shorter than the horizontal. In such a case, I would put the joint in the vertical leg so that the growth of the horizontal leg deflects the joint and filtering it's impact on the tank nozzle. This joint won't directly help your flexibility with regard to the pump nozzle, however, you would discount any thermal growth across the joint itself as the control rods (also known as tie-rods, particularly in metal bellows speak) force any expansion across the joint into compressing the bellows slightly. That reduction in expansion in the vertical will reduce the loads imparted on the pump nozzle.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

RE: Rubber Bellows vs Metal Bellows Expansion Joints

simon17

(Structural)

(OP)

6 Apr 15 18:32

Edward,

Thank you for your reply. Very well written and thought out. I very much appreciate it. It is pretty much along my line of thinking as well. I haven't been able to get back to that system and run the analysis to see whether or not one expansion joint will be enough to rectify the nozzle loads.

Your assumptions on the routing (vertical length < horizontal length) is correct, but both are still substantially long enough to place tied single OR universal joints. You recommended placing the joint in the vertical leg. Maybe it was a typo, but you stated that this would NOT reduce the pump nozzle loads. Certainly, the vertical joint will decrease some of the bending moments and shear loads on the vertical tank nozzle, but under the same principles, it should also reduce some of the axial loads on the pump nozzle.

I'm hoping to be able to get away with just one, but I'm fearing with this size and stiffness of pipe, I may need tied single expansion joints on both the vertical AND horizontal runs to relieve both nozzles.

D

RE: Rubber Bellows vs Metal Bellows Expansion Joints

ZDR

(Mechanical)

6 Apr 15 20:08

I would probably put the rubber bellow (restrained with tie rods up to max expansion) on the horizontal run on the pump side to protect the pipes from pump vibration. Your piping will be anchored by supports and your tank is static so I don't see any reason for additional rubber bellow on the vertical run or any other location away from pump. Just my opinion.

RE: Rubber Bellows vs Metal Bellows Expansion Joints

bellowsmfg

(Aerospace)

13 Apr 15 15:11

First of all, you need to be aware that a tank has some different characteristics then we normally see in a vessel. The nozzle at the bottom of tank will rotate downwards. This is due the shell deflecting out when the tank is full. For this reason it is not a good idea to anchor such a nozzle per pennpipers comments.

If can can avoid using an expansion joint, then great. If you have tried all other options then here is your approach: Your expansion joint selection should be done in conjunction with your pipe support design to resolve the forces on both your pump and tank nozzle. These go hand in hand. You will want to obtain the properties (axial, lateral, rotation and torsional stiffness's) of the joint you intent on using, or close too. This will allow you to determine the actual loads you will see on the pump nozzle. Your supports will protect the expansion joint from undesired deflections. Locating near the pump suction nozzle makes it easier the resolve nozzle loading as you are not dealing with friction from supports prior to the nozzle (if the joint was located somewhere else).

Your pressure is low so you won't have too much of an issue with pressure thrust but you must understand it, both now and moving forward.

I would not recommend using an expansion joint simply because of vibration unless it is the result of some previous concern or modal analysis. The pump should be on a solid foundation, base plate/frame and well balanced. The piping should be properly aligned prior to final bolt up, etc.

Expansion loops are rarely desirable in a pump suction lines. You have some straight lengths as you have mentioned. Carefully go through your design, minimize where you can see if you can solve this with one expansion joint. If your flow rates are low enough remember an 18" expansion joint will be cheaper that a 30" one. As I mentioned, make the supports work with your expansion joint to solve the problem after you have exhausted all other possibilities.

Conor Walshe

www.bellowsmfg.com

Edward hit on a lot of good points and I'd like to add to them.First of all, you need to be aware that a tank has some different characteristics then we normally see in a vessel. The nozzle at the bottom of tank will rotate downwards. This is due the shell deflecting out when the tank is full. For this reason it is not a good idea to anchor such a nozzle per pennpipers comments.If can can avoid using an expansion joint, then great. If you have tried all other options then here is your approach: Your expansion joint selection should be done in conjunction with your pipe support design to resolve the forces on both your pump and tank nozzle. These go hand in hand. You will want to obtain the properties (axial, lateral, rotation and torsional stiffness's) of the joint you intent on using, or close too. This will allow you to determine the actual loads you will see on the pump nozzle. Your supports will protect the expansion joint from undesired deflections. Locating near the pump suction nozzle makes it easier the resolve nozzle loading as you are not dealing with friction from supports prior to the nozzle (if the joint was located somewhere else).Your pressure is low so you won't have too much of an issue with pressure thrust but you must understand it, both now and moving forward.I would not recommend using an expansion joint simply because of vibration unless it is the result of some previous concern or modal analysis. The pump should be on a solid foundation, base plate/frame and well balanced. The piping should be properly aligned prior to final bolt up, etc.Expansion loops are rarely desirable in a pump suction lines. You have some straight lengths as you have mentioned. Carefully go through your design, minimize where you can see if you can solve this with one expansion joint. If your flow rates are low enough remember an 18" expansion joint will be cheaper that a 30" one. As I mentioned, make the supports work with your expansion joint to solve the problem after you have exhausted all other possibilities.Conor Walshe

Bellows Manufacturing and Research, Inc.
https://bellowsmfg.com

RE: Rubber Bellows vs Metal Bellows Expansion Joints

11echo

(Petroleum)

14 Apr 15 19:47

I've had some experience here, I worked for a major oil company that wanted us to use a "well known" companies rubber expansion joints at pump suctions to reduce stress on the pump nozzles. In theory it sounded good but these rubber joints would only last 6 to 9 months before there was some kind of issue. We finally ended up using braided stainless steel hose with flanged ends, never had an issue after that.

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