Questions and Answers

This is where you can ask the experts on rubber lining questions.



    • Gary
      The minimum diameter pipe that can be lined is dependant on the thickness of the rubber liner. For example if you were to use a 1/2″ rubber liner, you wouldn’t want to be any smaller than 8″ the rubber tube at that thickness is hard to form and can result in liner failures, wrinkles. For size down to 3″ in diameter 1/4″ rubber liners can be used. When getting into smaller sizes down to half inch pipe, than 1/8″ rubber will get you lined in that diameter. Any smaller than this will result in the rubber liner blocking the orifice of the pipe.

  1. I was wondering if you ever considered changing the structure of your blog? Its very well written; I love what youve got to say. But maybe you could a little more in the way of content so people could connect with it better. Youve got an awful lot of text for only having 1 or two pictures. Maybe you could space it out better?

    • Thanks for your feedback as this is a new blog I’m still working out what works best.

  2. Sir,
    Kindly provide feedback on “Root cause analysis for SPIDER CRACK’s FORMATION in Ebonite Rubber Lining of 70 -75 Shore D Dual Filter Media Tanks for Desalination Plant Application’s.

    • In order to give an accurate failure analysis I would need to know the following:

      – can you supply pics?
      – service conditions (chemical concentrations, heat etc…)
      – length of lining in service
      – how do they clean the vessels
      – are these tanks open top? Typically water tanks are not.
      – what was the original thickness of the rubber going into the tank and what thickness is it now
      – what is the current duro.

      This type of failure in hard rubbers are very common. The typical failure mode on these tanks are because of operator error, but with that said at times it could be something else and I’m not able to offer advice without some of these questions answered.

      Any questions feel free to call me @ 519-830-0546.


      Buck Meadows / Rubber Technologist
      Technical Sales Manager
      RubberSource Inc.
      Ph# (519) 620-4440
      Cell (519) 830-0546


    • When mating an HDPE flange to a valve you should always use a gasket. You don’t necessarily need to use a gasket when mating valve to a rubber lined flange. But for ease of disassemble using a gasket is always recommended. 3mm – 1/8” thick will work fine for most gasket applications.

      As a note the gasket needs only to seat where the serrations are along the razed face for it to seal properly. On a flat face the whole face is recommended, but the area with the holes are the only functioning sealing area.

      As for the type of gasket and strength, there are a plethora of gasket materials out there. Without knowing anything about your system, temperatures and application a good general gasket material would be a Nitrile, Garlock Blue Guard 3000 or equivalent. Although if it is a natural rubber lined piping system, a natural rubber gasket will do fine for a gasket as well.

  4. We appreciate your help. My colleague Orestis and me, are working on the mining plant SKOURIES in Greece, engineering point of view. We are handling the piping material specifications. We will revert with any query you may help. Thank you!

    • Glad we were able to help. If you have any technical piping questions do not hesitate to ask for feedback.

    • Shaelan

      Sorry for the delayed response. I am assuming you are speaking about Chemlock 286.
      It has a theoretical coverage of 500 SQ Feet per Gallon.

  5. Hi Dan

    Thanks for the reply. Your answer was a confirmation for me. I have another question for you; I am currently doing some research with regards to rubber lining acid tankers and the customer wants an 8 year warranty on the application. Now the acids in the tanker is Hydrochloric and Hypochlorite at maximum 40% concentrations. Here in South Africa none of the rubber suppliers can give me a warranty like that, even 5 years will work, is there any solution you can assist in even if I have to import the rubber. Please advise at your soonest

    • Shaelan

      I will send you an e-mail with contact information for a very reputable rubber supplier who can provide you material for that job. I will e-mail you their contact and a spec sheet for the rubber.


  6. What books or literature do you recommend in learning more about rubber linings and the design/inspection?

    • There is a lot of obscure publications on rubber lining. Some of these have valid sections. But for the most part I have never seen a complete rubber lining and inspection or design reference book. This is effectively why we decided to assemble this blog, to assemble the best information by professionals in the industry today. Many publications are outdated, irreverent or an attempt to write the rules without much industry knowledge.

      The best rubber selection book I have ever seen is the Chemical Resistance Guide for Elastomers 2 a compass publication form 1994
      Part of the puzzles are ASTM standards which apply to the manufacturing and testing for rubber sheet. Such as Hardness (ASTM D2240) Tensile (ASTM D412), Tear (Die C)
      For sandblasting the best guidance and or criteria for this aspect of Rubber would be Nace in particular. SSPC standards are good to know.
      Learning to inspect rubber and rubber lining is vary complicated affair. There is unfortunately no good source for learning this trade to my knowledge.

      The above standards and guidelines are a good start.

  7. Is it practical to combine an ell with a spool for the benefit of eliminating one pair of flanges? I am familiar with the lining procedure for spools but not for ells. The size range in question is 3-8″ and the lining thickness is 1/4″. My concern would be of wrangling the the liner through a spool and then around the 90 without ending up with wrinkles and bonding issues at the ell. Your thoughts?

    • Kevin

      That is a good question. That is dependant on the diameter. Good general rule of thumb is rubber lining is a manual process, if you can reach in and touch it than you can line it. So where a 3 inch is too small to reach in and fix anything. A 4″ elbow and the adjacent spool is less than 10′ is difficult, but able to be lined successfully. The bigger the diameter the better. The longer the radius the more challenging it becomes to line and going back to the first rule if you can’t touch the end of the radius with your hand then you can’t line it or find problems easily.

      The real problem with this scenario is wear. The piece most likely to wear out is the elbow, not the straight spool. You may change an elbow 3-4 times before ever touching a straight spool. So you may be saving up front on the initial install but loosing money every time you have to replace that piece due to wear. There is also something to be said about standardization. If you go to replace that spool, then it is custom, as opposed to having many 90 deg 3D’s or 1 1/2D where those can be generic and can go everywhere in your system.

      Hope this shed’s light on the debate one way or another.

  8. Hi gents,
    Can we do Rubber lining Holiday test for 35% in service HCL Acid tank, we flushed and degassed but still have wetness of the tank

    Sachu D

    • Sachu

      Any wetness, will result in incorrect holiday test results. The electricity will follow the wet surface rather than try to find ground through pinholes in the membrane to the the steel. The tank must be dry. This can also be dangerous depending on your tester settings.


  9. Can you tell me if possible how much compression 3/16″ thick rubber lining gives? Both horizontal and lateral.

    Thanks, Barry

    • Barry, in order to answer that question we would need to know the type of rubber lining being used and the durometer.

  10. What is the expected service life for a rubber lining system in a power plant flue gas scrubber? The scrubber is lined with 1/4″ chlorobutyl rubber that was steam cured in place. The environment is low pH (weak sulfuric and hydrochloric acid), 100% humidity at 140 F.

    • Tom, they should roughly see around 12 yrs. Sounds like they are seeing a failure, curious what the issue is.

      In this type of service there is 3 different style of compounds used.
      Good – 50 duro natural
      Better – 60 duro blended chlorobutyl
      Best – 60 duro general purpose neoprene

      People tend to take the the chlorobutyl over the neoprene due to the cost. I am currently on the road but when I get back next week I will write a blog for this website on rubbers used in the FGD markets.


    • Please see the article on rubber linings related to FGD on the home page. good information.

  11. This is the first time I’m involved with rubber lining so forgive me if I’m looking for the fundamentals. I want to know if a flanged fitting could be made out of a B16.9 elbow and two B16.5 slip on raised face.

    • Dimitris, you can make an elbow, but it needs pups (tangents). So if you are looking for something that equals vic dimensions it might not work for you, due to the fact that the elbow has no tangents, the flange does not slide on without ‘jamming’ (which is why they need to be pupped).
      Also, if you cut into the pressure boundary of the elbow it renders the CRN void, which can be an issue.

    • Yes it is possible to design any type of rubber as long as the manufacturer has be given all the parameters to work within.

  12. HI Dan,
    This is great information, thanks. We had a problem recently where a Rubber Lined pipe which was 3mtrs in lenght, about 4mm wall thickness and 50mm I.D. was cut in half using a cold cutting technique, after doing so the rubber lining inside of the cut length, close to the cut edge, started to peel off. Is this because of a bad vulcanization process or due to the cutting itself? Thanks.

    • Eddie,
      Good question. Was the cold cutting technique used a band saw? If so, there should be relatively little peel off as a result of this slow cutting process (you may get a millimetre or so right at the edge if the teeth were aggressively pulling on the rubber while cutting). On the other hand, if something like a zip cut disc was used, it could potentially generate enough heat during the grinding process to allow heat transfer through the steel to the bonding layer causing it to fail.

  13. Respected sir,
    I have tiny doubt about “Dew Point Temperature” Several time i found DP Temp. below 0 degree C means in minus during very law humidity. So is it possible to accept to approve rubber lining work? One more thing With the same figure DP Temp. Interval DP id more than 5 degree C. So i need solution for ths issue with your help.

    • It is a must to maintain air temperature, 50°F (10°C) to 90°F (32°C), relative humidity and shell temperature 5°F (2.8°C) above the dew point is required. If the piece cannot be brought into a facility with a controlled environment, you must hoard the area or tank and use conditioned air to achieve the required conditions.

  14. what kind of rubber gasket is used in a flange of hard rubber lined vessels. Sevice of cation anion interchange in demi water service

  15. What is different between ebonite rubber lining the vessel with hardness 70 shore D and 75-80 Shore D.Pl give both properties

    • Without seeing the data sheets it is hard to explain differences other than the given hardness. Would also need to understand the service conditions that the rubber would see to explain the differences.

  16. I am wondering if there is any training/certification available for rubber lining?
    Our line of work, rubber lining of tanks, repairing rubber line tanks, and rubber lining of pressure piping spools.

    In addition, are there any conferences available that could help us with the knowledge and continued education of rubbing lining?

    • There is no real formal training or course out there specifically designed for rubber lining certification. companies must familiarize themselves with any different standards that may apply. I can suggest NACE training, and for companies that perform hot work to repair stripped pipe, I would recommend welders know the customers code requirements and acceptance criteria.

  17. Hello, we are in the process of relining our Weak Acid Cation exchangers with HNBR rubber. What torque should we use on our manways to get a proper seal. They are 11/4 “B7 bolts on a 24” manway with no gaskets. Should we use a specific torque or measure the squish factor?
    Thank you.

    • Good question Sean. This is a question that seems to come up a lot. We recommend following torque specs on flanges. We also normally use 1/8″ rubber on flange faces to help minimize any inside ‘hump’ caused as a result of the ‘squish’ factor.

  18. Hi guys! That’s the first time I came on this blog and see it very interesting, even I didn’t find yet what I was looking for. Can anyone suggest on how and which company can provide an underground rubber lined tailing pipe? The cathodic protection (for external) seems to be effective, however we would like to assess the internal liner condition. Thanks.

  19. I wonder how much longer using rubber liner on metal would make it last. That is, if I were to spray metal with rubber liner, how much longer will it take it last?

  20. First time i have come accross this blog and think its a perfect oppertunity for all to share the vast experience that is out there. I have been rubberlining in South Africa for past 30 years. I have come accross many proceedures and requirements. For instance, the lining of pipes and over the flanges. To prevent the hump inside. I also use 3mm rubber on flange faces to help minimize any inside ‘hump’ caused as a result of the ‘squish’ factor. On Acid, Oil or Organics the rubber is taken half way over the flange. I buff it down to a 1.5 to 2mm and then line the flange with a 3mm. When bolting up. It eliminates the vhump and also passes all spark testing.

  21. An open top new tank about 18 mtr dia x 12 mtr height was rubber lined using chlorobutyl rubber. (Cold bonding using standard techniques). The tank is currently not in use as the project is still under construction. The tank was rubber lined about a month and a half ago. During the third party inspection, there were no bubbles, open joints or other defects. The bond strength was checked and found completely satisfactory. Now after a month of storage in ambient conditions, the lining has started showing several bubbles. Any ideas to what could be the cause?

    • Typically, you would see this happen with raw rubber that has gone through atmospheric curing process. Did the applicator use raw rubber or pre-cured rubber? Also, during the month of storage, has the ambient temperature been rising? The rise in temperature can lead to trapped air expanding, producing bubbles, however, once again, this would be an indicator that the rubber may still be raw.

      • The rubber sheets are pre-cured (63 Shore A). After the question sent to you, nearly a month ago, the problem still persists. The tanks are lined by maintaining internal temperature at 30 oC and this temp is maintained for another 48 hrs after lining. The bubbles start appearing after 5 to 10 days. Any comments or insight will be helpful.

          • There is generally no need to paste after white metal blast cleaning the surface in order to apply a rubber lining. The 3 coat adhesive system primes the metal substrate and is tied into the rubber adhesive with an intermediate coat.

  22. What is the method in doing peel of test vulcanized rubber into the internal vessel and what is the acceptable range criteria.

    • Sunny,

      Generally a test plate is made and cured at the same time as the vessel. after curing, a 1″ strip of rubber is cut and pulled at an angle, the acceptable range typically around 35 lbs.

  23. I am looking at a project to remove a vulcanized rubber lining. Replacement will be liquid applied coatings.
    My issue is the best method to disbond the existing lining and remove it prior to an abrasive blast for application of the new lining.
    What information can you offer for a removal method?

    • Hi Charles,
      There are options depending on the size of the vessel, the location of the vessel and the thickness of the rubber.
      1) There are debonding machines that are fairly effective, however, they are ussually cost prohibitive (starting around $ 250,000.00 US). so unless you are stripping something like multiple , large tanks, you may not choose this option.
      2) If you have a relatively small area (1 – 100 sq/ft or so), and the rubber is thin (1/8″), you can generally grind it off with a 24 or 16 grit sanding buffer.
      3) Mid sized liners are often stripped by heating the back of the substrate to break the bond. this can be done with tiger torches, but extreme care must be taken not to overheat the steel substrate, as this can result in damage such as warping and changes to the properties of the steel itself, and can also result in the rubber igniting. I know of more than one occasion (unfortunately) where overheating when stripping has resulted in a whole pipeline burning out.

  24. I’m curious about the vulcanization process. I’ve heard differing views on how to vulcanize such that a rubber lining forms a bond with a steel backing plate. Some say rubber sheet can be applied and then cured/vulcanized in a steam autoclave, while others say that raw rubber must be applied in a mold and then vulcanized in the autoclave. Which is correct?

    Thank you!

  25. Can you give me any information on portable electric skive saws? I was told there is one that comes with a lubricant bottle attached but can’t seem to find one.

    • Thenammai,

      Black natural rubber, or tan pure gum rubber lining works very well for slurry applications in pipelines.

  26. Hai Dan
    I face leaking problem on sight glass edge when carry the hydrotest at 6 bar. Our Contractor used 3mm EPDM plain gasket.Could i know the main rootcause?For your information, the tank was lined with 3mm THK ebonite rubber (70 shore D Hardness).

    • Anuar,
      It sounds like the rubber may be damaged, Or it may be too hard for the torque you are using (I may suggest a lower durometer rubber)

  27. I’ve been looking all around the internet for the correct methodology on how to determine the rubber lining on steel pipes but have found nothing very concrete. I need to determine the thickness of some slurry pipes that we are installing. Thank for any help.

    • Alberto,
      What in specific are you needing to determine? Is it the thickness of existing rubber in pipe? or how thick it should be?

  28. Could you please give a recommendation on What type of rubber would be best for long life within a
    PH 12
    CN <150/hr
    PAX 80g/t
    Na2s 150g/t
    RTD 25g/t
    DSF004 25g/t
    For a Copper/Gold flotation Tanks

  29. Hai Dan
    I have problem with ebonite rubber lining.small bubble appear on rubber surface after used for 2 years.FYI, its apply on 4″ straight pipe connection for mixed bed exchanger tank.Type of media =HCL acid at 30% concentration aT 40 degree working temp.Ebonite rubber =70 shore D, but used clay as filler.

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