Uncategorized Archives • Rubber Lining

Victaulic XL Fittings vs Additional Rubber on Elbow Extrados

Posted on May 4, 2015 by Dan Chamberland

Victaulic XL Fittings vs Additional Rubber on Elbow Extrados

Victaulic has come up with an interesting way to increase the longevity of fittings for mining and wear applications. For those of you who haven’t hear yet, the concept is to produce a larger ID fitting in order to add more rubber in the critical fittings, enabling your fittings to last longer. These fittings will than mate up to your standard sized ID, OD pipe. Using a stepped XL coupling it bolts up to your existing pipe with the same ease of all 07 and 77 couplings. The ID of the thicker lined fittings matches up perfectly to your thinner lined pipe.

The majority of wear occurs in changes in direction. Elbows are particularly vulnerable to wear do to this fact. By increasing the rubber in the fittings from 1/4″ thick rubber to 1/2″ rubber you get two benefits. You get a thicker wear sub-straight and a better cushion for the forces on the liner. The result is a significant increase in lifespan from these fittings.

The down side to these fittings is that you can no longer use the standard 77 or 07 couplings in your system. You will need to get the stepped XL couplings. Since these fittings are unique to rubber lined systems the availability and lead time on these components can be a challenge.

Traditionally the way to increase the life in your elbows is to add an additional layer of 1/4″ rubber on the extrados of the elbow. This created the 1/2″ of rubber desired. This allows users to keep their existing couplings and adds longenvity to the elbows..

The downside to this type of additional wear material is the transitions are not always made the same. Depending on the rubber liner installer, you can get various transitions in the rubber, some better than others. If a bad transition is made in the rubber, you can get an undesired turbulent effect. This will result in eddy currents in the elbows and fittings and this effect will prematurely wear out the liner.

Victaulic has created a good system which addresses the additional material required in high wear situations. It is an effective way to increase the life span of your fittings. The ID’s of the fittings and pipe having no transitions which ensures no unintended premature wear.

Celebrating 1 Year for RubberLining.org

Posted on April 7, 2015 by Dan Chamberland

Celebrating 1 year for RubberLining.org

We have had a fun year blogging about rubber lining and the associated disciplines.

More and more followers have been coming to visit our blog every month, averaging 300+ views per month. We are happy and able to help with any of the industries technical questions. If we don’t know the answer we are definitely able to point people in the right direction.

We want to send out a special thanks to Rubber Source for contributing articles to this open forum of rubber knowledge. If any of our readers feel inclined to submit a rubber lining industry articles, we would be happy to post them. We plan on having many more years of blogging to share in our industry specific knowledge. The more people who get involved in sharing rubber lining industry knowledge the better the industry will be.

Stay tuned for more articles on rubber lining.

Thanks for following along.

from the Rubberlining.org team.

Compressed Air Blotter Test for Rubber Lining and Painting

Posted on March 3, 2015 by Dan Chamberland

Compressed Air Blotter Test

What is it checking for?

The background behind this specification, which is becoming more and more prevalent in engineering documentation, has to do with the presence of oil and water in the air stream. As you can imagine having oil sprayed onto a surface prior to painting would be terrible. It would immediately create fish eyes, lack of adhesion and all types of terrible things for the paint. Water is just as bad as flash rusting can occur.

Rubber and hydrocarbons for the most part don’t get along. So the presence of oil on a surface will definitely have a negative impact on the adhesion and longevity of rubber on a steel sub straight.

Why would water be in the air line?

Humidity (water molecules suspended in the air) is found in the air all around us. When compressed the moisture forms into water. Most compressors are equipped with a water separator. But water separators are not all created equal. Based on the volume of blasting or painting, your air water separator may not be able to process the volume of water. Winter is a good gauge of if your water air separator is working for your setup. If your lines freeze in winter yours is not adequate for your work load.

Why would oil be in the air line in the first place?

Not all compressors are made the same. Piston compressors are more prone to oil in the air than screw compressors. Although all compressor designs offer various risk to oil in the air lines, there are many inline solution to capturing any residual oil left in the air.

How is the testing done?

You can use a 4″ X 4″ clean cotton cloth. Spray for a duration of 1-5 minutes and look to see if you any oil or water. This only needs to be done once per shift as objective evidence for your client if required. Otherwise it’s good practice to monitor your compressor air as well as you oil separation for long term performance issues.

For the exact specification the standard would be according to ASTM D 4285

The net result of good clean air!

A clean well blasted metal with no surface impurities will enable you to create a perfect adhesive bond that will ensure a rubber coating will last forever.

Good process equals good results…

PH and rubber lining

Posted on December 17, 2014 by Dan Chamberland

PH and Rubber Lining

The PH levels in the transport fluids is always a concern when selecting the proper rubber liner for pipe or chutes. If the transport fluid is Acidic, natural rubber can be the right selection. When using natural rubber with acids, swelling occurs dependent on concentration and you may not get the same abrasion resistance you would normally get from a liner. Alternately extremely alkaline solution or caustic materials can also be problematic.

As a general rule of thumb, any high corrosive or caustic application, will change the rubber selection from Natural rubbers to Chlorobutyls or Bromobutyls which can handle high chemical compositions and higher temperatures. The challenge with the Butyl family is that they sometime have difficulties adhering to sub-straights.

Rubber manufacturers know the adhesion problem and will some time use a pure natural gum layer on the bottom of the sheet. This helps adhere the sheet to the sub-straight. Liner applicators must be aware, that the natural rubber layer (tie gum layer) is there. If this is the case closed skives are recommended for all chemical applications.

When a rubber sheet has a tie gum layer it is susceptible to chemical and temperature attack. Many liners have failed due to this layer being dissolved or weakened because of the lower chemical resistance and temperature threshold of the tie gum layer.

When selecting rubber liners an understanding of the PH levels and the effect on the liner is critical to the selection of rubber for the application. Being able to describe the PH, material particle size and velocity can help you in designing the perfect piping system.

Toluene and Trichloroethylene

Posted on November 28, 2014 by Dan Chamberland

Toluene, Trichloroethylene and Rubber

Toluene (recommended for raw rubber use only)

The most common solvent in the sheet rubber industry has to be Toluene. For those of you that don’t know Toluene is used for tackifying raw rubber sheets, or to clean any surface impurities prior to application. In order to tackify the sheet a “GAS” is created to better promote adehsion. Gas is a slurry of rubber crumbs dissolved in Toluene. Toluene effectively breaks down the surface of the rubber sheet compound and makes it extremely sticky. It is a very flexible and forgiving solvent. Chemlock 289, 290, 286 etc.. is a commonly used Toluene based rubber adhesion systems, therefore it is a natural solvent for that application.

Some of the properties of Toluene are the following.

-Clear and water-insoluble

-Toluene is heavier than air so when it off gasses it falls to the ground.

-It is an aromatic hydrocarbon, meaning it is a derivative of oil product in particular a Benzine derivative.

-Smells like paint thinners

-Can be used in an internal combustion engine.

One of the negative side Toluene it is generally not good for you. Respirators face shields and gloves are recommended for handling it.

It is also not recommended to clean buffing’s off of a cured rubber sheet. What can happen is that by buffing a cured rubber sheet you effectively make the surface porous. The toluene will saturate and enter the rubber sheet. If not given enough time to evaporate out of the sheet, toluene will affect the adhesive layer negatively in a cured rubber sheet, cold bond cement is Trichloroethylene and zinc oxide based.

Check your adhesive system base solvent before deciding which solvent to use.

Trichloroethylene (recommended solvent for cured rubbers)

Anybody who has ever has spliced and bonded conveyor belting is familiar with this solvent. Trichloroethylene is actually part of the Halocarbon family. Halocarbons are used as an industrial solvents. When cleaning rubber buffing or removing surface impurities, in a cured sheet this is the solvent to use. When using SC2000 or any equivalent adhesive system the only solvent you should use is Trichloroethelene. These type of adhesive systems are 60-90% trichlorethylene with a zinc oxide.

-Trichloroethylene is a good solvent

-Great degreaser for hydrocarbons.

-Clear and water insoluble.

-Smells like paint thinner.

-Heavier than air and will pool at the bottom

One of the negative sides of this chemical is that it can react to soda lime. Can cause depression due to is’t general anesthesia effects. Respirators face shields and gloves are recommended for handling it.

Please consult manufacturers and available MSDS sheets for more information.

What elastomeric lining material is appropriate for what service?

Posted on October 31, 2014 by Dan Chamberland

Rubber selection can be intimidating as there are a number of engineered high performance linings which can have several different applications. I will list a few different elastomers and durometers as a general guideline.

There can be many different formulations of the compounds listed below with different physical properties than what is listed.

Soft Natural Rubber, 30-60 Duro Shore A, Temp Limit 160 Deg F, Resistance to Hydrocarbons Poor

Typical Uses: Acid Storage depending on concentration, Transportation equipment, Abrasive Services, Sulphur dioxide scrubbers.

Semi Hard Natural Rubber, 80-85 Duro Shore A, Temp Limit 180 Deg F, Resistance to Hydrocarbons-Fair

Typical Uses: Chemical Processing and Plating

Hard Natural Rubber, 90-100 Duro Shore A, Temp Limit 200 Deg F, Resistance to Hydrocarbons-Fair

Typical Uses: Chemical Processing, High temperature nickel-copper plating, steel pickling, vacuum service.

Graphite Loaded Hard Rubber, 90-100 Duro Shore A, Temp Limit 212 Deg F, Resistance to Hydrocarbons-Fair

Typical Uses: Special lining for wet chlorine gas, in chlorine cells and associated equipment. High wear applications.

Three-ply (Soft, Hard, Soft) 40-50 Duro Shore A, Temp Limit 230 Deg F, Resistance to Hydrocarbons-Fair

Typical Uses:Steel pickling lines, Phosphoric Acid

Neoprene 40-70 Duro Shore A, Temp Limit 230 Deg F, Resistance to Hydrocarbons-Very Good

Typical Uses: Chemical or abrasive services with oil present, best for strong bases, good weather resistance, fire retardant.

Nitrile, 60-90 Duro Shore A, Temp Limits 200 Deg F, Resistance to Hydrocarbons-Excellent

Typical Uses: Aliphatic hydrocarbons, kerosene, animal, vegetable and mineral oils.

Butyl, 50-75 Duro Shore A, Temp Limits 225 Deg F, Resistance to Hydrocarbons-Fair

Typical Uses: Oxidizing acids, 70 percent hydrofluoric acids, super phosphoric acid, best water resistance, good for alternative service.

Chlorobutyl, 40-60 Duro Shore A, Temp Limits 200 Deg F, Resistance to Hydrocarbons-Fair

Typical Uses: Much the same as butyl but easier to apply and faster curing, sulfur dioxide scrubbers.

EPDM, 40-60 Duro Shore A, Temp Limits 180 Deg F, Resistance to Hydrocarbons-Poor

Typical Uses: Hypochlorite bleach, ozone and weather resistant.

Feel free to ask about applications and we can suggest compounds.

Rubber Lined Piping & Engineering Manufacturing Procurement Process Challenges

Posted on October 10, 2014 by Dan Chamberland

Doing a large project for engineering firms can be rewarding and challenging depending on the contract at the same time. Here are some of the process challenges with rubber lined piping and piping projects in general.

The most common way to price many short lead, large scope projects is to bid a Bill of Material. These BOM’s are generally generated form a snapshot of their CAD system model. The CAD bill of materials unfortunate provides the first challenge such as how to price 10,000 feet of pipe when you don’t know the individual lengths? How many termination are there, how many branches are there, supports etc…? The descriptions of the piping will say rubber lined grooved. So to determine the quantities of grooves you must sometimes estimate based on the coupling count.

Some of these challenges have been overcome by providing welding rates, cutting rates, branch rates etc… This method of pricing does not provide the purchasing groups a clear cost on the project. As many of the welds and cuts do not get rolled up or counted into the price. The preferred alternative is to price a- la cart. This style of pricing would mean that any flange price listed for example in the BOM would include all the shop processes required to fasten a flange for example to any piece in the system. This provides a transparent all in fabrication price.

Assuming your prices are competitive and you won the contract, the next challenge is that generally the fabrication drawings are not complete. Hopefully the purchasing people will allow you to purchase the BOM as it stands, as waiting for drawings can delay projects, while the drawings are being completed you can purchase and stage your materials for fabrication. Next arrives the drawings and they pose their own problems as discussed in my blog on cad challenges.

Now you fabricate your rubber lined piping. When you ship your project to site you are not shipping flanges pipe and a branch separately. You are shipping a spool that contains all the materials listed in the BOM. Reconciling the original PO is extremely difficult as the original PO is based on a BOM. Depending on the purchasing team a backup document containing the price breakout of the spool may becomes a useful tool to reconcile the billing on the spool i n order to eventually consolidate the project purchase order at the ends

Keeping these interesting challenges in mind and discussing the challenges with an agreement ahead of time, before the issue of a purchase order will ensures a smooth trouble free contract.

Soluble Salts Testing

Posted on September 15, 2014 by Dan Chamberland

Soluble Salt testing is becoming the latest inclusion into EPCM specifications for quality requirements.

What are Soluble Salts and Sulphates?

Soluble Salts and Sulphates are the most dangerous forms of contaminants for paints and coatings. When they are painted over they have the power to draw moisture through Osmosis and cause blistering, detachment and accelerate corrosion of the underlying metal. When steel is repainted, rough or pitted areas are visible after dry abrasive blast cleaning. These may contain soluble salt contamination, especially in the base of the pits. Dry abrasive blasting does not remove these salts. It is wise to check for the presence of soluble salts with specially designed field test kits before painting and if they are present in detrimental amounts, to take additional cleaning steps to remove the salts.

How can you test for Soluble Salts?

The common tools used to test for soluable salts are the Chloride Iron Test Kit for Surfaces. This test looks for remaining chloride levels on a sub-straight prior to painting. The second tool is a Salt contamination Meter. This tests for soluble salts on the substrate surface prior to painting by absorbing distilled water soaked filter paper and then testing it.

How do Soluble Salts Occur?

There are many ways your steel can be exposed to soluble salts and sulphates. The most common way is through transportation. Pipe and steel travelling at sea can accumulate contaminants during travel to the fabricators. The other method is when trucking materials during the winter. Road salts can easily be distributed on to steel during the transportation process.

Is checking for Soluble salts necessary?

Soluble salts became an additional test required and recommended by Nace. As engineers attempt to cover off as many concerns with their specifications as possible, it is becoming a popular addition. The method of testing and the frequency required by this code make production volume of pipe spooling and steel testing costly and difficult. Most pipe from mill come with mill varnish helping protect the surface during travel. New steel will generally not be pitted, where a good sandblast profile will easily eliminate any surface contaminants. There are situations where you are on an oil platform, recoating old steel, in the middle of the ocean where this specification is highly advisable but for most steel processing this is considered over processing. The short answer is where required.

Soluble Salt in relation to rubber lining.

Generally speaking in a rubber lining application, the internal liner will fail far sooner than the steel or coating will deteriorate. Rubber lined product is generally considered a wear product. Warranties are difficult as process flow, materials configurations are always changing. Unless adamantly specified this specification should be avoided.

Shelf Life Of Uncured Protective Rubber Linings

Posted on June 16, 2014 by Dan Chamberland

In determining the shelf life of uncured rubber linings, several instances but be understood:

The level of heat memory built into a compound (ex. Synthetic Rubber takes more heat to break down than a Natural Rubber)
The lower the storage temperature, the longer the rubber lining will be useable.

As a rule of thumb the average uncured rubber linings (NR, IIR) will have a shelf life of approximate shelf life of 9 to 12 months if stored at a temperature of 10°C (also out of sunlight). If the linings are stored at a lower temperature the rubber lining will much longer the 12 month period. Please note that Neoprene (CR) and Nitrile (NBR) compounds have a typical shorter shelf life than the above mentioned compounds. In dealing with these compounds a great of caution is to be used as they can cure much faster. If storing rubber at a lower temperature that the recommended 10°C the rubber may become frozen, if this was to happen the roll will need to be unrolled and left at an ambient temperature for 2 weeks to thaw the rubber. After the 2 week interval the rubber will need to go on a hot table to help facilitate any shrink that might of occurred during the freezing process.

Any Questions please contact RubberSource @ 519-830-0546.

Buck Meadows / Rubber Technologist

Technical Sales Manager

RubberSource

Which Vic Specification is best for Rubber Lining?

Posted on April 29, 2014 by Dan Chamberland

25.03A and 25.03C

The Basics

When you manufacture a rubber lined pipe and create your own groove there is basically 2 types of grooves specification you can choose. Victaulic Spec 25.03 which has two sub categories.

25.03A The A stands for cut groove for abrasion only. If you refer to the diagram above you will see that the Victaulic coupling system has gaps when assembled and they vary based on diameter and coupling styles. A list of the gap sizes are listed below. The gaps are there to accommodate a certain amount of pipe line flex approx 1 deg depending on size. The more important fact is in a slurry application the gap exist and will fill with the slurry. In a slurry application with no corrosive material this is not a problem and will pack with fines. But is corrosive application such as Phosphates or Acid the steel in the gasket area is exposed and will deteriorate before the liner will. 25.03A is good for abrasion service but not corrosive service.

COMMON VICTAULIC END TO END COUPLING GAPS
PIPE SIZE (NPS)	CLAMP STYLE	END TO END GAP inches (mm)
2 ½ – 3	Style 07, Zero-Flex Rigid Coupling	0.067 (1.7)
4 – 6	Style 07, Zero-Flex Rigid Coupling	0.161 (4.1)
8	Style 07, Zero-Flex Rigid Coupling	0.189 (4.8)
10 – 12	Style 07, Zero-Flex Rigid Coupling	0.130 (3.3)
2 ½ – 3 ½	Style 77, Standard Flexible Coupling	0.063 (1.6)
4 – 12	Style 77, Standard Flexible Coupling	0.189 (4.8)
14 – 24	Style 77, Standard Flexible Coupling	0.189 (4.8)
26 – 44	Style 44, Ring Coupling with “D” Type Adapter	0.500 (12.7)

25.03C The C in this specification means cut groove for corrosion application. In other words if you have any transport material which has corrosive materials, this is the spec you require as rubber is returned into the groove or below the gaskert this can be seen in the diagram at the top. The exposed steel will be covered by a layer of rubber eliminating the opportunity for corrosion in this area. Only use for corrosive service as the additional cut in the steel ads costs to the pipe.

More Advanced 25.03?

25.03 is a good spec but was designed to accommodate a problem in the Vic system when used with rubber lining. When rubber lining a cast Vitc fitting, the recommendation is that you utilizes the specification VS-222 which we will call for this example 25.01B. “B” standing for Bad. This specification states that you add 1/8″ of rubber to the face of the fitting. That this does impede on the gap required in a Vic coupling system. So 25.03 is designed to add more space to the coupling groove, in the instance that a rubber lined cast fitting mates up to a pipe. The additional space is then maintained and the original gap is perfect. The challenge comes when you mate a cast fitting to a cast fitting 25.01B – 25.01B. This adds 1/8″ of rubber per gasket face and on a fitting that is 3″ in Dia. with a gap of 1/16″ and you put 1/4″ of rubber, it doesn’t work.

If this sounds complicated, we’ll, it is. Below is a diagram explaining what happens to the gap in different situations. There is a spec below which is called 25.01A which we will discuss after this diagram but it maintains the designed gap regardless of cast fittings or pipe assembly.

Advanced

The correct groove to use is 25.01A and 25.01C. These are the dimensions of 25.01 but with 1/8″removed on the face to be replaced with rubber. So the final finished dimension will be the same as 25.01 in all situations. The down side to this is that all cast fittings needed to be rubber lined will be required to be machined back 1/8″ for the addition of the rubber face gasket. No matter what you do this is the correct way to maintain the designed gap in cast fittings as well as the pipe.

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