Shop Talk

Rubber’s qualities make it the perfect match for many industrial and commercial uses, as well as a variety of other applications. Products made from rubber include: industrial hose, gasketing material, matting, conveyor belt systems and marine fenders.

Advantages of Rubber:

• Lightweight and easy to use
• Resistant to cuts and abrasions
• Resistant to weather and outdoor environments (ozone)
• Resistant to fuels, oils and chemicals
• Absorbs vibration and noise to act as an insulator
• Easy to fabricate parts and components
• Seals well for both fluids and gases
• Compatible and bondable with other engineering materials
• Thrives in a wide range of temperatures
• Clean, smooth surface allows for pressure sensitive adhesives
• Reduces heat transfer with a low thermal conductivity
• Flexible and malleable material
• Long shelf and application life
• Available in hard and soft materials

Consult our Chemical Resistance chart or S.T.A.M.P.E.D. guidelines to learn more about the properties of rubber and to find out what types of products will best fit your needs.

Storage and Product Life.
When properly stored, sheet rubber has a great shelf life. Remember the following tips to get the most out of your products:

• FIFO (first in, first out) methods should be used when storing rubber
• Store rubber in a cool, dry room with low humidity and temperatures
• Keep packaging on rubber for optimal protection against environmental exposures
• Do not store rubber in direct sunlight or near heat sources
• Care should be used when opening packing materials
• Do not stack product high to avoid crushing
• Store products on flat surfaces
• Do not hang rubber products from hooks

Measuring Roll Length
Need help determining how to measure the length of your sheet rubber? Here’s a simple, quick rule-of-thumb equation to assist you, whether you’re reviewing inventory or looking to help a customer place an order:

• Roll inside diameter in inches
• Roll outside diameter in inches
• Number of laps (or layers) on one side of the core only

Roll Length in Linear Feet = (OD + ID) x (# of Laps) x 0.131

Tagging Rolls.
Several methods can be used to tag and track sheet rubber rolls. While some spray paint the ends of rolls with different colors to indicate rubber compound, size and date received, others attach tags to keep track of this information.

The best method depends on several factors, including how the warehouse is managed. We prefer tagging the rolls because it is a cleaner process, and different color tags help identify rolls quickly.

Don’t forget — Texcel sheet rubber is continuously marked with a 1” high ink brand show the material type, durometer and production date code.

Whenever possible, tag rolls with weight and length when received and update tags whenever material is cut. The initial effort will save you time and money in the long run!

Determining Cloth Inserted Material.
Nylon, which has replaced cotton fibers as the predominant material inserted into sheet rubber, will not absorb water like cotton. This quality helps maintain seal stability and integrity.

You can determine which material is used with a flame test. Light the strands of the material with a lighter or match. Cotton will burn, whereas nylon will melt and “ball up” like plastic.

Performance Factors.
A gasket creates a positive seal between two relatively stationary parts to keep fluids or other materials from leaking out between the two surfaces. The gasket functions properly if it creates a seal, maintains the seal for the required length of time and can be easily replaced. The gasketing material must be matched to the fluid being conveyed, the fluid’s temperature and other application parameters.

Performance factors important to sealing include:

1. Systems fluids are successfully sealed. Material deforms to mate
   the gasket seating surfaces.
2. Gasketing material is chemically compatible with fluid.
3. Temperature ranges are within specifications for the application.
4. Gasketing material has good resiliency, strength and creep resistance
   to carry the application load.
5. Material does not contaminate the conveyed fluid or harm the gasket
   seating surfaces.
6. The gasket should be easily installed and removed.

Proper Gasket Installation
Proper installation of gaskets is critical to achieving a seal and avoiding problems. The parameters below are endorsed by leading industry organizations to ensure safety guidelines:

• Clean and examine.
• Remove all foreign material and debris form the seating surfaces, fasteners, nuts and washers. Dust removal processes vary, so please use those methods approved for the application.
• Examine fasteners, nuts and washers for defects such as burrs.
• Examine flanges surfaces for warping, radial scores, heavy tool marks or anything prohibiting proper gasket seating.
• Replace components if found to be defective.
• Align flanges.
• Align flange faces and bolt holes without using excessive force.
• Immediately report any misalignment.
• Install gasket.
• Ensure gasket is the specified size and material.
• Examine the gasket to ensure it is free of defects.
• Carefully insert gasket between the flanges.
• Do not use jointing compounds or release agents on the gasket or seating surfaces unless specified by the gasket manufacturer.
• Bring flanges together, ensuring the gasket is not pinched or damaged.
• Lubricate load-bearing surfaces.
• Use only specified or approved lubricants.
• Liberally apply lubricant uniformly to all thread, nut and washer load-bearing surfaces.
• Ensure lubricant does not contaminate either flange or gasket face.
• Install and tighten bolts.
• Always use proper tools, such as calibrated torque wrench or other controlled tensioning devices.
• Torque nuts in a cross bolt tightening pattern. See Bolt Tightening Sequence.
• Tighten the bolt in multiple steps.
• Tighten all nuts initially by hand. (Larger bolts may require a small hand wrench.)
• Torque each nut to 1/3 of full torque using the bolt tightening pattern.
• Torque each nut to 2/3 of full torque using the bolt tightening pattern.
• Torque each nut to full torque.
• Apply at least one final full torque to all nuts in a clock-wise direction until all torque is uniform.
• Retorque 12 to 24 hours after initial installation.
• Establish a maintenance program to regularly schedule testing of torque.

Inspection.
Hoses and couplings should be periodically inspected to ensure proper performance in use. Inspection intervals depend on the application. Important factors include:

• Critical nature of application
• Working temperature
• Working pressure
• Environmental influences/concerns

Safety experts recommend inspecting hose on a daily basis. Any change in the hose can indicate a possible problem. Possible causes include chemical incompatibility, leakage paths, ozone aging and damaged hose. It may be necessary to shut down operations in order to closely inspect a hose.

Signs to look for include:

• Cover or reinforcement damage such as blisters, crazing, abrasions, cuts, exposed reinforcement, etc.
• Change in cover or tube color
• Change in flexibility or hardness of hose
• Blisters on the hose cover
• Kinked or damaged hose
• Leaking

Maintenance and Care
With proper maintenance and care, industrial hose will have a long life even in tough applications. The following general guidelines can maximize your investment.

• Hose should be handled with reasonable care and not be subjected to any abuse.
• Avoid dragging hose over sharp or abrasive surfaces, unless specifically designed with an abrasion-resistant cover.
  
• Protect hose from severe end loads.
• Use working pressures at or below the working pressure for the assembly (see Hose: Pressure limitations on hose assemblies).
• Pressure changes should be made gradually.
• Avoid kinking or running over the hose with equipment.
• Dollies should be used to move large bore hose when possible.
• Slings or handling rigs should be used to support heavy hose.
• Inspect and pressure test hose on a periodic basis.
• Never pull a hose by its coupling.
• Do not lift large bore hoses by the middle with the ends hanging down.
• Remove kinked or crushed hose from service immediately.
• Protect hoses that may experience heavy wear with a nylon or PVC sleeve.
• Check for leaks on a regular basis, especially around couplings.

Hydrostatic Testing
Hoses and couplings should be periodically hydrostatic tested to ensure proper performance in use.

Caution: Hose under pressure can be dangerous and tests should be performed by trained personnel using appropriate tools and methods. Take necessary safety precautions to avoid property damage and bodily injury.

The following industry guidelines are used for hydrostatic testing:

• The testing area should be clear of debris and liquids.
• The hose should be laid out straight to its full length.
• Visually inspect the hose before performing the test for any signs of wear or failure. Replace any hose not passing visual inspection.
• Connect the hose to the test pump,
• Put a quick-opening valve on the free end and elevate it to help air escape.
• Fill the hose from the pump end with water only. Liquids other than water can be dangerous.
• Open the valve slightly to allow air to escape as the hose fills with water.
• Close the valve and place on the ground when all air has escaped.
• Test hose according to proper pressure testing levels.
• Drain the water and allow to dry.

Storage and Product Life
Remember the following tips when storing rubber hose and other rubber products:

• FIFO (first in, first out) methods should be used when storing rubber.
• Store rubber in a cool, dry room with low humidity and temperatures.
• Keep packaging on rubber for optimal protection against environmental exposures.
• Do not store rubber in direct sunlight or near heat sources.
• Care should be used when opening packing materials.
• Do not stack product high to avoid crushing.
• Store products on flat surfaces.
• Do not hang rubber products from hooks.

Static Electricity
Friction from materials flowing through hoses can cause the buildup of static electricity, which can cause serious safety concerns. Hoses handling dry powders and many fluids, such as petroleum products, generally need to be electrically bonded, allowing for static charges to be dissipated into the couplings and piping or machinery.

Get into the habit of static grounding every hose assembly unless instructed otherwise.

Three common methods for dealing with hose static:

• The hose wall includes static wire(s). You must trim the hose to expose an inch or so of wire “pigtail.” Fold the pigtail into the hose ID to make contact with the coupling shank during assembly.
• Helix wire type hoses allow the wire(s) to make the contact. With small helix wires you can bend the end of each wire into the ID of the hose before inserting couplings. For heavy wire hoses, a light electrical wire must be attached to the helix to make the connections.
• Some hoses use conductive tube materials to assure bonding. The most common examples include sandblast hose and dry cement discharge hose. After coupling, a simple electrical test can be made with batteries, a flash light bulb, or a bell to assure effective bonding. Most hardware or auto parts stores offer an inexpensive circuit tester suitable for this test.

Pressure Limits on Hose Assemblies
With thousands of potential coupling-hose combinations, remember that what fits is not necessarily what is right! Much like a spare tire on a car, it may fit but can be used only under a certain speed limit.

The working pressure of an assembly is the lowest working pressure of either the hose or the coupling. For example, if a hose is rated at 250 psi but the coupling is rated only at 150 psi then the working pressure of the assembly is no more than 150 psi. In this case, responsible steps to avoid bodily injury include the following:

• Remove 250 psi branding from the hose cover and remark as 150 psi.
• Indicate working pressure of 150 psi on the customer invoice.
• Consider adding a tag to the assembly indicating 150 psi working pressure.

Abrasive Applications
Abrasion resistant hoses and pipes occasionally fail from internal wear much faster than expected. Suddenly you’re confronted with a concerned customer, and everyone is unsure about how to fix the situation.

It can be challenging to understand the cause of premature wear, but here are a few suggestions:

The flow of abrasive material is like a high velocity stream going in a straight direction. As long as the hose or pipe goes in the same straight direction, there is hardly any wear. It’s like a racetrack that allows a car to go 250 miles per hour.

However, hose is used to re-direct the stream in a different direction, which is when abrasion becomes an issue. Unlike the racecar at a curve, the material flow does not slow down. It wears the hose at a rate proportional to the sharpness of the bend. Just like the racecar, if the curve is too sharp a collision is inevitable. Look for the following:

• Curves or bends in the hose that are too sharp. The stiffer the hose and the more gradual the curve, the better.
• Distortion in the hose, such as being laid out over a railing or curb or a kink, can literally put the tube in direct resistance to the flow.
• Determine if the material being conveyed has changed. More abrasive materials will wear the hose more quickly.
• Implement a hose maintenance care system. Ensure that solvents that will break down the rubber tube are not being used to flush the hose.
• Evaluate if the hose is being exposed to harsh environmental conditions.

Short Standard Lengths
We’ve all cut long hose lengths to make assemblies. Occasionally, there is a shorter length than expected, but here’s a simple solution:

Industrial hose is made longer than listed on technical data sheets. For example, a mandrel built hose is built on mandrels that are 102’ to 104’ long to allow for end trimming and shrinkage factors during vulcanization. This longer length ensures that the hose will be as close to the 100’ specified.

Shrinkage is predictable on many types of hoses. Styles produced with helix wires have the most shrinkage. In addition, they are the ones most commonly cut by distributors.

Water suction, tank truck and chemical suction styles have shrinkage due to the “coil spring” effect of the helix wires. Shrinkage increase as the diameter goes up. Cross-linked polyethylene chemical hose is known to shrink more than most.

Investing a few moments initially can help you overcome any challenges. Use the following tips to avoid problems:

• Develop the habit of rolling out the entire length before cutting. If you are cutting five pieces at 20’ from a 100’ length, you can evenly distribute the shortage on each section. This step is especially important with helix wire suction hose.
• Hose assemblies are measured as the overall length, including couplings unless specified otherwise. Use the “cutoff factor” of your couplings to determine your cut lengths.

For example, 3” x 20’ water suction hose with KC s. The assembly’s “cutoff factor” is 3 inches each. Cut the hose to 19’6” to give an assembly with 20’ overall all length (OAL).

U.S. Coast Guard Certification
The United States Coast Guard has the following requirements for any petroleum or hazardous material hose that is marked as "USCG Certified." For more information or to verify the most recent requirements, please visit www.uscg.mil.

Subpart C
Equipment Requirements
154.500 Hose assemblies.

Each hose assembly used for transferring oil or hazardous material must meet the following requirements:

(a) The minimum design burst pressure for each hose assembly must be at least four times the sum of the pressure of the relief valve setting (or four times the maximum pump pressure when no relief valve is installed) plus the static head pressure of the transfer system, at the point where the hose is installed.

(b) The maximum allowable working pressure (MAWP) for each hose assembly must be more than the sum of the pressure of the relief valve setting (or the maximum pump pressure when no relief valve is installed) plus the static head pressure of the transfer system, at the point where the hose is installed.

(c) Each nonmetallic hose must be usable for oil or hazardous material service.

(d) Each hose assembly must either have:

(1) Full threaded connections;

(2) Flanges that meet standard B16.5, Steel Pipe Flanges and Flange Fittings, or standard B.16.24, Brass or Bronze Pipe Flanges, of the American National Standards Institute (ANSI); or

(3) Quick-disconnect couplings that meet ASTM F-1122.

(e) Each hose must be marked with one of the following:

(1) The name of each product for which the hose may be used; or

(2) For oil products, the words "OIL SERVICE"; or

(3) For hazardous materials, the words "HAZMAT SERVICE--SEE LIST" followed immediately by a letter, number or other symbol that corresponds to a list or chart contained in the facility's operations manual or the vessel's transfer procedure documents which identifies the products that may be transferred through a hose bearing that symbol.

(f) Each hose also must be marked with the following, except that the information required by paragraphs (f)(2) and (3) of this section need not be marked on the hose if it is recorded in the hose records of the vessel or facility, and the hose is marked to identify it with that information:

(1) Maximum allowable working pressure;

(2) Date of manufacture; and

(3) Date of the latest test required by Sec. 156.170.

(g) The hose burst pressure and the pressure used for the test required by Sec. 156.170 of this chapter must not be marked on the hose and must be recorded elsewhere at the facility as described in paragraph (f) of this section.

(h) Each hose used to transfer fuel to a vessel that has a fill pipe for which containment cannot practically be provided must be equipped with an automatic back pressure shutoff nozzle.

[CGD 75-124, 45 FR 7172, Jan. 31, 1980, as amended by CGD 86-034, 55 FR 36253, Sept. 4, 1990; CGD 88-032, 56 FR 35820, July 29, 1991; CGD 92-027, 58 FR 39662, July 26, 1993; CGD 93-056, 61 FR 41459, Aug. 8, 1996]