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Lack of training and increased use of ethanol blends resulting in accelerated aging of petroleum hoses

Aug. 1, 2011
A THOROUGH visual inspection would eliminate two-thirds of the hose failures seen by Hart Industries in its work with tank truck fleets, according to

A THOROUGH visual inspection would eliminate two-thirds of the hose failures seen by Hart Industries in its work with tank truck fleets, according to Hart Industries President and Chief Executive Officer Kip Hart.

In “Tank Truck Unloading Equipment: Pumps, Compressors, Hoses, Best Practices,” Hart said that maintenance technicians are not always the best front-line advocates. He made the presentation during the 2010 Cargo Tank Maintenance Seminar.

“Your front-line man is the truck driver,” Hart said. “He's the one present when hoses fail, so we like to encourage safety departments to at least include some hose training in driver training segments, predominantly a visual inspection. They are not equipped to do testing and repairing, but they are well-equipped to do a good visual inspection prior to each use.

“Common sense tells us a lot of these things should have never been in place in the first place. Why were they? Often it's a lack of training or education in what is a usable hose and what is not. Recently, it has become more of a factor in the petroleum arena. With new gasoline fuel blends, and especially with ethanol blends, we're seeing accelerated aging of some of the hoses and seals. Be aware of that. Drying of elastomers inside is happening, primarily because of ethanol blends. We're not chemists, but we do see the results in the form of shorter hose life. Choose a hose that has a rich nitrile blend.”

Hart said a visual inspection tag check involves checking for the ID tag, fittings, or hose for markings indicating a test date. If it's been over 90 days, perform a visual inspection, pressure test, and conductivity test. If it's been under 90 days, visually inspect it and return to service if passed.

“This requirement can vary by customer,” Hart said. “Please check what the customer requirement is prior to performing the test service.”

Signs of impending hose failure can appear in what seems to be minor weather cracking that only a close visual inspection will reveal. A drop-hose-specific external visual inspection involves further investigation that may show that the drying of the hose actually began from the inside. This would be attributed to the drying of the elastomer, from chemical exposure, and subsequent aging/cracking of the hose liner.

A hose may have been bent beyond its minimum bending radius and may have damage that is not apparent to the naked eye. Some hoses have severe abrasion to the outer cover, exposing the carcass and reinforcing yarns.

Hart said he sees more hose failures as result of pressure washers. He recommended doing an internal inspection by using a flashlight and looking down inside the hose to examine for damage.

He suggested inspecting clamp tightness of banded assemblies. “Clamps should have rubber squeezed up above the metal band,” he said. “Inspect clamp placement. Clamps shouldn't be too close or far apart. They should be aligned with the barbs, seating just behind each barb.”

When is a hose required to be tested?

  • Whenever a hose assembly is manufactured.

  • Whenever a hose fitting is replaced in a hose.

  • Whenever a hose is re-banded or re-crimped without removing the hose fitting.

  • Whenever a hose fitting is repaired.

  • Whenever a hose is subjected to over-pressurization, overheating, overexposure to chemicals, over-bending or kinking, or assertive dragging or rubbing.

  • Whenever a hose is due for retesting, which should be done every six months.

An electrical continuity test can be done by using an OHM meter to check the conductivity of the hose from one end fitting to the other, making sure that the correct resistance reading appears on the meter. Hoses to be tested: petroleum drop hose, petroleum pump off hose, compressed gas hose (LPG, NH3, NGLs), chemical hose, plastics hose, flour hose, and all hoses used for combustibles/flammables.

If a hose fails, remove it from service, repair it, if feasible, and re-test. If it passes, the hose master log and hose identification tag must be updated with the new test date.

How often should a hose be retested?

  • When a customer requires.

  • Once every 90 days, according to the Rubber Manufacturers Association.

    “There's no legal requirement to test most hoses, except for MC331s or 338s,” Hart said. “But it's going to make your job and our job a lot easier and protect our people and the environment. We've seen worst-case scenarios that can happen with hose failures, and they're nasty. They're anywhere from a gas station blowing up and people dying to neighborhoods being evacuated.”

  • After any repair, over-pressurization, or any other unusual exposure (over-bending, high temperature, signs of aging).

Color-coded tape may be installed at the time of assembly to indicate the month placed in service. The colored tape is installed over the original “born-on” serialized tag. The retest color tape is replaced with the color of the current requirement. A quarter-inch band with the current test tag is installed over the tape for retests.

An RF Identification tag (RFID) is attached to each device and encoded with a unique serial number. The handheld reader/writer identifies each device by its serial number for reference in a database. Specific data is transferred to a local computer using the Lifecycle Analysis Tool (software) to catalog process equipment, maintain wear-related events, and store application data associated with a particular location.

“We're coming into area where it's much more affordable,” Hart said. “We can get around licensing fees. You just pay for the tags, and we help you develop the database, and you're off and running. It's a better system than barcodes because you can protect the information a lot easier on a RFID than a barcode.

“A test is only as good as the document you have to back it up. We have a form that addresses all government regulations and private industry standards. Anything we test or repair is done in this same format.”

He said hose racks have become standard practice among many big carriers and a growing practice among many others.

“The evolution in the tank truck industry has gone away from hoses carried on trailers to tractor-mounted hose racks, but that has created new safety challenges,” he said.

He said new tractor space restraints are driving the move to hydraulic drive systems, which negate the need for PTO drive shafts in lieu of routable hoses. There is flexibility in mounting locations.

“We're seeing a very strong, renewed interest in hydraulic systems, and it's more the result of how newer trucks are set up,” Hart said. “It's getting harder to run PTOs on these trucks. It's making hydraulics a lot more attractive. It's a safer and more reliable system.

“The other big development is product pumps. The DSA Packing that was introduced several years ago by Roper solved many problems by reducing seepage at the rotating shaft. The new triple lip seal takes dripless shaft-sealing to the next level in the move toward zero leakage.”  ♦

About the Author

Rick Weber | Associate Editor

Rick Weber has been an associate editor for Trailer/Body Builders since February 2000. A national award-winning sportswriter, he covered the Miami Dolphins for the Fort Myers News-Press following service with publications in California and Australia. He is a graduate of Penn State University.