Feb 1, 2007 12:00 PM
WHEN it comes to safety during hose testing, strict precautions and procedures are in order, said Kip Hart of Hart Industries.
“Make sure you are working in a safe environment and following any applicable OSHA (Occupational Safety and Health Administration) or company rules you have pertaining to these kinds of functions,” he said.
“You are working with hydrostatic pressure, and in the event a hose fails in a test, you want to make sure that nobody gets hurt,” he added. “We always encourage a safe area that's away from the main flow of traffic where passersby won't be getting blasted with test water. And, of course don't forget to use personal protective equipment, such as goggles and steel-toed shoes.”
Hart made the remarks about safety as part of a discussion on hose inspection, testing, and maintenance. He pointed out that a safe working environment calls for a clean and secured area and thorough personnel training.
He said that a hydrostatic test of the hose is to be performed at a maximum allowable working pressure (MAWP) times 1.5 for five minutes once every 90 days.
“Assure that you have a safe working area and that all required safety practices and equipment are in place,” he said. “Secure hose outlet ends in such a way that a blowout fitting will be stopped. Do not stand at either end while testing, in the event there is an end separation, and never test with compressed gas or air. This can be extremely hazardous.”
As for procedures to follow during testing, Hart recommended laying the hose out in a straight line, walking the full length to inspect condition, and then turning it over for the same review. Problems to look for include kinks or areas crushed beyond 20% of original roundness, cuts, or abrasions that expose the reinforcing textiles, cracking or signs of aging cover material, and wires or textiles protruding from the cover of the hose.
“If any of these conditions exist, the hose should be removed from service,” he said. “Signs of impending hose failure can appear in what seems to be minor weather cracking that only a close visual inspection will reveal. Further investigation is likely to show that the drying of the hose actually began from the inside. This would be attributed to the drying of the elastomers, from chemical exposure, and subsequent aging and/or cracking of the hose liner.”
In the pre-testing phase, all cam-arm assemblies and gaskets on the female end of the hose and machined surfaces of the male end should be inspected. They should be replaced if they are worn or if defective items are discovered. The presence of serialized identification tags should be determined. “If the tag is absent, replace it with a new one, but not until inspections and testing are completed,” Hart said.
In a presentation termed hose pressure testing procedure one, Hart said the hose should be attached to the pressure testing fixture where all cam-arms should be inspected to ensure they are in the closed position. If the fittings are not a lockable type, safety straps or tie-downs should be used to secure cam-arms during a pressure test.
Discussing a second procedure, Hart said a water supply hose should be attached to the test pump assembly. Then, open the valve and fill hose until water comes out of the bleeder valve at the end of the hose being tested, closing bleed valve once all air is evacuated. “It's important that the hose be filled with water and no air pockets exist,” he said.
Water can then be pumped into the hose using the test pump until pressure reaches 1½ times the MAWP of the hose assembly. Hose and fittings should be inspected for leaks or failures. If the fittings start moving out of the hose or a failure occurs, the test should be discontinued.
Hoses require testing:
Whenever a hose assembly is manufactured new.
Whenever a hose fitting is removed and re-attached or when it is re-banded and re-attached.
Whenever a hose is due for retesting by the carrier, insurance or customer requirements and for legal/regulation requirements.
Whenever a hose is subjected to overpressurization, pressure spike, over-heating, chemical exposure above ordinary recommendations, over bending/kinking, excessive abrading
Questionable results as a result of visual inspection.
“It's always good to educate your drivers as much as you can about hoses,” Hart added. “We always preach that driver training always include a segment on hoses because they are the guys on the front line.”
Certain hoses require certain tests, such as for conductivity. They include petroleum drop and pump-off hoses, as well as compressed gas, chemical, plastics, and flour hoses. “Any other hose that conveys combustible and or flammable material should be tested for conductivity,” Hart said. “Hoses designed to dissipate static should be tested frequently. The deteriorating effect that can occur from abrasion or aging of the inner tube can prevent static charge from dissipating through the tube to the static wire.”
He pointed out that static wires can break inside of a hose carcass and/or disconnect from the fitting from normal bending and flexing.
As for test frequency for the various types of hoses, Hart said pump, drop, chemical, and liquid petroleum gas hoses should be tested every 90 days at a test pressure 1.5 times the MAWP as determined by the hose manufacturer.
Turning to fittings, Hart advised that they should be inspected for cracks or flaws, pitting or corrosion, wear on surfaces, missing or damaged cam-ears, and pins, and distortions of tolerances and roundness.
“The use of a new fitting to gauge old fittings is recommended,” he said. “Make sure fittings are completely bottomed out against the hose end. Fittings not bottomed out could be loose, and should be reattached. Don't forget to check the condition of the gasket and replace it if it is worn, cracked, hardened, or discolored.”
Other checks should include:
Cam-locks for broken or missing arms, cracks or pits in fitting body, worn or cracked gaskets.
Auto-locks for malfunctioning locking mechanisms and make sure the locking cam-arms are operating properly so that they create a positive lock “click” when closed.
Inspect band clamps for tightness, type and material of construction, and correct placement of clamps.
Hart suggested that color-coded tape on hoses be attached at the time of assembly to indicate the date they are placed in service. At the time of retesting, the color tape is replaced with a color as determined by a color chart, and the test tag is attached over the tape. In addition, a log should be kept containing important information about all hoses, including testing and repairing.
Hoses should be stored on a solid support base foundation in a dry and cool area away from sunlight, electric motors, welding equipment, or any source of ozone. They should be coiled and stacked uniformly or laid out straight and stacked neatly.
Hose cleaning procedures should require caustic vats to be regulated to no more than 180°F and hoses should be in the vat for no more than 20 minutes.
“Never use pressure wands or steam lances to clean the interiors of hoses,” he cautioned. “This practice can severely damage the interior surface of a hose, leading to a leak or rupture at some point in the future.”
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