(Reprinted from RMA Hose Handbook IP-2 Sixth Edition 1996)
Hose has a limited life and the user must be alert to signs of impending failure,
particularly when the conditions of service include high working pressures and/or
the conveyance or containment of hazardous materials. The periodic inspection
and testing procedures described here provide a schedule of specific measures
which constitute a minimum level of user action to detect signs indicating hose
deterioration or loss of performance before conditions leading to malfunction
or failure are reached.
SAFETY WARNING: Failure to properly follow the manufacturer's recommended
procedures for the care, maintenance and storage of a particular hose might
result in its failure to perform in the manner intended and might result in
possible damage to property and serious bodily injury.
General instructions are also described for the proper storage of hose to minimize deterioration from exposure to elements or environments which are known to be deleterious to rubber products. Proper storage conditions can enhance and extend substantially the ultimate life of hose products.
General Care and Maintenance of Hose
Hose should not be subjected to any form of abuse in service. It should be handled
with reasonable care. Hose should not be dragged over sharp or abrasive surfaces
unless specifically designed for such service. Care should be taken to protect
hose from severe end loads for which the hose or hose assembly were not designed.
Hose should be used at or below its rated working pressure; any changes in pressure
should be made gradually so as to not subject the hose to excessive surge pressures.
Hose should not be kinked or be run over by equipment. In handling large size
hose, dollies should be used whenever possible; slings or handling rigs, properly
placed, should be used to support heavy hose used in oil suction and discharge
service.
General Test and Inspection Procedures for Hose
An inspection and hydrostatic test should be made at periodic intervals to determine
if a hose is suitable for continued service. A visual inspection of the hose
should be made for loose covers, kinks, soft spots which might indicate broken
or displaced reinforcement. The couplings or fittings should be closely examined
and, if there is any sign of movement of the hose from the couplings, the hose
should be removed from service. The periodic inspection should include a hydrostatic
test for one minute at 150% of the recommended working pressure of the hose.
An exception to this would be the woven jacketed fire hose.* During the hydrostatic
test, the hose should be straight, not coiled or in a kinked position. Water
is the usual test medium and, following the test, the hose may be flushed with
alcohol to remove traces of moisture. A regular schedule for testing should
be followed and inspection records maintained.
*Woven jacket fire hose should be tested in accordance with the
service test provisions contained in the current edition of National Fire Protection
Association Bulletin No. 1962 - Standard for the Care, Use and Service Testing
of Fire Hose.
SAFETY WARNING: Before conducting any pressure tests on hose, provisions
must be made to ensure the safety of the personnel performing the tests and
to prevent any possible damage to property. Only trained personnel using proper
tools and procedures should conduct any pressure tests.
1. Air or any other compressible gas must never be used as the test media because
of the explosive action of the hose should a failure occur. Such a failure might
result in possible damage to property and serious bodily injury.
2. Air should be removed from the hose by bleeding it through an outlet valve
while the
hose is being filled with the test medium.
3. Hose to be pressure tested must be restrained by placing steel rods or straps
close to each end and at approximate 10 foot (3m) intervals along its length
to keep the hose from "whipping" if failure occurs; the steel rods
or straps are to be anchored firmly to the test structure but in such a manner
that they do not contact the hose which must be free to move.
4. The outlet end of hose is to be bulwarked so that a blown-out fitting will
be stopped.
5. Provisions must be made to protect testing personnel from the forces of the
pressure media if a failure occurs.
6. Testing personnel must never stand in front of or in back of the ends of
a hose being pressure tested.
7. When liquids such as gasoline, oil, solvent, or other hazardous fluids are
used as the test fluid, precautions must be taken to protect against fire or
other damage should a hose fail and the test liquid be sprayed over the surrounding
area.
The Rubber Manufacturers Association has published separately a series
of Hose Technical Information bulletins describing Maintenance, Testing and
Inspection recommendations.
Reference should be made to the current RMA Catalog of Publications, to determine
the availability of the latest edition. Bulletins published as of January 1996
include the following:
Publication No.
IP 11-1-Steam Hose
IP 11-2-Anhydrous Ammonia Hose
IP 11-4-0il Suction and Discharge Hose IP 11-5-Welding Hose
IP 11-7-Chemical Hose
IP 11-8-Fuel Dispensing Hose
Storage
Rubber hose products in storage can be affected adversely by temperature, humidity,
ozone, sunlight, oils, solvents, corrosive liquids and fumes, insects, rodents
and radioactive materials.
The appropriate method for storing hose depends to a great extent on its size
(diameter and length), the quantity to be stored, and the way in which it is
packaged. Hose should not be piled or stacked to such an extent that the weight
of the stack creates distortions on the lengths stored at the bottom. Since hose products vary considerably in size, weight, and length, it is not
practical to establish definite recommendations on this point. Hose having a
very light wall will not support as much load as could a hose having a heavier
wall or hose having a wire reinforcement. Hose which is shipped in coils or
bales should be stored so that the coils are in a horizontal plane.
Whenever feasible, rubber hose products should be stored in their original shipping
containers, especially when such containers are wooden crates or cardboard cartons
which provide some protection against the deteriorating effects of oils, solvents,
and corrosive liquids; shipping containers also afford some protection against
ozone and sunlight.
Certain rodents and insects will damage rubber hose products, and adequate protection
from them should be provided.
Cotton jacketed hose should be protected against fungal growths if the hose
is to be stored for prolonged periods in humidity conditions in excess of 70%.
The ideal temperature for the storage of rubber products ranges from 50°F
to 70° F (10°C to 21°C) with a maximum limit of 100°F (38°C).
If stored below 32°F (0°C), some rubber products become stiff and would
require warming before being placed in service. Rubber products should not be stored near sources of heat, such as
radiators, base heaters, etc., nor should they be stored under conditions of
high or low humidity.
To avoid the adverse effects of high ozone concentration, rubber hose products
should not be stored near electrical equipment that may generate ozone or be
stored for any lengthy period in geographical areas of known high ozone concentration.
Exposure to direct or reflected sunlight, even through windows, should also be avoided. Uncovered hose should
not be stored under fluorescent or mercury lamps which generate light waves harmful to rubber.
Storage areas should be relatively cool and dark, and free of dampness and mildew.
Items should be stored on a first-in, first-out basis, since even under the
best of conditions, an unusually long shelf life could deteriorate certain rubber
products.