Composite hose is a unique hose composed of many layers of special materials, held together between an inner and outer wire. This type of hose is still subject to the same operational parameters as regular hose.
This type of hose can be maintained in accordance with the instructions provided on this site. The only additional points are:
- Care should be taken to not damage the exterior of the hose. If the outer wire is broken or damaged, the hose should be replaced.
- If the outer cover plies are abraded to the point the inner carcass plies are exposed, the hose should be replaced.
- Ensure the hose is used to transfer products in accordance with the chemical resistance chart.
Inspection and Testing of Composite Hose
This document provides procedures for the inspection and testing of composite hoses in-service, as well as criteria for their retirement. These include visual inspection, hydrostatic testing and service/age retirement criteria.
In the case of damaged or defective hose that may pass the hydrostatic test but does not satisfy the remaining criteria, burst testing of the hose is suggested to assess remaining hose strength as well as the mode of failure. This data is useful to verify or reassess the current retirement criteria.
To ensure long trouble free service with EVERNEW composite hoses, it is recommended that the following installation and maintenance procedures be followed:
Details of visual inspection should be recorded on the Inspection Form indicating location of significant damage or defects. The hose itself should also be marked at these locations prior to hydrostatic testing in order to determine if point of failure corresponds to observed damage or defect.
Composite hose retirement criteria based on visual inspection includes the following:
- Dents or kinks in the carcass and the inner or outer wire
- Displacement of two or more adjacent inner or outer wire helix from their normal pitch
- Corrosion or abrasion of the outer wire
- Displacement of end fittings or signs of leakage from the ends
- Damage to the outer cover and underlying reinforcement fabric
- Moderate abrasion of the outer cover is acceptable and repairable if the reinforcing fabrics below the cover are not damaged
|Support the hose near flange connections||Use the hose unsupported|
|Support the hose at the appropriate points||Support the hose with a single rope|
|Cushion the hose against sharp edges||Allow the hose to hang unsupported between two objects|
The hydrostatic test shall be performed as described below. Electrical continuity checks, as per part 4, shall also be done during the test.
Hose assembly lengths shall be measured between flange faces.
WARNING: The use of air and other gaseous material as testing media shall be avoided because of the risk to operators. Any failure during test is likely to be of a highly explosive nature. In special cases, where such media are required for the tests, compliance with strict safety measures is mandatory. It shall also be stressed that when a liquid is used as the test medium it is essential that all air is expelled from the hose or hose assembly because of the risk of injury to the operator due to the sudden expansion of trapped air being released when the hose bursts.
- Lay the hose straight out and permit free movement under pressure
- Place blanks over both ends and fill the hose with fresh water
- Vent the trapped arm raising one end of the hose. Raise the pressure to 50 psi (345 kPa) and hold for 10 min. while examining for leaks
- Check for electrical continuity
- Raise the pressure to 150% of rated pressure
- Hold pressure for 10 minutes while checking for leaks
- Measure the hose length from end-of-fabric to end-of-fabric
- Check for electrical continuity
Note: Due to the inherent nature of composite hose it is susceptible to stretching in length while under charge. Hose elongation while under pressure is not an indication of failure of films and fabrics.
Electrical continuity shall be maintained during and on completion of the hydrostatic testing (part 2) To simply check continuity, connect both end flanges with wire and check electric bond using a 4.5 volt battery and a 4 volt 0.3 amp test lamp. A dimly lamp is sufficient to indicate satisfactory continuity.
A measured electrical resistance on each hose assembly shall not exceed 0.25 ohm/ft. (0.75 ohms/m).
- Hoses should be thoroughly flushed out and drained before testing and after service or prolonged storage
- Flush with fresh water, detergent or suitable solvent at ambient temperatures
- Cleaning fluids should be flushed out with clean water to avoid chemical reactions with service products
Note:Hoses should be electrically grounded during cleaning. When cleaning to avoid internal damage to hose. Do not exceed maximum working temperature and pressure.
Post time: Jun-14-2019