SAFETY GUIDE AND BASIC FACTORS FOR THE SELECTION,
INSTALLATION AND MAINTENANCE OF HOSE AND HOSE ASSEMBLIES

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Hydraulic hose (and hose assemblies) has a limited life dependent on service conditions to which is applied. Subjecting hose (and hose assemblies to conditions more severe than the recommended limits significantly reduce service life. Exposure to combinations of recommended limits (i.e., continuous use at maximum rated working pressure, maximum recommended operating temperature and minimum bend radius) will also reduce service life.

1. Selection - The following is a list of factors which must be considered before the selection of a hose can be made.

1.1 Pressure :

After determining the system pressure for an hydraulic system, hose selection must be made so that the recommended maximum operating pressure specified by a given hose, is equal or greater than the system pressure. Dynamic pressure is common for all hydraulic systems.
Pressure surges which exceed the maximum working pressure (pressure relief valve setting) affect the service life of system components, including a hose assembly and therefore need to be taken into consideration. Hoses used for suction lines must be selected to ensure the hose will withstand the negative pressure of the system.

1.2 Temperature :

Care must be taken to ensure that the operating temperature of the fluid being conveyed and ambient temperatures, do not exceed the limitations of the hose.

1.3 Fluid Compatibility :

Hose selection must assure compatibility of the hose tube, cover, reinforcement, and fittings with the fluid used. Additional caution must be observed in hose selection for gaseous applications. Some fire resistant fluids require the same hose as petroleum oil. Some use a special hose, while a few fluids will not work with any hose at all.

1.4 Routing :

Determine hose lengths and configurations that will result in proper routing and protection from abrasion, snagging or kinking and provide leak resistant connections.

1.5 Environment :

Environmental conditions including but not limited to ultraviolet light, heat, ozone, moisture, water, salt water, chemicals, and air pollutants can cause degradation and premature failure and, therefore, must be considered.

1.6 Mechanical Loads :

Mechanical loads which must be considered include excessive flexing, twist, kinking, tensile or side loads, bend radius, and vibration. Use of swivel type fittings or adaptors may be required to ensure no twist is put into the hose. Unusual applications may require special testing prior to hose selection.

1.7 Abrasion :

Special care must be taken to protect the hose from excessive abrasion which can result in erosion, snagging, and cutting of the hose cover. Exposure of the reinforcement will significantly accelerate hose failure.

1.8 Proper End Fitting :

Special care must be taken to ensure proper compatibility exists between the hose and coupling selected based on the manufacturer's recommendations substantiated by testing to industry standards such as
SAE J517
DIN 20024, JIS B 8360.

1.9 Length :

When establishing proper hose length, motion absorption, hose length changes due to pressure, as well as hose and machine tolerances must be considered.

1.10 Specifications and Standards :

When selecting hose and fittings, government, industry, and manufacturer's specifications and recommendations must be reviewed as applicable.

1.11 Hose Cleanliness :

Hose components may vary in cleanliness levels. Care must be taken to ensure that the assemblies selected have an adequate level of cleanliness for the application.

1.12 Welding and Brazing :

Heating of plated parts, including hose fittings and adaptors, above 232° C (450° F) such as during welding, brazing, or soldering may emit deadly gases.

1.13 Electrical Conductivity :


Extreme care must be exercised when selecting hose and fittings for these or any other applications in which electrical conductivity or non-conductivity is a factor.

2. Installation - After the selection of the correct hose, the following factors must be considered prior to hose
and fitting assembly and installation.

2.1 Pre-Installation Inspection :


Prior to installation, a careful examination of the hose must be performed. All components must be checked for correct style, size, and length. The hose must be examined for cleanliness, obstructions, blisters, cover looseness, or any other visible defects.

2.2 Minimum Bend Radius :

Installation of a hose at less than the minimum listed bend radius may significantly reduce the hose life. Particular attention must be given to avoid sharp bending at the hose/fitting juncture.

2.3 Twist Angle and Orientation :

Hose installations must be such that relative motion of machine components does not produce twisting.

2.4 Securement :

In many applications, it may be necessary to restrain, protect, or guide the hose to protect it from damage by unnecessary flexing, pressure surges, and contact with other mechanical components. Care must be taken to ensure such restraints do not introduce additional stress or wear points.

2.5 Proper Connection of Ports :

Proper physical installation of the hose requires a correctly installed port connection while ensuring that no twist or torque is transferred to the hose.

2.6 External Damage :

Proper installation is not complete without ensuring that tensile loads, side loads, kinking, flattening, potential abrasion, thread damage, or damage to sealing surfaces are corrected or eliminated.

2.7 System Checkout :

After completing the installation all air entrapment must be eliminated and the system pressurised to the maximum system pressure and checked for proper function without any leaks, Personnel must stay out of potential hazardous areas while testing.

3. HOSE AND FITTING MAINTENANCE INSTRUCTION :

Even with proper selection and installation, hose life may be significantly reduced without a continuing maintenance program. Frequency should be determined by the severity of the application and risk potential, A maintenance program must be established and followed to include the following as a minimum:

3.1 Visual Inspection Hose :

Any of the following conditions require immediate shut down and replacement of the hose assembly:
Fitting slippage on hose.
Hard. stiff, heat cracked, or charred hose.
Cracked, damaged, or badly corroded fittings.
leaks at fitting or in hose.
Kinked, crushed, flattened or twisted hose.
Blistered, soft, degraded, or loose cover.

3.2 Visual Inspection :

The following items must be tightened, repaired or replaced as required :
Leaking port conditions.
Remove excess dirt build-up.
Clamp, guards, shields.
System fluid level, fluid type and any air entrapment.

3.3 Functional Test :


Operate the system at maximum operating pressure and check for possible malfunctions and freedom from leaks. Personnel must stay out of potential hazardous areas while testing.

3.4 Replacement Intervals :

Specific replacement intervals must be considered based on previous service life, government or industry recommendations, or when failures could results in unacceptable downtime, damage, or injury risk.

WARNING : FAILURE OF PROPER SELECTION, INSTALLATION AND MAINTENANCE PROCEDURES MAY RESULT IN PREMATURE FAILURES, BODILY INJURY, AND DAMAGE TO PROPERTY.


Pressure Conversion METRIC TO PSI (kPa = .145 psi)

Kilo
Pascals(k Pa)

Mega
Pascals(M Pa)
Bar
(Bar)
Pounds per
Square Inch
(psi)
100
0.1 1 14.5
200
0.2 2 29.0
300
0.3 3 43.5
400 0.4 4 58.0
500 0.5 5 72.5
600 0.6 6 87.0
700
0.7 7 101.5
800 0.8 8 116.0
900 0.9 9 130.5
1,000 1.0 10 145.0
2,000 2.0 20 290.1
3,000 3.0 30 435.1
4,000 4.0 40 580.2
5,000 5.0 50 725.2
6,000 6.0 60 870.2
7,000 7.0 70 1,015
8,000
8.0 80 1,160
9,000 9.0 90 1,305
10,000 10 100 1,450
20,000 20 200 2,901
30,000 30 300 2 4,351
40,000 40 400 5,802
50,000 50 500 7,252
60,000 60 600 8,702
70,000 70 700 10,153
80,000 80 800 11,603
90,000 90 900 13,053
100,000 100 1,000 14,504
200,000 200 2,000 29,008
300,000 300 3,000 43,511

PSI TO METRIC (1 psi = 6.89 kPa)

Pounds per
Square Inch(psi)
Kilo
Pascals(k Pa)
Mega
Pascals(M Pa)
Bar
(Bar)
10
68.9 0.07 0.7
20
137.9 0.14 1.4
30 206.8 0.21 2.1
40 275.8 0.28 2.8
50 344.7 0.34 3.4
60 413.7 0.41 4.1
70 482.6 0.48 4.8
80 551.6 0.55 5.5
90 620.5 0.62 6.2
100 689.0 0.7 6.9
200 1,379 1.4 13.8
300 2,068 2.1 20.7
400 2,758 2.8 27.6
500 3,447 3.4 34.5
600 4,137 4.1 41.4
700 4,826 4.8 48.3
800 5,516 5.5 55.2
900 6,205 6.2 62.1
1,000
6,895 6.9 68.9
2,000 13,790 13.8 147.9
3,000 20,684 20.7 206.8
4,000 27,579 27.6 275.8
5,000 34,474 34.5 344.7
6,000 41,369 41.4 413.7
7,000 48,263 48.3 482.6
8,000 55,158 55.2 551.6
9,000 62,053 62.1 620.5
10,000 68,948 68.9 689.0
20,000 137,895 147.9 1,379
30,000 206,843 206.8 2,068
40,000 275,790 275.8 2,758
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