JB/T 8727-2004Hydraulic hose assemblies (English PDF)

3.1 Maximum working pressure

The maximum working pressure of the hydraulic hose assemblies that ensures the system's normal operation under specified operational conditions.

3.2 Change length

The amount of axial length change of the hydraulic hose assemblies under the […]

5.1 Length changes

The length change of the hydraulic hose assemblies under the maximum working pressure is in accordance with the specifications in Table 6.

Table 6 Length changes

Hose types

Steel-wire-braided hydraulic hoses Steel-wire-wound hydraulic hoses

Type-1, Type-1T Type-2, 3 Type-2T, 3T Type-1 Type-2 Type-3 Type-4 Type-5 Type-6

Length changes

-4% ~ +2% ±2% […]

6.3.9

For bending joint cores, after bending, the deviation of included angle between

two axes is ±3°.

6.3.10

The surface of metal parts shall be processed, the processing method can be negotiated by the supplier and purchaser.

6.4 Hydraulic hoses

The hydraulic hose assemblies shall select the hydraulic rubber hoses which comply with the specifications in GB/T 3683 and GB/T 10544. If there are special requirements, it shall reach an agreement through negotiation of the purchaser and manufacturer, and shall be indicated in the order contract.

6.5 Assembly quality

The assembly requirements of hose assemblies is in accordance with the specifications of GB/T 7935.

6.5.1

The joint parts surface of hose assemblies is prohibited to have defects which affect the product quality, such as cracks, burrs, flashing, concave-convex traces, scratches, and corrosion.

6.5.2

The swaging joint position of hoses and joints shall be flat, the inner surface shall be smooth, unblocked and have no phenomenon of straining the inner rubber layer.

6.5.3

During the cutting, rubber stripping, and assembling process of hoses, it is prohibited to damage the reinforced layer of steel wire or appear the phenomenon of steel wire exposed.

6.5.4

The inner cleanliness requirement of hydraulic hose assembly products is in accordance with the specifications in JB/T 7858.

9.2 Sampling

The sampling inspection plan of batched products is in accordance with the specifications of GB/T 2828.1.

Note: Sampling for quality supervision and inspection shall be in accordance with the relevant specifications.

9.2.1 Sampling inspection of test items

a) The value of acceptable quality level AQL is 2.5;

b) Type of sampling scheme: single sampling scheme for the normal inspection;

c) The sample amount n is 8, the minimum sampling batch shall not be less than

40.

Note 1: The sample amount of durability test is 4.

Note 2: The sampling scheme of exit-factory proof pressure test shall be in accordance with the specifications of Annex B.

9.2.2 Sampling inspection of joint processing quality

9.2.2.1 Critical characters (class-A)

a) The value of acceptable quality level AQL is 1.0;

b) Type of sampling scheme: double sampling scheme for the normal inspection;

c) Inspection level: general inspection level I.

9.2.2 Important characters (class-B)

a) The value of acceptable quality level AQL is 6.5;

b) Type of sampling scheme: double sampling scheme for the normal inspection;

c) Inspection level: general inspection level I.

9.2.3 Sampling inspection of inner cleanliness and the minimum pass-through

a) The value of acceptable quality level AQL is 2.5;

b) Type of sampling scheme: double sampling scheme for the normal inspection;

c) Inspection level: general inspection level I.

9.3 Determination rules

According to the specifications of GB/T 2828.1.

10.1

The two ends of qualified hydraulic hose assembly products shall be blocked off.

10.2

The marking, packaging, and transportation of hydraulic hose assembly products shall meet the requirements of GB/T 9577.

10.3

The storage of hydraulic hose assembly products shall meet the requirements of

GB/T 9576. Manufacturers shall guarantee that within one-year storage period since the exit-factory date, the usability of products can still achieve the specifications of this

Standard.

10.4

The product qualification certificate of hydraulic hose assemblies shall include:

a) Manufacturer name;

b) Hose assembly name and specification;

c) Date of manufacture;

d) Signature and seal of quality inspection department.

11.5 a 0

18.0-8.11

11.2

a

19 0

18.0-14

0

18.0-8.13

22 0

18.0-

17

0

18.0-

8.16

25 0

21.0-

5.19

0

21.0-

5.18

21.0-

25

0

21.0-

24

38 0

25.0-30

0

25.0-5.29

51 0

25.0-5.40

0

25.0-40 a

It is the minimum pass-through size of flange hose assemblies, the tolerance value is 0

18.0-

.

Annex B (Normative)

Sampling specifications for proof pressure inspection of hydraulic hose assemblies

B.1 See Table B.1 for sampling specifications for proof pressure inspection of hydraulic hose assemblies.

Table B. 1 Sampling of proof pressure inspection of hydraulic hose assemblies

Batch

Piece

Acceptance standard

Amount of samples

Piece

Acceptability rate

%

<=25 Full inspection 100

26 ~ 50 8 100

51 ~ 90 13 100

91 ~ 150 20 100

151 ~ 280 32 100

281 ~ 500 50 100

501 ~ 1200 80 100

Annex C (Normative)

Length tolerance of hydraulic hose assemblies

C.1 See Table C.1 for the allowable length tolerance of hydraulic hose assemblies.

Table C.1 The allowable length tolerance of hydraulic hose assemblies mm

Hose assembly length

L

Length tolerance

Inner-diameter of hoses <=25 Inner-diameter of hoses >25

L<=630 +7, -3 +12, -4

630<L<=1250 +12, -4 +20, -6

1250<L<=2500 +20, -6 +25, -6

2500<L<=8000 +1.5%L, -0.5%L

L>8000 +3%L, -1%L

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