JT/T 496-2004High-density polyethylene silicon duct for highway communication conduit (English PDF)

3.1 Structure

Silicore duct consists of high density polyethylene (HDPE) outer wall, color bar

on the external layer and permanent solid siliceous lubricating layer. The

structure of cross section is shown in Figure 1.

3.2 Classification

3.2.1 Classification by structure.

- Smooth solid inner wall and outer wall of silicore duct, expressed by

English capital letter S;

- Silicore duct with smooth outer wall and inner wall carried with

longitudinal rib, expressed by English letter R1;

- Silicore duct with outer wall carried with rib and smooth inner wall,

expressed by English letter R2;

- Silicore duct with outer wall and inner wall carried with rib, expressed by

English letter R3.

air-tightness of plug shall satisfy the water tightness requirements.

5.1 State regulation and standard test environment

Unless otherwise specified, specimen shall be regulated for 24h at 23°C± 2°C

under the conditions stipulated in GB/T 2918-1998.Test shall be carried out

under such conditions.

5.2 Test instruments and preparation

5.2.1 The accuracy level of load sensor universal material testing machine

used in test shall be lower than grade 1 and the accuracy level of length

measuring tool, for steel ruler, not lower than grade 2 and for others, not lower

than grade 1.

5.2.2 Unless otherwise specified, the sampling and specimen preparation for

tensile test and the adjustment and operation of test machine shall be in

accordance with GB/T 1039-1992.

5.3 Appearance inspection

Visually observe the specimen under the natural light condition.

5.4 Measurement of dimensions of silicore duct

Dimensional measurement shall comply with the relevant provisions given in

GB/T 8806-1988.The measurement of length prefers the use of the flexible

rule, division of 1 mm. The measurement of outer diameter prefers the use of

vernier caliper, division of 0.02 mm. In measurement of wall thickness, the

impact of the pressure applied on the specimen to the measurement result

when using measuring tool shall be considered. In such case, the use of wall

thickness micrometer gauge with the division of 0.01 mm is preferred. The

measurement of ovality shall be in accordance with the provisions given in

Annex B.

5.5 Physical-chemical properties

5.5.1 Outer wall hardness

Cover 100 mm long silicore duct around a metal rod with appropriate outer

diameter. Put it below D Shore durometer. Measure the hardness of its outer

wall according to the method stipulated in GB/T 2411-1980.The instant

hardness displayed in durometer is taken as the measurement result. The

average of five tests is taken as the final hardness.

5.5.2 Inner wall friction coefficient

5.5.2.1 Static inner wall friction coefficient can be obtained in accordance

with the method given in Annex C.

5.5.2.2 In the condition that manufacturing process or formula improvement

scheme has been confirmed, in the case of manufacturer using the dynamic

inner wall friction coefficient for comparative test, the dynamic inner wall

friction coefficient test shall be carried out in accordance with Annex D.

NOTE. The official standard for the method of dynamic inner wall friction coefficient is in the

preparation process. This article will be withdrawn after the official issuance of Standard in the

preparation process.

5.5.3 Tensile strength

Clamp five blanking specimens obtained in accordance with the method given

in GB/T 8804.2-1988 on the test machine and then stretch them at the speed

of 100 mm/min until they are broken. Take down the maximum tensile value

during the tension process which is taken as the test result. The average of the

results of five valid tests is taken as the final test result.

5.5.4 Elongation at break

Stretch five blanked specimens which are obtained in accordance with the

method given in GB/T 8804.2-1988 at the speed of 100 mm/min...

......