GB/T 19472.1-2019Polyethylene structured-wall piping systems for underground use - Part 1: Polyethylene double-wall corrugated pipes (English PDF)

3.1 Terms and definitions

The terms and definitions as defined in GB/T 19278-2018, as well as the following terms and definitions, apply to this document.

3.1.1 Nominal size

The nominal value of the dimension specification, which is usually the rounded value for convenience. [GB/T 19278-2018, definition 2.3.4]

3.1.2 Nominal size DN/OD

DN/OD Nominal dimension, which is relative to outside diameter. [GB/T 19278-2018, definition 2.3.5]

3.1.3 Nominal ring stiffness

Nominal value of ring stiffness, which is usually a convenient round integer, representing the minimum specified value of ring stiffness. [GB/T 19278-2018, Definition 2.4.3]

3.2 Symbols

The following symbols apply to this document. A: Joint length. Dim,min: The minimum mean inside diameter of the socket. DN: Nominal size. DN/ID: Nominal size, which is expressed in inside diameter.

DN/OD: Nominal size, which is expressed in outside diameter. de: Outside diameter. dem: Mean outside diameter. di: Inside diameter. dim: Mean inside diameter. e: Wall thickness of the inside layer (waterway wall thickness). e1: Wall thickness of the inside layer under a hollow section. e2: Wall thickness of a socket. e3: Wall thickness of the outside layer under a hollow section. L: Effective length of pipe. SN: Nominal ring stiffness.

3.3 Abbreviations

The following abbreviations apply to this document.

MFR: Melt mass-flow rate

PE: Polyethylene

TIR: True impact rate

8.3.4 Wall thickness

According to the provisions of GB/T 8806-2008, cut the pipe into four equal parts, along the circumference; measure the wall thickness of the inside layer (waterway wall thickness), the wall thickness of the inside layer under a hollow section, the wall thickness of the outside layer under a hollow section; read the minimum value.

8.3.5 Mean inside diameter of socket

As shown in Figure 2, according to the provisions of GB/T 8806-2008, measure the two inside diameters of the socket, that are perpendicular to each other; take the arithmetic mean of the two inside diameters, as the measurement result.

8.3.6 Joint length

As shown in Figure 2, use a measuring tool, which has a minimum scale of not less than 0.02 mm, to measure the joint length.

8.3.7 Wall thickness of socket

Measure the wall thickness of the socket, according to the provisions of GB/T 8806-2008; read the minimum value.

8.4 Ring stiffness

Carry out the test, according to the provisions of GB/T 9647-2015; the cutting point shall be in the middle of the trough, when sampling.

8.5 Impact properties

8.5.1 Specimen

When the nominal size of the pipe is less than or equal to 500 mm, sampling shall be carried out according to the provisions of GB/T 14152-2001. When the nominal size is greater than 500 mm, it can be cut into pieces for testing. The size of the test block is as follows: the length is (200 ± 10) mm; the inner chord length is (300 ± 10) mm; the outer surface arc of the test block shall be upward; the two ends shall be placed horizontally on the bottom plate; the impact point shall be guaranteed to be the top end of corrugation.

8.5.2 Test procedure

The test is carried out, according to the provisions of GB/T 14152-2001. The test temperature is (0 ± 1) °C; the V-shaped pallet is used. The mass of the drop weight and the impact height are as shown in Table 8. When it is usually installed and laid at -10 °C, in the planned use area, the mass of drop weight and impact height are as shown in

Observe whether the pipe specimen is broken; whether the inner and outer walls are disengaged; whether the inner wall is reversely bent.

8.7 Oven test

8.7.1 Specimen

Take 3 segments of pipes of (300 ± 20) mm long. For pipes, which have a nominal size <= 400 mm, cut into two specimens of the same size, along the axial direction. For pipes, which have a nominal size > 400 mm, cut into four specimens of the same size, along the axial direction.

8.7.2 Test procedure

Set the oven temperature to (110 ± 2) °C. After the temperature is reached, place the specimen in the oven, so that it does not contact each other AND the four walls of the oven. When the wall thickness of the inside layer (waterway wall thickness) e is <= 8 mm, place it at (110 ± 2) °C for 30 min; when the wall thickness of the inside layer (waterway wall thickness) e is > 8 mm, place it at the same temperature for 60 min. Do not deform or damage it, when taking it out. Cool it to room temperature; observe it. If the specimen is delaminated, cracked or blistered, the specimen is unqualified.

8.8 Density

The test is carried out, according to the provisions of Method A in GB/T 1033.1-2008.

The inner and outer walls are measured, respectively. Take the maximum value.

8.9 Oxidative induction time

The test is carried out, according to the provisions of GB/T 19466.6-2009. The inner and outer walls are measured, respectively. Take the minimum value.

8.10 Creep ratio

The test is carried out, according to the provisions of GB/T 18042-2000. The test conditions are (23 ± 2) °C; the creep ratio is calculated and extrapolated to two years.

8.11 Suitability of the system

Follow the provisions of Appendix C.

9.1 Group-batching

The pipes of the same batch of raw materials, the same formula, the same specification, which are produced under the same conditions, form a batch. When the nominal size of

a) Trial type identification of new products or old products after trans-plant production;

b) When there are major changes in structure, material, process, that may affect the performance of the product;

c) When the production resumes after suspension for more than one year;

d) Where there is a big difference, between the exit-factory inspection results and the last type inspection results.

9.4 Judgment rules

If any of the items in 7.1, 7.2, 7.3 do not meet the requirements of Table 10, except the wall thickness of the inside layer (waterway wall thickness), the wall thickness of the inside layer under a hollow section, the wall thickness of the outside layer under a hollow section, THEN, the batch is judged to be unqualified. If any of the items of the wall thickness of the inside layer (waterway wall thickness), the wall thickness of the inside layer under a hollow section, the wall thickness of the outside layer under a hollow section in 7.3, as well as the ring stiffness, ring flexibility, oven test in 7.4, fail to meet the index, THEN, in the qualified samples as taken in accordance with the sampling plan in 9.2.2, re-take double quantity of samples for reinspection of such item; if it is still unqualified, this batch is unqualified.

10.1 Marking

10.1.1 There shall be the following permanent markings on the product:

a) The marks according to 5.2;

b) The name and trademark of the manufacturer;

c) Pipes, that can be installed and laid at -10 °C, shall be marked with an ice crystal (*) symbol.

10.1.2 The date of manufacture shall be marked on the product.

10.2 Transportation

When the product is loaded, unloaded, transported, it shall not be subjected to severe impact, throwing, high pressure.

10.3 Storage

The pipe storage site shall be flat; the stacking shall be neat; the stacking height shall […]

C.1 Overview

This Appendix specifies three basic test methods for evaluating the sealing performance of elastic sealing ring type joints, in buried thermoplastic piping systems, under selected test conditions.

C.2 Classification of test methods

C.2.1 General

The test methods are divided into the following three types:

- Method 1: Evaluate sealing performance, by the use of lower internal hydrostatic pressure;

- Method 2: Evaluate sealing performance, by the use of higher internal hydrostatic pressure;

- Method 3: Internal negative air pressure (partial vacuum).

C.2.2 Internal hydrostatic test

C.2.2.1 Principle

On the specimen, which is assembled by pipe and (or) pipe fittings, apply a specified internal static pressure p1 (method 1), to evaluate its sealing performance. If possible, then add a specified internal static pressure p2 (method 2), to evaluate its sealing performance (see C.2.2.4.4).

The test pressure shall be maintained for a specified time, during which it shall check the joint for leakage (see C.2.2.4.5).

C.2.2.2 Equipment

C.2.2.2.1 End seals

Seal the non-connected ends of the assembled specimens, through appropriate dimensions and appropriate sealing method. The device is fixed in such a way, that no axial forces can be created on the joint.

C.2.2.2.2 Hydrostatic source

Connect to one end of the sealing device. It can apply and maintain the specified pressure (see C.2.2.4.5).

C.2.2.2.3 Exhaust valve

It is capable of venting gas, from assembled specimen.

C.2.2.2.4 Pressure measuring device

It can check whether the test pressure meets the specified requirements (see C.2.2.4).

Note: To reduce the total volume of water used, a sealed tube or mandrel can be placed in the specimen.

C.2.2.3 Specimen

The specimen is assembled from one or several segments of pipe and (or) one or more pipe fittings, with at least one elastic sealing ring joint. The joint to be tested shall be assembled, in accordance with the manufacturer's requirements.

C.2.2.4 Procedure

C.2.2.4.1 Water temperature

The test water temperature is (23 ± 2) °C.

C.2.2.4.2 Installation

Install the specimen on the test equipment.

C.2.2.4.3 Test record

During the test according to C.2.2.4.4 and C.2.2.4.5, observe whether the specimen leaks. Record any leakage or non-leakage, during and at the end of the test.

C.2.2.4.4 Test pressure

Select the test pressure as follows:

- Method 1: The lower internal hydrostatic test pressure, p1, is 0.005 MPa (1±10%);

- Method 2: The higher internal hydrostatic test pressure, p2, is 0.05 MPa ( ).

C.2.2.4.5 Test method

Fill the assembled specimen with water. Discharge the air. In order to ensure the

pipe fittings, with at least one elastic sealing ring joint. The joint to be tested shall be assembled, in accordance with the manufacturer's requirements.

C.2.3.4 Procedure

C.2.3.4.1 Water temperature

The following steps are carried out, within the range of the ambient temperature (23 ± 2) °C. When the test is performed in accordance with C.2.3.4.5, the temperature change shall not exceed 2 °C.

C.2.3.4.2 Installation

Install the specimen on the test equipment.

C.2.3.4.3 Test pressure

Choose the test pressure, from the following methods:

- Method 3: The internal negative air pressure (partial vacuum)'s test pressure p3 is -0.03 MPa (1 ± 5%).

C.2.3.4.4 Initial air pressure

Subject the specimen to an initial negative air pressure, p3, as specified in C.2.3.4.3.

C.2.3.4.5 Test method

Isolate the negative gas source from the specimen. Measure the internal negative pressure. Determine and record the loss of partial vacuum, after 15 min.

C.2.3.4.6 Test record

Record whether the loss of partial vacuum exceeds the specified requirements of the internal negative pressure p3.

C.3 Test conditions

C.3.1 General

The test conditions are divided into the following three types:

- Condition A: There is no additional deformation or angular deviation;

- Condition B: There is radial deformation;

- Condition C: There is angular deviation.

C.3.2 Condition A: There is no additional deformation or angular deviation

When a specimen, which is assembled from one or several segments of pipe and/or one or more pipe fittings, is tested, it does not have any stress acting on the joint, due to deformation or deviation, respectively.

C.3.3 Condition B: Radial deformation

C.3.3.1 Principle

Before carrying out the required pressure test, the specimen which is assembled from pipe and/or pipe fittings have been subjected to the specified radial deformation.

C.3.3.2 Equipment

The equipment shall be capable of producing a constant radial deformation, at the same time on the pipe and additionally at the connection seal, increasing the internal hydrostatic pressure (see Figure C.2), which shall comply with C.2.2.2 and C.2.3.2:

a) A mechanical or hydraulic device, acting on the pressure block, that moves freely along the vertical plane, which is perpendicular to the axis of the pipe, to produce the necessary radial deformation of the pipe (see C.3.3.3). For pipes, which have a diameter equal to or greater than 400 mm, each pair of pressure blocks shall be oval, to suit the expected shape, when the pipe is deformed to the required value, OR be equipped with flexible belts or rubber pads, that can be adapted to the shape of the deformed pipe.

The width of the pressing block is b1, which is specified as follows, according to the outside diameter of the pipe:

- When de <= 710 mm, b1 = 100 mm;

- When 710 mm < de <= 1000 mm, b1 = 150 mm;

- When de > 1000 mm, b1 = 200 mm.

The distance 1, between the socket end and the pressure block shall be 0.5de or 100 mm, whichever is greater.

For double-wall corrugated pipe, the pressure block shall cover at least two corrugations.

b) A mechanical or hydraulic device, acting on the pressure block, that moves freely along the vertical plane, which is perpendicular to the axis of the pipe, to produce the necessary radial deformation, at the connection seal (see C.3.3.3).

The width b2 of the pressure block shall be specified as follows, according to the outside diameter de of the pipe:

- When de <= 110 mm, b2 = 30 mm; […]