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

1 Scope

China's national standard for buried polyethylene double-wall corrugated pipe - the pipe with a smooth bore and a corrugated outer wall that has largely replaced concrete in drainage and sewerage. It is Part 1 of GB/T 19472 and specifies the terms and definitions, symbols and abbreviations, the materials, the product classification and marking, the pipe structure and connection methods, the requirements, the test methods, the inspection rules and the marking, transport and storage. It applies to buried drainage and sewer pipe and to cable ducting for long-term use below 45 C, and, after evaluation of the material's chemical and temperature resistance, to buried industrial drainage and effluent pipe. A buried drain is not a pressure pipe: what it must resist is the soil above it and the traffic on the surface, and it does so as a flexible pipe, deflecting slightly and transferring load into the surrounding fill rather than carrying it in bending like a rigid concrete pipe. The property that governs that behaviour is ring stiffness, and it is the number the pipe is specified and classified by. The double-wall corrugated construction exists to deliver ring stiffness cheaply: the corrugated outer wall provides the section modulus while the smooth inner wall provides the hydraulic bore, and the result is far lighter than an equivalent solid-wall pipe. The standard therefore sets the ring stiffness classes and their verification, the ring flexibility - the ability to deflect substantially without cracking or delaminating, since a pipe that is stiff but brittle fails on installation - the impact resistance at low temperature, the creep ratio which predicts long-term deflection, and the oxidation induction time which measures the antioxidant stabilisation the polymer needs to survive decades underground. A normative annex covers the sealing test for the elastomeric ring joint. Issued on 30 August 2019 and in force since 1 March 2020, it replaces GB/T 19472.1-2004.

This Part of GB/T 19472 specifies the terms and definitions, symbols and abbreviations, materials, product classification and marking, pipe structure and connection methods, requirements, test methods, inspection rules and signs, transportation, storage of polyethylene double wall corrugated pipes for underground usage. This Part is applicable to pipes for buried drainage, sewage and communication sheath pipes, whose long-term use temperature is below 45 °C. After evaluating the chemical resistance and temperature resistance of the material, it can also be used for buried industrial drainage and sewage pipes.

2 Normative references

The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) is applicable to this standard.

GB/T 1033.1-2008 Plastics - Methods for determining the density of non-cellular plastics - Part 1: Immersion method, liquid pycnometer method and titration method

GB/T 2828.1-2012 Sampling procedures for inspection by attributes - Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection

GB/T 2918-2018 Plastics - Standard atmospheres for conditioning and testing of specimen

GB/T 3682.1-2018 Plastics - Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics - Part 1: Standard method

GB/T 6111-2018 Thermoplastics piping systems for the conveyance of fluids - Determination of the resistance to internal pressure

GB/T 8806-2008 Plastics piping systems - Determination of the size of plastic

GB/T 9647-2015 Thermoplastics pipes - Determination of ring stiffness

GB/T 14152-2001 Thermoplastics pipes - Determination of resistance to external blows. Round the clock method

GB/T 18042-2000 Thermoplastics pipes - Determination of creep ratio

GB/T 19278-2018 General terms and their definitions of thermoplastic pipes, fittings and valves

GB/T 19466.6-2009 Plastics - Differential scanning calorimetry (DSC) - Part 6: Determination of oxidation induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT)

GB/T 21873-2008 Rubber seals - Joint rings for water supply, drainage and sewerage pipelines - Specification for materials

ISO 13968:2008 Plastics piping and ducting systems - Thermoplastics pipes - Determination of ring flexibility

3 Terms and definitions, symbols and abbreviations

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 DN 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] 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 mean of the two inside diameters, as the mean inside diameter of the pipe.

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 Test methods...

9 Inspection rules

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.

Appendix C

(Normative) Sealing test method of elastic sealing ring 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.