This standard specifies the definitions, symbols and abbreviations for polypropylene Pipeline system for cool/hot water, and the requirements for application condition grade, materials and sanitary performance.

This standard, together with GB/T 18742.2 Polypropylene Pipeline system for cool/hot water – Part 2: pipes, GB/T 18742.3 Polypropylene Pipeline system for cool/hot water – Part 3: pipe fittings, applies to the cool/hot water pipeline system in buildings, including industrial and civil cold/hot water, drink water and heating system.

This standard does not apply to the fire extinguishing system and the system which does not use the water as medium.

The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.

GB/T 1844.1-1995 Symbols of plastics and resins--Part 1: Basic polymers and their special characteristics (neq ISO 1043 - 1:1987)

GB/T 2035 – 1996 Terms and definitions for plastics (eqv ISO 472:1988)

GB/T 6111 - 1985 Thermoplastics pipes for the conveyance of fluids-Resistance to internal pressure-Test method (eqv ISO/DP 1167:1978)

GB/T 10798 - 2001 Table of universal wall thickness of thermoplastics pipe (idt ISO 4065:1996)

GB/T 17219 - 1998 Standard for safety evaluation of equipment and protective materials in drinking water system

GB/T 18252 – 2000 Plastics piping and ducting systems--Determination of the long-term hydrostatic strength of thermoplastics materials in pipe form by extrapolation

GB/T 18742.2 - 2002 Polypropylene Pipeline system for cool/hot water, Part 2: Pipes

GB/T 18742.3- 2002 Polypropylene Pipeline system for cool/hot water, Part 3: Pipe fittings

ISO 10508:1995 Thermoplastics pipes and fittings for hot and cold water systems

Following definitions, symbols and abbreviations are used in this standard.

3.1 Definition

Following definitions are used in this standard except those provided in GB/T 2035 and GB/T 1844.1.

3.1.1 Geometric definition

3.1.1.1 Nominal outer diameter (dn): specified outer diameter, in mm.

3·1.1.2 Outer diameter at random point (de): measurement at random point of pipe or fittings socket passing through the outer diameter of cross section, which shall be of accuracy to 0.1mm and non-zero figure at the second position after decimal point shall be carried in.

3.1.1.3 Average outer diameter (dem): the value resulted from the measurement of random cross section ex-circle perimeter of pipe or fittings spigot end divided (≈3.142), which shall be of accuracy of 0.1 mm and non-zero figure at the second position after decimal point shall be carried in

3.1.1.4 Minimum average outer diameter (dcm, min): minimum value of average outer diameter, which equals to the nominal outer diameter.

3.1.1.5 Maximum average outer diameter (dem,max): maximum value of average outer diameter.

3.1.1.6 Average inner diameter of pipe socket (dsm): at middle point of length of pipe socket, arithmetic mean of two inner diameter measurement mutually perpendicular.

3.1.1.7 Out-of-roundness: difference of maximum and minimum outer diameter measurements of same cross section at pipe or fittings spigot end, or the difference of maximum and minimum outer diameter measurements of same cross section at socket end, in mm;

3.1.1.8 Nominal wall thickness (en): specified value of pipe or fittings wall thickness, in mm.

3.1.1.9 Wall thickness at random point (e): measurement of wall thickness at random point at perimeter of pipe or fittings, which shall be of accuracy of 0.1mm and the non-zero figure at second position after decimal point shall be carried in.

3.1.1.10 Minimum wall thickness (emin): the minimum value of wall thickness at random point at perimeter of pipe or fittings, which equals to nominal wall thickness.

3.1.1.11 Maximum wall thickness (emax.): maximum value of wall thickness at random point at perimeter of pipe or fittings.

3.1.1.12 Pipe series (S): according to GB/T 10798, non-dimensional number series indicating the pipe specs; it can be calculated with formula (1).

Where: d_n – Nominal outer diameter, mm;

e_n – Nominal wall thickness, mm.

3.1.2 Definition related to operation conditions

3.1.2.1 Nominal pressure (PN): Maximum allowable working pressure of pipe at 20℃, in MPa.

3.1.2.2 Design pressure (PD): Maximum design value of pipeline system pressure, in MPa.

3.1.2.3 Hydrostatic stress ( ): hoop stress in pipe wall under internal pressure with the water as medium, approximately calculated with formula (2), in MPa

Where: P – Internal pressure of pipe, MPa;

D_em – Average outer diameter of pipe, mm;

E_min – Minimum wall thickness of pipe, mm.

3.1.2.4 Design temperature (TD): temperature or temperature combination of transferring water designed for system.

3.1.2.5 Maximum design temperature(Tmax): Maximum value of TD in short time.

3.1.2.6 Malfunction temperature (Tmal): Maximum temperature when the system is beyond of the control limit.

3.1.2.7 Cooling water temperature (Tcold): temperature of transferring cooling water, maximum value approximates 25℃. Use 20℃ during design.

3.1.2.8 Treatment water for heating device: water containing additive for heating device without any harm to the system.

3.1.3 Definition related to material performance

3.1.3.1 Low confidence limit of forecasted long-time hydrostatic strength (LPL): a value with same dimension as the stress, in MPa. It indicates the 97.5% low confidence limit of forecasted hydrostatic strength at temperature T and time t.

3.1.3.2 Design stress (D): the allowable stress for given operation conditions, in MPa. Dp for pipe material and DF for plastic fittings material.

3.1.3.3 Overall utilization coefficient (c): an coefficient of more than 1; consider the performance and operation conditions of pipeline system not indicated in low confidence limit LPL.

3.1.4 Pipe with blocking layer: plastic pipe with a thin blocking layer to (for example) prevent or largely reduce the gas leakage and light penetration through the pipe wall, of which the design stress requirements shall be same as those of base polymer (PP).

3.2 Symbol

C: Overall coefficient of utilization

d_e: Outer diameter (random point)

d_em: Average outer diameter

d_em, min: Minimum average outer diameter

d_em, max: Maximum average outer diameter

d_n: Nominal outer diameter

d_sm: Average inner diameter of socket

e: Wall thickness at random point

e_max: Maximum wall thickness at random point

e_min: Minimum wall thickness at random point

e_n: Nominal wall thickness

P: inside hydrostatic pressure

P_N: Nominal pressure

P_D: Design pressure

T: Temperature

T_cold: Cold water temperature

T_D: Design temperature

T_mal: Malfunction temperature

T_max: Maximum design temperature

t: time

σ: Hydrostatic stress

σ_cold: design stress at 20C

σ_D: Design stress

σ_DF: Design stress of plastic pipe fittings material

σ_DP: Design stress of plastic pipe material

σ_F: Hydrostatic stress of plastic pipe fittings material

σ_P: Hydrostatic stress of plastic pipe material

σ_LPL: Low confidence limit of forecasted long-time hydrostatic strength

3.3 Abbreviation

LPL: Lower Confidence limit

MDP: Maximum design pressure

PP: polypropylene

S: Pipe series

Polypropylene pipeline system complies with the specification in ISO 10508, and select thereof four application grades according to operation conditions, which refers to table 1. Each grade corresponds to specified application range and 50 years’ operation life. In detailed application, the operation pressures of 0.4MPa, 0.6MPa, 0.8MPa and 1.0MPa shall be considered.

Table 1Operation conditions grade

The pipeline system of various operation condition grades in table 1 shall meet the service life requirement of 50 years’ cold water transfer under the conditions of 20℃ and 1 MPa.

Note: The manufacturers of plastic pipe and fittings shall provide the requirements of water treatment as well as the introduction of characteristics such as oxygen permeability.

The polypropylene pipe and fittings materials shall be selected of the suitable resin for pipe from following three types of polypropylene:

PP-H: homopolymerization polypropylene。

PP-B: Shockproof copolymerization polypropylene (once called block copolymerization polypropylene). Two-phase or multi-phase propylene copolymer formed from PP-H and/or PP-R and rubber. The rubber phase consists of the copolymer of propylene and another olefine monomer (or many olefine monomers). The olefine monomer has no functional group other than olefine.

PP-R: Random copolymerization. It is of a random copolymer of propylene and another olefine monomer (or many olefine monomers). The olefine monomer has no functional group other than olefine.

5.1 Polypropylene pipe and fittings materials shall contain necessary additives, which shall be evenly distributed.

5.2 The polypropylene pipe and fittings materials shall be made into pipe, and experienced for the long time hydrostatic tests under at least four different temperatures according to the test method in GB/T 6111 and requirement in GB/T 18252; calculate the LPL values under different temperatures and times from the test data according to the method in GB/T 18252 and make out the material creep fracture curve. Compare the material creep fracture curve with the forecasted strength reference curve in appendix A of the standard, and the LPL values in test results shall be higher than the corresponding values on reference curve within whole time and temperature range.

5.3 The melt quality flow rate of polypropylene pipe and fittings (MFR) ≤ 0.5 g/10 min (230℃ and 2.16 kg).

5.4 The recycled materials complying with the standard which are generated by the production plant during own production process can be re-used, and added into the non-used new materials. The recycled materials from other sources must not be accepted.

The polypropylene pipeline system for transfer drink water shall meet the requirements in GB/T 17219.

Appendix A

(Appendix to the standard)

Forecasted strength reference curve

The forecasted strength reference curve of PP-H refers to figure A1, A2 for PP-B and A3 for PP-R.

The reference curves within the range of 10℃ to 95℃ in figures A1, A2 and A3 come from following quotations:

First branch line (i.e. the straight line section at left of inflection point in figures A1, A2 and A3):

First branch line (i.e. the straight line section at right of inflection point in figures A1, A2 and A3):

In formula (A1) to (A6), where:

F – Breaking time, h;

T – Temperature, K;

σ- Hydrostatic stress, MPa.

Figure A1 PP – H Forecasting strength reference curve

 

Figure A2 PP – B Forecasting strength reference curve

 

Figure A3 PP – R Forecasting strength reference curve

Book No.: 155066·1-18745

Price: RMB 10.00 Yuan

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Subject 618-420

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