ICS 93.025, 23.040.20, 23.040.45     DMS 374 -2:2021  
Second edition  
ISO 4427 -2:2019  
IDT 
 
 
 
DRAFT MALAWI STANDARD  
 
 
 
 
 
 
 
 
 
 
 
 
Plastics piping systems — 
Polyethylene (PE) pipes and fittings for 
water supply —  
Part 2: Pipes  
 
 
 
 
 
 
 
 
 
 
 
 
 
NOTE: This is a Draft Malawi Standard  and should not be regarded or used as a Malawi Standard  
__________________  
 Published by  
MALAWI STANDARDS BOARD   
 
  
 
 ICS 93.025, 23.040.20, 23.040.45     DMS 374 -2:2021  
Second edition  
ISO 4427 -2:2019  
IDT 
 
 
 
 
 
 
Plastics piping systems — Polyethylene 
(PE) pipes and fittings for water supply —  
Part 2: Pipes  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Obtainable from the  
Malawi  Bureau of Standards  
P O Box  946 
BLANTYRE  
 
Tel: +265 1 870 488  
Fax: +265 1 870 756  
E-mail: mbs@mbsmw.org   
Website: www.mbsmw.org   
Price based on 18 pages  
© Copyright reserved   
 
  
  
i 
 TABLE OF CONTENTS  
 
Contents  ................................ ................................ ................................ ................................ ...................  Page  
Foreword  ................................ ................................ ................................ ................................ ....................   i 
Introduction  ................................ ................................ ................................ ................................ ................   i 
Scope  ................................ ................................ ................................ ................................ .........................   1 
Normative references  ................................ ................................ ................................ ................................   2 
Terms and definitions  ................................ ................................ ................................ ................................   2 
Symbols and abbreviated terms  ................................ ................................ ................................ ................   2 
Material  ................................ ................................ ................................ ................................ ......................   2 
General characteristics  ................................ ................................ ................................ ..............................   3 
Geometrical characteristics  ................................ ................................ ................................ .......................   4 
Mechanical characteristics ................................ ................................ ................................ .........................   9 
Physica l characteristics.  ................................ ................................ ................................ ............................   11 
Chemical characteristics of pipes in contact with chemicals  ................................ ................................ .....  12 
Performance requirements  ................................ ................................ ................................ ........................   12 
Marking  ................................ ................................ ................................ ................................ ......................   12 
Annex A (normative) Pipes with co -extruded layers  ................................ ................................ ..................   14 
Annex B (normative) Pipes with peelable layer  ................................ ................................ .........................   16 
Annex C (informative) Re lationship between PN, MRS, S and SDR  ................................ ........................   17 
Bibliography  ................................ ................................ ................................ ................................ ...............   18 
 
 
FOREWORD  
 
 
This Draft Malawi Standard is a review of MS 374 -2:1992, Black polyethylene pipes for the conveyance of 
liquids – Specification. Part 2: High density polyethylene pressure pipes . 
 
This Draft Malawi Standard  is an  identical adoption of the international standard, ISO 4427 -2: 2019  Plastics 
piping systems — Polyethylene (PE) pipes and fittings for water supply — Part 2: Pipes  
 
Acknowledgement is made for the use of the above standard.  
 
Introduction  
 
The DMS 374  series of standards are a set of system standards that specify the requirements for a piping 
system and its components when made from polyethylene (PE). The piping system is intended to be used in 
buried or above ground applications,  for the conveyance of water for human consumption, raw water prior to 
treatment, drainage and sewerage under pressure, vacuum sewer systems, and water for other purposes.  
 
In respect of potential adverse effects on the quality of water intended for human consumption caused by the 
products covered by the DMS 374  series, it does not provide information on the restriction on the use of 
products.  
 
NOTE  - Guidance for assessment of conformity can be found in Reference  [2] in the Bibliography . 
 
TECHNICAL COMMITTEE  
 
This Draft Malawi Standard  was developed by the Technical Committee MBS/TC 2 Pipes and fittings  and the 
following companies and organisations  were represented : 
 
Blantyre City Council;  
Blantyre Water Board;  
Flowtech Limited;   
ii 
 Lilongwe Water Board;  
Malawi University of Business and App lied Sciences;  
Ministry of Forestry and Natural Resources;  
O.G. Plastics Limited;  
Ruo Consultants; and  
Southern Region Water Board  
 
 
NOTICE  
 
This Draft Malawi Standard  shall be revi ewed every five years, or earlier  when  it is necessary  in order to 
keep abreast of progress.  Comments are welcome and shall be  considered when the standard  is being  
reviewed .  
 
  
  
1 
 DMS 374-2:2021 
DRAFT  MALAWI STANDARD  
Plastics piping systems — Polyethylene (PE) pipes and 
fittings for water supply —  
Part 2: Pipes  
 
 
1 SCOPE  
 
This document specifies the pipes made from polyethylene (PE) for buried or above ground applications, 
intended for the conveyance of:  
 
— water for human consumption;  
 
— raw water prior to treatment;  
 
— drainage and sewerage under pressure;  
 
— vacuum sewer s ystems;  
 
— water for other purposes.  
 
NOTE 1  - The intended uses include sea outfalls, laid in water and pipes suspended below bridges.  
 
Pipes complying with this document are not intended for the transport of water intended for human 
consumption in contam inated soils unless special consideration has been taken.  
 
NOTE 2  - For example, ISO 21004 provides an alternative solution for use in contaminated soils. See Reference [3] in the Bibliography.  
 
This document specifies three types of pipe:  
 
— PE pipes (out side diameter dn), including any identification stripes;  
 
— PE pipes with co -extruded layers on either or both the outside and/or inside of the pipe (total outside 
diameter  dn) where all layers have the same MRS rating;  
 
— PE pipes (outside diameter dn) having a peelable and contiguous thermoplastics additional layer on the 
outside of the pipe (“coated pipe”).  
 
This document also specifies the test parameters for the test methods referred to in this document.  
 
In conjunction with the other parts of the DMS 374 series, this document is applicable to PE pipes, their 
joints and to joints with components made of PE and other materials, intended to be used under the following 
conditions:  
 
a) a maximum allowable operating pressure (PFA) up to and including 25 bar1; 
 
b) an operating temperature of 20 °C as the reference temperature.  
 
NOTE 3  - For other operating temperatures, guidance is given in DMS 374 -1:2021, Annex A.  
 
This document covers a range of maximum allowable operating pressures and gives requirements 
concerning colours.  
 
NOTE 4  - It is the responsibility of the purchaser or specifier to make the appropriate selections from these aspects, taking into acc ount 
their particular requirements and installation practices or codes.  
 
 
                                                 
1 1 bar = 0 .1 MPa = 105 Pa; 1 MPa = 1 N/mm2  
2 
 2 NORMATIVE REFERENCES  
 
The following standards contain provisions which, through reference in this text, constitute provisions of this 
Draft Malawi S tandard. All standards are subject to revision and, since any reference to a standard is 
deemed to be a reference to the latest editio n of that standard, parties to agreements based on this Draft 
Malawi S tandard are encouraged to take steps to ensure the use of the most recent editions of the standards 
indicated below. Information on currently valid national and international standards c an be obtained from  the 
Malawi Bureau of Standards . 
 
DMS 374 -1:2021, Plastics piping systems — Polyethylene (PE) pipes and fittings for water supply — Part 1: 
General ; 
DMS 374 -5:2021, Plastics piping systems — Polyethylene (PE) pipes and fittings for water  supply — Part 5: 
Fitness for purpose of the system ; 
ISO 1133 -1, Plastics — Determination of the melt mass -flow rate (MFR) and melt volume -flow rate (MVR) of 
thermoplastics — Part 1: Standard method ; 
ISO 1167 -1:2006 , Thermoplastics pipes, fittings and asse mblies for the conveyance of fluids — 
Determination of the resistance to internal pressure — Part 1: General method ; 
ISO 1167 -2, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of 
the resistance to internal pressu re — Part 2: Preparation of pipe test pieces ; 
ISO 2505 , Thermoplastics pipes — Longitudinal reversion — Test method and parameters ; 
ISO 3126 , Plastics piping systems — Plastics components — Determination of dimensions ; 
ISO 4433 -1, Thermoplastics pipes — Resistance to liquid chemicals — Classification — Part 1: Immersion 
test method 9; 
ISO 4433 -2, Thermoplastics pipes — Resistance to liquid chemicals — Classification — Part 2: Polyolefin 
pipes ; 
ISO 6259 -1, Thermoplastics pipes — Determination of tensile prope rties — Part 1: General test method ; 
ISO 6259 -3, Thermoplastics pipes — Determination of tensile properties — Part 3: Polyolefin pipes ; and 
ISO 11357 -6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation 
induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT) . 
 
 
3 DEFINITIONS  
 
For the purposes of this document t he following definitions apply.  
 
For the purposes of this document, the terms and definitions given in DMS 374 -1 and the following apply . 
 
3.1 
application code  
code letter which identifies the intended use of the product  
 
Note 1 to entry : The code letter mentioned in this document is W indicating "water intended for human consumption".  
 
 
4 SYMBOLS AND ABBREVIATED TERMS  
 
For the purposes of  this document, the symbols and abbreviated terms given in DMS 374 -1 apply.  
 
 
5 MATERIAL  
 
5.1 Compound  
 
The pipes shall be made from virgin material or own reprocessed material from the same PE compound or a 
mixture of both materials.   
3 
 Own reprocessed mater ial from the base pipe of peelable -layer pipes can be used. Reprocessed (both own 
and external) material from peelable layers shall not be used.  
 
The compound(s) from which the pipes are made shall conform to DMS 374 -1. 
 
NOTE  - Since PE 40 is not commonly used for pressure applications, it is the intention of MBS/TC 40  to withdraw all references to this 
compound at the next revision of the DMS 374  series (all parts).  
 
5.2 Identification compound  
 
The compound used for identification stripes and co -extruded layers (see 6.2) shall be manufactured from a 
PE base polymer, which is the same as for one of the material producer’s pipe compounds for which fusion 
compatibility has been proven  
 
The compound used for identification stripes shall comply with the fusion compatibility requirements in               
DMS 374 -1 and with the resistance to weathering as described in DMS 374 -1, Table 2.  
 
The resistance to weathering of the identification stripe compound shall be declared by the manufacturer of 
the compound, confi rming whether either a cumulative radiant exposure of >3 .5 GJ/m2 or >7 GJ/m2 related 
to the outdoor storage ability limit is applicable.  
 
For co -extruded layers used for identification purposes, Annex A  applies.  
 
5.3 Reprocessed and recycled material  
 
Clean, reprocessed material generated from a manufacturer's own production and works testing of products 
according to the DMS 374  series may be used if it is derived from the same compound as used for the 
relevant production.  
 
Reprocessed material obtained fro m external sources and recycled material shall not be used.  
 
 
6 GENERAL CHARACTERISTICS  
 
6.1 Appearance  
 
When viewed without magnification, the internal and external surfaces of pipes shall be smooth and clean 
and shall have no scoring, cavities and other surface defects to an extent that would prevent conformity of 
the pipe to this document.  
 
The pipe ends shall be cut cleanly and square to the axis of the pipe.  
 
6.2 Colour  
 
Blue pipes or black pipes with blue stripes are intended for the conveyance of wat er for human consumption 
only.  
 
The outer coextruded layer of coextruded pipes (see Annex A ) or the peelable layer of peelable layer pipes 
(see Annex B ) for pipes intended for the conveyance of water for human consumption shall be either black 
or blue or b lack with blue stripes.  
 
Pipes intended for drainage and sewerage under pressure shall be black or black with brown stripes or 
according to national preference.  
 
For above -ground installations, all components with colours other than black should be protect ed from direct 
UV light.  
 
NOTE  - Yellow and orange colours are only used for gas applications, in accordance with the ISO 4437 series (all parts).  
 
6.3 Effect on water quality  
 
For pipes to be used in contact with water intended for human consumption, see DMS 374 -1. 
 
  
4 
 7 GEOMETRICAL CHARACTERISTICS  
 
7.1 Measurements  
 
The dimensions of the pipe shall be measured in accordance with ISO 3126.  In case of dispute, the 
measurements of dimensions shall be made not less than 24 h after manufacture and after conditio ning for 
at least 4 h at (23 ± 2) °C.  
 
Indirect measurement at the stage of production is allowed at shorter time periods, provided that evidence is 
shown of correlation.  
 
7.2 Mean outside diameter and out -of-roundness (ovality)  
 
The mean outside diameters , dem, and the out -of-roundness (ovality) shall conform to Table 1. For coiled 
pipes, the maximum out -of-roundness shall be specified by agreement between the manufacturer and the 
end-user.  
 
Pipe from PE 40 materials shall be limited to diameters up to and  including 63 mm.  
 
Table 1 — Mean outside diameters and out -of-roundness  
 
1 2 3 4 5 
Nominal size  
DN/OD  
 Nominal outside  
diameter  Mean outside diametera Maximum  
out-of-roundness  
(ovality)b dn dem min  dem max  
16 16 16.0 16.3 1.2 
20 20 20.0 20.3 1.2 
25 25 25.0 25.3 1.2 
32 32 32.0 32.3 1.3 
40 40 40.0 40.4 1.4 
50 50 50.0 50.4 1.4 
63 63 63.0 63.4 1.5 
75 75 75.0 75.5 1.6 
90 90 90.0 90.6 1.8 
110 110 110.0  110.7  2.2 
125 125 125.0  125.8  2.5 
140 140 140.0  140.9  2.8 
160 160 160.0  161.0  3.2 
180 180 180.0 181.1  3.6 
200 200 200.0  201.2  4.0 
225 225 225.0  226.4  4.5 
250 250 250.0  251.5  5.0 
280 280 280.0  281.7  9.8 
315 315 315.0  316.9  11.1 
355 355 355.0  357.2  12.5 
400 400 400.0  4002.4  14.0 
450 450 450.0  452.7  15.6 
500 500 500.0  503.0  17.5 
560 560 560.0 563.4  19.6 
630 630 630.0  633.8  22.1  
5 
 710 710 710.0  716.4  24.9 
800 800 800.0  807.2  28.0 
900 900 900.0  908.1  –d 
1,000  1,000  1,000.0  1,009.0  –d 
1,200  1,200  1,200.0  1,210.8c –d 
1,400  1,400  1,400.0  1,412.6c –d 
1,600  1,600  1,600.0  1,614.4c –d 
1,800  1,800 1,800.0  1,816.2c –d 
2,000  2,000  2,000.0  2,018.0c –d 
2,250  2,250  2,250.0  2,270.3c –d 
2500  2500  2500.0  2,522.5c –d 
2,800  2,800  2,800.0  2,825.2c –d 
3,000  3,000  3,000.0  3,027.0c –d 
a In accordance with ISO 11922 -1:2018  , grade B, for sizes ≤630 and grade A for sizes ≥710. (See Reference [4] in the 
Bibliography).  
b In accordance with ISO 11922 -1:2018 ,  grade N, for sizes ≤800, to be measured at the point of manufacture.  
c Tolerance calculated as 0,009 dem and does not conform to grade A in ISO 11922 -1:2018 . 
d For straight pipes with diameters ≥900, the maximum out -of-roundness shall be specified by an agreement between the 
manufacturer and the end -user.  
 
NOTE  - Tolerance bands in accordance with ISO 11922 -1:2018 ,  are calculated as follows, as applic able (see Reference [3] in the 
Bibliography):  
 
a) Grade A: 0 .009dn rounded to the next greater 0 .1 mm with a minimum value of 0 .3 mm and a maximum value of 10 .0 mm.  
 
b) Grade B: 0 .006dn rounded up to the next greater 0 .1 mm with a minimum value of 0 .3 mm a nd a maximum value of 4 .0 mm.  
 
c) Grade N:  
 
1) for diameters ≤75 mm    (0.008 dn + 1) mm,  
2) for diameters ≥90 mm and ≤250 mm   (0.02 dn) mm,  
3) for diameters >250 mm    (0.035 dn) mm,  
4) rounded up to the next greater 0 .1 mm.  
 
7.3 Wall thicknesses and their tolerances  
 
The wall thickness shall be in acco rdance with Table 2.  
 
NOTE  - The relationship between PN, MRS, S and SDR is given in Annex C.  
 
  
6 
 Table 2 — Wall thicknesses  
 
 1 2 3 4 5 6 7 8 9 10 
Pipe series  
SDR 6  SDR 7.4  SDR 9 SDR 11 SDR 13.6 SDR 17 SDR 21 SDR 26 SDR 33 SDR 41 
S 2.5  S 3.2  S 4 S 5 S 6.3  S 8 S 10 S 12.5  S 16 S 20 
Nominal Pressure (PN)  
bar 
PE 40  – PN 10  PN 8  PN 6  PN 5  PN 4  PN 3.2  PN 2.5  – – 
PE 80  PN 25  PN 20  PN 16  PN 12.5  PN 10  PN 8  PN 6  PN 5  PN 4  PN 3.2  
PE 100  – PN 25  PN 20  PN 16  PN 12.5  PN 10  PN 8  PN 6  PN 5  PN 4  
Nominal  
size  Wall thicknessb 
mm 
emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax 
16 3.0 3.4 2.3a 2.7 2.0a 2.3 – – – – – – – – – – – – – – 
20 3.4 3.9 3.0 3.7 2.3a 2.7 2.0a 2.3 – – – – – – – – – – – – 
25 4.2 4.8 3.5 4.0 3.0 3.4 2.3a 2.7 2.0a 2.3 – – – – – – – – – – 
32 5.4 6.1 4.4 5.0 3.6 4.1 3.0 3.4 2.4a 2.8 2.0a 2.3 – – – – – – – – 
40 6.7 7.5 5.5 6.2 4.5 5.1 3.7 4.2 3.0 3.5 2.4a 2.8 2.0a 2.3 – – – – – – 
50 8.3 9.3 6.9 7.7 5.6 6.3 4.6 5.2 3.7 4.2 3.0 3.4 2.4a 2.8 2.0a 2.3 – – – – 
63 10.5 11.7 8.6 9.6 7.1 8.0 5.8 6.5 4.7 5.3 3.8 4.3 3.0 3.4 2.5a 2.9 – – – – 
75 12.5 13.9 10.3 11.5 8.4 9.4 6.8 7.6 5.6 6.3 4.5 5.1 3.6 4.1 2.9a 3.3 – – – – 
90 15.0 16.7 12.3 13.7 10.1 11.3 8.2 9.2 6.7 7.5 5.4 6.1 4.3 4.9 3.5 4.0 – – – – 
110 18.3 20.3 15.1b  16.8 12.3 13.7 10.0 11.1 8.1 9.1 6.6 7.4 5.3 6.0 4.2 4.8 – – – – 
125 20.8 23.0 17.1 19.0 14.0 15.6 11.4 12.7 9.2 10.3 7.4 8.3 6.0 6.7 4.8 5.4 – – – – 
140 23.3 25.8 19.2 21.3 15.7 17.4 12.7 14.1 10.3 11.5 8.3 9.3 6.7 7.5 5.4 6.1 – – – – 
160 26.6 29.4 21.9 24.2 17.9 19.8 14.6 16.2 11.8 13.1 9.5 10.6 7.7 8.6 6.2 7.0 – – – – 
180 29.9 33.0 24.6 27.2 20.1 22.3 16.4 18.2 13.3 14.8 10.7 11.9 8.6 9.6 6.9 7.7 – – – – 
200 33.2 36.7 27.4 30.3 22.4 24.8 18.2 20.2 14.7 16.3 11.9 13.2 9.6 10.7 7.7 8.6 – – – –  
7 
  1 2 3 4 5 6 7 8 9 10 
Pipe series  
SDR 6  SDR 7.4  SDR 9 SDR 11 SDR 13.6 SDR 17 SDR 21 SDR 26 SDR 33 SDR 41 
S 2.5  S 3.2  S 4 S 5 S 6.3  S 8 S 10 S 12.5  S 16 S 20 
Nominal Pressure (PN)  
bar 
PE 40  – PN 10  PN 8  PN 6  PN 5  PN 4  PN 3.2  PN 2.5  – – 
PE 80  PN 25  PN 20  PN 16  PN 12.5  PN 10  PN 8  PN 6  PN 5  PN 4  PN 3.2  
PE 100  – PN 25  PN 20  PN 16  PN 12.5  PN 10  PN 8  PN 6  PN 5  PN 4  
Nominal  
size  Wall thicknessb 
mm 
emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax 
225 37.4 41.3 30.8 34.0 25.2 27.9 20.5 22.7 16.6 18.4 13.4 14.9 10.8 12.0 8.6 9.6 – – – – 
250 41.5 45.8 34.2 37.8 27.9 30.8 22.7 25.1 18.4 20.4 14.8 16.4 11.9 13.2 9.6 10.7 – – – – 
280 46.5 51.3 38.3 42.3 31.3 34.6 25.4 28.1 20.6 22.8 16.6 18.4 13.4 14.9 10.7 11.9 – – – – 
315 52.3 57.7 43.1 47.6 35.2 38.9 28.6 61.6 23.2 25.7 18.7 20.7 15.0 16.6 12.1 13.5 9.7 10.8 7.7 8.6 
355 59.0 65.0 48.5 53.5 39.7 43.8 32.2 35.6 26.1 28.9 21.1 23.4 16.9 18.7 13.6 15.1 10.9 12.1 8.7 9.7 
400 – – 54.7 60.3 44.7 49.3 36.3 40.1 29.4 32.5 23.7 26.2 19.1 21.2 15.3 17.0 12.3 13.7 9.8 10.9 
450 – – 61.5 67.8 50.3 55.5 40.9 45.1 33.1 36.6 26.7 29.5 21.5 23.8 17.2 19.1 13.8 15.3 11.0 12.2 
500 – – – – 55.8 61.5 45.4 50.1 36.8 40.6 29.7 32.8 23.9 26.4 19.1 21.2 15.3 17.0 12.3 13.7 
560 – – – – 62.5 68.9 50.8 56.0 41.2 45.5 33.2 36.7 26.7 29.5 21.4 23.7 17.2 19.1 13.7 15.2 
630 – – – – 70.3 77.5 57.2 63.1 46.3 51.1 37.4 41.3 30.0 33.1 24.1 26.7 19.3 21.4 15.4 17.1 
710 – – – – 79.3 87.4 64.5 71.1 52.2 57.6 42.1 46.5 33.9 37.4 27.2 30.1 21.8 24.1 17.4 19.3 
800 – – – – 89.3 98.4 72.6 80.0 58.8 64.8 47.4 52.3 38.1 42.1 30.6 33.8 24.5 27.1 19.6 21.7 
900 – – – – – – 81.7 90.0 66.1 73.0 53.3 58.8 42.9 47.3 34.4 38.3 27.6 30.5 22.0 24.3 
1,000  – – – – – – 90.2 99.4 73.5 79.9 59.3 65.4 47.7 52.6 38.2 42.2 30.6 33.5 24.5 27.1 
1,200  – – – – – – – – 88.2 97.2 71.1 74.8 57.2 63.1 45.9 50.6 36.7 40.5 29.4 32.5 
1,400  – – – – – – – – 102.8  113.3  83.0 90.8 66.7 73.5 53.5 59.0 42.9 47.3 34.3 37.9  
8 
  1 2 3 4 5 6 7 8 9 10 
Pipe series  
SDR 6  SDR 7.4  SDR 9 SDR 11 SDR 13.6 SDR 17 SDR 21 SDR 26 SDR 33 SDR 41 
S 2.5  S 3.2  S 4 S 5 S 6.3  S 8 S 10 S 12.5  S 16 S 20 
Nominal Pressure (PN)  
bar 
PE 40  – PN 10  PN 8  PN 6  PN 5  PN 4  PN 3.2  PN 2.5  – – 
PE 80  PN 25  PN 20  PN 16  PN 12.5  PN 10  PN 8  PN 6  PN 5  PN 4  PN 3.2  
PE 100  – PN 25  PN 20  PN 16  PN 12.5  PN 10  PN 8  PN 6  PN 5  PN 4  
Nominal  
size  Wall thicknessb 
mm 
emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax emin emax 
1,600  – – – – – – – – 117.5  129.5 94.3 103.7  76.2 84.0 61.2 67.5 49.0 54.0 39.2 43.3 
1,800  – – – – – – – – – – 106.6  116.6  85.8 94.4 68.8 76.2 55.1 60.1 44.0 48.3 
2,000  – – – – – – – – – – 118.5  129.5  95.3 104.9  76.4 84.7 61.2 66.8 48.9 53.8 
2,250  – – – – – – – – – – – – 107.2  118.1  86.0 94.8 68.9 75.9 55.0 60.7 
2,500  – – – – – – – – – – – – 119.1  131.2  95.5 105.2  76.5 84.3 61.2 67.5 
2,800  – – – – – – – – – – – – 133.4  146.9  107.0  117.8  85.7 94.4 68.5 75.5 
3,000  – – – – – – – – – – – – 142.9  157.3  114.6  126.2  91.8 101.1  73.4 80.9 
NOTE 1  - 1 bar = 0.1 MPa = 105 Pa; 1 MPa = 1 N/mm2. 
NOTE 2  - PN values are based on C = 1.25.  
NOTE 3  - Tolerances in accordance with ISO 11922 -1:2018 ,  grade V, calculated from (0.1 emin + 0.1) mm rounded up to the next 0.1 mm. For certain applications for  e > 30 mm, ISO 11922 -1:2018 , grade T, 
tolerances may be used calculated from 0.15 emin rounded up to the next 0.1 mm. (See Reference [3] in the Bibliography.)  
NOTE 4  - The calculated value of emin according to ISO 4065:2018  is rounded up to the nearest v alue of either 2.0, 2.3 or 3.0. This is to satisfy certain national requirements (see Reference [5] in the 
Bibliography.)  
a For practical reasons, a minimum wall thickness of 3.0 mm is recommended for electrofusion jointing and jointing with butt fu sion fi ttings and for lining applications.  
b See also Annex C  for actual calculated values.  
  
9 
 7.4 Coiled pipe  
 
The pipe shall be coiled such that localized deformation, e.g., buckling and kinking, is prevented.  
 
The minimum internal diameter of the coil shall be  not less than 18dn. 
 
7.5 Lengths  
 
No requirements have been set concerning particular lengths of coiled or straight pipe or the tolerance 
thereon; hence, it is necessary for lengths of pipe to be supplied by agreement between purchaser and 
manufacturer.  
 
 
8 MECHANICAL CHARACTERISTICS  
 
8.1 Conditioning  
 
Unless otherwise specified in the applicable test method, the test pieces shall be conditioned at (23 ± 2) °C 
prior to testing.  
 
8.2 Requirements  
 
The test pieces shall be tested in accordance with Table 3. When tested using the test method and 
parameters specified therein, the pipe shall have mechanical characteristics conforming to the requirements 
of Table 3 . 
 
For dimensions above and including DN1600, the requirements of Table 3 may be assessed by indirec t 
testing. The indirect test method used and the correlation or safe relationship of the indirect testing to the 
specification of Table 3 shall be documented in the manufacturer’s quality plan. The indirect test method 
shall be agreed between the manufactu rer and the end user.  
 
Table 3 — Mechanical characteristics  
 
1 2 3 4 5 
Characteristic  Requirement  Test parameters  
 Test 
method(s)  Parameter  Value  
Hydrostatic 
strength at 20 
°C No failure of any test 
piece during test 
period  End caps  
Conditioning per iod 
Number of test piecesc 
Type of test  
Test temperature  
Test period  
Circumferential (hoop) stress 
for: 
PE 40  
PE 80  
PE 100  Type a)a 
According to ISO 1167 -1 
3 
Water -in-waterd 
20 °C  
100 h  
 
 
7.0 MPa  
10.0 MPa  
12.0 MPa  ISO 1167 -1b 
ISO 1167 -2 
Hydrostatic 
streng th at 80 
°C No failure of any test 
piece during test 
period  End caps  
Conditioning period  
Number of test piecesc 
Type of test  
Test temperature  
Test period  
Circumferential (hoop)  
stress for:  
PE 40  
PE 100  
PE 80  
 Type a)a 
According to ISO 1167 -1 
3 
Water -in-waterd 
80 °C  
165 he  
 
 
2.5 MPa  
4.5 MPa  
5.4 MPa  ISO 1167 -1f 
ISO 1167 -2 
  
10 
 1 2 3 4 5 
Characteristic  Requirement  Test parameters  
 Test 
method(s)  Parameter  Value  
Hydrostatic 
strength at 80 
°C No failure of any test 
piece during test 
period  End caps  
Conditioning period  
Number of test piecesc 
Type of test  
Test temperature  
Test period  
Circumferential  (hoop)  
stress for:  
PE 40  
PE 80  
PE 100  Type a)a 
According to ISO 1167 -1 
3 
Water -in-waterd 
80 °C  
1,000 h  
 
 
2.0 MPa  
4.0 MPa  
5.0 MPa  ISO 1167 -1b 
ISO 1167 -2 
 
NOTE  - The characteristic resistance to slow crack growth is dealt with in DMS 374 -1 as a material pr operty measured in the form of 
pipe.  
a Type b) end caps may be used for batch release tests for diameters ≥500 mm.  
b The test shall be realized on basis of measured dimensions (OD and thickness), in accordance with ISO 1167 -1:2006, 7.2.  
c The number of tes t pieces given indicates the quantity required to establish a value for the characteristic described in this table. 
The number of test pieces required for factory production control and process control should be listed in the manufacturer’s quality 
plan.  
d For dn > 1 000 mm, the test can also be performed water -in-air. In case of dispute, water in water shall be used.  
e Premature ductile failures are not to be taken into account. For retest procedure, apply 8.3. 
f The test shall be realized on basis of nomi nal dimensions (OD and thickness), in accordance with ISO 1167 -1:2006, 7.3.  
 
8.3 Retest in case of failure at 80 °C  
 
A fracture in a brittle mode in less than 165 h shall constitute a failure; however, if a sample in the 165 h test 
fails in a ductile mode  in less than 165 h, a retest shall be performed at a selected lower stress in order to 
achieve the minimum required time for the selected stress obtained from the line through the stress/time 
points given in Table 4.  
 
Table 4 — Test parameters for the ret est of the hydrostatic strength at 80 °C  
 
1 2 3 4 5 6 
PE 40  PE 80  PE 100  
Stress  
MPa Test period  
h Stress  
MPa Test period  
h Stress  
MPa Test period  
h 
2.5 165 4.5 165 5.4 165 
2.4 230 4.4 233 5.3 256 
2.3 323 4.3 331 5.2 399 
2.2 463 4.2 474 5.1 629 
2.1 675 4.1 685 5.0 1,000  
2.0 1,000  4.0 1,000    
 
 
 
 
 
 
  
11 
 9 PHYSICAL CHARACTERISTICS  
 
9.1 Conditioning  
 
Unless otherwise specified in the applicable test method, the test pieces shall be conditioned at (23 ± 2) °C 
prior to testing.  
 
9.2 Requirements  
 
The test pi eces shall be tested in accordance with Table 5. When tested using the test method and 
parameters specified therein, the pipe shall have physical characteristics conforming to the requirements of 
Table 5.  
 
Table 5 — Physical characteristics — All pipes  
 
1 2 3 4 5 
Characteristic  Requirement  Test parameters  Test method(s)  
Parameter  Value  
Elongation at break 
for e ≤ 5 mm  ≥350 %  Test piece shape  
Test speed  
Number of test piecesa Type 2  
100 mm/min  
According to ISO 6259  ISO 6259 -1 
ISO 6259 -3 
Elongation at break  
for 5 mm < e ≤ 12 mm  ≥350 %  Test piece shape  
Test speed  
Number of test piecesa Type 1b 
50 mm/min  
According to ISO 6259  ISO 6259 -1 
ISO 6259 -3 
Elongation at break  
for e > 12 mm  ≥350 %  Test piece shape  
Test speed  
Number of test piecesa 
OR 
Test piece shape  
Test speed  
Number of test piecesa Type 1b 
25 mm/min  
According to ISO 6259  
 
Type 1b 
50 mm/min  
According to ISO  6259  ISO 6259 -1 
ISO 6259 -3 
Longitudinal 
reversionc ≤3 %  
No effect on 
surface  Length of piped and 
number of test pieces  
Test temperature:  
PE 40  
PE 80, PE 100  
Time  According to ISO 2505  
 
 
100 ± 2 °C  
110 ± 2 °C  
See ISO 2505  ISO 2505  
Melt mass -flow rate 
MFR  for PE 40  Change of MFR 
by processing 
±20 %e Load  
Temperature test  
Time  
Number of test piecesa 2.16 Kg  
190 °C  
10 min  
According to ISO 1133 -1 ISO 1133 -1 
Melt mass -flow rate 
MFR for PE 40  
PE 100  Change of MFR 
by processing 
±20 %e  Load  
Temperature test  
Time  
Number of test piecesa Kg 
190 °C  
10 min  
According to ISO 1133 -1 ISO 1133 -1 
Oxidation  
induction time  ≥20 min  Test temperature  200 °Cf ISO 11357 -6 
Test environment  Oxygen   
Number of test piecesa,g 3  
Effect on water 
quality  National regulations apply  
a The number of test pieces given indicates the quantity required to establish a value for the char acteristic described in this table. 
The number of test pieces required for factory production control and process control should be listed in the manufacturer’s 
quality plan.   
12 
 b Where practical, machined type 2 test pieces may be used for pipe wall thicknes ses ≤25 mm. The test may be terminated when 
the requirement is met, without continuing until the rupture of the test piece.  
c Only applicable for pipes with thickness ≤16 mm.  
d For pipes with an outside diameter >200 mm, longitudinally cut segments may be used.  
e Value as measured on the pipe relative to the value measured on the compound used.  
f The test may be carried out as an indirect test at 210 °C or 220 °C provided that a clear correlation has been established. I n case 
of dispute, the test temperatur e shall be 200 °C.  
g Samples are to be taken from the inner wall surface.  
 
 
10 CHEMICAL CHARACTERISTICS OF PIPES IN CONTACT WITH CHEMICALS  
 
If, for a particular application, it is necessary to evaluate the chemical resistance of the pipe, then the pipe 
shall be classified in accordance with ISO 4433 -1 and ISO 4433 -2. 
 
NOTE  - Guidance for the resistance of polyethylene pipes to chemicals is given in ISO/TR 10358  (see Reference [ 6] in the 
Bibliography). This guidance only addresses chemical resistance of pro ducts not submitted to any stress, and can need to be completed 
to additional testing.  
 
 
11 PERFORMANCE REQUIREMENTS  
 
When pipes conforming to this document are assembled to each other or to components conforming to other 
parts of the DMS 347  series, the j oints shall be in accordance with DMS 374-5. 
 
 
12 MARKING  
 
12.1 General  
 
The marking elements shall be printed or formed directly on the pipes in such a way that after storage, 
weathering, handling, and installation, legibility is maintained during the use  of the pipes.  
 
NOTE  - The manufacturer is not responsible for marking being illegible, due to actions caused during installation and use such as 
painting, scratching, covering of the components, or by use of detergents, etc. on the components unless agree d or specified by the 
manufacturer.  
 
Marking shall not initiate cracks or other types of defects which adversely influence the performance of the 
pipes.  
 
If printing is used, the colour of the printed information shall differ from the basic colour of the p ipes.  
 
The size of the marking shall be such that it is legible without magnification.  
 
 
12.2 Minimum required marking of pipes  
 
The minimum required marking shall be in accordance with Table 6, with the frequency of marking being not 
less than once per me tre. 
 
Table 6 — Minimum required marking  
 
1 2 
Aspect  Marking  
Standard number  DMS 374 -2 
Manufacturer's identification  Name or symbol  
Dimensions ( dn × en) e.g. 110 × 10  
SDR series (for dn > 32)  e.g. SDR 11   
13 
 1 2 
Aspect  Marking  
Material and designation  e.g. PE 100  
Pressure  rating in bar  e.g. PN 16  
Intended use  e.g. Wa,b 
Meteragec  
Type of pipe, if applicable  e.g. co -extruded or peelable layer  
Traceability information  e.g. 0204d 
a Applicable for blue pipes and black pipes with blue stripes.  
b Instead of W, marking accor ding to local or national rules may be applied (e.g. "Drinking water" or "potable water").  
c Only for coiled pipes, indicating remaining length on coil.  
d In clear figures or in code providing traceability to the production period within year and month and , if the manufacturer is 
producing at different sites, the production site.  
 
In addition to Table 6, the minimum marking of pipes with peelable layer shall comply with the requirements 
of Annex B.  
  
14 
 Annex A  
(normative)  
 
Pipes with co -extruded layers  
 
A.1 General  
 
This annex specifies the additional geometrical, mechanical and physical properties of polyethylene (PE) 
pipes with co -extruded layer(s), intended to be used in buried or above ground applications for the 
conveyance of water for general purposes, including water intended for human consumption and raw water 
prior to treatment.  
 
NOTE  - Other types of pipes with co -extruded layers are covered by other standards (e.g. References [3] in Bibliography).  
 
A.2 Material  
 
The PE compounds used for the layer(s ) of the pipes shall be in accordance with DMS 374 -1 and have the 
same MRS rating. The use of reprocessed or recycled material shall be in accordance with 5.3. 
 
A.3 Geometrical characteristics  
 
The wall thickness, en, is defined as the total wall thickness  including all layers.  
 
The outside diameter, de, is defined as the total outside diameter.  
 
A.4 Pipe with coloured identification layer  
 
A.4.1  Geometrical characteristics  
 
The geometrical characteristics of the pipe, inclusive of the coloured identificati on layer, shall be in 
accordance with Clause 7.  
 
A.4.2  Mechanical characteristics  
 
The mechanical characteristics of the pipe, inclusive of the coloured identification layer, shall be in 
accordance with Clause 8.  
 
A.4.3  Physical characteristics  
 
The physic al characteristics shall be in accordance with Clause 9. The requirements for thermal stability 
(OIT) and for melt -flow rate shall apply to the individual layers respectively. L  
 
A.4.4  Marking  
 
The marking of pipes with coloured identification layers shall  be in accordance with Clause 12.  
 
A.5 Delamination  
 
No delamination shall occur during all tests of the co -extruded pipe.  
 
A.6 Integrity of the structure  
 
When tested in accordance with the test methods as specified in Table A.1 using the indicated parame ters, 
the pipes shall have the structural performance conforming to the requirements given in Table A.1.  
 
Table A.1 — Integrity of the structure  
 
1 2 3 4 5 
Characteristic  Requirement  Test parameters  Test method  
Integrity of the 
structure after 
deflection  >80 % of the initial 
stiffness value  Deflection  
Position of test piece  30 % of dem 
When applicable, at 0°, 45° 
and 90° from the upper plate  ISO 13968   
15 
 For the determination of the integrity of the structure after deflection of co -extruded pipes, the follo wing 
procedure shall be applied:  
 
a) determine the initial ring stiffness of the pipe according to ISO 9969;  
 
b) carry out the ring flexibility test according to ISO 13968;  
 
c) after a 1 h period for recovery, determine again the ring stiffness according t o ISO 9969.  
 
The ring stiffness of the co -extruded pipe shall be at least 80 % of the initial ring stiffness.  
 
 
 
  
16 
 Annex B  
(normative)  
 
Pipes with peelable layer  
 
B.1 General  
 
This annex specifies the geometrical, mechanical, and physical properties of tho se polyethylene (PE) pipes 
(outside diameter dn) having a peelable and contiguous thermoplastics layer on the outside of the pipe 
("coated pipe"). Marking requirements are also given.  
 
The PE compound used for the production of the base pipe shall be in ac cordance with DMS 374 -1 and the 
base pipe shall fulfil all the requirements of this document after removal of the peelable layer, with the 
exception of appearance, colour, and marking.  
 
The peelable layer shall be manufactured from a thermoplastic material . When attached, the peelable layer 
shall not affect the ability of the PE pipe to meet the performance requirements of this document.  
 
If an adhesive layer is used to attach the peelable layer, it shall be easily removed, without affecting the 
jointing pr ocess. The preparation for the jointing process shall follow normal procedures.  
 
NOTE  - Other types of layered pipes are covered by other international standards (See References [7] and [8] in the Bibliography).  
 
B.2 Geometrical characteristics  
 
The geomet rical characteristics of the pipe, with the peelable layer removed, shall be in accordance with 
Clause 7.  
 
B.3 Mechanical characteristics  
 
The peelable layer shall not have a detrimental effect on the pipe or vice versa.  
 
The mechanical characteristics of the pipe, with the peelable layer removed shall be in accordance with 
Clause 8, and the attachment of the peelable layer shall not affect the ability of the pipe to conform to those 
requirements.  
 
When the pipe is tested with the peelable layer attached, c onformity to Clause 8  before and after weathering 
according to DMS 374 -1, Table 2  shall be assessed. The conditions selected shall ensure that pipe is 
subjected to the specified test stresses.  
 
B.4 Physical characteristics  
 
The physical  characteristics of the pipe, with the peelable layer removed, shall be in accordance with             
Clause 9.  The peelable layer shall not have a detrimental effect on the pipe or vice versa.  
 
B.5 Peelable layer adhesion  
 
The peelable layer shall be resistant to detachment  during storage and installation.  
 
The peelable layer shall be easily removed using an appropriate tool as recommended by the pipe 
manufacturer.  
 
B.6 Marking  
 
Marking shall be applied to the coating and shall be in accordance with Clause 12.  
 
In addition, the peelable layer shall be provided with marking clearly distinguishing the pipe from non -coated 
pipes in service, for example, identification stripes may be used for this purpose.  
 
The peelable layer shall also carry marking that warns that the peelable layer shall be removed prior to 
electrofusion, buttfusion and mechanical jointing.  
  
17 
 Annex C  
(informative)  
 
Relationship between PN, MRS, S and SDR  
 
The relationship between nominal pressure, PN, design stress, σs, and the series S/SDR is given by the 
following formula:  
 
SPNs10
 OR 
120
SDRPNs  
 
Examples of the relationship between PN, MRS, S, and SDR based on  
 
 
CMRS
s RS/C  
 
are given in Table C.1, where C = 1 .25. 
 
NOTE  - The nominal pressures (PN) given in Table C.1 are based on the use of an overall design coefficient of C = 1.25. However, if a 
higher value for C is required, the PN values will have to be recalculated using the above equations and based on the calculated d esign 
stress, σs, for each material class. A higher value for C can also be obtained by choosing a higher PN class.  
 
Table C.1 — Examples of the relationship between PN, MRS, S and SDR at 20 °C ( C = 1.25) 
 
1 2 3 4 5 
SDR  S Nominal pressure for material class  
bar 
PE 4 0 PE 80  PE 100  
41 20 – 3.2 4 
33 16 – 4 5 
26 12.5 2.5 5 6a 
21 10 3.2 6a 8 
17 8 4 8 10 
13.6 6.3 5 10 12.5 
11 5 – 12.5 16 
9 4 8 16 20 
7.4 3.2 10 20 25 
6 2.5 – 25 – 
NOTE  - 1 bar = 0.1 MPa = 105 Pa; 1 MPa = 1 N/mm2. 
a Actual calculated values are 6.4  bar for PE 100 and 6.3 bar for PE 80.  
 
 
 
 
 
  
18 
 Bibliography  
[1] ISO 4437 -2, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 2: 
Pipes  
[2] CEN/TS 12201 -7, Plastics piping systems for water supply — Polyethylene (PE) — Part 7: Guidance 
for the assessment of conformity  
[3] ISO 21004, Plastics piping systems — Multilayer pipes and their joints, based on thermoplastics, for 
water supply  
[4] ISO 11922 -1, Thermoplastics pipes for the conveyance of fluids — Dimensions and tolerance s — 
Part 1: Metric series  
[5] ISO 4065, Thermoplastics pipes — Universal wall thickness table  
[6] ISO/TR 10358, Plastics pipes and fittings — Combined chemical -resistance classification table  
[7] ISO 17484 -1, Plastics piping systems — Multilayer pipe syste ms for indoor gas installations with a 
maximum operating pressure up to and including 5 bar (500 kPa) — Part 1: Specifications for 
systems  
[8] ISO 18225, Plastics piping systems — Multilayer piping systems for outdoor gas installations — 
Specifications for  systems  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
  
 
  
 
 
ICS 93.025, 23.040.20, 23.040.45     DMS 374 -2:2021  
Second edition  
ISO 4427 -2:2019  
IDT 
 
 
 
 
 
 
 THE MALAWI BUREAU OF STANDARDS               CERTIFICATION MARK SCHEME  
The Malawi Bureau of Standards is the 
standardizing  body in Malawi under the aegis 
of the Ministry of Industry and Trade.  Set up 
in 1972 by the Malawi Bureau of Standards 
Act (Cap: 51:02), the Bureau is a parastatal 
body whose activities aim at formulating and 
promoting the general adoption of standards 
relating to structures, commodities, materials, 
practices, operations and from time to time 
revise, alter and amend the same to 
incorporate advanced technology.  To bring the advantages of standardization 
within the reach of the common consumer, the 
Bureau o perates a Certification Mark Scheme. 
Under this scheme, manufacturers who 
produce goods that conform to national 
standards are granted permits to use the 
Bureau’s “Mark of Quality” depicted below on 
their products.  This Mark gives confidence to 
the consum er of the commodity’s reliability.