§ 17

PE pipe: wall thickness and pressure from SDR

Which material thickness and which pressure has this PE pipe?

Answer: Before you weld PE pipe you should know which material thickness and pressure class the pipe has. SDR is ratio of outside diameter to material thickness. Together with material's minimum strength (MRS: 10 MPa for PE 100 and 8 MPa for PE 80) and safety factor C it gives pressure: PN for water pipes and MOP for gas pipes. Calculator works out material thickness pipe series design stress and pressure from pipe marking.

Formula

SDR = d ÷ e, altså e = d ÷ SDR.

Rørserie S = (SDR − 1) ÷ 2. Designspænding σs = MRS ÷ C.

PN (bar) = 20 · MRS ÷ (C · (SDR − 1)) = 10 · σs ÷ S.

Eksempel: PE 100, SDR 11, vand (C 1,25): 20 · 10 ÷ (1,25 · 10) = 16 bar. Samme rør til gas (C 2,0): 10 bar.

Symbols and units in the formula
Symbol	Meaning	Unit
d	Outside diameter	mm
sdr	SDR (written on pipe)	—
mrs	Material	—
c	Use and safety factor C	—
=	Pressure (PN for water / MOP for gas)	bar
=	Wall thickness e	mm
=	Pipe series S	—
=	Design stress σs	MPa

Validity and source

Source: DS/EN 12201-2 og ISO 4427-2 (vand, C ≥ 1,25) · DS/EN 1555-2 (gas, C ≥ 2,0) · PN = 20 · MRS ÷ (C · (SDR − 1))

Does not apply when

Material thickness in standard's table is rounded up to nearest 0.1 mm so may be bit larger than d ÷ SDR (eg d 160 SDR 17: 9.41 mm calculated 9.5 mm in table). Pressure applies to water or gas at 20 °C for 50 years. At higher operating temperature pressure must be reduced per manufacturer's table. Gas network has their own requirements from system owner.

Worked example

The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.

Substituted

Outside diameter110 mm
SDR (written on pipe)11
Material10
Use and safety factor C1.25

Giver

Pressure (PN for water / MOP for gas)16.0 bar
Wall thickness e10.0 mm
Pipe series S5.0
Design stress σs8.0 MPa

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Sådan bruger du den

Før du svejser PE-rør, skal du kende godstykkelsen, fordi den bestemmer svejsetryk og tider. Og du skal vide, om røret kan tåle trykket i ledningen. Beregneren regner godstykkelse og tryk ud fra SDR-mærkningen.

Step by step

Aflæs diameter, SDR og materiale (PE 80 eller PE 100) på rørets mærkning.
Vælg om røret er til vand (C 1,25) eller gas (C 2,0).
Læs godstykkelse og tryk af.
Brug godstykkelsen i stuksvejsnings-beregneren.

Typical errors

At tro at højere SDR betyder et kraftigere rør. Det er omvendt: højere SDR, tyndere væg.
At bruge vandrørets PN til gas. Gas har højere sikkerhedsfaktor.
At svejse rør med forskellig SDR sammen med stuksvejsning.

Examples from everyday life

d 110 SDR 11 PE 100 til vand

Du skal svejse en vandledning af d 110 SDR 11 PE 100.

Outside diameter: 110 mm
SDR (written on pipe): 11
Material: PE 100 (MRS 10 MPa)
Use and safety factor C: Vand (EN 12201: C = 1,25)

It means: Godstykkelsen er 10 mm, og røret er PN 16 bar.

d 63 SDR 11 PE 100 til gas

Et gasstik laves i d 63 SDR 11 PE 100.

Outside diameter: 63 mm
SDR (written on pipe): 11
Material: PE 100 (MRS 10 MPa)
Use and safety factor C: Gas (EN 1555: C = 2,0)

It means: Til gas giver det et højeste driftstryk (MOP) på 10 bar. Godstykkelsen er 5.7 mm; tabellen siger 5,8 mm.

Ældre d 160 SDR 17 PE 80

Du skal svejse et nyt stykke ind i en ældre vandledning af d 160 SDR 17 PE 80.

Outside diameter: 160 mm
SDR (written on pipe): 17
Material: PE 80 (MRS 8 MPa)
Use and safety factor C: Vand (EN 12201: C = 1,25)

It means: Røret er godkendt til 8 bar, og godstykkelsen er 9.4 mm. Nyt PE 100-rør i samme SDR tåler mere, men svejses med samme godstykkelse.

Rule of thumb

PE 100 til vand: SDR 11 = 16 bar, SDR 17 = 10 bar.

How to check the answer

Godstykkelse × SDR skal give diameteren.