PE100 vs PE80 Polyethylene Pipe: Differences, Pressure and Wall Table

The difference between PE100 and PE80 pipe starts with the raw material: PE100 has higher long-term strength, so for a given pressure it needs a thinner wall. As a result, at the same diameter and pressure, PE100 pipe is lighter and has a larger inside diameter for the water. Both grades are used for water supply and pressurised irrigation, and both are identified by a blue stripe.

The number in each grade name refers to the minimum required strength, MRS: 10 MPa for PE100 and 8 MPa for PE80, at the reference temperature of 20 °C. MRS gives the allowable design stress, 8 MPa for PE100 and 6.3 MPa for PE80, and these two numbers produce the pressure class of each SDR.

In this guide we show the same difference with a full SDR and PN table for both grades, a wall and weight comparison for 110 mm pipe from our catalogue rows, the diameters and supply forms, and a guide to choosing for a project.

• PE100 water pressure pipe
• PE80 water pressure pipe

MRS is the minimum required strength, the hydrostatic stress the material withstands at 20 °C in long-term service. The PE100 grade is defined at an MRS of 10 MPa and PE80 at 8 MPa. The allowable design stress follows from MRS with a safety factor: 8 MPa for PE100 and 6.3 MPa for PE80.

The nominal pressure of a pipe is calculated from PN = 20 × design stress ÷ (SDR − 1). For PE100 at SDR 11, 20 × 8 ÷ 10 = 16 bar, and for PE80 at the same SDR 11, 20 × 6.3 ÷ 10 = 12.6, rounded to 12.5 bar in the standard table. Both grades are used for water supply under ISO 4427 and EN 12201-2.

The table below shows the pressure class of each SDR in the two grades. The key point is that for a given PN, PE80 needs a smaller SDR, that is a thicker wall: for 16 bar, PE100 at SDR 11 is enough, but PE80 must be SDR 9. For 10 bar, PE100 at SDR 17 and PE80 at SDR 13.6 are used.

SDR 41 appears only for PE100 at 4 bar and has no PE80 row. In the lowest classes where pressure is low, for example 6 and 10 bar on sub-networks, both grades answer, and the difference is mostly price and availability.

To see the practical effect, compare 110 mm (4 inch) pipe at several SDRs. SDR 17 gives 10 bar in PE100 with a 6.5 mm wall, but the same SDR in PE80 is only 8 bar; to reach 10 bar, PE80 must be SDR 13.6 with an 8.1 mm wall. That is 1.6 mm more wall and about 0.45 kg more weight per metre.

At 16 bar it is the same: PE100 at SDR 11 with a 10 mm wall (3.14 kg/m) is enough, but PE80 must be SDR 9 with a 12.3 mm wall (3.78 kg/m). On long lines this weight difference has a direct effect on transport, loading and pipe price, and the thinner wall also leaves a larger inside diameter.

• 110 mm PE pipe
• 63 mm PE pipe
• PE pipe weight calculator

In our catalogue PE100 pipe is supplied from 20 to 630 mm in classes PN4 to PN25, and PE80 pipe from 16 to 630 mm in classes PN4 to PN16. PE80 is used mostly for rural water branches, irrigation and wells, and PE100 for mains and high-pressure lines.

Diameters up to 110 mm are available in coils of 50, 100 and 200 m, and from 63 mm up also in 6 and 12 m bars. A coil reduces the number of intermediate joints, and bars suit straight, short runs, trenches and places where a large coil is hard to handle. To estimate the weight of each coil or bar, use the weight table and the site calculator.

• How many metres in a PE pipe coil or bar?
• PE pipe weight table

For a city water main, a long transmission line, high pressure or large diameter, PE100 is usually the better choice, because its thinner wall needs less weight and material and gives more flow capacity. For small rural water branches, orchards, farms and wells at low to medium pressure, PE80 is also common and sufficient, and sometimes easier to get.

When comparing the price of the two grades, always compare two pipes of the same pressure class, not two pipes of the same wall; a PE80 pipe of equal wall withstands less pressure. If pump pressure, line elevation, water hammer or fluid temperature matter to you, set the final class with the design engineer.

All the pressure classes in the table above are for water at 20 °C. If the fluid temperature rises, the polymer loses strength and a pressure reduction factor from the standard table must be applied; so ordinary polyethylene pipe is not suitable for hot water. Those factors are not given in this article and must be taken from the standard and the designer.

Besides temperature, the dynamic pressure of the line also affects the class: water hammer from a valve closing suddenly or a pump stopping, the elevation difference along the route and the hydrostatic test pressure on site. Check these with the design engineer and do not choose the class on static pressure alone.

On agricultural projects a simple rule is to write down, for each part of the network, the pump working pressure and the largest elevation difference, then choose the smallest pressure class above them, and compare the price of the two grades within that same class.

The jointing methods are the same for both grades. In the rows of our catalogue compression fittings run from 20 to 125 mm, butt fusion from 63 to 630 mm and electrofusion from 20 to 250 mm; so joining PE80 or PE100 pipe to a fitting of the same diameter poses no problem of method, and the choice depends on diameter and type of line. A fitting used on pipe of either grade must be of the same SDR rating and pressure as the pipe.

To be sure the pipe that arrives is the grade you ordered, match the details of the pipe maker, that is grade, diameter, SDR and standard, on the pipe body and in the delivered documents with your order, and if the client asked for particular documents, ask the supplier for them. We hold no certificate of our own and are a supplier, so follow up the documents of the pipe maker in your order and invoice.

• Polyethylene fittings guide: compression, butt fusion, electrofusion

In your enquiry put the grade (PE100 or PE80), the outside diameter in millimetres, the pressure class or SDR, the supply form (coil or bar and its length) and the total length. If you have the class from the designer, copy it word for word. The approximate daily price of each size is on the pipe price page, and the final price is given on enquiry.

We give technical advice on choosing grade and size before you buy, issue an official invoice and deliver to other cities as well. Send your full list from the contact page and a pro-forma invoice will be prepared for you.

• PE pipe price today
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• SDR and PN pressure class of PE pipe