Pressure-class selection for PE100 HDPE pipe
SDR 11 vs SDR 17 HDPE Pipe — Which Pressure Class for Your Project?
TL;DR
SDR 11 and SDR 17 are the two most commonly specified PE100 pressure classes — choose SDR 11 when working pressure is above 10 bar at 20°C, when surge protection budget is limited, or when impact loads (trenchless install, point loads) need extra wall safety. Choose SDR 17 when working pressure is ≤ 10 bar with adequate surge mitigation, when budget matters more than over-rated capacity, or when bend radius / coil supply at large diameter matters.
Side-by-side comparison
| Dimension | SDR 11 (PN 16) | SDR 17 (PN 10) |
|---|---|---|
| Pressure class (PE100 water 20°C) | PN 16 (16 bar)✓ | PN 10 (10 bar) |
| Wall thickness (DN 110) | 10.0 mm✓ | 6.6 mm |
| Mass per metre (DN 110) | ≈ 3.2 kg/m | ≈ 2.2 kg/m✓ |
| Inside diameter (DN 110) | 90.0 mm | 96.8 mm✓ |
| Flow capacity (relative) | Baseline | + 7–9% (larger ID)✓ |
| Material cost per metre | Higher (more PE per metre) | Lower (~30% less PE per metre)✓ |
| Surge tolerance | Higher — extra wall absorbs shock✓ | Lower — protect with surge tanks |
| Trenchless install | First choice for HDD / pipe-bursting✓ | OK for HDD if pull force < limit |
| Coil supply ≥ DN 110 | Limited — heavier | Easier — lighter, smaller minimum bend✓ |
| Typical applications | Gas, mining slurry, fire mains, trunk mains | Distribution water, irrigation, low-pressure transmission |
Pick SDR 11 (PN 16) when:
Working pressure exceeds 10 bar at the operating temperature, or surge / water-hammer events are reasonably foreseeable and surge tanks / protection devices are limited. The line will be installed by trenchless methods (HDD pull-forces, pipe-bursting) where extra wall reduces the risk of buckling. Gas distribution work, where most national regulators specify SDR 11 minimum regardless of design pressure. Mining slurry service where abrasion will remove ~ 1 mm of wall over 5 years and SDR 17 wouldn't have spare wall to lose.
Pick SDR 17 (PN 10) when:
Working pressure is comfortably below 10 bar with surge mitigation budgeted (surge tanks, slow-closing valves, soft-start pumps). Hydraulic flow capacity matters — SDR 17 gives ~ 7–9% larger inside diameter for the same outside diameter, reducing pumping head loss. Project budget pressure makes the ~ 30% cost saving per metre attractive. Standard buried water distribution in stable soils, where there's no surge / impact concern.
Cost considerations
SDR 17 typically saves 25–35% per metre on material cost compared to SDR 11 at the same DN, because there's less PE100 resin in each metre of pipe. For a 5 km DN 315 water-distribution main, that can mean USD 25,000–40,000 saving on material — significant on smaller projects. Caveat: don't trade pressure class for short-term saving if surge / pressure rise could exceed PN 10 in operation. Lifetime cost of a single burst water main usually dwarfs the entire material saving.
Real-world example
A 12 km copper-concentrator dewatering main in Peru (Primepoly, 2022) initially priced at SDR 17 PE100-RC. Surge analysis showed peak transient pressures up to 12.5 bar at pump start-stop events. Upgraded to SDR 11 PE100-RC at 18% cost increase; two seasons in, zero failures and no surge-related issues. Cheaper insurance than installing surge tanks.
Frequently asked questions
Q. Can I mix SDR 11 and SDR 17 in the same network?
Yes. Common practice: SDR 11 for high-pressure sections (pump discharges, river crossings, surge-prone areas) and SDR 17 for steady-state distribution. The change is made with a butt-fused reducer or socket fitting — same fitting catalogue.
Q. Does derating for temperature apply?
Yes. At 30°C operating temperature the PN rating drops by ~ 12% compared to 20°C; at 40°C by ~ 25%. For hot-climate buried mains (Middle East, Sahel) factor this in — a SDR 11 line at 40°C operates at ~ 12 bar maximum, not 16.
Q. Is SDR 17 acceptable for fire-protection mains?
Marginal. Most AHJ-approved fire main specifications require SDR 11 minimum for DN ≥ 150 to provide pressure rating headroom and meet flow-spike tolerance during hydrant flush events. Check the local fire authority's spec before quoting SDR 17 for fire-rated work.
Q. Is there a SDR between 11 and 17?
Yes — SDR 13.6 (≈ PN 12.5). Less common because most national standards round to SDR 11 or SDR 17, but it's a legitimate intermediate choice for projects where surge analysis points to a 10–13 bar peak.
Need help spec'ing your project?
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