HDPE Pipe Size Chart: Easy & Complete SDR and PN Guide

A buyer calls and asks for “4 inch HDPE, 10 kg.” Simple order? Not quite. The pipe he wants is 110 mm, not 101.6 mm, and “10 kg” means a different wall thickness depending on which standard his tender follows. This HDPE pipe size chart gives you the diameters in mm and inches, the wall thickness for each pressure class, and the checks that stop a wrong lot leaving your godown.

How are HDPE pipe sizes measured?

HDPE pipe sizes are named by outside diameter (OD) in millimetres. A 110 mm pipe measures 110 mm across the outside, whatever its pressure class. The inch size is only a trade name.That one rule clears up most of the confusion at the counter. Steel and GI pipes are named by nominal bore. HDPE isn’t. Its outside stays fixed so fittings and fusion machines fit every time, and the bore shrinks as the wall gets thicker. A 110 mm pipe at SDR 17 has a bore of about 96.8 mm. At SDR 11 it drops to 90 mm.

HDPE pipe size chart: diameters and wall thickness

The chart lists common HDPE pipe diameters with their trade inch size, the true OD in inches, and the minimum wall thickness in mm for four SDR series.

A dash means that size isn’t normally made in that series. Wall figures are ISO 4427 minimums for each SDR. IS 4984 pipe of the same SDR sits at or very near these values, but confirm against your manufacturer’s table before quoting.

What do SDR and PN mean in HDPE pipe specifications?

SDR (Standard Dimension Ratio) is the outside diameter divided by the wall thickness. PN is the rated working pressure in bar, which the trade loosely calls “kg”. Lower SDR means a thicker wall and a higher pressure rating.Here’s the catch most online charts miss. The same pipe carries a different PN under Indian and international standards. IS 4984:2016 rates PE 100 pipe more conservatively than ISO 4427, so an SDR 11 pipe is PN 12.5 on an Indian tender and PN 16 on an ISO one.

So when a customer wants PN 10 in 110 mm, ask which standard. Under IS 4984 that’s SDR 13.6 with an 8.1 mm wall. Under ISO 4427 it’s SDR 17 at 6.6 mm. Quote the wrong one and you’re either overpriced or supplying pipe that fails inspection.

Is a 4 inch HDPE pipe really 110 mm?

In the Indian and ISO metric series, yes: 4 inch is the trade name for 110 mm OD. American IPS-sized HDPE is a different animal. It follows ASTM steel-pipe diameters, and those don’t match.

A 4.3 mm gap sounds small. It’s enough to stop a butt-fusion joint or an electrofusion coupler from working. If an enquiry comes from an export job or an American consultant’s drawing, get the OD in millimetres before you quote.

Which HDPE pipe diameters should a dealer stock?

Stock by application, not by guesswork. As a working guide:

• 20 to 32 mm: house service connections and domestic supply
• 50 to 160 mm: agriculture and irrigation mains
• 110 to 630 mm: municipal water supply, usually bought against tenders

Coils cover the small diameters; straight lengths take over as the pipe gets bigger. Order the larger sizes against a confirmed enquiry. Each pressure class is a separate product, and dead stock in 315 mm ties up real money.

How do HDPE pipe fittings follow the size chart?

HDPE pipe fittings are sized by the pipe’s outside diameter, so a 110 mm tee fits a 110 mm pipe. For butt fusion the fitting must also match the pipe’s SDR, because the two walls have to meet face to face.Moulded fittings to IS 8008 run from 20 mm to 1000 mm and must carry the maker’s name, size, material grade and working pressure. That marking is your quickest quality filter. Reliable HDPE fittings manufacturers print all four on every piece. If a bend or reducer arrives blank, send it back.One habit worth building: write reducers and reducing tees as OD × OD in millimetres (110 × 63), never in inches.

Ordering mistakes that cost dealers money

1. Converting inches by calculator. 4 × 25.4 gives 101.6 mm. No such HDPE pipe exists.
2. Quoting PN without the standard. IS 4984 and ISO 4427 give different walls for the same PN.
3. Ignoring the grade. PE 80 needs a thicker wall than PE 100 for the same pressure, so the two can’t share one line on a rate list.
4. Mixing SDRs at a joint. A thin-wall fitting on a thick-wall line becomes the weak point.
5. Checking weight only. Weight per metre can hide an uneven wall. Measure it at several points with a vernier.

Frequently asked questions

What are the standard HDPE pipe sizes?

Standard HDPE pipe sizes for water and irrigation work run from 20 mm to 630 mm outside diameter: 20, 25, 32, 40, 50, 63, 75, 90, 110, 125, 140, 160, 180, 200, 225, 250, 280, 315, 355, 400, 450, 500, 560 and 630 mm. Larger diameters are made for big municipal projects.

What is 110 mm HDPE pipe in inches?

A 110 mm HDPE pipe is sold as 4 inch. Its true outside diameter is 4.33 inches, because the inch size is a trade name and not a conversion.

How do I calculate HDPE pipe wall thickness from SDR?

Divide the outside diameter by the SDR. A 160 mm pipe at SDR 11 works out to 14.55 mm, and the table value is 14.6 mm. Use the formula as a quick check and the standard table for orders.

Which SDR is PN 10 in HDPE pipe?

For PE 100 pipe, PN 10 is SDR 13.6 under IS 4984:2016 and SDR 17 under ISO 4427. Always confirm which standard the order follows.

Do HDPE pipe fittings come in the same sizes as pipes?

Yes. Fittings for HDPE pipe are made to the pipe’s outside diameter, and IS 8008 covers moulded fittings from 20 mm to 1000 mm. For fusion joints, match the SDR and material grade as well as the size.

Read the chart, then check the pipe

Keep this HDPE pipe size chart near the billing counter and take down every enquiry in the same four terms: OD in mm, grade, SDR, and PN with its standard. Arihant Plast manufactures HDPE pipe fittings at its factory in Jaipur and has been supplying them since 1998. For fittings matched to your pipe’s size and SDR, call 9829010745 or email info@arihantplast.in.