HDPE Tube

High-density polyethylene tube - the cheap, tough, chemically indifferent one. HDPE shrugs off acids, alkalis and salts, takes knocks without cracking, will not absorb water, and is the lowest-cost way to move or sleeve almost anything that does not get hot. It is also the lightest of the common engineering plastics at specific gravity 0.96, so it floats.

Published figures for HDPE: tensile strength around 4,000 psi, flexural modulus about 180,000 psi, Shore D hardness around 69, and a service ceiling near 180F. It stays usable well below freezing, where many plastics turn brittle. The trade-off for all that chemical resistance is low stiffness and real creep under sustained load - HDPE will slowly deform if you keep a load on it, so it is the wrong material for a part that has to hold a dimension under stress.

Where it goes: liquid and slurry transfer, chemical drain and vent lines, cable and hose sleeving, protective sheathing, rollers and spacers, and anything agricultural or marine where the alternative would corrode.

How tube is specified, because it trips people up. We list bore, outside diameter and wall thickness for every size so you can see all three at once - the trade more often quotes ID plus wall, or OD plus wall, and the two conventions get confused in both directions. Tell us which dimension is the critical one for your part and we will quote to that one.

One thing to be clear about: several of these sizes are pipe dimensions rather than tube dimensions - a 1.90 inch outside diameter is a standard iron-pipe-size equivalent, not a round number someone chose. Pipe is specified by outside diameter and wall, tube more often by bore. We list all three figures so it does not matter which convention you are working from, but tell us if the part has to mate with a pipe fitting and we will confirm the size against the standard.

Machining and joining: it cuts easily but it is soft and gummy, so it wants sharp tools, high rake and plenty of chip clearance, and it will spring back from a cut. Nothing glues to it - HDPE cannot be solvent bonded or reliably adhesive bonded without surface treatment, so parts are joined by heat welding or mechanically. Paint and ink will not key to it either.