PTFE hose explained: smoothbore against convoluted, and where each one belongs

PTFE — polytetrafluoroethylene — is about as close to universally chemically resistant as an engineering material gets. As a hose liner it carries acids, solvents, steam and hot oils that would swell, harden or dissolve rubber, it does not age on the shelf, and nothing sticks to it. The choice is less about whether PTFE will handle the medium than about which construction suits the installation.

/01Smoothbore or convoluted.

A smoothbore PTFE hose has a plain, round PTFE tube under the braid. It carries high pressure, drains completely and cleans easily, which suits process lines, steam and hydraulic duty — but the plain tube kinks if bent too tightly. A convoluted PTFE hose has a tube formed into corrugations, like a metal hose. It bends far more tightly and resists kinking, which suits tight routing and frequent movement, at a lower pressure and with a bore that is harder to clean and drain.

/02What the braid adds.

PTFE on its own is not strong; the braid carries the pressure and protects the tube. A 304 stainless braid gives the high ratings and abrasion resistance. A polypropylene braid on the convoluted hose keeps it light and metal-free where the outside atmosphere would attack stainless, at the cost of pressure. The temperature limit on our listings is the same for all three — −73 to +260 °C — but the end fittings, and any gaskets in them, need to match it.

/03Hydraulic PTFE: R14.

For hydraulic circuits there is a PTFE hose built to the SAE 100R14 standard: our R14 has a virgin PTFE tube under a single stainless braid (Type A) or stainless braid plus aramid (Type B), rated from 200 bar at −03 down to 65 bar at −16, and from −54 to +204 °C. It is the answer where a hydraulic line runs near heat, carries a fluid nitrile cannot, or blisters a rubber tube through permeation. For large-bore chemical transfer, the PTFE chemical composite hose takes PTFE to 1"–DN100 at 20 bar.