Fuel Resistant 3D Printing: Nylon 12 or SLS PP GB?
Fuel resistant 3D printing starts with nylon 12, the polymer in many car fuel lines. Where printed PA12 and SLS PP GB fit near fuel, and what to test.
Fuel caps, carburetor spacers, fixtures for an engine shop. People want printed parts near fuel, and fuel resistant 3D printing depends on the polymer far more than the printer.
What Material Won't Break Down in Contact With Gasoline or Diesel?
Of the powder materials we print, nylon 12 is the safest place to start around fuel, because the same polymer is widely used in automotive fuel lines. Splashes and vapor are a reasonable bet. A part that sits wet in fuel needs a soak test first.
The question comes from an r/3Dprinting thread. A friend's business wanted printed parts that would touch gas and diesel, with no pressure involved, and that wouldn't break down or turn hazardous over time. The poster was thinking filament. The answer changes a bit once you move to SLS and MJF.
Why nylon 12 leads for fuel resistant 3D printing
On its fuel-line page, Evonik says its VESTAMID is the most widely used polyamide 12 in fuel lines, and that most of its fuel-line compounds suit both gasoline and diesel. HP's PA 12 data sheet, for its own MJF powder, claims "excellent chemical resistance to oils, greases, aliphatic hydrocarbons, and alkalies," and its footnote lists unleaded petrol and motor oil among the fluids tested.
There are two catches. Fuel-line grades are extrusion compounds, not printing powder, so the same polymer name doesn't promise the same result. And Evonik says multilayer tubing cut fuel permeation by one to two orders of magnitude compared with single-wall tubing. Hydrocarbons work their way through plastic walls. Thin powder-bed walls can also leak through pores, as our post on watertight MJF parts covers, so test anything that has to hold fuel rather than just shrug off a splash.
Where SLS PP GB fits
Our materials page lists SLS PP GB Glass Filled for "chemical resistance, stiff printed PP." We don't have gasoline or diesel data for it to quote here. If you're weighing it against nylon for a fuel part, ask us when you quote.
Picking from our list
For parts near fuel, oil or grease, start with SLS Nylon PA12. If you'd rather print in MJF Nylon, ask us when you quote which powder it runs on, since the HP figures above only cover HP's PA 12. If you're weighing a desktop print against a powder-bed part, FDM nylon vs MJF and SLS covers where filament falls short, and MJF vs SLS covers the process choice.
For fuel resistant 3D printing, the soak test is the real answer. Put a printed coupon in your actual fuel for a few weeks, then weigh it and flex it. That tells you more than any chart.
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