Chemical resistant. Low cost. Weldable.

PP: higher temperature (100 °C vs 85 °C for HDPE), slightly stiffer, better clarity. HDPE: better impact resistance especially at low temperature, better chemical resistance to some solvents, cheaper. Both FDA compliant. For higher temperature: PP. For cold impact or chemical solvent service: HDPE. Often interchangeable for general chemical handling.

PP machines easily — soft, cuts cleanly. Sharp carbide tooling, moderate speeds, avoid melting from friction. Tolerance ±0.1 mm typical (PP has higher thermal expansion than engineering plastics). Not recommended for precision ±0.025 mm work. For precision mechanical, use Delrin or PEEK instead.

Hot gas welding: heated air softens PP rod and base material, welder fuses them. Slow but inexpensive. Extrusion welding: PP rod melted and extruded into weld joint. Faster for production. Butt welding: heated platen melts two ends, pressed together. Used for pipe joints. PP welding is standard industrial process — we coordinate through plastic welding partner for large tank fabrication.

PP continuous service: 100 °C homopolymer, 85 °C copolymer. Above this, PP softens and loses mechanical properties. Short-term: PP can handle 120 °C briefly. For higher-temperature plastic applications (above 100 °C continuous), use PPS, PEEK, or polysulfone.

PP resists: most acids (HCl, H2SO4 dilute), most bases, most alcohols, aqueous solutions. PP attacked by: strong oxidizers (conc nitric, fuming sulfuric), aromatic solvents (benzene, toluene), chlorinated solvents (methylene chloride), concentrated oxidizing acids. Check specific chemistry before specification.

PP raw material: $2-4/kg. Machined PP parts: about 50% cost of equivalent HDPE, 20% of Delrin, 10% of PEEK. For cost-sensitive chemical hardware, PP is the cheap option. For applications where engineering properties matter, premium plastic cost is usually justified. Volume production in PP via injection molding (at quantities above 5000+ parts) is very cost-effective.