Polypropylene (PP)

PP-H is stiffer, slightly more chemical-resistant and the standard choice for warm-fluid chemical tanks. PP-C handles cold-impact and vibration better, which is why it is preferred for tanks that sit outside, on trailers, or in mobile equipment. Both are weldable; both are food-safe. Send us the application and we will recommend the right grade.

Polypropylene handles concentrated sulphuric, hydrochloric and nitric acid at higher concentrations than HDPE, and it tolerates higher continuous service temperatures in air (around 100°C for PP-H versus 80°C for HDPE). It is the standard tank material for anodising lines, pickling lines and acid neutralising tanks. It will still degrade in aromatic and chlorinated solvents.

Natural and grey polypropylene are not UV stable for long-term outdoor exposure and will become brittle after a few years of full sun. For outdoor use we specify either black PP with carbon black, or a UV-stabilised grade with HALS additives. Tanks installed inside a shed or under cover are fine in natural.

Yes. PP welds the same way as HDPE using hot air or extrusion welding with PP rod. A clean extrusion weld will hold up under hydrostatic test to tank duty pressures and is the only reliable joining method for watertight or load-bearing work.

Yes, food-grade polypropylene is available and certified to FDA 21 CFR 177.1520. It is widely used for food processing equipment, surge tanks, brine tanks and dairy fittings. Specify food-grade at quote time so we draw from the right stock.

It depends on the grade. PP-H (homopolymer) is rated for continuous service in air to around 100°C, with a short-term peak around 110°C, but turns brittle near 0°C. PP-C (copolymer) trades some heat resistance for low-temperature toughness: continuous service to around 80°C, short-term peak around 90°C, and impact-tough down to -20°C. These are unloaded-in-air figures from Simona and Roechling datasheets; under sustained load (a tank wall under hydrostatic head, a pressurised pipe) the allowable design stress drops sharply and is calculated to DVS 2205. For chemical tanks above ambient temperature, tell us the medium, the load and the temperature swing so we pick the right grade.

Adhesive bonding of polypropylene is unreliable because of its low surface energy. Flame or corona treatment plus a polyolefin primer can give a serviceable bond on signage or decorative work, but for tanks, bunds and any load-bearing fabrication we weld every joint.