? Excellent corrosion resistance

? Easy to be corroded

? Long service life: 30-50 years

? Short service life: 5-10 years

? Excellent anti-freezing property: No pipe cracking at -40 ℃

? Easy to crack in case of freeze

? Smooth inner surface, low friction, few chance to have paraffin deposit.

? Rough inner surface, high friction, easy to have paraffin deposit.

? Low maintenance cost

? No maintenance except damaged by the external cause.

? High maintenance cost

? Anti-corrosion coating , cathode protection.

? Lightweight: ? of steel pipe

? Heavy weight

? Low thermal conductivity

? High thermal conductivity

? Good insulation property

? Poor insulating property