Practice of silicone coatings in the corrosion protection of petrochemical pipelines
Hits: 147
img
Silicone coatings have irreplaceable advantages in the field of corrosion protection of petrochemical pipelines. Their core value is reflected in their adaptability to extreme environments and long-term protection capabilities. The specific practice points are as follows:
1. Anti-corrosion mechanism and technical characteristics
High temperature tolerance
The Si-O bond energy (444 kJ/mol) of the main chain of silicone resin gives the coating excellent thermal stability:
Pure silicone coatings can withstand 250℃ for a long time, and aluminum powder reinforced coatings can withstand 700℃ (such as cracking towers and high-temperature reaction pipelines);
Still maintain flexibility in a low temperature environment of -50℃ to avoid cold and brittle cracking of pipelines.
Chemical inert protection
Resistant to acid, alkali, and organic solvent erosion: Only slightly expanded after immersion in 5% NaOH solution for 100 hours;
Salt spray tolerance ＞10 years (traditional coatings <5 years), suitable for coastal petrochemical facilities.
Composite protection system
Adopts "primer + topcoat" double coating structure:
Primer: Epoxy zinc-rich primer (adhesion>10MPa) enhances substrate bonding;
Topcoat: Silicone high temperature resistant topcoat provides the main protective layer, and solvent resistance meets ASTM D5402 standard. 2. Comparison of key technical indicators
Performance Silicone coating Traditional epoxy coating
Temperature range -50℃ ~ 700℃ -20℃ ~ 120℃
Salt spray resistance time ＞6000 hours ＜2000 hours
Acid resistance (30% H₂SO₄) No blistering/shedding4 72 hours slight corrosion
VOC content ≤100g/L (water-based formula) ＞300g/L
3. Key points of engineering practice
Substrate pretreatment
Sandblasting to Sa2.5 level (GB/T 8923.1), roughness 40-70μm;
Complete painting within 4 hours to prevent secondary rust. Coating construction specifications
Environmental control: temperature 5-35℃, humidity ≤75%; two-component coatings need to be matured for 20 minutes; Thickness control: primer ≥60μm, topcoat ≥35μm/coat, total thickness >120μm; Curing test: surface drying ≤1 hour at 25℃, actual drying ≤24 hours.
