FIELD: process engineering.
SUBSTANCE: invention relates to coat and method of coating outer surfaces. Proposed method of coating pipeline outer surfaces by polymer capable of forming cross-links under action of water comprises the following stages: a) pipeline outer surface is coated by, at least, one polymer that forms cross-links under action of water. Note here that said polymer represents HDPE grafted by alkoxy silane. b) Polymer is cross linked on subjecting it to water at increased temperature to produce cross-linked polymer layer unless cross linking degree makes ≥30% to ≤80%. c) Polymer is cross linked that can form cross links under action of water at ≥50°C to ≤350°C, preferably at ≥150°C to ≤300°C, more preferably at ≥200°C to ≤260°C. Note here that during these stages, pipeline is heated to ≥170°C to ≤230°C, preferably to ≥180°C to ≤220°C, more preferably to ≥190°C to ≤210°C. Powder ionic spraying method is used epoxy resin layer is applied with thickness of ≥0.08 to ≤0.16 mm, preferably of ≥0.10 to ≤0.13 mm, more preferably, 0.125 mm. Method of envelopment extrusion is used to apply a layer of glue with thickness of ≥0.15 mm to ≤0.30 mm, preferable of ≥0.22 mm to ≤0.27 mm, more preferably of 0.25 mm. By method of extrusion, applied is upper layer of HDPE with thickness of ≥2.8 mm to ≤3.2 mm, preferably of ≥2.9 mm to ≤3.1 mm, more preferably of 3 mm. Extrusion is used to apply layer of HDPE cross linked by silane with thickness of ≥0.8 mm to ≤1.2 mm, preferably of ≥0.9 mm to ≤1.1 mm, more preferably of 1 mm. Now, pipeline is treated by water with temperature of ≥10°C to ≤40°C, preferably of ≥20°C to ≤30°C, more preferably of 25°C. Coat is made as described above. Invention covers also coated pipeline.
EFFECT: improved operating performances and expanded applications.
11 cl, 2 tbl, 3 dwg, 2 ex
