{"id":4444,"date":"2026-09-01T07:01:32","date_gmt":"2026-09-01T07:01:32","guid":{"rendered":"https:\/\/www.wldsteel.com\/?p=4444"},"modified":"2026-09-01T07:01:34","modified_gmt":"2026-09-01T07:01:34","slug":"construction-technology-of-coal%e2%80%91tar-epoxy-anticorrosive-steel-pipe","status":"publish","type":"post","link":"https:\/\/www.wldsteel.com\/ar\/construction-technology-of-coal%e2%80%91tar-epoxy-anticorrosive-steel-pipe\/","title":{"rendered":"Construction Technology Of Coal\u2011Tar Epoxy Anticorrosive Steel Pipe"},"content":{"rendered":"

Applicable Industry Standard: SY\/T 0447\u20112014 Technical Standard for Epoxy Coal\u2011tar Anticorrosive Coating of Buried Steel Pipelines
The whole process consists of five stages: Factory Pre\u2011fabrication of Anticorrosive Coating \u2192 Hoisting & Welding of Pipes \u2192 Field Joint Coating & Repair of Damages \u2192 Pipe Lowering and Backfilling in Trench \u2192 Completion Acceptance<\/p>\n\n\n\n

Construction Environmental Requirements<\/p>\n\n\n\n

Construction temperature: 5\u201140\u2103; Low\u2011temperature curing coating shall be adopted when ambient temperature is below 5\u2103.<\/p>\n\n\n\n

Air humidity: Relative humidity \u2264 85%; The steel pipe surface temperature shall be 3\u2103 higher than the dew\u2011point temperature.<\/p>\n\n\n\n

Open\u2011air anticorrosion work is forbidden in rainy, snowy, foggy weather or when wind force reaches Grade 5 or above.<\/p>\n\n\n\n

Procedures for Factory Pre\u2011fabrication of Outer\u2011wall Anticorrosive Coating<\/p>\n\n\n\n

Steel Pipe Surface Derusting (Quality Control Point)<\/p>\n\n\n\n

Derusting grade by sandblasting \/ shot blasting: Sa 2.5, anchor profile depth: 40\u201170\u202f\u03bcm.<\/p>\n\n\n\n

Remove rust, mill scale and oil contamination; Grind weld beads and burrs smoothly. Where weld reinforcement\uff1e2\u202fmm, putty shall be applied for smooth transition afterwards.<\/p>\n\n\n\n

The primer shall be applied within 8 hours after derusting\u00a0to prevent rerusting of steel pipe.<\/p>\n\n\n\n

Leave bare sections of 150\u2011250\u202fmm\u00a0at both pipe ends without anticorrosive coating for field welding.<\/p>\n\n\n\n

Coating Mixing<\/p>\n\n\n\n

Coal\u2011tar epoxy paint is a two\u2011component material (primer, topcoat + curing agent)<\/p>\n\n\n\n

Mix base material and curing agent thoroughly in the ratio specified by the manufacturer.<\/p>\n\n\n\n

Stand and age for 10\u201130 minutes.<\/p>\n\n\n\n

The maximum dosage of thinner shall not exceed 5\u202f%; No thinner is allowed for solvent\u2011free coatings.<\/p>\n\n\n\n

Mixed paint shall be consumed within its pot life; discard expired cured paint.<\/p>\n\n\n\n

Painting and Fiberglass Winding (Three Anticorrosion Grades)<\/p>\n\n\n\n

Use dewaxed medium\u2011alkali fiberglass cloth.<\/strong><\/p>\n\n\n\n

Ordinary grade (no cloth): Primer \u2192 Topcoat \u2192 Topcoat \u2192 Topcoat, minimum thickness \u2265400\u202f\u03bcm, spark test voltage 15\u202fkV<\/p>\n\n\n\n

Reinforced grade (one\u2011cloth\u2011two\u2011coat): Primer \u2192 Topcoat \u2192 Wind fiberglass cloth \u2192 Topcoat \u2192 Topcoat, minimum thickness \u2265600\u202f\u03bcm, spark test voltage 15\u202fkV<\/p>\n\n\n\n

Extra\u2011reinforced grade (two\u2011cloth\u2011three\u2011coat, most commonly adopted in municipal engineering): Primer \u2192 Topcoat \u2192 Wind cloth \u2192 Topcoat \u2192 Wind the second layer of cloth \u2192 Topcoat, minimum thickness \u2265700\u202f\u03bcm, spark test voltage 20\u202fkV<\/p>\n\n\n\n

Technical Parameters for Cloth Winding<\/p>\n\n\n\n

Stretch fiberglass cloth tightly, free of wrinkles and hollow blisters.<\/p>\n\n\n\n

Circumferential overlap width: 20\u201130\u202fmm; Longitudinal overlap: 100\u2011150\u202fmm.<\/p>\n\n\n\n

Fiberglass mesh shall be fully saturated with topcoat, no dry yarn is permitted.<\/p>\n\n\n\n

Curing and Maintenance<\/p>\n\n\n\n

Natural curing at ambient temperature, fully cured in 7 days. Protect coating from rain, collision and direct sunlight during curing (Asphalt layer will crack and pulverize under ultraviolet radiation).<\/p>\n\n\n\n

Factory Inspection<\/p>\n\n\n\n

100\u202f% visual inspection: Smooth and glossy black coating, free of bubbles, hollowing, sagging and holidays.<\/p>\n\n\n\n

Measure dry\u2011film thickness with magnetic thickness gauge.<\/p>\n\n\n\n

Holiday detection by spark tester (mandatory), no pin\u2011hole defects.<\/p>\n\n\n\n

Sampling cross\u2011cut adhesion test with qualified result.<\/p>\n\n\n\n

Field Welding and Installation of Steel Pipes<\/p>\n\n\n\n

Pipe hoisting and transportation: Use soft slings; Steel wire ropes shall not scratch anticorrosive coating directly.<\/p>\n\n\n\n

Butt\u2011weld the pipes and complete weld inspection. Do not carry out joint anticorrosion work until welds cool down fully to ambient temperature.<\/p>\n\n\n\n

Field Joint Coating & Damage Repair (High\u2011frequency Defect\u2011prone Positions on Site)<\/p>\n\n\n\n

Weld\u2011joint Coating<\/p>\n\n\n\n

Anticorrosion structure and grade shall be identical to that of pipe body.<\/p>\n\n\n\n

Derusting: Sandblasting to Sa\u202f2.5 is preferred; Manual derusting to minimum St\u202f3 when site condition is restricted.<\/p>\n\n\n\n

Roughen the end of original anticorrosive coating by sandpaper; The overlap between new and old coating \u2265100\u202fmm, finished in stepped lap shape.<\/p>\n\n\n\n

Construction sequence is exactly the same as factory prefabrication: Primer \u2192 Topcoat \u2192 Fiberglass cloth \u2192 Topcoat \u2026<\/p>\n\n\n\n

Spark holiday test is required after joint coating completion.<\/p>\n\n\n\n

Repair of Damaged Anticorrosive Coating<\/p>\n\n\n\n

Where steel substrate is exposed at damaged spot: Grind for derusting \u2192 Apply primer \u2192 Restore original coating layers with cloth and topcoat.
Where only surface coating is damaged without exposed steel: Polish old coating surface \u2192 Patch topcoat, overlap width \u2265100\u202fmm.<\/p>\n\n\n\n

Pipe Lowering and Backfilling Construction<\/p>\n\n\n\n

Lower the pipe into trench only after coating is surface\u2011dry. Dragging pipes is forbidden to avoid coating damage.<\/p>\n\n\n\n

Lay 200\u202fmm fine loose soil at trench bottom; No stone or sharp hard objects are allowed inside the trench.<\/p>\n\n\n\n

Backfill fine soft soil within 300\u202fmm above the pipe crown. Crushed stone and bricks shall not contact the pipe directly; Original soil backfilling can be implemented afterwards.<\/p>\n\n\n\n

Completion Acceptance Items<\/p>\n\n\n\n

100\u202f% visual inspection for anticorrosive coating appearance.<\/p>\n\n\n\n

Sampling inspection on dry\u2011film thickness of anticorrosive layer.<\/p>\n\n\n\n

Full\u2011line spark holiday detection (core acceptance item).<\/p>\n\n\n\n

Sampling adhesion test.<\/p>\n\n\n\n

As\u2011built documents: Factory certificate, inspection reports, field joint\u2011coating construction records.<\/p>\n\n\n\n

Common Construction Quality Defects & Prevention Measures<\/p>\n\n\n\n

Unsaturated fiberglass cloth \u2192 Hollow blister & delamination: Apply topcoat immediately after cloth winding; No dry cloth allowed.<\/p>\n\n\n\n

Rerusting after long\u2011time exposure post\u2011derusting: Apply primer within 8 hours after derusting.<\/p>\n\n\n\n

Insufficient overlap width at repaired joints: Maintain overlap \u2265100\u202fmm.<\/p>\n\n\n\n

Rainfall and sunlight exposure before full curing: Provide covering protection during construction.<\/p>\n\n\n\n

Reduced cloth layers and insufficient coating thickness: Adopt dual control measures: spark holiday test + dry\u2011film thickness measurement.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

<\/p>","protected":false},"excerpt":{"rendered":"

Applicable Industry Standard: SY\/T 0447\u20112014 Technical Standard for Epoxy Coal\u2011tar Anticorrosive Coating of Buried Steel PipelinesThe whole process consists of five stages: Factory Pre\u2011fabrication of Anticorrosive Coating \u2192 Hoisting & Welding of Pipes \u2192 Field Joint Coating & Repair of Damages \u2192 Pipe Lowering and Backfilling in Trench \u2192 Completion Acceptance Construction Environmental Requirements Construction […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"yoast_head":"\nConstruction Technology Of Coal\u2011Tar Epoxy Anticorrosive Steel Pipe - API steel oilfield pipeline, casing pipe, OCTG manufacturer and supplier<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wldsteel.com\/ar\/construction-technology-of-coal\u2011tar-epoxy-anticorrosive-steel-pipe\/\" \/>\n<meta property=\"og:locale\" content=\"ar_AR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Construction Technology Of Coal\u2011Tar Epoxy Anticorrosive Steel Pipe - 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