Excavación
COATINGS USED IN WRPL
1. COAL TAR ENAMEL COATING (CTE) 2. COAL TAR BASED TAPE COATING (Hot tape) Above two coatings stopped using for field application due toenvironmental issues 3. FUSION BONDED EPOXY (FBE) 4. 3LAYER POLY-ETHYLENE COATING (3LPE) Above coatings are suitable for plant coating only. 5. COLD TAPE COATING (Poly Ethylene) 6. POLY URETHENE (PU)Above coatings are presently being used for field applications
7. LIQUID EPOXY COATING- Under trial run for bulk use
DESIRED PROPERTIES OF COATINGS
EASE OF APPLICATION GOOD ADHESION TO PIPE
GOOD IMPACT RESISTANCE
FLEXIBILITY RESISTANCE TO SOIL STRESS RESISTANCE TO FLOW (CREEP) GOOD ELECTRICAL RESISTANCE CHEMICAL STABILITY RESISTANCE TO SOIL BACTERIARESISTANCE TO MARINE ORGANISMS RESISTANCE TO CATHODIC DISBONDMENT WATER PROOF
PERTOLEUM RESISTANCE
ECONOMICAL
Cold Tape Coating
Instruments required at site
Ultrasonic gauge SurfaceProfile Gauge SA 2 ½ films Coat meter for measurement of primer thickness/ Coating thickness Holiday Detector Adhesion Tester Thermometer
Mirror
EXCAVATION
Sand Blasting-cleaning of pipeRequirements of sand blasting
Inspect surface the pipe for pitting/ any defects Check compressor, requirement – 7kg/sq.cm, 5.6 to 7 Cubic m/min, swing 15m
Abrasive size 1mm ( max), nozzleangle 30 deg.
Cleaning of pipe: Inspect surface after blasting ( Ref SA 2 ½ visual standard of SIS05 5900 “ Pictorial surface prep…. Steel surface”.
surface profile:
50-75microns
SA 2 ½film-Before cleaning of pipe
SA 2 ½ film-After cleaning of pipe
3ply/2ply Cold tape
Inner PE
Outer-
Pipe
Butyl rubber
Inner two layer+Outer two layer
Butyl rubber
COLD TAPE COATINGAPPLICATION Primer:
Primer is a mix, of butyl rubber, synthetic compound and solvent confirming to DIN-30672 Primer thickness shall requirement. (25 microns DFT) coat be as per
Before...
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