COATING AND WRAPPING.pptx

For removal of organic contaminations preheating of

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) for removal of organic contaminations - Preheating of pipe surface by flame burners to 75 degree C for loosening mill scale, removing moisture, burning of organic
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2- Shot/Grit Abrasive Blast Cleaning : The purpose of cleaning is to obtain clean steel surface with the cleanliness degree of Sa 2 ½ and an anchor pattern with the average profile depth of 25 – 80 microns . Blast cleaning may also remove pipe defects ( slivers, burrs, laminations, scabs, gouges ). If not, grinding can be also used for removal of such defects on pipe
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3- Heating of the Pipes The pipe surface shall reach the temperature of 200 – 220 degree C prior to powder epoxy application. The pipe surface temperature shall not exceed 270 degree C. Metallurgical or surface defects can occur at over 270 degree C. Bluing or darkening of the pipe surface is an indication for over heating of pipes.
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4. Surface Treatment Chromate pretreatment ( 1% - 5% of concentrated solution ) 5- Coating Thickness : - Epoxy powder 80 – 100 microns - Adhesive film 350 microns - PE film 1.5 – 3 mm
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6- Cleaning / Process Line Conveyors The pipes move helically over the conveyors through : - preheating unit - blast cleaning cabinet - chromate application - heating coil or flame heating furnace - epoxy spray booth - water cooling tunnel Adhesive and Polyethylene films are wrapped around the pipe in a helical motion
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7- Water Cooling The pipes are cooled by water at least to 70 degree C after extruded adhesive and polyethylene film application. 8- Pipe End Preparation All pipes are cleaned for field joint welding. The coatings at pipe ends are removed by rotary brushes for the length
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9- On-line Quality Control - The pipes are tested on-line after cooling for holiday at 25 kV. - Temperature check of pipe surface prior to epoxy powder spraying is done by infrared temperature measurement device 10- On-line Spot Check - Non destructive coating thickness measurement - Temperature check of the bare pipe surface after heating unit and coated pipe surface after adhesive and polyethylene film application is done by manual – roller type temperature measurement device.
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INSPECTIONS AND TESTS On-line continuous inspections and tests : 1- Surface Inspection 2- Thickness Test 3- Temperature Check 4- Holiday Inspection Off-line periodical inspections and tests : 1.Impact Resistance Test 2- Adhesion ( Peeling ) Resistance Test 3- Hardness ( Indentation ) Test 4- Tensile ( Elongation ) Test 5- Cathodic Disbonding Test 6- Coating Resistivity Test -REPAIR There are two main repair methods in case the coating is damaged during the transportation and storage of the coated pipe and also during the pipe line construction. 1- Stick embedding method for small size repair
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Joint coating
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  • Fall '19
  • Pipeline transport, Powder coating, Pipeline Coatings

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