Field joint for 3lpe pipe
This step follow during Field Joint Coating of Pipeline as below, which we have experienced many desalination water project for SWCC, SWPC and ACWA:
- Chamfering of 3LPE Coating at angle 30° with horizontal, 3LPE coating from Factory was chamfered at site.
- Checking of Relative Humidity with Hygrometer. As per standard relative humidity is less than 85 %.
- Blasting of Welded exposed Metal surface with Nozzle and sweep blast- 100 mm sleeve
overlap area on 3LPE mill coating. - After Blasting check for surface roughness with Press-O-Film which is 50-70 micron as per standard specification..
- Dust Contamination check with Tape (As per ISO-8502-3) maximum allow rating is 2.
- Pre-heat the surface before applying the epoxy primer. Pre-heat Temperature 60-70 ℃.
- application of Epoxy Primer
Mixed epoxy primer Part A : Part B in ration of 3:1 mixing duration is 30-60 Sec.
Primer application only on steel surface. - check the primer thickness with the Wet Film Thickness Gauge. Primer thickness is greater than 200 microns.
9.Apply HTLP-80 sleeve on wet primer in Centre of weld joint. Sleeve overlap is at 10 or 2 O’clock. - Application of Closure Patch with inner preheating and apply roller by pressing over it or all over the surface of sleeve.
- Holiday test at 15 kv for 12.75 inch pipe Diameter.

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Visual Inspection:
- Adhesive flow evident over the entire circumference on both edges.
- Coating Sleeve free from Air Entrapments & Air Voids.
- Sleeve Surface free from Bums & Punctures.
Equipment Required for Blasting work:
- Air compressor with Moisture separator.
- Copper Slag/ Sand Blasting with hose pipe connected Nozzle.
- LPG Burner, Hose pipe and LPG Cylinders.

Measuring and Test Equipments:
- Peel Gauge Tester. (Weight Balance for weight check while removing of peel)
- Pyrometer/ Infrared Temp. Gun. (For Measuring temp of pipe surface)
- Holiday Detector. (For Coating Damage Check)
- Hygrometer(For Relative Humidity Check)
- Coat meter / Elcometer (For Coating Sleeve Thickness Measurement)
- Wet film thickness gauge (For Primer Thickness Measurement)
- Roughness profile measuring (Styled) instrument. (For Surface Roughness Comparison)
- Press O Film (Thickness 50µm for roughness impression on it)
- Digital Micrometer (For Roughness measurement printed on Press-O-Film)
Note – All measuring and test Equipment shall be calibrated.
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C&N industrial Group, pipe, fitting and flanges manufacturers,fbe epoxy and pe coating for pipeline since 1991,with brand C&N huitong ,C&N hongcheng.