Steel

Developing Pakistan’s Energy Infrastructure

Manufacturing and Coating Processes

The plant manufactures SAWH pipes in diameters ranging from 8.625 inches to 120 inches, wall thicknesses ranging from 4 millimeters to 25.4 millimeters and material grades up to API 5L X-100 for oil, gas, water transmission and construction projects. The company has been gradually enhancing and upgrading its pipe production capacity to the present notional capacity of 200,000 tonnes per annum.

Spiral Pipe Mill
  • Hot Rolled Coil is loaded on the de-coiler of the Spiral Pipe machine.
  • The strip is straightened and edges are milled to desired joint geometry.
  • The strip is then guided into the Forming Station where it is helically formed into a cylindrical shape.
  • Once internal and external welding has been completed, the weld seam, HAZ and the pipe body is examined by the Automatic Ultrasonic Unit for possible defects.
  • Pipes are visually inspected for any possible imperfections.
  • The pipes are cut to a predetermined length by an Automatic Plasma Arc cutting device.
Pipe Finishing Line
  • Flux and slag left inside the pipes after welding are cleaned/recovered.
  • During fluoroscopic inspection, the entire spiral seam of the pipe is analysed for defects identified by the ultrasonic testing machine.
  • Both ends of the pipes are bevelled to suit site butt welding.
  • Individual pipes are hydrostatically tested as per client specifications.
  • At the final stage, the X-Ray station radiographs the weld seam on each end of the line pipe.
External Shot Blasting Line
  • The bare pipes are received at the incoming racks and are then pre-heated and shot- blasted to achieve desired level of cleanliness and surface profiles.
  • As each pipe is shot-blasted, the blasted profile and depth of anchor pattern is tested to ensure quality.
External Coating Line
  • The shot-blasted pipes are acid washed before entering the induction heater/gas furnace where the pipe is heated to a temperature recommended by the epoxy manufacturers.
  • Epoxy powder is sprayed onto the pipes in the Epoxy Booth.
  • If three layer coating is required, co-extruded layers of Co-Polymer Adhesive and Polyethylene/Polypropylene are applied on the pipe surface.
  • The pipes are subsequently cooled at the Quench station and 100% inspected for holiday. Cut back process is done to remove coating from the pipe ends according to specifications.
  • Final inspection and marking of coated pipes are carried out as required.
Internal Coating
  • Bare pipes are shot-blasted to achieve desired level of cleanliness and surface profile.
  • The coating is applied to attain the uniform coating thickness and required properties.
  • Once coating is completed the pipe is left for curing.
  • Final inspection of internally coated pipe is carried out as per the requirement.