Manufacturing Methods of Pipe

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Any pipe can be manufactured  using several different techniques, each of which produces a pipe with certain characteristics. these characteristics include Strenght, Wall thickness, corrosion resistance and temperature and pressure limitations.

The Methods to manufacture Pipes are

  1. Seamless Pipe
  2. Butt-Welded Pipe
  3. Spiral Welded pipe
These three are the most commonly used methods 

1) Seamless Pipe :



  • Seamless pipes is formed by piercing a solid near molten steel rod called a billet, with a mandrel to produce a pipe that has no seams or joints.
  • It is produced in single and double random lenghts.
  • Single random lengths vary from 16'-0" to 20'-0" long, whereas Double random lengths vary from 35'-0" to 40'-0" long.

2) Butt Welded Pipe :



  • It is formed by feeding hot steel plate through shapers that will roll it into a hollow circular shape.
  • Forcibly squeezing the two ends of the plate together will produce a fused joint or seam.
  • Welding can be two types :
      1) Electric Resistance Welding : The edge of the pipe are heated  to the welding temperature by their resistance to the flow  of  electric current. At the appropriate welding temperature, rollers forces the edge together. ERW is not strong as EFW. It is cheaper compared to the other. this type of welding is used in water service pipe. Quality factor E is 0.85 for ERW.  
     2) Electric Fusion Welding : Welding of Carbon steel and low alloy steel is accomplished by submerged arc welding, an automatic electric arc process is used with the filler metal coming from the electrode supplying the electric arc. E is 1.

3) Spiral Welded Pipe :



  • This is the least common method.
  • It is formed by twisting metal strips in to a spiral shape, similar to a barber's pole, then welding where the edges join one another to form a steam.
  • This type of pipe is restricted to piping systems using low pressures due to its thin walls.

Summary :



Each of the three methods has its advantages and disadvantages
  • Butt welded pipe has more uniform wall thickness and can be inspected for defects prior to forming and welding. This method is used when thin walls and long lenghts are needed.
  • Wider wall thickness are produced by the seamless method.
  • Pressure Piping Code B31 governs the manufacture of pipes.
  • The strength factor of seamless pipe is 100%, Buttwelded pipe is 85%, Spiral welded pipe is 60%.

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