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INTERFERENCE FIT PIPE COUPLING ANALYSIS

 

THE PROBLEM

Jetair International, a division of Marubeni-Itochu Tubulars America, Inc. developed and patented an interference fit pipe coupling and the machinery required for installation for water-injection and oil pipelines. The coupling, called Positive Seal Coupling (PSC) allows pipelines to be built faster with smaller crews and doesn’t damage the internal coating of the pipe, which increases the life of the pipeline and eliminates the need for injecting corrosion-inhibiting chemicals in water-injection lines. Click here to visit Jetair’s website.

In the past, traditional engineering analysis methods were used to determine interference forces between the coupling and the pipe and thus the strength of the joint; in an effort to better understand the performance of the PSC, Jetair turned to Endesin to apply cutting-edge engineering analysis methods.

 

THE ANALYSIS

The steps used to perform the analysis were as follows:

  • PDF drawing files were received from Jetair and CAD models were made from these drawings using NX.
  • The CAD model was reduced considerably to take advantage of the symmetry of the PSC and pipe.
  • The inner face of the PSC is serrated and therefore, it was necessary to refine the mesh on the inner face of the PSC to accurately mesh the serrations. It was also necessary to refine the mesh on the outer face of the pipe to get accurate contact.
  • Internal pressure loads, contact conditions and symmetry conditions were applied to the model.
  • A Nonlinear dynamic analysis was performed to determine the stresses and interference forces.

 

THE TOOLS

The analysis was completed using NX Advanced Simulation for pre and post processing and the solver was NX Nastran.

 

THE SOLUTION            

Recognizing that traditional engineering methods did not accurately assess the performance of the PSC, Jetair chose Endesin to apply the latest Computer-Aided engineering analysis methods so they could fully understand the capabilities of their product.