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AT – Pipe Couplings

Basic Concept

The AT – Pipe Umbrella System is installed using conventional drilling machines. Single pipes are installed piecewise at a length that fits the drill boom length. Type and quality of the pipe coupling are decisive factors for the maximum achievable load-bearing capacity of the support system. For this reason, three different types of couplings are available for the AT – Pipe Umbrella System.

Description

Standard Thread Connection

  • Installed tubes show a constant inner diameter
  • The stiffness and strength of the connection is considerably lower than those of standard pipes
  • The rupture load of the connections is comparable to the design load of standard pipes; it is clearly lower for non-calibrated tubes
  • Further decrease of the load-bearing capacity if mistakes occur during connecting or grouting of the pipes
  • A lower load-bearing capacity can only be compensated by a higher number of pipes
  • Dislocation of the coupling positions in the longitudinal direction does not significantly increase the load-bearing Capacity
  • Installation can be accomplished with or without an AT – Pipe Umbrella Automation Unit

 

Squeezed Connection

  • Simplest connection type
  • The ultimate load of this connection is considerably higher than the elastic design load of a normal pipe (> 1.5)
  • Transition from elastic to plastic material behavior begins at approximately 2/3 of the elastic design load (standard pipe)
  • Reduction of the inner diameter in the connection area
  • Reduction of the stiffness against bending in the connection area
  • Installation is accomplished with a so-called AT – Squeezing Unit, preferably in combination with an AT – Pipe Umbrella Automation Unit

 

Nipple Coupling

  • The elastic design load is equal to the one of a standard pipe
  • Stiffness in the elastic range is comparable to the one of a standard pipe
  • Reduction of the inner cross-section
  • Installation can be accomplished with or without an AT – Pipe Umbrella Automation Unit