  We present a study on the nonlinear dynamics of a disturbance to the laminar
state in non-rotating axisymmetric Poiseuille pipe flows. The associated
Navier-Stokes equations are reduced to a set of coupled generalized
Camassa-Holm type equations. These support singular inviscid travelling waves
with wedge-type singularities, the so called peakons, which bifurcate from
smooth solitary waves as their celerity increase. In physical space they
correspond to localized toroidal vortices or vortexons. The inviscid vortexon
is similar to the nonlinear neutral structures found by Walton (2011) and it
may be a precursor to puffs and slugs observed at transition, since most likely
it is unstable to non-axisymmetric disturbances.
