Bounded smooth solutions of the stationary axially symmetric Navier-Stokes equations in an infinite pipe, equipped with the Navier-slip boundary condition, are considered in this paper.Here "smooth" means the velocity is continuous up to second-order derivatives, and "bounded" means the velocity itself and its gradient field are bounded. It is shown that such solutions with zero flux at one cross section, must be swirling solutions: u = (−Cx 2 , Cx 1 , 0). A slight modification of the proof will show that for an alternative slip boundary condition, solutions will be identically zero.Meanwhile, if the horizontal swirl component of the axially symmetric solution, u θ , is independent of the vertical variable z, it is proven that such solutions must be helical solutions:In this case, boundedness assumptions on solutions can be relaxed extensively to the following growing conditions:With respect to the distance to the origin, the vertical component of the velocity, u z , is sublinearly growing, the horizontal radial component of the velocity, u r , is exponentially growing, and the swirl component of the vorticity, ω θ , is polynomially growing at any order.Also, by constructing a counterexample, we show that the growing assumption on u r is optimal.