We　establish　viscosity　vanishing　limit　of　the　nonlinear　pipe　magnetohydrodynamic　flow　by　the　mathematical　validity　of　the　Prandtl　boundary　layer　theory　with　fixed　diffusion.　The　convergence　is　verified　under　various　Sobolev　norms,　including　the　L-infinity(H-1)　norm.