In　this　study,　the　static　and　dynamic　responses　of　functionally　graded　material　(FGM)　pipes　with　porosities　and　geometric　imperfections　are　investigated.　The　material　properties　of　the　porous　FGM　pipe　are　assumed　to　vary　continuously　and　smoothly　along　the　radial　direction　based　on　the　modified　power-law　distribution.　The　nonlinear　equations　of　motion　are　derived　on　the　basis　of　the　Euler-Bernoulli　beam　hypothesis　incorporating　the　effects　of　von　Kármán　nonlinearity　and　initial　imperfection.　Two　general　cases　of　pipes　with　movable　and　immovable　ends　are　considered.　Closed-form　solutions　for　nonlinear　critical　buckling　velocity　and　nonlinear　stability　behavior　of　system　under　different　boundary　conditions　are　proposed.　Subsequently,　the　free　vibration　problem　around　the　buckled　configuration　is　solved　as　a　eigenvalue　problem,　and　the　natural　frequencies　are　calculated　using　a　new　exact　solution　procedure　that　considers　the　gyroscopic　effect.　The　effects　of　important　parameters　including　the　initial　imperfection,　the　power-law　index,　the　porosity　volume　fraction,　and　geometric　properties　on　buckling　and　post-buckling　behavior　of　system　are　explored　in　numerical　results.　©　2020