There are few researches concerning the effects of tube thickness, clearances between tube and plate, residual stress of tube material for the pipe of vessel penetration. So, deformations after welding were measured on the thinner tube models than those of ICM penetration to magnify the effects. And clarified the effects on weld deformations and residual stresses by conducting FEM analysis. In this [Part 1], investigated results on the effects of tube thickness, clearances between tube and plate to weld deformations are reported.