limit application_number US 5268305 A description fig1 shows a portable tank assembly 10 which includes a trailer deck 16 a stationary tank section 14 and a pivot tank section 12 supporting trailer wheels 18 are provided on the trailer deck 16 and are located towards the rear of the trailer deck 16 the stationary tank section 14 rests on supports not shown on the trailer deck 16 towards the front of the trailer deck 16 and the pivot tank section 12 rests on supports not shown on the trailer deck 16 towards the rear of the trailer deck 16 the supports are constructed of hollow structural steel welded to the trailer deck 16 and support each of tank sections 12 and 14 at three points on the respective tank sections 12 and 14 the supports for the stationary tank section 14 are permanently welded while the supports for the pivot tank section 12 are bolted to allow the pivot tank section 12 to pivot as required the pivot tank section 12 and the stationary tank section 14 are semi cylindrical tank halves with vertical side walls a semi conical shaped bottom an open face and an open top fig1 shows an interior view of the tank sections 12 and 14 vertical flanges 60 are.