A clamping tool for use with manway covers may be selectively attached to a manway to permit the manway cover to be separated from its opposing manway flange without having to completely disassociate such manway cover with its corresponding manway. One possible arrangement makes use of at least two clamps, a manway cover clamp and a manway flange clamp, each of the clamps having portions which can be inserted between opposing portions of the manway cover and the manway flange. The clamping tool maintains the relative alignment of the manway cover and the manway flange, yet permits the manway to be selectively opened by separating the manway cover from such manway flange, or closed after such opening.