in embodiments , a large diameter , low pressure plug can be used to seal a pipe subsea . the large diameter , low pressure plug comprises a nose , two or more counter - rotating rings , and one or more seals . other embodiments disclosed have varying additional structure . the large diameter , low pressure plug is inserted into the inner annulus of a tubular and a sealing action created by rotating the counter - rotating rings to create axial compression , in turn causing radial expansion in the seal against the inner annulus of the tubular , sealing the tubular .