Systems and methods for shutting off or stopping fluid flow through a pipe are provided. An inflatable bag stopper assembly is inserted through an opening into the pipe. The assembly includes one or more inflatable bags with each inflatable bag having a check valve positioned at an inlet. In inflatable bag stopper assemblies of two or more inflatable bags, the inflatable bags are connected in series. The inflatable bag stopper assembly is inflated such that the inflatable bag or bags act or serve to obstruct, block, close, or otherwise effectively foreclose passage of the fluid through the pipe.