Abstract: Systems and methods for continuously circulating fluid, e.g., drilling mud, through a wellbore tubular string, the systems in certain aspects including a sub positionable in fluid communication with the tubular string, the sub with a body, a plug releasably closing off a side opening of the body, and a closure apparatus for selectively closing off flow from the top of the sub into and through the body, while flow is permitted below the closure apparatus through the side opening down through the body into the tubular string; and, in certain aspects, such systems and methods including tubular manipulation apparatus, e.g. an iron roughneck and working with wellbore tubulars with the tubular manipulation apparatus.