Pipeline testing apparatus

Claim 1

Apparatus adapted for selective pressure testing of pipelines and comprising: an elongated body adapted to be moved axially through a pipeline; sealing means mounted around said body and adapted to be in sealing sliding contact with the internal walls of a pipeline containing said apparatus for propelling said apparatus therethrough upon imposition of an upstream fluid pressure behind said sealing means greater than the downstream fluid pressure there ahead to develop a selected pressure differential; first passage means along said body and adapted for bypassing pipeline fluids therethrough as said apparatus is being propelled through a pipeline; means adapted for releasably anchoring said apparatus against continued forward movement in a pipeline and including wall-engaging means operatively arranged on said body ahead of said sealing means and adapted for moVement outwardly into anchoring engagement with such internal pipeline walls, piston means on said body and operatively arranged for selectively moving said wall-engaging means outwardly in response to pressure differentials greater than said selected pressure differential, and second passage means adapted for communicating such upstream fluid pressures to said piston means; and means adapted for selectively controlling fluid communication through said first passage means and including valve means adapted for opening and closing said first passage means, first means normally retaining said valve means open at pressure differentials no greater than said selected pressure differential, and second means adapted for closing said valve means in response to upstream fluid pressures producing pressure differentials greater than said selected pressure differential.