Patent ID: 7717136

Claim:
A pipeline closing apparatus comprising: a lid member attachable to a downstream end portion of a sluice valve or an end portion of a pipe portion connected thereto, the lid member adapted to close an end opening of a branch pipe connected to and diverging from a fluid transmitting main and having the sluice valve disposed therein; a cylindrical first control shaft extending through the lid member to be axially slidable in a sealed condition; a second control shaft extending through the first control shaft to be axially slidable; a first pressing plate attached to an inward end region of the first control shaft; a second pressing plate attached to an inward end region of the second control shaft upstream of the first pressing plate; an elastic annular member disposed between the first pressing plate and the second pressing plate and elastically deformable to a diameter-increased position for tight contact with an inner peripheral surface of the branch pipe by being clamped and pressed between both of the pressing plates from axial directions, thereby blocking the inner peripheral surface and outer peripheral portions of the pressing plates; and a retaining device provided between the inward end region of the second control shaft and the second pressing plate, and including engaging link pairs flexing and bulging to a diameter-increased position to engage with positions upstream of a position blocked by the elastic annular member in response to outward sliding movement of the second control shaft relative to the first control shaft, wherein, in said second control shaft, there is provided a reversal preventing device having an elastic correcting member which, when the engaging link pairs of the retaining device are stretched to a diameter-reduced position, contacts and limits the engaging link pairs to an outwardly bent position where flexing pivotal portions of the engaging link pairs project radially outward.