PURPOSE: To skillfully perform locking of a laid pipeline by adopting such a configuration that a hollow cylindrical body comprises, on its inside surface, an annular portion; a groove; and a surface having a substantially constant inside diameter smaller than the inside diameter of the groove in this order, and a sealing packing comprises at least two members including a solid body; an annular projection; and a locking structural body.

CONSTITUTION: A locking means of a pipeline 1 includes a mono-block sealing packing 2, and a member constructing a substantially cylindrical hollow body 4 to cooperate with the seal packing 2. The cylindrical hollow body 4 includes, on its inside surface, a ring portion 5; a groove 6; and a surface 7 having a constant inside diameter smaller than that of the groove 6 in this order, and on its outside surface, a surface having a constant diameter; and a groove constructing a fixing means 8 in this order. The sealing packing 2 comprises a solid body 9; an annular projection 10; and an insert 14 of high hardness material such as sintered alloy, ceramics. The insert 14 abuts the solid body 9 of the sealing packing 2 made of elastic material in case of locking, and can angularly deform.