Pipe piece for introduction into a pipeline which can be closed at both ends

In the case of water-safeguarding systems, the pipelines of which can be closed at both ends and which exhibit a manually actuable valve which has a so-called displacement screwing arrangement, there is the danger that the quantity of water displaced upon closing the manually actuable valve builds up a harmful pressure with respect to the switchable safety valve. The superatmospheric dynamic pressure damages such valves. The abovedescribed danger is avoided in that the pipe piece has, in its inner walls, compensation space which is sealed by means of an elastic pipe body with respect to the flow space and whose volume is defined by the maximum reduction volume.