Expansion & Contraction

Viking Johnson couplings and flange adaptors are also capable of absorbing significant regular expansion and contraction, which occurs in pipelines because of temperature fluctuations, without the need for special expansion joints.

This is achieved by deformation of the gaskets rather than by sliding on the pipe surface; if the maximum movement is exceeded then there is risk that the gasket will slide on the pipe surface breaking the contact seal with the pipe potentially leading to a leak.  Most expansion movements due to normal ambient temperature variations can be accommodated using Viking Johnson couplings.

Under certain circumstances, e.g. occasional or long-term slow movement, it may be possible to allow for increased expansion and contraction, but this should not be attempted without first contacting Viking Johnson.

Stepped couplings permit the same total expansion movement as straight couplings.  However, pressure thrust may act on the stepped coupling causing it to move along the pipe with repeated expansion movement; to negate this restraint for the coupling will be required.