In a factory, a pump starting up operation or shutting down, or an air vent suddenly closing are examples of when this might occur.
In addition to water transport piping systems, water hammer also occurs in steam and condensate recovery (i.e. water circulation) systems. This series of articles will focus on water hammer in these latter two systems. Note that as steam is involved, this type of water hammer is also sometimes referred to as 'steam hammer'.
http://www.tlv.com/global/TI/steam-theory/what-is-waterhammer.html
http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=2204779
http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2500649
http://www.sciencedirect.com/science/article/pii/0029549375900941
http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2472105
http://www.boydeng.com/WaterHammer.htm