Definition(s)
Multistage Cross-Over Spool
Flanged or other connected equipment with more than one restricted-area sealing means to provide suitable capability to suspend and seal around multiple inner strings of casing or tubing at several stages. NOTE A multistage cross-over spool may have a top connector with a pressure rating above that of the lower connector.
Source: API RP 17A Addendum 1, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, December 2010. Global Standards