Rigid-pipe integral riser
The lines of a rigid-pipe integral riser cannot be retrieved separately. An integral riser with external lines includes a central structural member which can carry fluids or perform other functions in addition to providing structural support to the lines by means of external brackets. An integral riser with internal lines may support these lines at intermediate points along the joint to prevent line buckling. On either integral riser type, the ends of the structural member are fitted with couplings. A section of the production riser, consisting of the structural member, lines and coupling, is collectively called a “riser joint”. When two joints of integral riser are connected, the coupling causes the simultaneous connection of all of the lines with full design-pressure capacity. Integral risers are compact and simple to run, however they require system shut in and retrieval for repair/replacement.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards