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answered Jul 11, 2016 by antonjoh (2,870 points)

The landing string is composed of joints of oilfield tubulars (either casing or tubing) which are terminated with premium connections.  The purpose of the landing string is the containment of pressurized well fluids during their conveyance between the subsea well and the surface tree at the drill floor.  Pup joints of various lengths of the same pipe are to be provided to allow for proper space-out of components and to act as saver subs or crossover subs.

Externally, the landing string should have a profile suitable to enable it to be installed within the internal profile of the BOP stack and marine riser.

Internally, the landing string should have a minimum bore suitable to enable the passage of wireline tools and tree equipment.  All internal bore transitions are to be tapered so as not to interfere or snag the wireline tools and equipment.

Consideration should be given to the use of drill pipe/work string and pipe handling equipment (slips, elevators, and tongs) available on the installation vessel.  If possible, standard rig tubulars or tubulars that the Company has available to them, should be used as a riser where technically suited.  Crossover subs to interconnect various SSTT and equipment thread forms to the landing string should be manufactured by the Contractor as required.  Specific details of the landing string tubulars are given in the "Technical Specifications.”

The structural integrity of the landing string tubular joints will be adequate to withstand the combinations of internal and external loading possible under all conditions expected during handling, including both normal and contingency operations.

The material from which the landing string tubular joints are made will be suitable for the duty required, and for the fluids with which it may come into contact.  Consideration must be given to corrosion mitigation, as corrosion debris originating from the landing string can lead to serious completion problems.  Plastic coating the inside of the landing string tubulars should be evaluated.