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Zawartość zarchiwizowana w dniu 2022-12-27

REPAIRS OF UNDERSEA PIPELINES BY MECHANICAL CONNECTIONS

Cel

The aim of the project was to prove the feasibility of a subsea pipeline repair method in deep seas. The concept is based on the shaping of a conical collet at both extremities of the pipe and on the installation of a repair spool formed by an expandable loop fitted with mechanical and hydraulical connectors ensuring a metal on metal seal, between the roughly shaped collet and the connector nose, through plastic deformation of a metal joint.
All these operations are remote controlled from the surface.
Approximately 50 collets have been made on pipes of 20" x.65 either on drawn pipes or on rolled and welded pipes with implementation of the remote control forming module. Feasibility of the forming module was demonstrated in 36". Metallurgical analyses made on these collets show that the characteristics after forming are very satisfactory.
On the other hand, the important flexibility of the metrology beam has led us to abandon this technique which did not provide sufficiently reliable results that could serve to design and build the repair spool.
Manufacture and underwater tests of a repair loop of a 20" diameter pipeline with a coupling device at each extremity have proven the perfect efficiency of metal on metal sealing on non-machined collets, even in the case of rolled-welded pipes which present an important longitudinal weld bead.
Additional tests on the 20" connectors proved their waterproofness at least up to 300 bars with water tests and up to 250 bars with nitrogen tests. Severe tests run on a connection made underwater demonstrated good resistance of the material vis-a-vis flexion and torsion.
The collets forming module operates on a mobile trolley which allows introduction inside the pipeline of the force transmitting device which consists of a flexible ring. Parallel to this, a shaping matrix, surrounded by a cog-crown which will serve to anchor the connector, is fitted outside the pipeline. The collet is shaped thanks to a hydraulic punch.
A metrology beam with hydraulically remote controlled articulated extremities then allows the collets to be positioned in relation to one another according to the right angle.
To avoid using telescopic joints and ball-joints and to minimize the number of seals, the repair spool consisted in an expandable "S" shaped loop. Its flexibility allows it to be contracted so as to engage the connectors and compensate for metrology clearances. The connectors are seated behind the cog-crown of the matrice flange and are hydraulically actuated which provokes the deformation of the sealing joint. The screwing tightness is then held mechanicallyby the elastic extension of the tie bars.

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GERTH
Wkład UE
Brak danych
Adres
232 AV. NAPOLEON BONAPARTE
92500 Rueil Malmaison
Francja

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