Resident subsea pig launcher and receiver station
The present invention proposes a resident station of launching and receiving subsea pigs installed in place of THE PLET, in order to enable the application of subsea rigid pipes and the full compliance with the routine internal inspection requirement for monitoring internal corrosion, through bi-directional pigging, mitigating existing operational risks in this type of operation. The invention enables the safe bi-directional pigging of a non-pigable pipe by installing the proposed equipment at the end of the subsea rigid pipe, connecting the pipeline to the main branch in order to ensure shutdown of the pig until the flow is reversed, importing gas from the main branch pipeline, causing the pig to return and be received in the launcher/receiver residing at the FPSO. Thus, the equipment can safely guarantee the periodic and instrumented bi-directional pigging of the pipeline, acting as a launcher/receiver (FIG. 1 ) residing and aligned to the pipe.
1 . A subsea pig launcher and receiver comprising:
a main hub;
a service hub;
a main valve;
shunt valves;
a first locking cover for the main hub, wherein the first locking cover is configured for connection testing/remediation, combat of hydrates by pressurization/depressurization, and/or filling with monoethylene glycol;
a second locking cover for the service hub, wherein the second locking cover is configured to allow installation of connection of a pre-commissioning subsea pig launcher;
branches;
a nominal pipe in fluid communication with the main hub, wherein the nominal pipe is configured to launch and/or receive an instrumented pig provided to bi-directional and periodic pigging of a pipeline;
equalization lines; and
an instrument assembly.
2 . The subsea pig launcher and receiver of claim 1 , wherein the main hub interconnects to surface equipment.
3 . The subsea pig launcher and receiver of claim 1 , wherein the service hub is configured to allow access to the subsea pig launcher in pre-commissioning phases and in case of need in contingency.
4 . The subsea pig launcher and receiver of claim 3 , wherein the service hub is horizontally or vertically in line with a pipeline end termination nominal pipe.
5 . The subsea pig launcher and receiver of claim 1 , wherein the main valve is configured to provide a primary sealing barrier.
6 . The subsea pig launcher and receiver of claim 5 , wherein the main valve is in a horizontal section, upstream of a curved section.
7 . The subsea pig launcher and receiver of claim 1 , wherein the shunt valves provide a primary sealing barrier, provide through operational maneuvers, and provide a safe receipt/launch of instrumented pigs.
8 . The subsea pig launcher and receiver of claim 1 , wherein the branches are responsible for passage of fluid of a pipeline and comprise a main branch and two bypasses.
9 . The subsea pig launcher and receiver of claim 1 , wherein the instrument assembly comprises subsea corrosion probes, valve placement mechanisms, detectors of passage, and location of pigs and indicators.