# US 2014/0190574 A1 · Pig assembly and method for maintaining a functional line for conveying fluid > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190574 A1 - Document ID: US20140190574A1 - Status: Published application - Kind: A1 - Application number: 13/738,740 - Filed: 2013-01-10 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: Chevron U.S.A. Inc. - Inventors: Farzan Parsinejad; Antonio Carlos Falcao Critsinelis; Sid A. Mebarkia; Christopher Allen Kassner - Web page: https://patentgrep.com/patent/US20140190574A1 ## CPC - F16L 55/46: Launching or retrieval of pigs or moles - B08B 9/055: the cleaning devices conforming to, or being conformable to, substantially the same cross-section of the pipes, {e.g. pigs or moles (pigs or moles per se F16L55/26; their launching and detection F16L55/46; separating pigs in pipelines F17D3/00)} - B08B 9/0555: {Gelled or degradable pigs} - Y10T 137/0435: Mechanical cleaning [e.g., pig, etc.] - Y10T 137/4273: Mechanical cleaning - Y10T 137/4891: With holder for solid, flaky or pulverized material to be dissolved or entrained - F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL - B08B: CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Disclosed is a pig assembly for maintaining a functional line for conveying fluid. In one aspect, the pig assembly includes a larger diameter pig having an internal compartment and at least one smaller diameter pig adapted to fit therein. The larger diameter pig is capable of passing through a larger diameter functional line and the smaller diameter pig is capable of passing through a smaller diameter functional line. In another aspect, a method for maintaining a functional line for conveying fluid is provided which includes pigging a subsea line having at least a larger diameter functional line and a smaller diameter functional line in fluid communication with one another using a pig assembly as described herein. ## Claims ### Claim 1 A pig assembly for maintaining a functional line for conveying fluid, comprising: a. a larger diameter pig having an internal compartment, wherein the larger diameter pig is capable of passing through a larger diameter functional line; and b. at least one smaller diameter pig capable of passing through a smaller diameter functional line wherein the at least one smaller diameter pig is adapted to fit within the internal compartment of the larger diameter pig; wherein the diameters of the larger diameter functional line and the smaller diameter functional line differ by more than 1 standard API 5L pipeline diameters. ### Claim 2 (depends on 1) The pig assembly of claim 1, wherein the larger diameter functional line has a diameter of from 5.1 cm to 102 cm; and the smaller diameter functional line has a smaller diameter than the larger functional line. ### Claim 3 (depends on 1) The pig assembly of claim 1, further comprising a release mechanism for releasing the at least one smaller diameter pig from the larger diameter pig into the smaller diameter functional line. ### Claim 4 (depends on 3) The pig assembly of claim 3, wherein the release mechanism for releasing the at least one smaller diameter pig from the larger diameter pig is activated in response to a physical impact of a mechanical release mechanism, an impact with a spring-loaded mechanism, an acoustic signal, a magnetic field, a wireless signal or a timing device. ### Claim 5 (depends on 3) The pig assembly of claim 3, wherein the release mechanism is adapted to release the at least one smaller diameter pig from the larger diameter pig into the smaller diameter functional line when the larger diameter pig is proximate a juncture between the larger diameter functional line and the smaller diameter functional line. ### Claim 6 (depends on 3) The pig assembly of claim 3, wherein the release mechanism is adapted to release the at least one smaller diameter pig from the larger diameter pig into the smaller diameter functional line when the larger diameter pig is proximate an at least partial blockage within the smaller diameter functional line. ### Claim 7 (depends on 1) The pig assembly of claim 1, wherein the smaller diameter pig is connected by a tether to the larger diameter pig. ### Claim 8 (depends on 1) The pig assembly of claim 1, wherein the smaller diameter pig is connected by an umbilical capable of transmitting data and/or power from the larger diameter pig to the smaller diameter pig. ### Claim 9 (depends on 1) The pig assembly of claim 1, wherein at least one of the larger diameter pig and the smaller diameter pig further comprises a battery for power storage and supply. ### Claim 10 (depends on 1) The pig assembly of claim 1, wherein the smaller diameter pig further comprises a seal capable of isolating a section of the smaller diameter functional line. ### Claim 11 (depends on 10) The pig assembly of claim 10, wherein the seal comprises an expandable sleeve. ### Claim 12 (depends on 1) The pig assembly of claim 1, wherein the larger diameter pig further comprises an expandable sleeve. ### Claim 13 (depends on 1) The pig assembly of claim 1, wherein at least one of the larger diameter pig and the smaller diameter pig further comprises a sensor or an in line inspection tool. ### Claim 14 (depends on 1) The pig assembly of claim 1, wherein the smaller diameter pig comprises a chemical treatment module for chemically treating a section of the functional line. ### Claim 15 (depends on 1) The pig assembly of claim 1, wherein the smaller diameter pig comprises a repair module having rotary blades. ### Claim 16 (depends on 1) The pig assembly of claim 1, wherein the smaller diameter pig comprises an expansion sleeve for sealing a section of the functional line. ### Claim 17 (depends on 1) A method for maintaining a functional line for conveying fluid, comprising: with the pig assembly of claim 1, pigging a subsea line comprising at least a larger diameter functional line and a smaller diameter functional line in fluid communication with one another; wherein the larger diameter pig passes through the larger diameter functional line and the smaller diameter pig passes through the smaller diameter functional line; and wherein the diameters of the larger diameter functional line and the smaller diameter functional line differ by more than 1 standard API 5L pipeline diameters. ### Claim 18 (depends on 17) The method of claim 17, wherein the larger diameter functional line has a diameter of from 5.1 cm to 102 cm; and the smaller diameter functional line has a smaller diameter than the larger functional line. ### Claim 19 (depends on 17) The method of claim 17, wherein the pigging of the subsea line is initiated by launching the larger diameter pig of the pig assembly from a pig launcher into the larger diameter functional line such that the larger diameter pig travels in the direction of the smaller diameter functional line; and upon arriving proximate a juncture between the larger diameter functional line and the smaller diameter functional line, the at least one smaller diameter pig is released from the larger diameter pig into the smaller diameter functional line such that the smaller diameter pig travels in the smaller diameter functional line. ### Claim 20 (depends on 17) The method of claim 17, wherein the smaller diameter pig further arrives at a second larger diameter pig in a second larger diameter functional line and is received by the second larger diameter pig. ### Claim 21 (depends on 17) The method of claim 17, wherein the travel of the larger diameter pig and/or the smaller diameter pig is controlled by wireless signals. ### Claim 22 A pig assembly for maintaining a pipeline wye apparatus comprising a junction of a largest diameter section of pipeline and two smaller diameter sections of pipeline; wherein the diameters of the two smaller diameter sections of pipeline differ by more than 2 standard API 5L pipeline diameters from the largest diameter section of pipeline, comprising: a. a larger diameter pig having an internal compartment, wherein the larger diameter pig is capable of passing through the largest diameter section of pipeline; and b. at least two smaller diameter pigs adapted to fit within the internal compartment of the larger diameter pig and be released from the larger diameter pig into each of the two smaller diameter sections of pipeline.