US-12618505-B2 - Insulated welded joint for pipe-in-pipe systems

US12618505B2US 12618505 B2US12618505 B2US 12618505B2US-12618505-B2

Abstract

An insulated joint in a pipe-in-pipe system comprises a weld that connects two inner pipes while respective outer pipes circumferentially enclose the inner pipes and terminate at a position distal from the weld. Respective rings are coupled to the inner pipes at the distal position and the outer pipes are welded to the rings. A joint insulation material covers the weld, and a sleeve segment covers the weld and joint insulation material. Preferably, the sleeve segment is formed from two half-pipe sleeve portions and welded to the rings to so secure the sleeve segment to the joined pipe-in-pipe segments. Contemplated pipe-in-pipe systems have significantly reduced thermal loss and provide strength sufficient for a pipe laying process that includes pipe bending and pipe straightening.

Inventors

Piotr D. Moncarz
Mark McGilvray, JR.
Henryk Man

Assignees

XGS ENERGY, INC.

Dates

Publication Date: 20260505
Application Date: 20220727

Claims (20)

1 . An insulated joint in a pipe-in-pipe system in a geothermal energy production plant, comprising: a first pipe-in-pipe segment and a second pipe-in-pipe segment, each pipe-in-pipe segment having an outer pipe enclosing an inner pipe, and each pipe-in-pipe segment having insulation material in an annular space between the outer pipe and the inner pipe; wherein each pipe-in-pipe segment has a ring between the outer and inner pipe at which the outer pipe terminates and to which the outer pipe is coupled, and to which the inner pipe is coupled and beyond which the inner pipe extends; a weld joint between respective ends of the inner pipes of the first and second pipe-in-pipe segments; first and second half-pipe sleeves coupled to each other via longitudinal welds to form a sleeve segment; wherein the sleeve segment is welded to the rings of the first and second pipe-in-pipe segments such that (a) the welds at the rings connect the outer pipes of the first and second pipe-in-pipe segments via the sleeve, and (b) the welds at the rings connect the outer pipes of the first and second pipe-in-pipe segments to the respective inner pipes of the first and pipe-in-pipe segments via the rings to so allow for transfer of bending and straightening forces from the outer to the inner pipe; and a joint insulation material between the rings of the first and second pipe-in-pipe segments and between the weld joint and the sleeve.
2 . The insulated joint of claim 1 , wherein each of the pipe-in-pipe segments have a length of about 10-20 m.
3 . The insulated joint of claim 1 , wherein the inner pipe of the first and second pipe-in-pipe segments has a diameter of about 10-20 cm and wherein the outer pipe of the first and second pipe-in-pipe segments has a diameter of about 15-25 cm, and wherein the sleeve segment has a length of about 20-50 cm.
4 . The insulated joint of claim 1 , wherein the ring has a radial width of about 3-10 cm and a thickness of about 2-5 cm, and/or wherein a distance between the inner pipe and the outer pipe is the same as a radial width of the ring.
5 . The insulated joint of claim 1 , wherein the ring is welded to the inner pipe in each of the first and second pipe-in-pipe segments.
6 . The insulated joint of claim 1 , wherein the first and/or the second half-pipe sleeve comprise a backer bar along the longitudinal welds.
7 . The insulated joint of claim 1 , wherein the sleeve segment and the outer pipes of the first and second pipe-in-pipe segments have the same outer diameter, and/or wherein the joint insulation material is wrapped around the weld joint.
8 . The insulated joint of claim 1 , wherein the welds, the ring, and the sleeve segment of the joined pipe-in-pipe segments have a strength sufficient for a pipe laying process that includes pipe bending and pipe straightening.
9 . A method of joining a first pipe-in-pipe segment to a second pipe-in-pipe segment, each pipe-in-pipe segment having an outer pipe enclosing an inner pipe that extends beyond the outer pipe, and each pipe-in-pipe segment having insulation material in an annular space between the outer pipe and the inner pipe for use in a geothermal energy production plant, comprising: forming a weld joint between respective ends of the inner pipes of the first and second pipe-in-pipe segments; covering the weld joint with joint insulation material; welding first and second half-pipe sleeves together via longitudinal welds to form a sleeve segment above the weld joint; and welding the sleeve segment to respective rings on the first and second pipe-in-pipe segments such that (a) the welds at the rings connect the outer pipes of the first and second pipe-in-pipe segments via the sleeve, and (b) the welds at the rings connect the outer pipes of the first and second pipe-in-pipe segments to the respective inner pipes of the first and second pipe-in-pipe segments via the rings to so allow for transfer of bending and straightening forces from the outer to the inner pipe.
10 . The method of claim 9 , wherein the weld joint is covered by wrapping the joint insulation material about the weld joint.
11 . The method of claim 9 , wherein the first and second half-pipe sleeves comprise a backer bar along the longitudinal welds.
12 . The method of claim 9 , wherein the respective rings on the first and second pipe-in-pipe segments are welded to the inner pipe of the first and second pipe-in-pipe segments.
13 . The method of claim 9 , wherein the sleeve segment and the outer pipes of the first and second pipe-in-pipe segments have the same outer diameter, and/or wherein the sleeve segment and the outer pipes of the first and second pipe-in-pipe segments share a common weld at the respective rings.
14 . The method of claim 9 , wherein at least 20 pipe-in-pipe segments are serially joined, wherein each of the pipe-in-pipe segments have a length of about 10-20 m, and wherein the sleeve segment has a length of about 20-50 cm.
15 . The method of claim 9 , wherein the inner pipe of the first and second pipe-in-pipe segments has a diameter of about 10-20 cm and wherein the outer pipe of the first and second pipe-in-pipe segments has a diameter of about 15-25 cm.
16 . The method of claim 9 , wherein the welds, the ring, and the sleeve segment of the joined pipe-in-pipe segments have a strength sufficient for a pipe laying process that includes pipe bending and pipe straightening.
17 . A geothermal energy production plant, comprising: a casing in a geological formation, wherein the casing encloses a pipe-in-pipe system comprising a plurality of serially joined pipe-in-pipe segments, each having an outer pipe enclosing an inner pipe, and each pipe-in-pipe segment having insulation material in an annular space between the outer pipe and the inner pipe; wherein the pipe-in-pipe segments are coupled to each other such that (1) respective ends of the inner pipes are welded to each other; (2) respective ends of the outer pipes are welded to respective rings on the inner pipes of the pipe segments; (3) a sleeve segment is placed between and welded to the rings of the pipe-in-pipe segments and further welded to the respective ends of the outer pipes to thereby form a continuous outer pipe enclosing the weld connecting the inner pipes and to allow for transfer of bending and straightening forces from the outer to the inner pipe; and wherein the casing and the pipe-in-pipe system are fluidly coupled to each other and a heat exchanger to form a closed loop working fluid circuit for heat recovery and power generation.
18 . The plant of claim 17 , wherein the geological formation is at a depth of at least 500 m, and/or wherein the geological formation has a temperature of at least 200° C.
19 . The plant of claim 17 , wherein the serially joined pipe-in-pipe segments have a length of at least 1,000 m.
20 . The plant of claim 17 , wherein the closed loop working fluid circuit is thermally coupled to an electric generator.

Description

This application claims priority to our U.S. Provisional patent application with the Ser. No. 63/228,301, which was filed Aug. 2, 2021, and which is incorporated by reference herein. FIELD OF THE INVENTION The field of the invention is devices and methods for joining insulated pipe-in-pipe systems. BACKGROUND OF THE INVENTION The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. All publications and patent applications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. There are numerous manners of joining pipes known in the art such as use of threads, flanges, or welds. In many cases, however, conventional pipe connections will not be suitable where the pipe is an insulated pipe-in-pipe system in which an inner pipe is disposed within an outer pipe, and in which the space between the pipes must be insulated to avoid heat or cold loss. To allow for joining such pipe-in-pipe systems, each insulated pipe-in-pipe segment can be capped at the ends of the insulated space to so enclose an annular insulated space, and the respective capped ends can then be connected together via welds or a sleeve. While such connections are relatively simple to implement in the field, numerous drawbacks remain. Most significantly, the end caps at the annular insulated space will form a conductive heat transfer path that will lead to significant heat or cold loss. Such loss is particularly undesirable where the pipe-in-pipe system has a significant length and as such requires a relatively large number of connections. In an attempt to reduce thermal loss and thermal stress, a bulkhead can be employed between two pipe-in-pipe segments as is described in U.S. Pat. No. 8,998,267. Here, the bulkhead in a cryogenic pipe-in-pipe system has an inner transition element, and distinct first and second outer transition elements that are coupled to and at least partially surround the inner transition element. The bulkhead can then be welded to respective ends of inner and outer pipelines of adjoining pipe-in-pipe segments. Such system advantageously reduces heat transfer paths and as such reduces heat or cold loss. Moreover, thermal stresses (e.g., due to contraction upon receiving a cryogenic liquid) can be transferred from the inner to the outer pipe. However, due to the relatively complex configuration, a relatively large number of welds and welding steps are required and therefore require significant time for assembly and expense. In addition, pipe-in-pipe systems with capped insulated annular space or bulkheads will also be prone to mechanical failure where the pipe-in-pipe system is subject to significant mechanical forces, and particularly forces as will be encountered with pipe laying that requires pipe bending and pipe straightening steps. Thus, even though various systems and methods of insulated pipe-in-pipe systems are known in the art, all or almost all of them suffer from several drawbacks. Therefore, there remains a need for compositions and methods for improved insulated pipe-in-pipe systems, and especially systems that allow for simple assembly, that can withstand significant bending and straightening forces, and that minimize thermal loss across joints between pipe-in-pipe segments. SUMMARY OF THE INVENTION The inventive subject matter is directed to various insulated pipe-in-pipe systems and methods in which inner and outer pipes of a pipe-in-pipe segment are coupled to each other by a ring that is coupled to the outer surface of the inner pipe. Most typically, the outer pipe is recessed from the inner pipe and terminates at the ring, and once respective ends of the inner pipes of two pipe-in-pipe segments are welded together, a sleeve segment is formed and coupled to the rings after coupling a joint insulation material to the weld joint, thereby enhancing mechanical strength of the joint while minimizing thermal conductivity. In one aspect of the inventive subject matter, the inventors contemplate an insulated joint in a pipe-in-pipe system that comprises a first pipe-in-pipe segment and a second pipe-in-pipe segment, with each pipe-in-pipe segment having an outer pipe enclosing an inner pipe, and each pipe-in-pipe segment having insulation material in an annular space between the outer pipe and the inner pipe. Furthermore, each pipe-in-pipe segment has a ring between the outer and i