Device for welded joints in pipework

Abstract

A piping device that includes two parts, each consisting of two concentric rings joined together by a solid steel mantle that when assembled produce a confined space between the pieces of at least 50 mm and house a guide wedge and an elastomeric ring that It produces the hydraulic seal and the thickness of this solid steel mantle and the assembly area between the cavity and the guide wedge is at least twice the thickness of the pipe. The heat of the welding process between the external concentric rings is released by the device itself and the temperature inside the pipe does not exceed 120+/20 C., eliminating any possible internal corrosion in the areas of the welded joints, since it prevents damage to the internal lining and increases the useful life of the pipe during it operation.

Claims

1. A device to be installed in pipes, that eliminates internal corrosion in the welded joints because it prevents the damage of the welding heat to the inner coating of said pipes by dissipating it naturally and spontaneously, comprising a first part (1) which is assembled to a second part (2) producing a confined space (51) where both parts (1 and 2) are formed by two concentric rings, an inner ring (4, 21) of the same diameter as the pipe (38), and an outer ring (3, 20) with the rings joined together by a solid steel mantle (5, 22); the inner ring (4) has a cavity (8) where a guide wedge (29) of the inner ring (21) is assembled and at the bottom of the cavity (8) of the first part (1) there is a concavity (9) to accommodate an fluor elastomer ring (45) and at the end of the guide wedge (29) of the second part (2) there is a concavity (30) confining said ring of fluor elastomer (45) to the concavity (9), and the inner area of the contact surfaces (39) between the inner rings (4, 21) are protected with a highly adhesive epoxy seal, a separation of 2 to 3 millimeters (46) is achieved between the outer rings (3, 20) where the welded joint (44) is done, wherein the width (10, 23) of the solid steel mantle (5, 22) that separates the inner and outer rings of the first part and the second part is at least 50 mm and the thickness (14, 24) of this solid steel mantle (5,22) as well as the thickness of the assembly area (52) between the cavity (8) of part (1) and the guide wedge (29) of part (2) is at least twice the thickness of the pipe (40, 41).

2. The device according to claim 1, wherein the inner ring (4) has a minimum width (12) corresponding to 30 millimeters plus twice the thickness of the pipe (40, 41) plus the width of a welding neck (18).

3. The Device according to claim 1, wherein the inner ring (21) has a minimum width (32) corresponding to the width of the guide wedge (29) plus 20 mm, plus twice the thickness of the pipe (40, 41) plus the width of a welding neck (26).

4. The device according to claim 1, wherein the outer rings (3 and 20) have a minimum outer diameter (11 and 33) equivalent to the inner diameter of the pipe (38) plus 100 millimeters, plus 6 times the pipe thickness (40, 41) and the minimum width (16 and 34) of these rings is at least 23.5 millimeters plus twice the thickness of the pipe (40, 41).

5. The device according to claim 1, wherein the ring of fluor elastomer (45) remains compressed between the concavity (9) of the first part (1) and the concavity (30) of the second part (2).

6. The device according to claim 1, wherein the contact area (39) of both faces of the inner rings (4, 21) where the epoxy seal is applied has a minimum separation of 0.5 millimeters with a maximum clearance of +/20% which prevents electrical contact between the faces forming a crevice (47), preventing crevice corrosion in the device.

Description

DESCRIPTION OF THE FIGURES

(1) The Figures shown in this patent application are the following:

(2) FIG. 1: Part 1

(3) FIG. 2: Part 1. Front View

(4) FIG. 3: Part 1. Section AA of the Front View

(5) FIG. 4: Part 2

(6) FIG. 5: Part 2. Front View

(7) FIG. 6: Part 2. Section BB of the Front View

(8) FIG. 7: Pipes Alignment and Assembly

(9) FIG. 8: Isometric Section CC of FIG. 7

(10) FIG. 9: Zone of the adhesive seal in Inner Rings of Parts 1 and 2

(11) FIG. 10: Details of Parts 1 and 2 of the assembled device

(12) FIG. 11: Details of the assembly zone between Parts 1 and 2

(13) FIG. 12: Scheme of heat and temperature dissipation and distribution in the welding point (Q.sub.1, T.sub.1) between Parts 1 and 2

DETAILED DESCRIPTION OF THE DEVICE

(14) This device to be installed in pipes, eliminates the internal corrosion at the welded joints by preventing the welding heat to damage the inner coating of said pipes, dissipating it in a natural and spontaneous way, that includes a first part (1) which is assembled to a second part (2) generating a confined space (51) where both parts (1 and 2) are formed by two concentric rings, one inner ring (4, 21) of the same diameter as the pipe (38), and an outer ring (3, 20), with the rings joined together by a solid steel mantle (5, 22); the inner ring (4) has a cavity (8) where the guide wedge (29) of the inner ring (21) is assembled and at the bottom of the cavity (8) of the first part (1) there is a concavity (9) to accommodate a cylindrical fluorelastomer ring (45) and at the end of the guide wedge (29) of the second part (2) there is a concavity (30) confining said cylindrical ring (45) to the concavity (9), and the inner area of the contact surfaces (39) between the inner rings (4, 21) are protected with a highly adhesive epoxy seal, and by the type of assembly (52) of parts (1 and 2), a separation of 2 to 3 millimeters (46) is achieved between the outer rings (3, 20) where the welded joint (44) is done, where the width (10, 23) of the solid steel mantle (5, 22) that separates the inner and outer rings of both parts (1 and 2) is at least 50 mm and the thickness (14, 24) of this solid steel mantle (5,22) as well as the thickness of the assembly area (52) between the cavity (8) of part (1) and the guide wedge (29) of part (2) is at least twice the thickness of the pipe (40, 41).

(15) Likewise, the inner ring (4) has a minimum width (12) of 30 millimeters plus twice the thickness of the pipe (40, 41) plus the width of the welding neck (18) and the inner ring (21) has a minimum width (32) corresponding to the width of the guide wedge (29) plus 20 millimeters, plus twice the thickness of the pipe (40, 41) plus the width of the welding neck (26).

(16) On the other hand, the outer rings (3 and 20) have a minimum outer diameter (11 and 33) equivalent to the inner diameter of the pipe (38) plus 100 millimeters, plus 6 times the pipe thickness (40, 41) and the minimum width (16 and 34) of these rings is at least 23.5 millimeters plus twice the thickness of the pipe (40, 41).

(17) The cylindrical fluorelastomer ring (45) acts as a tight seal preventing the fluid transported by the pipe (50) to enter and cause corrosion inside the confined space (51) and the contact area (39) of both faces of the inner rings (4, 21) where the epoxy seal is applied, has a minimum separation of 0.5 millimeters with a maximum clearance of +/20% which prevents electrical contact between the faces forming the crevice (47), preventing crevice corrosion in the device.

(18) In keeping with the same, a carbon steel device is manufactured which includes two parts (1 and 2) which, when welding them in the field to build the pipe, most of the welding heat dissipates naturally and spontaneously through the device itself (FIG. 12), without damaging the pipe wall.

(19) The description, structure and dimensions of the parts that make up the device are shown in FIGS. 1 to 6, which are detailed below.

(20) Part 1 (FIGS. 1, 2 and 3):

(21) Part (1) is formed by two concentric rings, an outer (3) and an inner ring (4), joined together by a solid steel mantle (5). The clearance between these rings (10) should be at least 50 millimeters. The thickness of the mantle (14) joining the rings should be at least twice the pipe thickness (40, 41).

(22) The inner ring (4) corresponds to the area of the device through which the fluid carried by the pipe (50) travels and therefore must have the same inner diameter (6) as the diameter of the pipe (38). The thickness (13) of the inner ring (4) in the coupling area should be the same as that of the pipe (40, 41) and the thickness (15) in the assembly zone with the part (2) must be at least twice the thickness of the pipe (40, 41). The inner ring (4) is welded (42) to the pipe on a beveled (7) welding neck (18). The minimum width (12) of the inner ring (4) should be 30 mm+twice the thickness of the pipe (40, 41)+the width of the welding neck (18).

(23) The inner ring (4) has a cavity (8) to couple and guide part (2), the bottom of this cavity is concave (9) intended to house a cylindrical fluorelastomer ring (45) preventing the fluid from passing into the body of the device, sealing hermetically the joints between the parts (1 and 2). This cavity (8) must have a minimum depth of 10 millimeters.

(24) The outer ring (3) has a minimum outer diameter (11) equivalent to the inner diameter of the pipe (38)+100 mm+6 times the pipe thickness (40, 41). The minimum width (16) of the outer ring (3) should be 23.5 mm+twice the pipe thickness (40, 41). The thickness (17) of the outer ring (3) should correspond to at least the thickness of the pipe (40, 41) and its finishing should be beveled (19) to be welded to the outer ring (20) of part (2).

(25) Part 2 (FIGS. 4, 5 and 6):

(26) Part (2) is formed by two concentric rings, an outer (20) and an inner ring (21), joined together by a solid steel mantle (22). The clearance between these rings (23) should be at least 50 millimeters. The thickness of the sheet (24) joining the two rings should be at least twice the pipe thickness (40, 41).

(27) The inner ring (21) corresponds to the area of the device through which the fluid carried by the pipe (50) travels and thus, it should have the same inner diameter (25) as the diameter of the pipe (38), this inner ring (21) is welded to the pipe (43) on a beveled (27) welding collar (26) of the same thickness (28) as the thickness of the pipe (40, 41). In this inner ring (21) there is a guide wedge (29) protruding from the part and serves for coupling and matching with part (1), the end side of the guide wedge has a concavity (30) which confines the cylindrical fluorelastomer ring (45) to the concave bottom (9) of the cavity (8) of the part (1), the thickness (31) of the area where tis inner ring (21) joints with the part (1) must be at least twice the thickness of the pipe (40, 41). The width (32) of this inner ring (21) must correspond at least to the width of the guide wedge (29)+20 millimeters+twice the thickness of the pipe (40, 41)+the width of the welding neck (26).

(28) The outer ring (20) has a minimum outer diameter (33) equivalent to the inner diameter of the pipe (38)+100 mm+6 times the pipe wall thickness (40, 41). The width (34) of the outer ring (20) should be at least 23.5 millimeters+twice the pipe thickness (40, 41). The outer ring (20) must have a beveled finishing (35) to be or welded to the outer ring (3) of the part (1).

(29) FIG. 7 shows the alignment of the pipes in the field and finished system with the relevant fittings. The fitting (36) corresponds to the end side of the pipe coupled to the part (1) and the fitting (37) corresponds to the end side of the pipe coupled to the part (2).

(30) FIG. 8 shows a cross-sectional view of the device coupled to an inner diameter pipe (38).

(31) FIG. 9 shows the area of the surfaces (39) of the parts (1 and 2) where the epoxy seal is applied.

(32) FIG. 10 shows a section and details of the welded device. The description of these is as follows:

(33) (40 and 41): Main pipe, wall thickness specified by the engineering.

(34) (42): Welded joint of the pipe with part 1 of the beveled device 38 ANSI B 16.5.

(35) (43): Welded joint of the pipe with part 2 of the beveled device 38 ANSI B 16.5.

(36) (44): Area where the outer rings of parts 1 and 2 of the device are welded, both with bevel 38 ANSI B 16.5.

(37) (45): Cylindrical fluorelastomer ring for joint tightness. The manufacturing material of the ring is known as Viton and has high chemical resistance.

(38) (46): A 2 to 3 millimeters' clearance between the outer ring (3, 20) bevels in the weld of part 1 with part 2.

(39) (47): Surface of the crevice between parts 1 and 2 of the device, where the epoxy seal is applied (FIG. 9).

(40) (48): Internal surface of the pipe, painted in the workshop.

(41) (49): External surface of the pipe, painted in the workshop.

(42) (50): Internal zone of the pipe through which the fluid passes.

(43) (51): Confined space between parts 1 and 2.

(44) (1): Part 1 of the device.

(45) (2): Part 2 of the device.

(46) FIG. 11 shows a detail of the assembly area between the inner rings (4 and 21) of parts 1 and 2. This detail shows the fit between the guide wedge (29) of part 2 and the cavity (8), of the part 1 for the confinement of the fluorelastomer ring (45) and surfaces protected (39) by the epoxy seal.

(47) FIG. 12 shows the schematic design of natural and spontaneous heat dissipation of the weld. In this, Q1 and T1 represent the amount of heat and temperature at the welding point; Q2 and T2 the amount of heat and temperature that is dissipated by part 1 of the device; Q3 and T3 the amount of heat and temperature being dissipated by the part 2 of the device; Q4 and T4, the amount of heat and temperature that radiates to the confined space between the parts 1 and 2 of the device, and Q5 and T5 the amount of heat and temperature reaching the inner wall (48), of the pipe.

(48) The back up in terms of dimensions, shape and design of the device proposed by this patent application was based on a calculation report and a finite elements modeling of the distribution of heat generated at the welding point. Both methods confirm the hypothesis that gave rise to this patent application, regarding the natural and spontaneous dissipation of the heat at the welding point achieved by this device according to its design, and indicate that the maximum temperature in the inner wall of the pipe does not exceed 120 C.+/20 C., a temperature range that remains constant and reproducible for any pipe diameter greater than 152.4 millimeters (6).

(49) According to the above, prototypes were made for pipes of 203.2 millimeters (8) in diameter, Schedule 40, and the results of practical tests assisted by thermography, showed a maximum temperature on the inner wall of the pipe (48) of 108 C. with MIG welding system and 133 C. with Arc welding system.

(50) In the figures and description, we can see how to prevent: The fluid transported by the pipe (50) from entering the confined space of the device (51) with the use of the cylindrical fluorelastomer ring (45). The crevice corrosion (47) between parts 1 and 2, which is exposed to the fluid transported by the pipe (50) by applying a firm and adhesive epoxy seal to the surface of both Parts (FIG. 9).

(51) In any given project, the engineers design the coating according to the chemical and physical requirements of the fluid transported by the pipe and, as this patent application allows the use of all types of paint, including AWWA and other related standards, it gives the engineers the technical independence to select the most suitable coating without being damaged or destroyed, eliminating the risk of corrosion in welded joints.

(52) Device Assembly Procedure:

(53) Before treating the pipes in the workshop with abrasive blasting and the application of coating, a part 1 is welded (42) to one end and a part 2 is welded (43) to the opposite end, both parts being left as fittings (36 and 37) of each pipe. After the parts have been welded all weld slag and blobs must be removed.

(54) Prior to the treatment with abrasive blasting and painting the inner side of parts (1 and 2) of both fittings must be protected. With the parts (1 and 2) protected, all the surfaces of the pipe and parts (1 and 2), must be treated with abrasive blasting and then apply the coating as specified by the engineering, both joints being welded (42 and 43), protected by the coating and, therefore, eliminating all possible electrochemical corrosion of the areas affected by heat (ZAC) produced in the welding process.

(55) Once the paint is cured, the protection of the parts (1 and 2) of both fittings must be removed and a highly adhesive epoxy seal (FIG. 9) is applied to the entire internal area of the contact surfaces between them (39), protecting the device from any possible crevice corrosion.

(56) The epoxy seal must have the following properties: Excellent adhesion to carbon steel surfaces. Be of liquid consistency, with a thixotropy suitable to ensure an adequate protection thickness to the surfaces that form the crevice. No solvents or toxic elements content. Be highly resistant to water, salts and chemicals.

(57) The pipes, coated in the inside and outside as stated in the engineering specifications, are taken to the field and aligned in such a way that the fitting (36) joint to the part (1) of a pipe is faced with the fitting (37) joint to the part (2) of the adjacent pipe (FIG. 7).

(58) Assembling the fitting (36) of one pipe with the fitting (37) of another pipe produces a continuous separation of 2 to 3 millimeters (46) throughout the perimeter of the central bevel of the outer rings (3 and 20) of both fittings, and the joint (44) is welded.

(59) The installation of the device (parts 1 and 2 welded in the workshop) allows the elimination of slag and weld blobs from this process and therefore, eliminate the risk of internal corrosion in the zone where joints of parts 1 and 2 are welded to the pipe, that is to say, the working procedure offers full guarantee in terms of decontamination and elimination of any impurity and/or obstruction, hampering the free flow of the fluid transported by the pipe (50).