WO2015004538A2

WO2015004538A2 - Multilayer repair of thick wall vessels

Info

Publication number: WO2015004538A2
Application number: PCT/IB2014/002281
Authority: WO
Inventors: Abdulaziz AL-MESHARI; Gysbert Nicolaas VAN ZYL
Original assignee: Saudi Basic Industries Corporation
Priority date: 2013-06-28
Filing date: 2014-06-26
Publication date: 2015-01-15
Also published as: WO2015004538A3

Abstract

The present disclosures and inventions relate to a layered weld joint, comprising: a weld zone defined by at least one connecting surface of an outer wall of at least one work piece, the outer wall of each work piece of the at least one work piece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a work piece of the at least one work piece; and a plurality of stacked metallic layers disposed within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges and wherein at least a portion of the first and second side edges of each metallic layer is welded to the at least one connecting surface of the outer wall of a work piece of the at least one work piece.

Description

MULTILAYER REPAIR OF THICK WALL VESSELS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This Application claims the benefit of U.S. Provisional Application No.

61/840,694 filed on June 28, 2013, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Currently to repair a welded vessel, the entire weld is removed and then re- weided. This technique can consume a significant amount of time, causing an elongated shutdown period, due to the high amount of welding required. Further, this technique also uses a high amount of welding and can result in a higher probability of inducing a weld defect. Lastly, the technique can have less resistance to cracking initiation and propagation.

[0003] Accordingly, there remains a need for a weld joint and a method for forming a weld joint.

SUMMARY

[0004] In accordance with the purpose(s) of the invention, as embodied and broadly described herein, the invention, in one aspect, relates to a layered weld joint, comprising: a weld zone defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a workpiece of the at least one workpiece; and a plurality of stacked metallic layers disposed within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges and wherein at least a portion of the first and second side edges of each metallic layer is welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece.

[0005] Disclosed are methods for forming a layered weld joint, comprising: sequentially welding each of a plurality of metallic layers within a weld zone, the weld zone being defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wail of a workpiece of the at least one workpiece, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges, wherein the plurality of metallic layers are sequentially welded such that at least a portion of each first side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece and at least a portion of each second side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece, thereby providing a weld joint comprised of a plurality of stacked metallic layers welded within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis,

[0006] While aspects of the present invention can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present invention can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

BRIEF DESCRIPTION OF THE FIGURES

[0007] The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects and together with the description serve to explain the principles of the invention.

[0008] FIG. 1 schematically shows the presence of defects in a workpiece, as well as an area of the workpiece to be removed to permit formation of a layered weld joint as disclosed herein.

[0009] FIG, 2 shows an exemplary layered weld joint as disclosed herein,

[0010] FIG, 3 shows an exemplary layered weld joint as disclosed herein.

[0011] FIG, 4 shows a design assessment for the local strain for one aspect of a vessel with a layered weld joint, [0012] FIG. 5 shows a design assessment for the plastic strain for one aspect of a vessel with a layered weld joint.

[0013] FIG. 6 shows a graph of the elastic-plastic analysis for the design assessment for one aspect of a vessel with a layered weld joint with the applied load factor as compared to the maximum displacement in millimeters.

[0014] FIG. 7 shows a design assessment for the total displacement for one aspect of a vessel with a layered weld joint.

[0015] FIG. 8 shows a design assessment for the stress levels for one aspect of a vessel with a layered weld joint.

[0016] Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DESCRIPTION

[0017] The present invention can be understood more readily by reference to the following detailed description of the invention and the Examples included therein.

[0018] Before the present compounds, compositions, articles, systems, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, example methods and materials are now described.

[0019] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

A. DEFINITIONS

[0020] As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a functional group," "an alkyl," or "a residue" includes mixtures of two or more such functional groups, alkyls, or residues, and the like.

[0021] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, a further aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms a further aspect, It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as "about" that particular value in addition to the value itself. For example, if the value "10" is disclosed, then "about 10" is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0022] As used herein, the terms "optional" or "optionally" means that the subsequently described event or circumstance can or can not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0023] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order.

Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0024] Disclosed are the components to be used to prepare the compositions of the invention as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds can not be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively

contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions of the invention. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the methods of the invention.

B. LAYERED WELD JOINT

[0025] Typical weld defects are shown in FIG. 1. When cracks, such as the defects 1 labeled in FIG. I, develop on the internal surfaces of a workpiece, portions of the outer surfaces of the workpiece proximate the defects can be deformed, such as by, for example and without limitation, bowing or buckling. Typically, the only access for a repair is from the outside of the workpiece by the removal of all defects, and the removal of all defects and deformities in the workpiece often necessitates that a large region of the workpiece be excavated. In exemplary procedures, portions of the workpiece can be removed using conventional grinding procedures as are known in the art. As shown in FIG. 1, the excavated area 3 of the workpiece should include— and, preferably, should extend beyond— all of the defects and deformities in a given region of the workpiece. Typically, the excavated area 3 is completely filled in with a single repair well, in one aspect, instead of repairing the excavated area with a single repair weld, the excavated area 3 can be repaired by a layered weld joint as shown in FIG. 2. [0026] in FIG. 2, one aspect of the layered weld joint is shown. The layers 30 of the layered weld joint can be welded to one or more connecting surfaces using one or more welding materials as further disclosed herein. The locations of the welds 50 between the connecting surfaces and the weld joint layers 30 are shown in FIG. 2. The inside diameter 24 of the vessel is also shown in FIG. 2.

[ΘΘ27] In various aspects, in FIG. 3, a layered weld joint 10 comprises: a weld zone defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a workpiece of the at least one workpiece; and a plurality of stacked metallic layers disposed within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges and wherein at least a portion of the first and second side edges of each metallic layer is welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece.

[0028] As used herein, the term "weld zone" refers to any opening or void space defined by the at least one connecting surface of an outer wall of a workpiece as disclosed herein. Examplary "weld zones" include, without limitation, holes, leaks, cavities, recesses, dents, openings, bores, slits, slots, notches, and other void spaces formed within one or more workpieces. In some aspects, a weld zone can be defined within a single workpiece.

However, in other aspects, it is contemplated that two or more workpieces can cooperate to define the weld zone. In exemplary aspects, the weld zone can be defined by a vessel having an interior space in communication with the weld zone.

[0029] FIG. 3 illustrates one aspect of the present invention. FIG. 3 shows a layered weld joint 10 with stacked metal layers 30 built up to repair a weld cavity (corresponding to the weld zone 12), FIG. 3 also shows a layered weld joint with a tell-tale hole (i.e., weep hole 40). As further described herein, it is contemplated that this hole 40 can allow for early detection of failure. FIG, 3 further shows a layered weld joint with layers for additional reinforcement that extend beyond the outer wall 22 of the at least one workpiece 20,

[0030] As depicted in FIG. 3, the weld zone 12 is defined by at least one connecting surface 28 of the outer wall 22 of the at least one workpiece 20. The outer wall 22 of each workpiece 20 of the at least one workpiece has an interior surface 24 and an exterior surface 26, Each connecting surface 28 of the at least one connecting surface extends between the interior and exterior surfaces 24, 26 of a workpiece of the at least one workpiece 20. When the at least one workpiece comprises a single workpiece 20, it is contemplated that the at least one connecting surface can comprise a single, continuous connecting surface 28. Similarly, when the at least one workpiece comprises a plurality of workpieces 20, it is contemplated that the at least one connecting surface can comprise a plurality of connecting surfaces 28 that cooperate to define the weld zone 12,

[0031] As shown in FIG. 3, the plurality of stacked metallic layers 30 is stacked within the weld zone 12 relative to the weld axis 14. In some aspects, the weld axis can be substantially perpendicular to at least one of the interior surface 24 and the exterior surface 26 of the work piece 20. Alternatively, it is contemplated that the weld axis can be at an oblique angle relative to at least one of the interior surface 24 and the exterior surface 26 of the work piece 20. Each metallic layer 30 has a first face 32 and an opposed second face 34. Each respective first face and second face 32, 34 extend between opposed first and second side edges 36, 38. At least a portion of the first and second side edges 36, 38 of each metallic layer 30 is welded to the at least one connecting surface 28 of the outer wall 22 of a workpiece 20 of the at least one work piece. In exemplary aspects, the weld axis 14 can pass through a center point on the first and second faces 32, 34 of each respective layer 30. In additional exemplary aspects, it is contemplated that the first and second faces 32, 34 of each layer 30 of the plurality of layers can be positioned in a substantially perpendicular orientation relative to the weld axis 14. However, in other exemplary aspects, it is contemplated that the first and second faces 32, 34 of at least one layer 30 of the plurality of layers can be positioned at an oblique angle relative to the weld axis 14.

[0032] In one aspect, the stacked metallic layers 30 comprise carbon steel, low alloy steel, high alloy steel, or non-ferrous metal, or a combination thereof. In another aspect, the layered weld joint is not specific to any kind of material. In a further aspect, the layered weld joint 10 can be applied to any metal used in a welded construction, pressure-containing component. In an even further aspect, the weld metal can be chosen to be compatible with a base material used in standard industry practice.

[0033] In one aspect, the layered construction can be weaker than a solid component. Accordingly, depending on the specific design details, the invention can compensate for the strength reduction by using a higher strength material, by adding additional metallic layers on or extending beyond the exterior surface 26 of the at least one workpiece 20, or a

combination of both, in another aspect, the layered construction can be stronger than a solid component.

[0034] in another aspect, the at least one workpiece 20 comprises at least a portion of a vessel. Thus, it is contemplated that the layered weld joint 10 can be located on a vessel or in a vessel, in a further aspect, the vessel is a pressure-retaining vessel. In an even further aspect, the vessel comprises a thick outer wall.

[0035] in one aspect, the usefulness of the repair joint can be determined by the thickness of the outer wall 22 of the at least one workpiece 20 (e.g. vessel). In another aspect, it is contemplated that the thicker the outer wall 22 of the at least one workpiece 20 (e.g., vessel), the more useful the repair. In a further aspect, it is contemplated that a small workpiece (e.g., vessel) can have less wall thickness. In an even further aspect, the repair can be performed for larger equipment having a thicker outer wall.

[0036] In one aspect, the layered weld joint 10 extends beyond the exterior surface 26 of the outer wall of the at least one workpiece 20 relative to the weld axis 14. In another aspect, the layered weld joint 10 is substantially flush with— or extends minimally beyond— the exterior surface 26 of the outer wall 22 of the at least one workpiece 20 relative to the weld axis 14. In a further aspect, the layered weld joint 10 can extend significantly beyond the exterior surface 26 of the outer wall 22 of the at least one workpiece 20 relative to the weld axis 14. In a yet further aspect, the extent of the additional metallic layers will be determined by the structural design of the workpieces.

[0037] In an even further aspect, the layered weld joint 10 can extend beyond the exterior surface 26 of the outer wall 22 of the at least one workpiece 20 relative to the weid axis 14 by a distance corresponding to 1% to 20% of the total thickness of the layered weld joint. For example, it is contemplated that the layered weld joint 10 can extend beyond the exterior surface 26 of the outer wall 22 of the at least one workpiece 20 relative to the weld axis 14 by a distance corresponding to 2 ¾, 3 %, 4 %, 5 %, 6 %, 7 ¾, 8 %, 9 %, 10 %, 11 %, 12 %, 13 %, 14 %, 15 %, 16 %, 17 %, 18 %, and 19 % of the total thickness of the layered weld joint. In another aspect, the range ca be derived from any two exemplary values. For example, 1 % to 10 % of the layered weld joint 10 can extend beyond the exterior surface 26 of the outer wall 22 of the workpieces 20. [ΘΘ38] In one aspect, the stacked metallic layers 30 comprise the same material as the at least one workplace 20 (e.g., vessel). In another aspect, some of the stacked metallic layers 30 comprise the same material as the at least one workpiece 20 (e.g., vessel). In a further aspect, the stacked metallic layers 30 comprise a different material than the at least one workpiece 20 (e.g., vessel). In an even further aspect, the stacked metallic layers 30 comprise a similar material to the at least one workpiece 20 (e.g., vessel). In one aspect, the stacked metallic layers 30 comprise a material with a higher strength than the at least one workpiece 20 (e.g., vessel).

[0039] in one aspect, some of the stacked metallic layers 30 are insert plates. The insert plates can be inserted into the at feast one workpiece 20 (e.g., vessel), in another aspect, the material of the insert plates can be the same as the at least one workpiece 20 (e.g., vessel). In a further aspect, the material of the insert plates can be similar to the at least one workpiece 20 (e.g., vessel). In an even further aspect, the material of the insert plates can be modified to be more resistant to process conditions. In a yet further aspect, the material of the insert plates can be a higher strength material to provide improved structural integrity.

[0040] In one aspect, the stacked metallic layers 30 comprise a weep hole 40. As used herein, the weep hole 40 is a small opening in the outermost surface of the weld. In another aspect, the weep hole 40 can extend at least partially through a single, outermose layer 30 of the plurality of stacked metallic layers. Alternatively, it is contemplated that the weep hole 40 can extend through a plurality of adjacent layers 30. in a further aspect, the weep hole 40 does not penetrate to the inside diameter of the vessel when originally added to the vessel. The weep hole can also be referred to herein as a "tell-tale hole." It is contemplated that the weep hole 40 can allow a person to determine the stability of the weld. In another aspect, it is contemplated that the weep hole 40 can allow a person to determine whether the weld is leaking.

[0041] In one aspect, the at least one workpiece 20 (e.g., vessel) comprises a weldable material, The at least one workpiece 20 (e.g., vessel) can be made of a weldable metallic material. In another aspect, the at least one workpiece 20 (e.g., vessel) does not comprise a non-metallic material. In a further aspect, the at least one workpiece 20 (e.g., vessel) substantially does not comprise any non-metallic material. [0042] In a further aspect, it is contemplated that the weld joint 10 can restore the structural integrity of the at least one workpiece 20 (e.g., vessel) so that it can handle operating conditions within the original design specifications of the workpieces (vessel).

[0043] In one aspect, the stacked metallic layers 30 comprise metal strips.

[0044] In one aspect, the stacked metallic layers 30 do not comprise an adhesive between the layers. In another aspect, the stacked metallic layers 30 comprise an adhesive between the layers. In a further aspect, the plurality of stacked metallic layers 30 can be joined using welding between the layers. In still a further aspect, adjacent layers 30 of the plurality of stacked layers can be positioned in contact with one another. In a yet further aspect, at least two adjacent layers 30 of the plurality of stacked metallic layers 30 are not in contact. When the plurality of stacked metallic layers 30 are not in contact, it is contemplated that a gas, for example, air or an inert gas, or another material, such as another metal, a nonmetal, or a plastic, can be positioned between adjacent layers 30. As used herein, the term "stacked" refers to a configuration of layers in which the layers are positioned in close proximity relative to the weld axis, regardless of the orientation of the weld axis. It is understood that the layers 30 can be "stacked" when each layer is in physical contact with its adjacent layers, and when there is a space between at least two adjacent layers.Thus, the term "stacked" does not require that the layers 30 touch one another. ΘΘ45] In another aspect, the at least one connecting surface 28 of the at least one workpiece is axially tapered relative to the weld axis 14. Thus, it is contemplated that the diameter of the weld zone 12 proximate the interior surface 24 of the at least one workpiece 20 can be smaller or larger than the diameter of the weld zone proximate the exterior surface 26 of the at least one workpiece. Optionally, the weld zone has a single V-shape. In a further aspect, the weld zone can have any suitable shape.

[0046] In one aspect, each metallic layer 30 has a thickness ranging from 5 mm to 15 mm, including exemplary values of 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, and 14 mm. The range can be derived from any two exemplary values. For example, each metallic layer 30 can have a thickness ranging from 6 mm to 15 mm.

[0047] In one aspect, the metallic layers 30 can have different thicknesses. In another aspect, the thickness of each metal layer 30 can be a fraction of the thickness of the outer wall 22 of the at least one workpiece 20. For example, the thickness of each respective metallic layer 30 can be between 5 % to 15 % of the thickness of the outer wall 22, including exemplary values of 5 %, 6 %, 7 %, 8 %, 9 %, 10 %, 11 %, 12 %, 13 %, and 14 % of the thickness of the outer wall. In a further aspect, the range can be derived from any two exemplary values. For example, the thickness of each respective metallic layer 30 can range from 8% to 13 % of the thickness of the outer wall 22.

[0048] In another aspect, the combined thickness of all the metallic layers 30

substantially equals the thickness of the outer wall 22 of the workpiece or workpieces 20 (e.g., vessel) being repaired. In a further aspect, additional metallic layers 30 can be added over the exterior surface 26 of the outer wall 22 of the at least one workpiece 20, thereby providing reinforcement to the weld joint 10. In this aspect, as shown in FIG. 3, it is contemplated that the metallic layers 30 positioned over the exterior surface 26 of the outer wall 22 can have a greater diameter than the metallic layers positioned within the weld zone 12. Thus, it is further contemplated that the metallic layers 30 positioned over the exterior surface 26 of the outer wall 22 can radial ly extend beyond the weld zone 12 relative to the weld axis 14.

[0049] In another aspect, the stacked metallic layers 30 comprise a corrosion resistant material or a cracking resistant material, or a combination thereof. In one aspect, the layered weld joint 10 can use a lower strength metal than commonly used. In another aspect, the lower strength metal can have a greater resistance to stress corrosion cracking. In a further aspect, the lower strength metal can be used for the innermost, service-exposed layer of the stacked material layers 30. In an even further aspect the higher corrosion and cracking resistant material can be used at the outermost layer of the stacked material layers 30, such as, for example and without limitation, an insert layer exposed to the external environment.

[0050] In one aspect, the layered weld joint 10 satisfies the local strain evaluation at 1,7 x design load as measured by ASME VIII Div 2 §5.3.3. The layered weld joint 10 can satisfy the local strain evaluated using the equation (1):

* (1) wherein: asl = material factor for the multiaxial strain limit

— limiting triaxial strain

— uniaxial strain limit rn_? = material factor for the multiaxial strain limit

σ₁, σ₂, σ₃ = principal stresses in the three directions

a_e = von Mises stress

[0051] At 1.7 times the design load, the design shows: e_p.«≤ ¾ (2) wherein:

^£peq— equivalent plastic strain

[0052] The plot of the safety factor of the design is shown by the following equation:

(3)

speq

[0053] In another aspect, the layered weld joint 10 satisfies the plastic collapse evaluation at 2.4 x design loads as measured by ASME VIII Div 2 §5.2.4. In a further aspect, the layered weld joint 10 satisfies the elastic-plastic analysis as per the requirements of ASME VIII Div 2, Part S.

[0054] In one aspect, the layered weld joint meets the requirements of ASME VIII Div 2, Part 5 for protection against local failure and protection against plastic collapse.

[ΘΘ55] The layered weld joints 10 disclosed herein can be performed by the methods disclosed herein.

C. METHODS OF FORMING THE LAYERED WELD JOINT

[0056] Also disclosed herein are methods for forming a layered weld joint, comprising: sequentially welding each of a plurality of metallic layers within a weld zone, the weld zone being defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a workpiece of the at least one workpiece, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges, wherein the plurality of metallic layers are sequentially welded such that at least a portion of each first side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece and at least a portion of each second side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece, thereby providing a weld joint comprised of a plurality of stacked metallic layers welded within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis.

[0057] In another aspect, the method can comprise any weld process appropriate for the materials to be welded. In a further aspect, the weld process can use the standard industry approach. In one aspect, the weld process can be any weld process appropriate for the construction of pressure vessels and/or thick-walled piping. In another aspect, the welding comprises arc welding.

[0058] In one aspect, forming a layered weld joint takes less time than the time for forming a conventional weld joint. In another aspect, the amount of weld metal deposited during the subject methods is lower than weld metal deposited during conventional weld repairs. In a further aspect, using a reduced amount of weld metal reduces the amount of weld defects. In a yet further aspect, using the layered weld joint can arrest or slow down cracks staring at the inner metal insert,

[0059] In one aspect, where the at least one workpiece comprises at least a portion of a vessel, the welding restores the structural integrity of a vessel to within the vessel's original design specification. In another aspect, the welding arrests or slows the formation of cracks in the vessel.

[0060] In another aspect, the connecting surfaces 28 of the at least one workpiece 20 can be axially tapered relative to the weld axis 14. In an additional aspect, the weld zone 12 has a single V-shape. In a further aspect, the weld zone 12 can have any suitable shape.

[0061] The methods disclosed herein can prepare the layered weld joints disclosed herein.

D. ASPECTS

[0062] The disclosed compositions and methods include at least the following aspects.

[0063] Aspect 1 : A layered weld joint, comprising; a weld zone defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a workpiece of the at least one work piece; and a plurality of stacked metallic layers disposed within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges and wherein at least a portion of the first and second side edges of each metallic layer is welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece.

[0064] Aspect 2: The layered weld joint of aspect I, wherein the stacked metallic layers comprise carbon steel low alloy steel, high alloy steel, or non-ferrous metal, or a

combination thereof.

[0065] Aspect 3 : The layered weld joint of any of aspects 1 -2. wherein the at least one workpiece comprises at least a portion of a vessel.

[0066] Aspect 4: The layered weld joint of aspect 3, wherein the vessel has a thick outer wall.

[0067] Aspect 5: The layered weld joint of any of aspects 1-4, wherein the layered weld joint extends beyond the exterior surface of the outer wall of the at least one workpiece relative to the weld axis.

[0Θ68] Aspect 6: The layered weld joint of any of aspects 3-5, wherein the stacked metallic layers comprise the same material as the vessel.

[0069] Aspect 7: The layered weld joint of any of aspects 3-6, wherein the stacked metallic layers comprise a material with a higher strength than the vessel.

[0070] Aspect 8: The layered weld joint of any of aspects 1-7, wherein the stacked metallic layers comprise a weep hole.

[0071] Aspect 9: The layered weld joint of any of aspects 3-8, wherein the vessel comprises a weldable material.

[0072] Aspect 10: The layered weld joint of any of aspects 1-9. wherein the stacked metallic layers comprise metal strips.

[0073] Aspect 11 : The layered weld joint of any of aspects 1-11, wherein the stacked metallic layers do not comprise an adhesive between the layers. [0074] Aspect 12: The layered weld joint of any of aspects 1-12, wherein the at least one connecting surface of the at least one workpiece is axialiy tapered relative to the weld axis.

[0075] Aspect 13: The layered weld joint of any of aspects 1 -12, wherein each metallic layer has a thickness ranging from 5 mm to 15 mm.

[0076] Aspect 14: The layered weld joint of any of aspects 1-13, wherein the stacked metallic layers comprise a corrosion resistant material or a cracking resistant material, or a combination thereof,

[0077] Aspect 15 : The layered weld joint of any of aspects 3-14, wherein the vessel is a pressure-retaining vessel.

[0078] Aspect 16: A method for forming a layered weld joint, comprising: sequentially welding each of a plurality of metallic layers within a weld zone, the weld zone being defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a workpiece of the at least one workpiece, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges, wherein the plurality of metallic layers are sequentially welded such that at least a portion of each first side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece and at least a portion of each second side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece, thereby providing a weld joint comprised of a plurality of stacked metallic layers welded within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis.

[0079] Aspect 17: The method of aspect 16, wherein forming a layered weld joint takes less time than the time for forming a conventional layered weld joint,

[0080] Aspect 18: The method of any of aspects 16-17, wherein the welding comprises arc welding.

[0081] Aspect 19: The method of any of aspects 16-18, wherein the at least one workpiece comprises at least a portion of a vessel, and wherein the welding restores the structural integrity of a vessel to within the vessel's original design specification. [0082] Aspect 20: The method of any of aspects 16-19, the at least one workpiece comprises at least a portion of a vessel, and wherein the welding arrests or slows the formation of cracks in a vessel.

[0083] Aspect 21 : The layered weld joint of aspect 1 , wherein the layered weld joint meets at least one requirement of ASME VIII Div 2, Part 5.

[0084] Aspect 22: The layered weld joint of aspect 1 or 21, wherein the layered weld joint protects against local failure at 1.7 times a design load of the layered weld joint.

[0085] Aspect 23: The layered weld joint of aspect 1 or 21, wherein the layered weld joint avoids plastic collapse at 2.4 times a design load of the layered weld joint.

E, EXPERIMENTAL

[0086] The following example is put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.

[0087] The design of the proposed layered weld joint was evaluated using computer modeling by means of elastic-plastic analysis. The elastic-plastic analysis was performed as per the requirements of ASME VIII Div 2, Part 5. The local strain evaluation was evaluated using computer modeling at 1.7 x design load (ASME VIII Div 2 §5.3.3) and the plastic collapse evaluation was evaluated using computer modeling at 2.4 x design loads (ASME VIII Div 2 §5.2.4).

[0088] The cylindrical shell in the model has an internal design pressure of 6.85 MPa, an internal design temperature of 280 °C, an inner diameter of 7670 mm, and a wall thickness of 118 mm. The material of construction is SA-543 GR B CL 1 carbon steel. The tested model has twelve layers with a thickness of each layer is 10 mm, and the layer material is SA-516 GR 70 carbon steel. [0089] The protection against local failure was demonstrated by the local strain evaluation. The equation used to evaluate the local strain is:

( ^&sl σ^ +σ^σ^_„I

(1)

material factor for the m ultiaxial stra dn limit

¾ = limiting triaxial strain

uniaxial strain limit

m₂ = material factor for the m ultiaxial stra dn limit

, σ₃ ~ principal stresses in the t hree directii 3 s

a_e = von Mises stress

[ΘΘ90] At 1.7 times the design load, the design shows

(2)

wherein:

E_vm — equivalent plastic strain

[0091] The plot of the safety factor of the design is shown by the following equation:

[0092] The results of the local strain assessment are shown in FIG. 4 for one aspect of a vessel with a layered weld joint. FIG. 4 shows that the design protects against local failure by being within the requirement of 1.7 times the design load, as defined by ASME VIII Div 2 §5.3.3.

[0093] The calculated plastic strain levels {e_peq) are shown in FIG. 5 for one aspect of a vessel with a layered weld joint. FIG. 5 shows that low levels of plastic strain are generated in all layers at 1.7 times the design load.

[0094] A load-deflection graph of the elastic-plastic analysis for the design assessment is shown in FIG. 6 for one aspect of a vessel with a layered weld joint. FIG. 6 shows the applied load factor as compared to the maximum displacement in millimeters. The graph

I ? illustrates that successful convergence up to 2.4 times the design load was achieved, thereby meeting the requirements for protection against plastic collapse as per ASME VIII Div 2 §5.2.4.

[0095] The results of the design assessment are shown in FIG, 7 for one aspect of a vessel with a layered weld joint. FIG. 7 illustrates the total displacement at 2.4 times the design load.

[0096] The results of the design assessment are shown in FIG. 8 for one aspect of a vessel with a layered weld joint. FIG. 8 shows the equivalent (von-Mises) stress levels at 1.0 times the design load.

[0097] According to the results from the computer modeling, the layered weld joint meets the requirements of ASME Vill Div 2, Part 5 for protection against local failure and protection against plastic collapse. As such, the computer modeling shows that the procedure to prepare a layered weld joint will be a suitable repair method.

Claims

What Is claimed is:

1. A layered weld joint, comprising:

a weld zone defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a workpiece of the at least one workpiece; and

a plurality of stacked metallic layers disposed within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges and wherein at least a portion of the first and second side edges of each metallic layer is welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece.

2. The layered weld joint of claim 1 , wherein the stacked metallic layers comprise

carbon steel, low alloy steel, high alloy steel, or non-ferrous metal, or a combination thereof,

3. The layered weld joint of claim 1, wherein the at least one workpiece comprises at least a portion of a vessel.

4. The layered weld joint of claim 3, wherein the vessel has a thick outer wall.

5. The layered weld joint of claim 1 , wherein the layered weld joint extends beyond the exterior surface of the outer wall of the at least one workpiece relative to the weld

6. The layered weld joint of claim 3, wherein the stacked metallic layers comprise the same material as the vessel,

7. The layered weld joint of claim 3, wherein the stacked metallic layers comprise a material with a higher strength than the vessel.

8. The layered weld joint of claim 1, wherein the stacked metallic layers comprise a weep hole.

9. The layered weld joint of claim 3, wherein the vessel comprises a weldable material.

10. The layered weld joint of claim 1, wherein the stacked metallic layers comprise metal strips.

11. The layered weld joint of claim 1, wherein the stacked metallic layers do not comprise an adhesive between the layers,

32. The layered weld joint of claim 1, wherein the at least one connecting surface of the at least one workpiece is axialSy tapered relative to the weld axis.

13. The layered weld joint of claim 1, wherein each metallic layer has a thickness ranging from 5 mm to 15 mm.

14. The layered weld joint of claim 1, wherein the stacked metallic layers comprise a corrosion resistant material or a cracking resistant material, or a combination thereof.

15. The layered weld joint of claim 3, wherein the vessel is a pressure-retaining vessel.

16. A method for forming a layered weld join comprising:

sequentially welding each of a plurality of metallic layers within a weld zone, the weld zone being defined by at least one connecting surface of an outer wall of at least one workpiece, the outer wall of each workpiece of the at least one workpiece having an interior surface and an exterior surface, wherein each connecting surface of the at least one connecting surface extends between the interior and exterior surfaces of the outer wall of a workpiece of the at least one workpiece, each metallic layer having a first face and an opposed second face wherein each respective first face and second face extends between opposed first and second side edges, wherein the plurality of metallic layers are sequentially welded such that at least a portion of each first side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece and at least a portion of each second side edge of each metallic layer is sequentially welded to the at least one connecting surface of the outer wall of a workpiece of the at least one workpiece, thereby providing a weld joint comprised of a plurality of stacked metallic layers welded within the weld zone, the plurality of stacked metallic layers being stacked relative to a weld axis.

17. The method of claim 16, wherein forming a layered weld joint takes less time than the time for forming a conventional layered weld joint.

18. The method of claim 16, wherein the welding comprises arc welding.

19. The method of claim 16, the at least one workpiece comprises at least a portion of a vessel, and wherein the welding restores the structural integrity of the vessel to within the vessel's original design specification.

20. The method of claim 16, the at least one workpiece comprises at least a portion of a vessel, and wherein the welding arrests or slows the formation of cracks in the vessel.

21. The layered weld joint of claim 1, wherein the layered weld joint meets at least one requirement of ASME VIII Div 2, Part 5.

22. The layered weld joint of claim 21, wherein the layered weld joint is configured to protect against local failure at 1.7 times a design load of the layered weld joint.

23. The layered weld joint of claim 21, wherein the layered weld joint is configured to avoid plastic collapse at 2.4 times a design load of the layered weld joint.