Manufacturing method of double-lug type storage tank barrel

Abstract

The invention discloses a manufacturing method of a double-lug type storage tank barrel. The manufacturing method comprises the steps that barrel section blocks are manufactured, a single-side barrel is installed and welded, an inlaying barrel section is cut off to form a C-shaped first side barrel and a C-shaped second side barrel, a longitudinal partition plate is installed, and the first side barrel and the second side barrel are folded. The manufacturing method has the following technical advantages: 1, the problems of roundness maintenance and assembly precision of the first side barrel and the second side barrel in the assembly welding process are solved by adopting the reusable inlaying barrel section blocks; 2, the inlaying cylinder section blocks and the body cylinder section blocks are spliced and welded to form a plurality of circular cylinder sections, and circular seams of the circular cylinder sections are assembled and welded on a welding roller frame, so that the problem that automatic or semi-automatic welding cannot be realized due to incomplete structures of the C-shaped first side cylinder body and the C-shaped second side cylinder body is solved; and 3, the problem that a large number of scaffolds need to be erected for high-altitude operation in the assembling and welding process of the first side barrel body, the second side barrel body and the longitudinal bulkhead is solved through the assembling platform during folding.

Description

Technical Field

[0001] The invention relates to the technical field of LNG transport ships, and in particular to a method for manufacturing a double-ear storage tank cylinder. Background Art

[0002] LNG (liquefied natural gas) carriers are a major industry in the LNG industry chain. They play the role of "super refrigerated trucks" for transporting LNG at sea and have become the main mode of ocean-going natural gas transportation. LNG storage tanks are the core equipment of C-type independent tank LNG carriers. With the surge in domestic LNG demand and transportation volume, LNG carriers and LNG storage tanks are also developing in the direction of large-scale.

[0003] At present, in order to increase the loading capacity of the liquid cargo tanks of large LNG transport ships, their LNG storage tanks generally adopt the structure of double-ear storage tanks, which have the advantages of reducing related equipment, optimizing the layout in the cabin, and large cargo capacity. The cylinder of the double-ear storage tank is formed by connecting two groups of C-type cylinder sections with the longitudinal bulkhead, and the cylinder as a whole is a structure formed by two single cylinders intersecting. Different from general cylindrical storage tanks, the two groups of C-type cylinder sections of the double-ear storage tank are incomplete cylindrical structures. Whether the cylinder sections are welded in the vertical or horizontal direction, the circumferential seam can only be welded in all positions or horizontally by arc welding. There are technical problems such as low welding efficiency, high welding difficulty, difficult to ensure welding quality, and poor weld surface forming quality. The process is complicated, the construction is difficult, and a lot of weld surface grinding is required.

[0004] Therefore, how to design a new cylinder assembly and welding method for double-ear storage tanks for LNG transport ships is a technical problem that urgently needs to be solved in the installation of large double-ear storage tanks. Summary of the invention

[0005] In order to overcome the technical problems described in the prior art, the object of the present invention is to provide a method for manufacturing a double-ear storage tank cylinder.

[0006] The present invention provides a method for manufacturing a double-ear storage tank cylinder, comprising the following steps:

[0007] Step 1, making cylinder segment blocks: the cylinder of the double-ear storage tank includes a first side cylinder, a second side cylinder and a longitudinal bulkhead, and a plurality of main cylinder segment blocks and inlay cylinder segment blocks used to form the first side cylinder and the second side cylinder are made;

[0008] Step 2, assembling and welding the first side cylinder: on the assembly platform, vertically weld a number of main cylinder segments and embedded cylinder segments to form a number of circular cylinder segments, turn each circular cylinder segment 90 degrees, hoist it onto the welding roller frame, and horizontally weld it to form a single-side cylinder, hoist the single-side cylinder onto the assembly platform and place it vertically, cut and remove the embedded cylinder segment blocks to form a C-shaped first side cylinder;

[0009] Step 3, assembling and welding the second side cylinder: repeat step 2 to complete the assembly and welding of the second side cylinder that is axially symmetrical with the first side cylinder;

[0010] Step 4, closing the first side cylinder and the second side cylinder: inserting the longitudinal bulkhead between the first side cylinder and the second side cylinder on the assembly platform, and welding them together to form a double-ear storage tank cylinder.

[0011] As a preferred technical solution, the implementation of step 1 also includes the following contents: according to the circumference and height dimensions of the double-ear storage tank cylinder, the number of main cylinder segment blocks, embedded cylinder segment blocks and circular cylinder segments is set.

[0012] As a preferred technical solution, when making the patched cylinder segment blocks in step 1, ordinary steel plates are used to reduce material costs.

[0013] As a preferred technical solution, when making the main body cylinder segment block in step 1, the main body cylinder segment block to be welded with the embedded cylinder segment block should retain a cutting margin of 30 to 40 mm.

[0014] As a preferred technical solution, an assembly platform needs to be set up before assembling and welding the first side cylinder in step 2. The assembly platform setting up includes the following: first prepare a number of assembly jigs that can be fixed to the ground, draw the assembly jig layout line along the vertical projection of the first side cylinder, and then evenly distribute the several assembly jigs along the layout line and fix them on the ground to complete the setting up, so as to provide vertical assembly for a number of main cylinder segment blocks and embedded cylinder segment blocks.

[0015] As a preferred technical solution, a welding roller frame needs to be set up before assembling and welding the first side cylinder in step 2. The setting up of the welding roller frame includes the following: first prepare three groups of support rods that can be fixed to the ground, evenly distribute the three groups of support rods according to the radial size of the circular cylinder segment and fix them to the ground, and symmetrically configure two groups of pulleys on the top of the support rods to complete the setting up, so that the circular cylinder segment can be rotatably placed on the welding roller bracket in the transverse direction to perform circumferential welding of adjacent circular cylinder segments.

[0016] As a preferred technical solution, in step 2, the single-side cylinder is hoisted onto the assembly platform and the patched cylinder segments are cut and removed to form the first side cylinder. The removed patched cylinder segments are further used for assembly and welding of the second side cylinder.

[0017] As a preferred technical solution, the main body cylinder segment blocks and the patch cylinder segment blocks in step S1 are formed by roller molding.

[0018] As a preferred technical solution, when each circular cylinder segment is flipped 90 degrees and hoisted onto the welding roller frame for assembly welding in step 2 and step 3, a temporary internal support frame is added to each circular cylinder segment to prevent the circular cylinder segment from deforming due to its own weight.

[0019] As a preferred technical solution, the following contents are also included after step S4: non-destructive testing is performed on the cylinder of the binaural storage tank; wherein the testing methods include radiographic testing, ultrasonic testing, coloring and visual inspection.

[0020] In summary, the present invention has the following technical effects:

[0021] The present invention discloses a method for manufacturing a cylinder body of a double-ear storage tank, which comprises manufacturing cylinder segment blocks, assembling and welding a first side cylinder body, assembling and welding a second side cylinder body, closing the first side cylinder body and the second side cylinder body, and welding the C-shaped cylinder bodies on both sides of the double-ear storage tank to the longitudinal partition plate; wherein, in the assembly and welding of the first side cylinder body and the second side cylinder body, main cylinder segment blocks and inlay cylinder segment blocks are used, and the inlay cylinder segment blocks are subsequently cut and removed. The manufacturing method of the double-ear storage tank cylinder body has the following technical advantages: 1. The present application adopts a method that reusable patching cylinder segment blocks are used to assemble the main cylinder segment blocks into a circular cylinder segment structure, which solves the problem of maintaining the roundness and assembly accuracy of the first side cylinder body and the second side cylinder body of the C-shaped body during the assembly and welding process; 2. The present application adopts the patching cylinder segment blocks and the main cylinder segment blocks to first assemble and weld to form a plurality of circular cylinder segments for forming the first side cylinder body and the second side cylinder body, and assembles and welds the annular seams of each circular cylinder segment on a welding roller frame, which solves the problem of the first side cylinder body and the second side cylinder body of the C-shaped body. The problem that the side cylinder cannot be welded automatically or semi-automatically due to its incomplete structure is solved, the quality and efficiency of the circumferential seam welding of the double-ear storage tank cylinder is improved, and the surface grinding process of the weld is eliminated; 3. In this application, a new method of welding the first side cylinder, the second side cylinder and the longitudinal bulkhead on the assembly platform is adopted when closing the first side cylinder and the second side cylinder, which avoids the problem that a large number of scaffoldings need to be set up for high-altitude operations during the assembly of the first side cylinder and the second side cylinder, reduces the difficulty of assembling the first side cylinder and the second side cylinder, and improves the construction quality of the double-ear storage tank cylinder. Therefore, compared with the existing double-ear storage tank manufacturing technology, the manufacturing method of the double-ear storage tank cylinder provided by the present invention has obvious technical advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 2 is a schematic diagram of the three-dimensional structure of a double-ear storage tank cylinder according to an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of the process of assembling and welding the first side cylinder according to an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of a process of closing a first side cylinder and a second side cylinder according to an embodiment of the present invention;

[0026] The meanings of the reference numerals are as follows:

[0027] 1-first side cylinder, 11-main cylinder segment block, 12-embedded cylinder segment block, 2-second side cylinder, 3-longitudinal bulkhead, 4-assembly jig, 5-welding roller frame, 6-temporary inner support frame. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings in this embodiment to clearly and completely describe the technical solution in this embodiment. The present embodiment described herein is only for illustrative purposes and is not intended to limit the scope of protection of the present invention. Therefore, it should be understood that various modifications and changes can be made to this embodiment without departing from the scope of protection of the present invention.

[0029] In the description of the present invention, unless otherwise clearly specified and limited, the term "and / or" includes any and all combinations of one or more associated listed items. Unless otherwise specified or explained, the terms "connection", "fixed", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, an integral connection, an electrical connection, or a signal connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Further, in the description of the present invention, it should be understood that the directional words described in the present embodiment are described at the angles shown in the accompanying drawings and should not be understood as limiting the present embodiment. It should also be understood that in the context, when it is mentioned that an element or feature is connected to another element (one or more), it can not only be directly connected to the other (one or more) elements, but also indirectly connected to the other (one or more) elements through an intermediate element.

[0031] Before introducing the technical solution of the present invention, it is necessary to explain the background of the invention. It is common that, at present, in order to increase the loading capacity, the LNG storage tanks of large LNG transport ships generally adopt the structure of double-ear storage tanks, which have the advantages of reducing related equipment, optimizing the layout in the cabin, and large cargo capacity. The cylinder of the double-ear storage tank is formed by connecting two groups of C-type cylinder sections with longitudinal bulkheads, and the cylinder as a whole is a structure formed by two single cylinders intersecting. Different from general cylindrical storage tanks, the two groups of C-type cylinder sections of the double-ear storage tank are incomplete cylindrical structures. Whether the cylinder sections are welded in the vertical or horizontal direction, the circumferential seam can only be welded in all positions or horizontally by arc welding. There are technical problems such as low welding efficiency, high welding difficulty, difficult to ensure welding quality, and poor weld surface forming quality. The process is complicated, the construction is difficult, and a large amount of weld surface grinding is required.

[0032] In order to overcome the technical problems of the prior art, the present invention aims to provide a method for manufacturing a double-ear storage tank cylinder. Figures 1 to 3 An exemplary embodiment of the present invention provides a method for manufacturing a double-ear storage tank cylinder body, wherein a reusable patching cylinder segment block 12 is used to assemble the main cylinder segment blocks 11 of the double-ear storage tank cylinder body into a circular cylinder segment structure, and the circular cylinder segment annular seams are assembled and welded on a welding roller frame 5. The circular cylinder segment annular seams are welded by submerged arc flat welding to form a circular cylinder body, and then the circular cylinder segment is turned 90 degrees and placed vertically on an assembly platform, and the patching cylinder segment blocks 12 are cut and removed to form a C-shaped first side cylinder body 1. The cut patching cylinder segment blocks 12 can be used in the assembly and welding operation of a second side cylinder body 2 which is a symmetrical structure with the first side cylinder body 1. After the circular cylinder body is formed, the patching cylinder segment blocks 12 are cut and removed in the same way to form a second side cylinder body 2. Finally, the C-shaped first side cylinder body 1 and the second side cylinder body 2 are welded with the middle longitudinal bulkhead 3 to complete the manufacture of the double-ear storage tank cylinder. This manufacturing method has the advantages of ingenious cylinder segment assembly method, high assembly efficiency, automatic submerged arc flat welding, high quality and reliable welding efficiency, good weld surface formation, and can avoid weld surface grinding. Figures 1 to 3 , this production method comprises the following steps:

[0033] Step 1, making cylinder segment blocks: the double-ear storage tank includes a first side cylinder 1, a second side cylinder 2 and a longitudinal bulkhead 3, and a plurality of main cylinder segment blocks 11 and inlay cylinder segment blocks 12 used to form the first side cylinder 1 and the second side cylinder 2 are made;

[0034] It should be noted that, in some embodiments, the implementation of step 1 also includes the following content: according to the circumference and height size of the binaural storage tank cylinder, the number of the main body cylinder segment block 11, the patch cylinder segment block 12 and the circular cylinder segment is set. Preferably, in this embodiment, the circular cylinder segment is set to three groups. In some embodiments, when making the patch cylinder segment block 12 in step 1, the main body cylinder segment block 11 uses 7Ni steel, which has the characteristics of high strength and excellent low-temperature toughness, and the patch cylinder segment block 12 uses ordinary steel plate. Because the patch cylinder segment block 12 will be separated from the main body of the binaural storage tank cylinder during subsequent cutting, the use of ordinary steel plate can reduce material costs. In some embodiments, when making the main body cylinder segment block 11 in step 1, when making the main body cylinder segment block 11 in step 1, the main body cylinder segment block 11 welded with the patch cylinder segment block 12 should retain a cutting margin of 30 to 40 mm to avoid damaging the structure of the first side cylinder 1 or the second side cylinder 2 during subsequent cutting. As a preferred technical solution, in some embodiments, the main body cylinder segment block 11 and the patch cylinder segment block 12 in step S1 are formed by roller molding.

[0035] Step 2, assembling and welding the first side cylinder 1: on the assembly platform, vertically weld a number of main cylinder segment blocks 11 and inlay cylinder segment blocks 12 to form three groups of circular cylinder segments, turn each circular cylinder segment 90 degrees, hoist it onto the welding roller frame 5, and horizontally weld it to form a single-side cylinder, hoist the single-side cylinder onto the assembly platform and place it vertically, cut and remove the inlay cylinder segment blocks 12 to form a C-shaped first side cylinder 1;

[0036] It should be noted that, before assembling and welding the first side cylinder in step 2, an assembly platform needs to be set up, and the assembly platform setting up includes the following steps: first prepare a number of assembly jigs that can be fixed on the ground, such as Figure 2 As shown, this assembly jig can clamp the main body cylinder section blocks and the patch cylinder section blocks, draw the assembly jig layout line along the vertical projection of the first side cylinder, and then evenly distribute a number of assembly jigs along the layout line and fix them on the ground to complete the erection, so as to provide a number of main body cylinder section blocks and patch cylinder section blocks for vertical assembly and layout.

[0037] Furthermore, in some embodiments, before assembling and welding the first side cylinder 1 in step 2, a welding roller frame 5 needs to be set up. The setting up of the welding roller frame 5 includes the following steps: first, three groups of support rods that can be fixed to the ground are prepared, and the three groups of support rods are evenly spaced and fixed to the ground according to the radial size of the circular cylinder segment, and two groups of pulleys are symmetrically arranged on the top of the support rods to complete the setting up, so that the circular cylinder segment can be rotatably placed on the welding roller bracket in the horizontal direction to perform the circumferential seam welding of adjacent circular cylinder segments. After the circumferential seam welding of two adjacent circular cylinder segments is completed, a third group of welding roller frames are set on both sides thereof to perform the subsequent circumferential seam assembly and welding of the cylinder segments.

[0038] Step 3, assembling and welding the second side cylinder 2: repeat step 2 to complete the assembly and welding of the second side cylinder 2 which is axially symmetrical with the first side cylinder 1; it should be noted that, as a preferred technical solution, in some embodiments, in step 2, the single-sided cylinder is hoisted onto the assembly platform and the patching cylinder segment blocks 12 are cut and removed to form the first side cylinder 1, and the patching cylinder segment blocks 12 after removal are continuously used for the assembly and welding of the second side cylinder. The method of assembling the main body cylinder segment blocks 11 into a circular cylinder segment structure using reusable patching cylinder segment blocks 12 solves the problem of maintaining roundness and assembly accuracy of the C-shaped first side cylinder 1 and the second side cylinder 2 during the assembly and welding process.

[0039] In addition, as a preferred technical solution, please refer to Figure 2 In some embodiments, when each circular cylinder segment is flipped 90 degrees and hoisted onto the welding roller frame 5 for assembly welding in steps 2 and 3, a temporary internal support frame 6 is added to each circular cylinder segment. The temporary internal support frame 6 is composed of a plurality of cross bars that are intersected and inserted into the circular cylinder segment and abut against its inner wall to prevent the circular cylinder segment from deforming due to its own weight.

[0040] Step 4, closing the first side cylinder 1 and the second side cylinder 2: place the first side cylinder 1 and the second side cylinder 2 on the assembly platform, and then place the longitudinal bulkhead 3 between the first side cylinder 1 and the second side cylinder 2, and weld them together to form a double-ear storage tank cylinder. Specifically, first adjust the position of the assembly platform according to the vertical projection of the double-ear storage tank, place the opening sides of the first side cylinder 1 and the second side cylinder 2 opposite to each other on the assembly platform, and then hoist the longitudinal bulkhead 3 to the junction of the first side cylinder 1 and the second side cylinder 2, and adjust the weld position of the longitudinal bulkhead 3 and the first side cylinder 1 and the second side cylinder 2 and connect them with a clamp, and after the gap, misalignment, angular deformation, straightness, and ovality are adjusted to meet the requirements, point fixation is performed, and after the point fixation is completed and passed the inspection, welding is performed to complete the closing operation of the first side cylinder 1 and the second side cylinder 2.

[0041] It should be noted that the following contents are also included after step S4: non-destructive testing is performed on the cylinder of the binaural storage tank; wherein the testing methods include radiographic testing, ultrasonic testing, coloring and visual inspection.

[0042] In summary, the above-mentioned method for manufacturing the double-ear storage tank cylinder has the following technical advantages:

[0043] 1. The present application adopts a method of assembling the main body cylinder segment blocks into a circular cylinder segment structure by using reusable embedded cylinder segment blocks, which solves the problem of maintaining roundness and assembly accuracy during the assembly and welding process of the first side cylinder body and the second side cylinder body of the C-type; 2. The present application adopts embedded cylinder segment blocks and main body cylinder segment blocks to first assemble and weld to form a number of circular cylinder segments for forming the first side cylinder body and the second side cylinder body, and assembles and welds the annular seams of each circular cylinder segment on a welding roller frame, which solves the problem that the first side cylinder body and the second side cylinder body of the C-type cannot be welded due to incomplete structure. The present invention solves the problem of automatic or semi-automatic welding, improves the quality and efficiency of the circumferential seam welding of the double-ear storage tank cylinder, and eliminates the surface grinding treatment process of the weld; 3. In the present application, a new method of welding the first side cylinder, the second side cylinder and the longitudinal bulkhead on an assembly platform is adopted when closing the first side cylinder and the second side cylinder, which avoids the problem of setting up a large number of scaffoldings for high-altitude operations during the assembly of the first side cylinder and the second side cylinder, reduces the difficulty of assembling the first side cylinder and the second side cylinder, and improves the construction quality of the double-ear storage tank cylinder.

[0044] Therefore, compared with the existing double-ear storage tank manufacturing technology, the manufacturing method of the double-ear storage tank cylinder provided by the present invention has obvious technical advantages.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a double-ear storage tank cylinder, characterized in that: The following steps are involved: Step 1, making cylinder segment blocks: the cylinder of the double-ear storage tank includes a first side cylinder, a second side cylinder and a longitudinal bulkhead, and a plurality of main cylinder segment blocks and inlay cylinder segment blocks used to form the first side cylinder and the second side cylinder are made; Step 2, assembling and welding the first side cylinder: on the assembly platform, vertically weld a number of main cylinder segments and embedded cylinder segments to form a number of circular cylinder segments, turn each circular cylinder segment 90 degrees, hoist it onto the welding roller frame, and horizontally weld it to form a single-side cylinder, hoist the single-side cylinder onto the assembly platform and place it vertically, cut and remove the embedded cylinder segment blocks to form a C-shaped first side cylinder; Step 3, assembling and welding the second side cylinder: repeat step 2 to complete the assembly and welding of the second side cylinder that is axially symmetrical with the first side cylinder; Step 4, closing the first side cylinder and the second side cylinder: inserting the longitudinal bulkhead between the first side cylinder and the second side cylinder on the assembly platform, and welding them together to form a double-ear storage tank cylinder.

2. The method for manufacturing a double-ear storage tank body according to claim 1, characterized in that: The implementation of step 1 also includes the following contents: according to the circumference and height dimensions of the double-ear storage tank cylinder, the number of main cylinder segment blocks, embedded cylinder segment blocks and circular cylinder segments is set.

3. The method for manufacturing a double-ear storage tank body according to claim 2, characterized in that: When making the patching tube segment blocks in step 1, ordinary steel plates are used for the patching tube segment blocks to reduce material costs.

4. The method for manufacturing a double-ear storage tank body according to claim 3, characterized in that: When making the main body cylinder segment block in step 1, the main body cylinder segment block to be welded with the patch cylinder segment block should retain a cutting allowance of 30 to 40 mm.

5. The method for manufacturing a double-ear storage tank body according to claim 1, characterized in that: Before assembling and welding the first side cylinder in step 2, an assembly platform needs to be set up. The assembly platform setting up includes the following: first prepare a number of assembly jigs that can be fixed to the ground, draw the assembly jig layout line along the vertical projection of the first side cylinder, and then evenly distribute the several assembly jigs along the layout line and fix them on the ground to complete the setting up, so as to provide vertical assembly for a number of main cylinder segment blocks and embedded cylinder segment blocks.

6. The method for manufacturing a double-ear storage tank body according to claim 5, characterized in that: Before assembling and welding the first side cylinder in step 2, a connecting roller frame needs to be set up. The setting up of the welding roller frame includes the following: first prepare three groups of support rods that can be fixed to the ground, evenly distribute the three groups of support rods according to the radial size of the circular cylinder segment and fix them to the ground, and symmetrically configure two groups of pulleys on the top of the support rods to complete the setting up, so that the circular cylinder segment can be rotatably placed on the welding roller bracket in the horizontal direction to carry out the circumferential welding of adjacent circular cylinder segments.

7. The method for manufacturing a double-ear storage tank body according to claim 1, characterized in that: In step 2, the single-side cylinder is hoisted onto the assembly platform, and the patched cylinder segments are cut and removed to form the first-side cylinder. The removed patched cylinder segments are further used for assembly and welding of the second-side cylinder.

8. The method for manufacturing a double-ear storage tank body according to claim 1, characterized in that: The main body cylinder segment blocks and the patch cylinder segment blocks in step S1 are formed by roller molding.

9. The method for manufacturing a double-ear storage tank body according to claim 1, characterized in that: When each circular cylinder section is turned 90 degrees and hoisted onto the welding roller frame for assembly welding in step 2 and step 3, a temporary inner support frame is added in each circular cylinder section to prevent the circular cylinder section from deforming due to its own weight.

10. The method for manufacturing a double-ear storage tank body according to claim 1, characterized in that: The following contents are also included after step S4: non-destructive testing is performed on the cylinder of the binaural storage tank; wherein the testing methods include radiographic testing, ultrasonic testing, coloring and visual inspection.

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