CN111715978A

CN111715978A - Welding method and construction method for large-scale inner floating roof storage tank

Info

Publication number: CN111715978A
Application number: CN202010539821.8A
Authority: CN
Inventors: 姜栓; 张永昌; 娄战士
Original assignee: China Eleventh Chemical Construction Co Ltd
Current assignee: China Eleventh Chemical Construction Co Ltd
Priority date: 2020-06-13
Filing date: 2020-06-13
Publication date: 2020-09-29

Abstract

The invention discloses a welding construction method and a construction method of a large-scale inner floating roof storage tank, and relates to the technical field of chemical equipment. The welding method of the large-scale inner floating roof storage tank comprises the following steps: laying a plurality of medium width plates and a plurality of ring plates; welding the bottoms of the butt joints between the adjacent ring plates; with CO₂Gas is used for carrying out shielded welding bottoming on adjacent medium-width plates, and submerged arc automatic welding cover surfaces are carried out; welding the remaining portions of the butt seams between adjacent ring plates; weld the tortoise shell seam between a plurality of ring plates and a plurality of middle panels(ii) a Assembling and welding four layers of wall rings; carrying out T-shaped large-angle seam welding on the bottom wall ring and the plurality of ring plates; adopting manual welding circumferential symmetric segmented skip welding to back weld the annular seams between the plurality of annular plates and the plurality of middle panels; and (4) performing cover surface welding on the annular seams between the plurality of annular plates and the plurality of middle panels by adopting automatic welding circumferential symmetric seam-separating skip welding. The welding construction method of the large-scale inner floating roof storage tank provided by the invention can improve the welding quality of the large-scale inner floating roof, thereby improving the safety.

Description

Welding method and construction method for large-scale inner floating roof storage tank

Technical Field

The invention relates to the technical field of chemical equipment, in particular to a welding construction method and a construction method of a large-scale inner floating roof storage tank.

Background

At present, for the bottom plate welding of the inner floating roof storage tank in the market, the adjacent middle webs and the middle webs are directly welded with the ring plates by adopting a manual electric arc welding mode. The welding quality of the welding mode is limited, and the welding mode has extremely high safety risk for welding the bottom plate of the large or super-large inner floating roof storage tank.

Disclosure of Invention

The invention aims to provide a welding method for a large-sized inner floating roof storage tank, which can improve the welding quality and safety of a large-sized inner floating roof.

Another object of the present invention is to provide a construction method for a large-sized internal floating roof tank, which can improve the welding quality of the large-sized internal floating roof and improve the safety.

The invention provides a technical scheme that:

a welding method for a large-sized inner floating roof storage tank comprises the following steps:

laying a plurality of medium width plates and a plurality of ring plates;

welding the bottoms of the butt joints between the adjacent ring plates;

with CO₂Gas is used for carrying out shielded welding bottoming on the adjacent medium-width plates, and submerged arc automatic welding cover surface is carried out;

welding the remaining portions of the butt seams between adjacent ring plates;

welding a plurality of tortoise-shell seams between the ring plates and the middle panels;

assembling and welding four layers of wall rings, wherein each layer of wall ring is formed by welding and surrounding a plurality of corresponding wall plates of each layer;

carrying out T-shaped large-angle seam welding on the bottom wall ring and the plurality of ring plates;

performing backing welding on annular seams between the plurality of annular plates and the plurality of middle panels by adopting manual welding circumferential symmetric sectional skip welding;

and performing cover surface welding on the annular seams between the plurality of annular plates and the plurality of middle panels by adopting automatic welding circumferential symmetric seam skip welding, wherein the plurality of middle panels and the plurality of annular plates form a bottom plate.

Further, after the step of performing cover surface welding on the circular seams between the plurality of circular plates and the plurality of middle panels by adopting automatic welding circumferential symmetric seam skip welding, the method further comprises the following steps:

and carrying out vacuum leakage test on the plurality of welding lines on the bottom plate by adopting a vacuum generator.

Further, the step of assembling and welding the four-layer wall ring comprises:

according to R₁Calculating the inner radius of the bottom layer wall ring (R-100mm) + na/2 pi, wherein R is the radius of a circular ring area surrounded by a plurality of ring plates, n is the number of welding seams of the bottom layer wall ring, and a is the shrinkage of each welding seam of the bottom layer wall ring;

in a circular ring region surrounded by a plurality of said ring plates according to R₁Drawing a circular line at the radius;

vertically arranging a plurality of bottom layer wall plates on the plurality of ring plates and arranging the bottom layer wall plates according to the circular lines on the plurality of ring plates;

welding perpendicularity adjusting inclined struts and wall plate fixing inclined struts on the inner walls of the bottom wall plates, adjusting the bottom wall plates to be perpendicular to the ring plates, adjusting vertical seam gaps between the adjacent bottom wall plates to 4mm through clamps, and adjusting the misalignment amount between the adjacent bottom wall plates to be less than or equal to 1 mm;

welding the outer sides of the vertical seams between the adjacent bottom layer wall plates by adopting electric vertical welding;

and welding the inner sides of the vertical seams between the adjacent bottom-layer wall plates by adopting electric vertical welding to obtain the bottom-layer wall ring.

Further, the step of assembling and welding the four-layer wall ring further comprises:

an operation platform is erected on the inner wall of the bottom layer wall ring;

sequentially vertically arranging a plurality of second-layer wall plates on the top of the bottom-layer wall ring, arranging a back bar between each second-layer wall plate and the bottom-layer wall ring;

processing the vertical seam between the adjacent second-layer wall plates into a double-sided symmetrical groove, and welding the outer side of the vertical seam first and then welding the inner side of the vertical seam by adopting electric vertical welding to obtain a second-layer wall ring;

and processing the circular seam between the second-layer wall ring and the bottom-layer wall ring into an asymmetric groove, and welding by adopting automatic submerged arc welding.

an operation platform is erected on the inner wall of the second-layer wall ring;

sequentially vertically arranging a plurality of third-layer wall plates on the top of the second-layer wall ring, arranging one third-layer wall plate at each vertical position, and arranging a back bar between each third-layer wall plate and the second-layer wall ring;

processing vertical seams between the adjacent third-layer wall plates into double-sided V-shaped grooves, and welding by adopting electric vertical welding to obtain a third-layer wall ring;

and processing the circular seam between the third layer of wall ring and the second layer of wall ring into an asymmetric groove, and welding by adopting automatic submerged arc welding.

an operation platform is erected on the inner wall of the third layer of wall ring;

sequentially vertically arranging a plurality of fourth-layer wall plates on the top of the third-layer wall ring, arranging a back bar between each fourth-layer wall plate and the third-layer wall ring;

processing vertical seams between the adjacent fourth-layer wall plates into double-sided V-shaped grooves, and welding by adopting electric vertical welding to obtain a fourth-layer wall ring;

and processing the circular seam between the fourth layer of wall ring and the third layer of wall ring into an asymmetric groove, and welding by adopting automatic submerged arc welding.

Further, the step of welding the bottom wall ring with the plurality of ring plates by T-shaped large angle seam welding comprises:

manually welding and bottoming inner corner seams between the wall plates and the ring plates in circumferential symmetry;

performing coloring inspection on the inner corner seam subjected to manual welding priming;

carrying out circumferential symmetric submerged arc automatic welding cover surface on the inner corner seam;

and polishing the welding line to ensure smooth transition between the welding line of the inner fillet seam and the bottom plate.

The invention also provides a construction method of the large-scale inner floating roof storage tank, which comprises the welding method of the large-scale inner floating roof storage tank, and the welding method of the large-scale inner floating roof storage tank comprises the following steps: laying a plurality of medium width plates and a plurality of ring plates; welding the bottoms of the butt joints between the adjacent ring plates; with CO₂Gas is used for carrying out shielded welding bottoming on the adjacent medium-width plates, and submerged arc automatic welding cover surface is carried out; welding the remaining portions of the butt seams between adjacent ring plates; welding a plurality of tortoise-shell seams between the ring plates and the middle panels; assembling and welding four layers of wall rings, wherein each layer of wall ring is formed by welding and surrounding a plurality of corresponding wall plates of each layer; carrying out T-shaped large-angle seam welding on the bottom wall ring and the plurality of ring plates; performing backing welding on annular seams between the plurality of annular plates and the plurality of middle panels by adopting manual welding circumferential symmetric sectional skip welding; and performing cover surface welding on the annular seams between the plurality of annular plates and the plurality of middle panels by adopting automatic welding circumferential symmetric seam skip welding, wherein the plurality of middle panels and the plurality of annular plates form a bottom plate. After the step of welding the cover surfaces of the plurality of ring plates and the plurality of medium-width plates by adopting automatic welding circumferential symmetric seam skip welding, the construction method of the large-scale inner floating roof storage tank further comprises the following steps: assembling and welding the remaining multi-layer wall ring; an inner floating roof installation platform is erected on the bottom plate, and the inner floating roof is installed on the installation platform; building a tank top reticulated shell structure on the floating disc of the inner floating roof; lifting the tank top latticed shell structure to the top of the multilayer wall ring and connecting the tank top latticed shell structure with the top layer wall ring; laying a tank top skin on the tank top latticed shell structure; and (5) carrying out storage tank inspection after installing the rest accessories.

Further, the step of performing a tank check after installing the remaining accessories comprises:

carrying out a tightness test on all the welding seams of the bottom plate by adopting a vacuum box method, wherein the test negative pressure value is not lower than 53 Kpa;

carrying out tightness test on all welding lines on the floating roof plate of the inner floating roof by adopting a vacuum box method, wherein the test negative pressure value is not lower than 53Kpa, and the pressure stabilizing time is not lower than 10 s;

performing a tightness test on welding seams of the inner and outer edge plates and the partition plate of the floating cabin plate of the inner floating roof by adopting a kerosene leakage test method;

blowing 785Pa of compressed air into the cabin of the inner floating roof for a tightness test, and stabilizing the pressure for 10 s;

and carrying out a water filling test on the tank body.

Further, the step of carrying out the water filling test to the tank body includes:

filling water into the tank to 1/4 of the vertical height of the tank body, wherein the leakage observation time is not less than 24 h;

filling water to 1/2 of the vertical height of the tank body, and observing the leakage for not less than 24 h;

filling water to 3/4 of the vertical height of the tank body, and observing the leakage for not less than 24 h;

filling water to the full tank, and observing the leakage for not less than 24 h.

Compared with the prior art, the welding method for the large-sized inner floating roof storage tank provided by the invention has the advantages that after butt joints between adjacent annular plates are preliminarily welded, CO is used₂The gas is adjacent to the middle breadth plate for shielded welding bottoming, and the cover surface is welded automatically by submerged arc, so that the welding quality is greatly improved, fine adjustment of the position can be carried out among a plurality of annular plates, and the annular plates are tightly attached to the middle breadth plate. And then sequentially finishing the welding between the adjacent ring plates and the welding of the tortoise-shell seam between the ring plate and the middle amplitude plate. And then assembling the four layers of wall rings in advance, and then carrying out T-shaped large-angle seam welding on the bottom layer wall ring and the plurality of ring plates to prevent the problem of damage after T-shaped large-angle seam welding caused by directly assembling the wall rings on the ring plates. Then, a plurality of ring plates and the ring plates are welded by manual welding in a circumferentially symmetrical segmented stitch welding mannerAnd backing welding the annular seams among the plurality of middle panels, and performing cover welding on the annular seams among the plurality of annular plates and the plurality of middle panels by adopting automatic welding circumferential symmetric seam skip welding. Therefore, the welding method of the large-scale inner floating roof storage tank provided by the invention has the beneficial effects that: the welding quality of the large-scale inner floating roof can be improved, and therefore the safety is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly described below. It is appreciated that the following drawings depict only certain embodiments of the invention and are therefore not to be considered limiting of its scope. For a person skilled in the art, it is possible to derive other relevant figures from these figures without inventive effort.

Fig. 1 is a schematic block diagram of a welding method for a large-sized internal floating roof tank according to a first embodiment of the present invention;

FIG. 2 is a schematic block diagram of the process for assembling the bottom wall ring in the sub-step of step S106 in FIG. 1;

FIG. 3 is a schematic block diagram illustrating a flow of sub-steps of step S107 in FIG. 1;

FIG. 4 is a schematic block diagram illustrating a flow of a construction method for a large internal floating roof tank according to a second embodiment of the present invention;

FIG. 5 is a block diagram illustrating a flow of substeps of step S216 of FIG. 4;

fig. 6 is a schematic block diagram illustrating a flow of sub-steps of step S2165 in fig. 5.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "inside", "outside", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, or the orientations or positional relationships that the products of the present invention are conventionally placed in use, or the orientations or positional relationships that are conventionally understood by those skilled in the art, and are used for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is also to be noted that, unless otherwise explicitly stated or limited, the terms "disposed" and "connected" are to be interpreted broadly, and for example, "connected" may be a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; the connection may be direct or indirect via an intermediate medium, and may be a communication between the two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The following detailed description of embodiments of the invention refers to the accompanying drawings.

First embodiment

Fig. 1 is a block diagram illustrating a flow of a welding method for a large internal floating roof storage tank according to this embodiment, and referring to fig. 1, the welding method for the large internal floating roof storage tank includes:

step S101: and laying a plurality of medium webs and a plurality of ring plates.

In this embodiment, the radius of the scribe line laid by the ring plate is R30100 mm, a 30kg cylindrical spring scale is used for drawing dots during scribing, the tension of the spring scale is set to 15kg, and after the dots are drawn, the arc-shaped templates of R30100 mm are connected to form a complete circle. The method comprises the steps of determining the laying direction of a ring plate and a middle breadth plate by using a theodolite, drawing the azimuth lines of 0 degree, 90 degrees, 180 degrees, 270 degrees and the like, marking, displacing after laying is finished, and punching a sample. Before the ring plate butt joint base plate is laid, the base plate is accurately scribed to determine the laying position of the base plate. The ring plate is laid symmetrically in two directions, and two adjusting plates are reserved. The middle breadth plates are laid according to the sequence of firstly laying the base plate and then laying the middle breadth plates, the middle breadth plates are laid according to the sequence of laying from the center to the outside, the center positioning plate is firstly laid, and then the strip-shaped plates are sequentially laid.

Step S102: and welding the bottoms of the butt joints between the adjacent ring plates.

Step S103: with CO₂And (4) performing shielded welding bottoming on the adjacent medium-width plates by using gas, and performing submerged arc automatic welding capping.

With CO₂Filling gas into the butt joint seam between adjacent middle panels for backing welding, filling broken welding wires into the butt joint seam, and then automatically welding the cover surface by using submerged arc. Compared with direct manual electric arc welding, the welding device has better welding effect, higher welding quality and more reliability.

Step S104: the remaining portions of the butt seams between adjacent ring plates are welded.

The mode of partially welding the adjacent ring plates at first and completely welding the adjacent ring plates after the welding of the adjacent middle webs is completed is to consider that the gaps of the middle webs can be changed in the process of welding the adjacent middle webs, and the radian and the like of the ring plates are required to be finely adjusted to ensure that the ring plates can be kept attached to the edges of the middle webs, so that the welding reliability is ensured.

Step S105: and welding the tortoise-shell seams between the plurality of ring plates and the plurality of middle panels.

Step S106: and assembling and welding the four layers of wall rings.

Every layer of wall circle is enclosed by the wallboard welding that a plurality of each layers correspond, and bottom layer wall circle comprises a plurality of bottom wallboards, and second floor wall circle comprises a plurality of second floor wallboards, and third layer wall circle comprises a plurality of third layer wallboards, and fourth layer wall circle comprises a plurality of fourth layer wallboards.

Fig. 2 is a block diagram illustrating a flow of assembling the bottom wall ring in the sub-step of step S106, and referring to fig. 2, step S106 includes:

substep S1061, pressing R₁Calculating the inner radius of the bottom layer wall circle (R-100mm) + na/2 pi, wherein R is the radius of a circular ring area formed by the ring plates, n is the number of welding seams of the bottom layer wall circle, and a is the shrinkage of each welding seam of the bottom layer wall circle.

R30100 mm in this example, therefore₁And (2) calculating a by taking 2.5mm as 30000mm + na/2 pi, and calculating the inner radius of the bottom wall ring by only estimating the total number of welding seams on the bottom wall ring in practical application.

Substep S1062, pressing R in the circular ring area formed by the plurality of ring plates₁The radii draw circular lines.

Marking lines on the plurality of ring plates according to the inner radius of the bottom wall ring, marking by using a total station, punching a sample hole, making a mark, spot-welding a limiting block, and then separating the installation position of each bottom wall plate by using a theodolite.

And a substep S1063 of erecting the bottom wall plates on the ring plates and arranging the bottom wall plates according to the circular lines on the ring plates.

And a substep S1064 of welding perpendicularity adjusting inclined struts and wall plate fixing inclined struts on the inner walls of the bottom wall plates, adjusting the bottom wall plates to be perpendicular to the ring plate, adjusting the vertical seam gaps between the adjacent bottom wall plates to 4mm through the clamps, and adjusting the misalignment between the adjacent bottom wall plates to be less than or equal to 1 mm.

And a substep S1065 of electrically welding the outer sides of the vertical seams between the adjacent bottom-layer wall plates by vertical welding.

And a substep S1066 of welding the inner sides of the vertical seams between the adjacent bottom-layer wall plates by adopting electric vertical welding to obtain the bottom-layer wall ring.

The assembly process of the second layer wall ring is as follows:

an operation platform is erected on the inner wall of the bottom layer wall ring; sequentially vertically arranging a plurality of second-layer wall plates on the top of the bottom-layer wall ring, arranging a back bar between each second-layer wall plate and the bottom-layer wall ring, wherein the back bar plays a role in fixing the second-layer wall plates on the bottom-layer wall ring; processing vertical seams between adjacent second-layer wall plates into double-sided symmetrical grooves, and welding the outer side and the inner side firstly by adopting electric vertical welding to obtain a second-layer wall ring; and processing the circular seam between the second layer wall ring and the bottom layer wall ring into an asymmetric groove, and welding by adopting automatic submerged arc welding.

The assembly process of the third layer wall ring is as follows:

an operation platform is erected on the inner wall of the second-layer wall ring; sequentially vertically arranging a plurality of third-layer wall plates on the top of the second-layer wall ring, arranging one third-layer wall plate at each vertical position, and arranging a back bar between each third-layer wall plate and the second-layer wall ring; processing vertical seams between adjacent third-layer wall plates into double-sided V-shaped grooves, and welding by adopting electric vertical welding to obtain a third-layer wall ring; and processing the circular seam between the third layer of wall ring and the second layer of wall ring into an asymmetric groove, and welding by adopting automatic submerged arc welding.

In this embodiment, the assembling process of the fourth layer wall ring to the nth layer wall ring is the same as that of the third layer wall ring.

Referring to fig. 1, the welding method for the large-sized internal floating roof tank further includes:

step S107: and carrying out T-shaped large-angle seam welding on the bottom layer wall ring and the plurality of ring plates.

Fig. 3 is a schematic block diagram illustrating a flow of sub-steps of step S107, and referring to fig. 3, step S107 includes:

and a substep S1071 of manually welding and bottoming the inner corner seams between the wall plates and the ring plates in circumferential symmetry.

In the manual welding and bottoming process, welders are symmetrically distributed and cannot continuously weld for several times in a short distance, and the phenomena that the lower opening of a wallboard is oval due to uneven contraction and the corner seam generates angular deformation due to the concentrated input heat are avoided.

And a substep S1072 of performing coloring inspection on the inner corner seam subjected to manual welding priming.

And a substep S1073 of performing circumferential symmetric submerged arc automatic welding cover surface on the inner corner seam.

Similarly, welders are also symmetrically distributed during the submerged arc automatic welding.

And a substep S1074 of polishing the welding line to ensure smooth transition between the welding line of the inner fillet seam and the bottom plate.

Smooth transition between the welding seam of the inner fillet seam and the bottom plate is ensured, and stress concentration is eliminated.

step S108: and backing welding the annular seams between the plurality of annular plates and the plurality of middle panels by adopting manual welding circumferential symmetric sectional skip welding.

When manual backing welding is adopted, welders need to be symmetrically distributed, a segmentation and skip welding mode is adopted, and meanwhile the backing thickness is not less than 5mm, so that the backing plate is prevented from being punctured during automatic welding.

Step S109: and (3) performing cover surface welding on the annular seams between the plurality of annular plates and the plurality of medium-width plates by adopting automatic welding circumferential symmetric seam skip welding, wherein the plurality of medium-width plates and the plurality of annular plates form a bottom plate.

When the cover surface is filled by adopting automatic welding, the welding machines are also symmetrically distributed, and a gap skip welding method is adopted, so that multiple welding is strictly forbidden in a short distance, and the deformation of the bottom plate caused by heat concentration is avoided.

Step S110: and carrying out vacuum leakage test on a plurality of welding lines on the bottom plate by adopting a vacuum generator.

The vacuum generator utilizes the spray pipe to spray compressed air at a high speed to form jet flow at the outlet of the spray pipe to generate entrainment flow, and under the entrainment action, the air around the outlet of the spray pipe is continuously pumped away, so that the pressure in the adsorption cavity is reduced to be lower than the atmospheric pressure, and the vacuum degree is formed. Compared with the traditional mode of manufacturing the vacuum box on the spot by using the vacuum pump, the working efficiency is high and the cost is lower.

Second embodiment

Fig. 4 is a block diagram illustrating a flow of a construction method of a large internal floating roof storage tank according to this embodiment, which includes steps S101 to S110 in a welding method of a large internal floating roof storage tank according to a first embodiment, and referring to fig. 4, the construction method of the large internal floating roof storage tank includes:

step S201, a plurality of middle webs and a plurality of ring plates are laid.

Step S202: and welding the bottoms of the butt joints between the adjacent ring plates.

Step S203: with CO₂And (4) performing shielded welding bottoming on the adjacent medium-width plates by using gas, and performing submerged arc automatic welding capping.

Step S204: the remaining portions of the butt seams between adjacent ring plates are welded.

Step S205: and welding the tortoise-shell seams between the plurality of ring plates and the plurality of middle panels.

Step S206: and assembling and welding the four layers of wall rings.

Step S207: and carrying out T-shaped large-angle seam welding on the bottom layer wall ring and the plurality of ring plates.

Step S208: and backing welding the annular seams between the plurality of annular plates and the plurality of middle panels by adopting manual welding circumferential symmetric sectional skip welding.

Step S209: and (3) performing cover surface welding on the annular seams between the plurality of annular plates and the plurality of medium-width plates by adopting automatic welding circumferential symmetric seam skip welding, wherein the plurality of medium-width plates and the plurality of annular plates form a bottom plate.

Step S210: and carrying out vacuum leakage test on a plurality of welding lines on the bottom plate by adopting a vacuum generator.

Step S211: assembling and welding the remaining multi-layer wall ring.

The remaining multi-layer wall panel refers to the plurality of wall panels extending to the height of the roof that meets construction requirements.

Step S212: and (4) erecting an inner floating roof installation platform on the bottom plate, and installing the inner floating roof on the installation platform.

The height of the inner floating roof mounting platform is 200mm higher than the design height of the floating roof bottom plate, so that the height of the support is adjusted after the tank body is flushed and settled.

Installing a floating cabin: and assembling the prefabricated floating cabins, and performing grouped and segmented welding during welding to reduce welding deformation.

Installing a floating roof plate: and a strip-shaped plate arranging mode is used, and the plates are lapped with one another. And (4) aligning the center line of the tank bottom plate by using a line bob, drawing the center line on the central plate of the floating top plate, and determining the center of the floating top plate. When the plate is paved, the plate is paved outwards in sequence from the center, and the installation radius of the plate is enlarged by 50mm to ensure the geometric dimension of the floating roof.

Installing a floating roof plate: the plates are firstly divided into a plurality of piles by a crane and are uniformly stored to different parts of the temporary floating roof support, centralized stacking is absolutely not allowed, the storage of each pile cannot exceed 1.5t, and the crane is light and stable when falling the plates. A temporary roller (10 # I-steel) is arranged on the floating roof support, and a winch and a pulley are matched with a dragging plate to be in place for installation.

After the floating roof is laid, only performing positioning spot welding, and paying attention to spot welding to compact and tightly lean the long edges of the plates; and then marking position lines of a floating roof pillar, a vent valve, a floating roof manhole, an outer side plate and the like on the floating roof plate according to the drawing marking directions, marking obvious marks by using paint after marking, finding out the intersection position of a welding seam of the floating roof member and the floating roof plate, firstly welding the welding seam of the intersection position, preferably welding the welding seam with the length of about 600mm, and installing the floating roof member after the welding seam is qualified through vacuum leak testing.

The upward welding work of the floating roof pillar sleeve, the ventilation valve, the floating roof manhole, the outer side plate and the like is finished by laying the edge of the floating roof plate, so that the limited space operation can be reduced.

Step S213: and a tank top reticulated shell structure is built on the floating plate of the inner floating roof.

The tank top latticed shell structure is a meridian latticed shell, the meridian latticed shell is formed by crossing an upper net rod and a lower net rod (i-shaped steel HN125 with radian) to form a framework, and angle steel with radian is arranged in the middle of the meridian latticed shell to be used as a reinforcing support of a skin plate. Considering that each net rod is transported to be composed of a plurality of sections, each section is connected by a connecting plate. The net rod is connected with the tank body through a connecting plate, and all welding seams are fillet welds.

Step S214: and hoisting the tank top latticed shell structure to the top of the multi-layer wall ring and connecting the tank top latticed shell structure with the top layer wall ring.

Step S215: and laying a tank top skin on the tank top latticed shell structure.

Step S216: and (5) carrying out storage tank inspection after installing the rest accessories.

Fig. 5 is a schematic block diagram illustrating a flow of sub-steps of step S216, and referring to fig. 5, step S216 includes:

in the substep S2161, a tightness test is performed on all the welded seams of the base plate by using a vacuum box method, and the negative pressure value of the test is not less than 53 Kpa.

And a substep S2162, performing a tightness test on all welding lines on the floating roof plate of the inner floating roof by using a vacuum box method, wherein the negative pressure value of the test is not lower than 53Kpa, and the pressure stabilizing time is not lower than 10S.

And a substep S2163, performing a tightness test on welding seams of the inner and outer edge plates of the floating cabin plate and the partition cabin plate of the inner floating roof by adopting a kerosene leakage test method.

And a substep S2164, blowing 785Pa compressed air into the cabin of the inner floating roof for a tightness test, and stabilizing the pressure for 10S.

And a substep S2165 of performing a water filling test on the can body.

Fig. 6 is a schematic block diagram illustrating a flow of sub-steps of sub-step S2165, and referring to fig. 6, sub-step S2165 includes:

in the substep S2165a, the time for observing the leakage is not less than 24h for 1/4 of filling water in the tank to the vertical height of the tank.

And the substep S2165b, filling water to 1/2 of the vertical height of the tank body, and observing the leakage for not less than 24 h.

And the substep S2165c, filling water to 3/4 of the vertical height of the tank body, and observing the leakage for not less than 24 h.

And the substep S2165d, filling water to full tank, and observing the leakage for not less than 24 h.

In conclusion, the welding method and the construction method for the large-sized inner floating roof storage tank provided by the invention can improve the welding quality of the large-sized inner floating roof, so that the safety is improved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A welding method for a large-sized inner floating roof storage tank is characterized by comprising the following steps:

laying a plurality of medium width plates and a plurality of ring plates;

welding the bottoms of the butt joints between the adjacent ring plates;

welding the remaining portions of the butt seams between adjacent ring plates;

2. The welding method for the large-sized internal floating roof tank according to claim 1, wherein after the step of performing the facing welding on the annular seams between the plurality of annular plates and the plurality of middle panels by using the automatic welding circumferentially symmetrical seam skip welding, the welding method further comprises:

3. The welding method for the large-sized internal floating roof tank according to claim 1, wherein the step of assembling and welding the four-layer wall ring comprises:

4. The welding method for the large-sized internal floating roof tank according to claim 3, wherein the step of assembling and welding the four-layer wall ring further comprises:

5. The welding method for the large-sized internal floating roof tank according to claim 4, wherein the step of assembling and welding the four-layer wall ring further comprises:

6. The welding method for the large-sized internal floating roof tank according to claim 5, wherein the step of assembling and welding the four-layer wall ring further comprises:

7. The welding method for the large-sized internal floating roof tank according to claim 1, wherein the step of welding the bottom wall ring and the plurality of ring plates by T-shaped large angle seam welding comprises:

8. A construction method of a large inner floating roof tank, comprising the welding construction method of the large inner floating roof tank as claimed in any one of claims 1 to 7, wherein after the step of welding the plurality of ring plates and the plurality of middle webs with automatic welding circumferentially symmetrical gap skip welding, the construction method of the large inner floating roof tank further comprises:

assembling and welding the remaining multi-layer wall ring;

an inner floating roof installation platform is erected on the bottom plate, and the inner floating roof is installed on the installation platform;

building a tank top reticulated shell structure on the floating disc of the inner floating roof;

lifting the tank top latticed shell structure to the top of the multilayer wall ring and connecting the tank top latticed shell structure with the top layer wall ring;

laying a tank top skin on the tank top latticed shell structure;

and (5) carrying out storage tank inspection after installing the rest accessories.

9. The construction method of the large internal floating roof tank according to claim 8, wherein the step of performing tank inspection after installing the remaining accessories comprises:

carrying out a tightness test on all welding seams of the bottom plate by adopting a vacuum box method, wherein the test negative pressure value is not lower than 53 Kpa;

and carrying out a water filling test on the tank body.

10. The construction method of the large-sized internal floating roof tank according to claim 9, wherein the step of performing the water filling test on the tank body comprises: