CN111794549A - Construction method for lowering height and changing bottom of vertical storage tank - Google Patents
Construction method for lowering height and changing bottom of vertical storage tank Download PDFInfo
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- CN111794549A CN111794549A CN202010647950.9A CN202010647950A CN111794549A CN 111794549 A CN111794549 A CN 111794549A CN 202010647950 A CN202010647950 A CN 202010647950A CN 111794549 A CN111794549 A CN 111794549A
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/06—Separating, lifting, removing of buildings; Making a new sub-structure
- E04G23/065—Lifting of buildings
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
- E04H7/00—Construction or assembling of bulk storage containers employing civil engineering techniques in situ or off the site
- E04H7/02—Containers for fluids or gases; Supports therefor
- E04H7/04—Containers for fluids or gases; Supports therefor mainly of metal
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Abstract
A construction method for lowering height and changing bottom of a vertical storage tank comprises the following specific steps of step one; construction preparation: step two: and (3) related accessories and connecting parts are protectively dismantled: step three: positioning the distribution positions of the cutting lines and the holding poles; step four: replacing a tank bottom plate edge plate; step five: cutting the wallboard; step six: descending the tank body; step seven: welding the tank body; step eight: inspecting, testing and preserving; step nine: restoring the installation of the accessories; step ten: and (4) performing lifting test and integral acceptance inspection on the inner floating plate. The invention provides a construction method for lowering height and changing bottom of a vertical storage tank, which takes a single edge plate as a cutting unit, separates a bottom band plate from the edge plate, partially and symmetrically replaces the edge plate, and then erects a holding pole, reduces the procedures of dismantling the holding pole and erecting the holding pole for the second time, has advanced and reasonable process, and belongs to the leading level in the same industry.
Description
Technical Field
The invention relates to the field of storage tank replacement construction, in particular to a construction method for lowering height and replacing bottom of a vertical storage tank.
Background
The storage tank is usually corroded on a bottom plate and a bottom wall plate of the storage tank after being used for a certain period, and when the corrosion is large in area and large in range, thorough replacement measures are generally taken. Storage tanks with ultra-high walls above 24m will also face a height reduction problem during bottom replacement service. And because the construction equipment belongs to maintenance projects, the installation site is often limited by a fire wall of a tank field and other adjacent steel structures, equipment and the like, and the type selection of the construction equipment is limited. The currently common bottom plate replacement technology is as follows: firstly, erecting a holding pole lifting system, separating a bottom plate and a wall plate, and lifting a tank body; and then, removing a single holding pole, replacing the edge plate of the position where the holding pole is located, resetting the holding pole, and repeating the steps until all the edge plates are replaced.
Disclosure of Invention
Aiming at the problems, the invention provides a construction method for lowering and changing bottom of a vertical storage tank, which is based on the lifting principle of a pole of an inverted installation method, but updates the conventional process of firstly lifting a tank body and then changing an edge plate, fully utilizes the self-supporting force of the tank body, realizes that the edge plate is firstly changed and then the pole is erected, avoids the two-step and two-disassembly process of the pole in the conventional method, has advanced process and reasonable optimization, is very suitable for the maintenance environment that large lifting workers and machinery cannot enter the field in a limited space, and has wide application prospect in the field of maintenance of the storage tank.
The technical purpose of the invention is realized by the following technical scheme that the construction method for lowering the height and changing the bottom of the vertical storage tank comprises the following specific steps:
step one; construction preparation:
1) compiling a detailed operation instruction book before starting work, and performing safety technology exchange on all operating personnel;
2) cleaning residual liquid level residual oil in the storage tank, thoroughly eliminating and cleaning dirt and impurities deposited in the storage tank, and meeting the conditions of internal maintenance and fire driving of the storage tank;
3) confirming to stop the nitrogen sealing system, disconnecting the nitrogen pipeline connected with the tank body, and then removing accessories in the tank body;
4) the manholes at the periphery of the tank body, the pipe connecting openings and the pipe connecting openings at the top are all opened, an inward axial flow blower is arranged at one of the manholes, and an outward axial flow blower is arranged at the manholes or the pipe connecting positions at the opposite side so as to keep the air in the tank fresh and qualified;
5) lifting the system component for model selection;
6) inspecting the specification, the model and the quality of the lifting system component;
7) carrying out sand blasting and corrosion prevention on the replaced plate, blanking according to the size of the typesetting drawing, and prefabricating a split heads, lifting lugs and a tool clamp;
8) 1.5m x H is arranged on the bottom wall plate, wherein H is a temporary door opening for designing the height to be lowered, and the position selection is convenient for a crane to transport the lifting system component;
step two: and (3) related accessories and connecting parts are protectively dismantled:
1) dismantling the inner floating disc;
marking each part of the original floating disc before dismantling, and ensuring each part of the floating disc not to be damaged as much as possible in the dismantling process;
fixing the edge plate of the floating disc by using a positioning plate to ensure the stability of the floating disc;
loosening a fastening bolt of a sealing device, removing a sealing batten and an edge batten, taking an upper layer of sealing adhesive tape from the bolt, unfolding the upper layer of sealing adhesive tape along the wall of the tank, taking out sealing filler in the adhesive tape, moving the filler to the outside of the tank for proper storage, and taking a lower layer of sealing adhesive tape from the bolt and moving the lower layer of sealing adhesive tape to the outside of the tank;
loosening the pressing bar bolt, removing the pressing bar, the floating disc manhole, the oil measuring hole and the floating disc accessory of the liquid level meter, and removing the cover plate;
removing the fixing bolts at the two ends of the main beam, removing the floating pipe clamp bolts, and sequentially removing the floating pipe, the main beam, the positioning beam, the frame beam and the strut;
after the floating plate is disassembled, the floating plate is transported to a storage yard outside the tank for storage and protection;
2) dismantling the electric instrument;
dismantling electrical instrument equipment parts and cables at the top and the bottom of the storage tank, using the dismantled parts as marks, wrapping the marks with plastic films, and transporting the covered parts to a warehouse or a yard to be placed with skid blocks; digging a pit on the bottom concrete ground, drawing out the cable, storing the cable in a winding manner, covering the pit with a steel plate, and making a protective mark; cutting the height to be lowered from the bottom upwards by the threading pipe from the periphery of the tank wall to the tank top;
3) removal of accessories outside tank
And (3) protectively detaching the connecting part at the root of the storage tank: the root parts of the storage tanks, such as a pneumatic valve, a gate valve, a check valve, a metal hose and the like, are dismantled and then transported to a storage yard for protection and storage;
adopting a protection measure for installing a temporary blind plate on the flange surface of the connected process pipeline;
and (3) protective dismantling of the fire pipeline: marking the lower ends of the vertical pipes around the tank wall, cutting the tank body to be lowered, sealing and protecting the tank body by using a plastic film, and conveying the cut pipe sections to a material storage yard for placement; the fire-fighting pipelines from the firewall to the periphery of the tank body are all protectively dismantled and marked to be transported to a material storage yard for storage;
cutting the coiling ladder and the high manhole ladder stand, and transporting to a material storage yard for storage;
4) dismantling accessories in the tank;
disconnecting the in-tank diffusion tube and the tank wall connecting tube, cutting the height of the tank body to be lowered by the lower ends of the oil measuring tube and the guided wave tube, and reinforcing the tank body according to design requirements before cutting;
step three: positioning the distribution positions of the cutting lines and the holding poles;
uniformly dotting positioning lines on the outer side of the tank at the positions of the T-shaped fillet welds of the wall plate and the bottom plate and the positions of the tank body with the reduced height of 300mm above the seam by using a level gauge; the position of the central point of the tank is measured by utilizing the intersection point of the two lines on the inner side of the tank, the central point is marked, and a line is positioned and drawn on the wall of the tank according to the distribution position diagram of the holding poles;
step four: replacing a tank bottom plate edge plate;
1) a circle of lap welding seam of the middle panel and the edge panel is cut by using a carbon arc gouging to protect the tar sand at the bottom;
2) the method comprises the following steps that a first batch of edge plates are formed by taking a single edge plate in the direction of 0 degree as a first plate, clockwise symmetrical cutting and replacement are carried out at intervals, the first batch of edge plates are cut at a position which is 100mm away from a weld joint of a short edge of the first edge plate, the edge plates are convenient to replace and install, the tank wall corresponding to the first edge plate is cut, a forklift is used for drawing out, the surface of asphalt sand is cleaned and repaired, a hydraulic ground is used for dragging the tank to assist the forklift to install the edge plates, a split stool is added on the edge plates along the lower opening of a tank wall slot after adjustment is finished, welding and fixing are carried out, and a first batch of lifting systems such as holding;
3) after the first batch of lifting systems are in place, checked and accepted, the residual edge plates are symmetrically replaced according to the first batch of modes, the split heads, the residual holding rods and the electric block are installed, and finally the tops of the holding rods are connected into a whole through pull rods;
4) welding the weld joint of 300mm at the outer end of the short side weld joint of the new edge plate, and carrying out ray detection on the weld joint according to the design requirement, wherein the detection cannot be carried out due to the limitation of the spatial position in transformation, so that TOFD (time difference diffraction) ultrasonic detection and penetration detection assistance are additionally adopted for innovatively adopting the surface of the weld joint of the edge plate;
step five: cutting the wallboard;
1) adjusting all electric hoists before cutting the wall plate to enable the electric hoists to be stressed uniformly, and carrying out test hoisting inspection;
2) cutting longitudinal seams of the bottom wall plate in blocks, cutting all longitudinal seams of each wall plate, radially and symmetrically cutting annular seams of the wall plates at intervals after welding lifting lugs, enabling a forklift to be in a supporting state when the cutting of the annular seams of each wall plate is about to finish, taking out the wall plates after the cutting is finished, transferring and carrying out centralized treatment, finishing the cutting operation in the same day, lowering the tank body onto a bottom plate, and fixing the tank body by spot welding to avoid strong wind weather at night;
step six: descending the tank body;
1) the PLC is used for controlling, and the console is used for operating in a unified way, so that the synchronous operation of the electric hoists is achieved;
2) the holding pole is used for making a striking mark every 300mm from the bottom for observing the synchronism of the tank body falling;
3) in the landing process, four persons are arranged to patrol the working states of the electric hoist, the expansion ring and the holding pole, the operation is immediately stopped and the power supply is cut off when the abnormality is found, and the operation can be continued after the potential safety hazard is eliminated until the electric hoist falls on the bottom plate;
4) a limiting block is arranged on the edge plate of the tank bottom before the tank body falls;
step seven: welding the tank body;
1) after the tank body is put in place by descending assembly, welding T-shaped fillet welds of the tank wall and the edge plate, welding two layers outside and two layers inside, in order to prevent welding deformation, firstly backing up the outside, then welding the inside fillet welds, finally welding the outside, uniformly distributing the inside and outside of the tank, wherein the welding workers in the tank should go beyond 500mm, and perform segmented welding along the same direction, and the welding bead of the initial layer should adopt a segmented back welding or skip welding method;
2) welding the residual welding seams of the edge plates after the T-shaped fillet welding seam is welded, and finally welding the contraction joint between the edge plates and the middle web plate;
3) opening a hole in the tank body according to design requirements, and installing a sewage drainage hole, a connecting pipe, a reinforcing ring, a manhole and a platform;
step eight: inspecting, testing and preserving;
1) carrying out nondestructive testing on the welding line according to the design requirement, carrying out a vacuum test on the welding line of the bottom plate, and checking the tightness test of the welding line by the reinforcing plate;
2) performing a water filling test on the sealing of the manhole and the flange surface of the connecting pipe of the tank body, and checking the tightness of the tank bottom, the strength and the tightness of the tank wall in the process, wherein the tank bottom and the tank wall are free of leakage and abnormal deformation and are qualified;
3) carrying out in-tank and out sand blasting anticorrosion painting according to design requirements;
step nine: restoring the installation of the accessories;
1) and (3) recovering and installing process pipelines: the pneumatic valve, the gate valve, the check valve and the metal hose are reinstalled according to the original design positions; the original positions of the nitrogen sealing pipeline and the oil expansion pipeline are recovered and installed; the original position of the gap bridge platform is restored and installed;
2) and (3) recovering and installing the fire pipeline: the fire-fighting water pipeline, the foam pipeline and the summer cooling spraying pipeline are reinstalled according to the original positions;
3) and (3) recovering and installing the inner floating disc: sequentially restoring and installing the edge plates, the edge pillars, the main beams, the floating pipes, the middle pillars, the paving plates, the pressing strips, the sealing devices and other accessories according to the typesetting layout;
4) the radar liquid level meter, the multi-point thermometer, the oil-water interface instrument, the servo, the automatic sampling instrument, the high-low level alarm instrument, the toxic gas alarm instrument and the like are reinstalled according to the original display positions; restoring the wiring of the instrument and the cable penetrating from the ground plane to the top of the tank and the lighting cable penetrating from the coiled ladder to the top of the tank; mounting the pneumatic valve air source pipe again;
step ten: performing an inner floating disc lifting test and overall acceptance inspection;
according to the design requirement, the inner floating disc is filled with water for a lifting test, the floating roof and the inner floating roof should stably lift in the lifting test, the guide mechanism, the sealing device and the automatic vent valve strut should not be jammed, the escalator should flexibly rotate, the floating roof and the accessories thereof should not interfere with other accessories on the tank body, the contact part of the floating roof and the liquid level should not leak, and the storage tank is integrally checked and accepted after the inspection is qualified.
As a further improvement of the invention, in the first step, the lifting system component in the construction preparation comprises a holding pole, an electric hoist, an expansion ring and a lifting lug, and the lifting system component is based on the following steps: and calculating the quantity of the electric hoists by the upper load and the rated hoisting load of the electric hoists, and calculating the load of the electric hoists, analyzing the stress of the holding pole, and checking and calculating the lifting lugs and the welding lines.
As a further improvement of the invention, the bottom electric instrument detached in the second step comprises a radar liquid level meter, a multi-point thermometer, an oil-water interface instrument, a servo, an automatic sampling instrument, a high-low position alarm instrument, a toxic gas alarm instrument and a pneumatic valve.
As a further improvement of the method, in the sixth step, when the tank body descends, limiting blocks are arranged on the edge plate of the bottom of the tank, the thickness of the limiting blocks is 200mm plus 150mm, the limiting blocks are 20mm, the limiting blocks are evenly arranged at intervals of 2 meters, the ovality deviation of the wall plate is large, the limiting blocks are arranged in an encrypted mode, the intervals are not more than 0.5 meter, the limiting blocks and the stressed friction surface of the wall plate are coated with molybdenum disulfide for lubrication, the limiting blocks are disassembled after assembly is completed, and polishing treatment is carried out on corresponding parts.
In summary, the present invention has the following features:
1) the storage tank bottom plate and the wall plate are replaced by matching the holding rod, the electric hoist and the split heads, the problem of site limitation of maintenance projects is solved, and high-altitude operation and dependence on large-scale hoisting machinery are reduced;
2) in the construction process, the bottom edge plates are symmetrically disassembled in two batches at intervals, the bottom plate is replaced first, then the holding poles are erected, and a batch of holding poles are erected by replacing a batch of edge plates by utilizing the self-supporting force of the tank wall and matching with the split heads, so that the operation is compact in process, and large-scale mechanical matching is not needed;
3) in the whole process of replacing the bottom edge plate, the tank body is supported in situ, lifting is not needed, and the operation is more convenient;
4) when the wall plate of the storage tank is cut, the tank body is stabilized by utilizing the holding rod lifting system and supporting with the split heads, the suspension time of the tank body is short, and the tank body is cut symmetrically at radial intervals as the edge plate, so that eccentric instability is prevented;
5) this application whole end process jar body normal position of trading supports, and jar body unsettled time is short when taking the cutting of wallboard at the bottom of the jar wall, simultaneously innovatively is applied to the bottom plate with TOFD detection technique and detects in.
Drawings
FIG. 1 is a schematic view of the construction process of the present application;
FIG. 2 is a schematic view of the present application of edge panel cutting;
fig. 3 is a schematic view and an installation schematic view of the stopper of the present application.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The invention provides a construction method for lowering height and changing bottom of a vertical storage tank, which is based on the pole lifting principle of an inverted installation method, but updates the conventional process of firstly lifting a tank body and then replacing an edge plate, fully utilizes the self-supporting force of the tank body, realizes that the edge plate is firstly replaced and then the pole is erected, avoids the two-step disassembly process of the pole in the conventional method, has advanced and reasonable process, is very suitable for the maintenance environment in which large lifting workers and machinery cannot enter a limited space, and has wide application prospect in the field of storage tank maintenance.
As an embodiment of the invention, the construction process of the present application is shown in fig. 1, and specifically includes the following steps:
step one; construction preparation:
1) and compiling a detailed operation instruction book before starting work, and performing safety technology interaction on all operating personnel.
2) The residual liquid level residual oil in the storage tank is cleaned, dirt, impurities and the like deposited in the storage tank are thoroughly eliminated and cleaned, and the conditions of internal maintenance and fire driving of the storage tank are met.
3) And confirming to stop the nitrogen sealing system, and detaching the accessories in the tank after disconnecting the nitrogen pipeline connected with the tank body.
4) The manholes at the periphery of the tank body, the pipe connecting ports and the pipe connecting ports at the top are all opened, an inward axial flow blower is arranged at one of the manholes, and an outward axial flow blower is arranged at the manholes or the pipe connecting positions at the opposite sides so as to keep the air in the tank fresh and qualified.
5) The model selection basis of the lifting system component (holding pole, electric block, expanding ring, lifting lug and the like) is as follows: and calculating the quantity of the electric hoists by the upper load and the rated hoisting load of the electric hoists, and carrying out load calculation, pole holding stress analysis and lug and welding line checking calculation on the electric hoists. Construction project change project 4 of 25000m of six-tank group of Qingjiang oil depot relocation project of Qingjiang petrochemical distribution Limited company of Nanjing3For example, 45 sets of 15t electric hoists are finally selected,
The steel pipe comprises a carbon steel seamless steel pipe, 525 × 200 × 20mm lifting lugs and a set of [25b expansion rings.
6) And (5) carrying out entrance inspection on the specification, the model and the quality of the lifting system component.
7) And (4) carrying out sand blasting corrosion prevention on the replaced plates, blanking according to the size of the typesetting drawing, and prefabricating a split heads, lifting lugs, a clamping apparatus and the like.
8) A temporary door opening of 1.5m H (H is the designed height to be lowered) is formed in the bottom wall plate, and the position is selected to facilitate the reverse transportation of the lifting system component by a crane.
Step two: and (3) related accessories and connecting parts are protectively dismantled:
1) inner floating disc dismantling
Because the floating disc needs to be installed again for use, all parts of the original floating disc are marked before being detached, and all parts of the floating disc are guaranteed not to be damaged as much as possible in the detaching process.
The edge plate of the floating plate is fixed by the positioning plate, so that the stability of the floating plate is ensured.
Loosening the fastening bolt of the sealing device, removing the sealing pressing strip and the edge pressing strip, taking the upper layer of sealing adhesive tape from the bolt, unfolding the upper layer of sealing adhesive tape along the wall of the tank, taking out the sealing filler in the adhesive tape, moving the filler to the outside of the tank for proper storage, and taking the lower layer of sealing adhesive tape from the bolt and moving the lower layer of sealing adhesive tape to the outside of the tank.
Loosening the bolt of the pressing bar, removing the fittings of the floating plate, such as the pressing bar, the manhole of the floating plate, the oil metering hole, the liquid level meter and the like, and then removing the cover plate.
And (3) removing the fixing bolts at the two ends of the main beam, removing the floating pipe clamp bolts, and sequentially removing the floating pipe, the main beam, the positioning beam, the frame beam, the strut and the like.
And (4) transporting the floating plate after disintegration to a storage yard outside the tank for storage and protection.
2) Electrical instrument removal
Dismantling the equipment parts and cables of the electrical instruments (such as a radar liquid level meter, a multipoint thermometer, an oil-water interface instrument, a servo instrument, an automatic sampling instrument, a high-low alarm instrument, a toxic gas alarm instrument, a pneumatic valve and the like) at the top and the bottom of the storage tank, using the dismantled parts as marks, wrapping the marks by using a plastic film, and transporting the covered parts to a warehouse or a yard to lay a lumber skid well; digging a pit on the bottom concrete ground, drawing out the cable, storing the cable in a winding manner, covering the pit with a steel plate, and making a protective mark; and cutting the height to be lowered from the bottom to the top of the threading pipe from the periphery of the tank wall to the tank top.
3) Removal of accessories outside tank
And (3) protectively detaching the connecting part at the root of the storage tank: and the root parts of the storage tanks, such as the pneumatic valve, the gate valve, the check valve, the metal hose and the like, are dismantled and transported to a storage yard for protection and storage.
And a temporary blind plate is arranged on the flange surface of the connected process pipeline for protection.
And (3) protective dismantling of the fire pipeline: marking the lower ends of the vertical pipes around the tank wall, cutting the tank body to be lowered, sealing and protecting the tank body by using a plastic film, and conveying the cut pipe sections to a material storage yard for placement; and 4, carrying out protective dismantling on all fire-fighting pipelines from the firewall to the periphery of the tank body, marking and transporting to a material storage yard for storage.
Cutting the coiling ladder and the high manhole ladder stand, and transporting to a material storage yard for storage.
4) In-tank fitment removal
And (3) disconnecting the in-tank diffusion tube and the tank wall connecting tube, cutting the height of the tank body to be lowered by the lower ends of the oil measuring tube and the guided wave tube, and reinforcing the tank body according to design requirements before cutting.
Step three: positioning the distribution positions of the cutting lines and the holding poles;
uniformly dotting positioning lines on the outer side of the tank at the positions of the T-shaped fillet welds of the wall plate and the bottom plate and the positions of the tank body with the reduced height of 300mm above the seam by using a level gauge; the position of the central point of the tank is measured by the intersection point of the two lines on the inner side of the tank and marked, and the tank wall is positioned and drawn according to the distribution position diagram of the holding poles.
Step four: replacing a tank bottom plate edge plate;
1) and a lap welding seam of the middle panel and the edge panel is cut by using a carbon arc air gouging to protect the tar sand at the bottom.
2) The first batch of edge plates are formed by taking a single edge plate in the direction of 0 degrees as a No. I plate, and are cut and replaced clockwise at intervals and radially and symmetrically. And (3) cutting the tank wall along the position 100mm outside the welding seam of the short edge of the No. I edge plate, as shown in fig. 2, conveniently replacing and installing the edge plate, and then cutting the tank wall corresponding to the No. I edge plate. And (3) drawing out the sand by using a forklift, cleaning and repairing the surface of the bituminous sand, dragging the sand in the tank by using a hydraulic ground to assist the forklift to install the edge plate, adding a split heads on the edge plate along the lower opening of the tank wall slot after the adjustment is finished, supporting and welding the split heads, and installing a first batch of lifting systems such as holding rods at the positioned positions.
3) After the first batch of lifting systems are in place, checked and accepted, the residual edge plates are symmetrically replaced according to the first batch of modes, the split heads, the residual holding rods and the electric block are installed, and finally the tops of the holding rods are connected into a whole through the pull rods.
4) And (3) welding the welding seam of 300mm at the outer end of the short side welding seam of the new edge plate, performing ray detection on the welding seam according to the design requirement, and performing the detection because the reconstruction is limited by the spatial position, so that the diffraction time difference method ultrasonic detection (TOFD) is additionally adopted for the innovation of the surface of the welding seam of the edge plate and the penetration detection is assisted.
Step five: cutting the wallboard;
1) and adjusting all electric hoists before cutting the wall plate to enable the electric hoists to be stressed uniformly, and carrying out test hoisting inspection.
2) The method comprises the following steps of cutting longitudinal seams of the bottom wall plate in a partitioning mode, cutting all longitudinal seams of each wall plate, after a lifting lug is welded, radially and symmetrically cutting annular seams of the wall plates at intervals, enabling a forklift to be in a supporting state when the cutting of the annular seams of each wall plate is about to be finished, and taking out the wall plates after the cutting to be transported and processed in a centralized mode. The cutting operation must be accomplished on the same day to descend the jar body to the bottom plate on, spot welding is fixed, avoids the strong wind weather to appear night.
Step six: descending the tank body;
1) the PLC is used for controlling, the console is used for unified operation, and the synchronous operation of the electric hoists is achieved.
2) The holding pole is used for observing the synchronism of the falling of the tank body by making a striking mark every 300mm from the bottom.
3) The working states of the electric hoist, the expansion ring and the holding pole are arranged for four persons to patrol in the descending process, the operation is immediately stopped and the power supply is cut off when the abnormality is found, and the operation can be continued after the potential safety hazard is eliminated until the electric hoist falls on the bottom plate.
4) The pot body sets up the stopper before descending on the tank bottoms edge board, 200 150 thickness are 20mm, and the interval is 2 meters evenly arranged. The great region of wallboard ovality deviation, the stopper is encrypted the setting, and the interval is not more than 0.5 meter, and stopper and wallboard atress friction face coat molybdenum disulfide and lubricate, demolish the stopper after the group is accomplished, polish the processing to corresponding position, as figure 3.
Step seven: welding the tank body;
1) after the tank body is lowered and assembled in place, the T-shaped fillet weld between the tank wall and the edge plate is welded, two layers are welded at the outer side and two layers are welded at the inner side, in order to prevent welding deformation, the outer side is bottomed, the inner side fillet weld is welded, and the outer side is welded finally. The welders are uniformly distributed in the tank and outside (the welders in the tank should lead by about 500 mm) and perform sectional welding along the same direction, and the initial welding bead is subjected to sectional back welding or skip welding.
2) And welding the residual welding seams of the edge plates after the T-shaped fillet welding seam is welded, and finally welding the contraction joint between the edge plates and the middle web plate.
3) And (4) opening the tank body according to design requirements, and installing a sewage discharge hole, a connecting pipe, a reinforcing ring, a manhole and a platform.
Step eight: inspecting, testing and preserving;
1) and carrying out nondestructive testing on the welding line according to the design requirement, carrying out vacuum test on the welding line of the bottom plate, and inspecting the tightness of the welding line by the reinforcing plate.
2) And (3) performing a water filling test on the sealing of the manhole and the flange surface of the connecting pipe of the tank body, and checking the tightness of the tank bottom, the strength and the tightness of the tank wall in the process, wherein the tank bottom and the tank wall are free of leakage and abnormal deformation and are qualified.
3) And carrying out in-tank and out-tank sand blasting anticorrosion painting according to design requirements.
Step nine: restoring the installation of the accessories;
1) and (3) recovering and installing process pipelines: the pneumatic valve, the gate valve, the check valve and the metal hose are reinstalled according to the original design positions; the original positions of the nitrogen sealing pipeline and the oil expansion pipeline are recovered and installed; and (5) restoring and installing the gap bridge platform at the original position.
2) And (3) recovering and installing the fire pipeline: the fire-fighting water pipeline, the foam pipeline and the summer cooling spraying pipeline are reinstalled according to the original positions.
3) And (3) recovering and installing the inner floating disc: and (5) sequentially restoring and installing the edge plates, the edge pillars, the main beams, the floating pipes, the middle pillars, the paving plates, the pressing strips, the sealing devices and other accessories according to the typesetting layout.
4) The radar liquid level meter, the multi-point thermometer, the oil-water interface instrument, the servo, the automatic sampling instrument, the high-low level alarm instrument, the toxic gas alarm instrument and the like are reinstalled according to the original display positions; restoring the wiring of the instrument and the cable penetrating from the ground plane to the top of the tank and the lighting cable penetrating from the coiled ladder to the top of the tank; and the pneumatic valve air source pipe is reinstalled.
Step ten: performing an inner floating disc lifting test and overall acceptance inspection;
according to the design requirement, the inner floating disc is filled with water for a lifting test, the floating roof and the inner floating roof should stably lift in the lifting test, the guide mechanism, the sealing device and the automatic vent valve strut should not be jammed, the escalator should flexibly rotate, the floating roof and the accessories thereof should not interfere with other accessories on the tank body, the contact part of the floating roof and the liquid level should not leak, and the storage tank is integrally checked and accepted after the inspection is qualified.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (4)
1. A construction method for lowering height and changing bottom of a vertical storage tank comprises the following steps:
step one; construction preparation:
1) compiling a detailed operation instruction book before starting work, and performing safety technology exchange on all operating personnel;
2) cleaning residual liquid level residual oil in the storage tank, thoroughly eliminating and cleaning dirt and impurities deposited in the storage tank, and meeting the conditions of internal maintenance and fire driving of the storage tank;
3) confirming to stop the nitrogen sealing system, disconnecting the nitrogen pipeline connected with the tank body, and then removing accessories in the tank body;
4) the manholes at the periphery of the tank body, the pipe connecting openings and the pipe connecting openings at the top are all opened, an inward axial flow blower is arranged at one of the manholes, and an outward axial flow blower is arranged at the manholes or the pipe connecting positions at the opposite side so as to keep the air in the tank fresh and qualified;
5) lifting the system component for model selection;
6) inspecting the specification, the model and the quality of the lifting system component;
7) carrying out sand blasting and corrosion prevention on the replaced plate, blanking according to the size of the typesetting drawing, and prefabricating a split heads, lifting lugs and a tool clamp;
8) 1.5m x H is arranged on the bottom wall plate, wherein H is a temporary door opening for designing the height to be lowered, and the position selection is convenient for a crane to transport the lifting system component;
step two: and (3) related accessories and connecting parts are protectively dismantled:
1) dismantling the inner floating disc;
marking each part of the original floating disc before dismantling, and ensuring each part of the floating disc not to be damaged as much as possible in the dismantling process;
fixing the edge plate of the floating disc by using a positioning plate to ensure the stability of the floating disc;
loosening a fastening bolt of a sealing device, removing a sealing batten and an edge batten, taking an upper layer of sealing adhesive tape from the bolt, unfolding the upper layer of sealing adhesive tape along the wall of the tank, taking out sealing filler in the adhesive tape, moving the filler to the outside of the tank for proper storage, and taking a lower layer of sealing adhesive tape from the bolt and moving the lower layer of sealing adhesive tape to the outside of the tank;
loosening the pressing bar bolt, removing the pressing bar, the floating disc manhole, the oil measuring hole and the floating disc accessory of the liquid level meter, and removing the cover plate;
removing the fixing bolts at the two ends of the main beam, removing the floating pipe clamp bolts, and sequentially removing the floating pipe, the main beam, the positioning beam, the frame beam and the strut;
after the floating plate is disassembled, the floating plate is transported to a storage yard outside the tank for storage and protection;
2) dismantling the electric instrument;
dismantling electrical instrument equipment parts and cables at the top and the bottom of the storage tank, using the dismantled parts as marks, wrapping the marks with plastic films, and transporting the covered parts to a warehouse or a yard to be placed with skid blocks; digging a pit on the bottom concrete ground, drawing out the cable, storing the cable in a winding manner, covering the pit with a steel plate, and making a protective mark; cutting the height to be lowered from the bottom upwards by the threading pipe from the periphery of the tank wall to the tank top;
3) removal of accessories outside tank
And (3) protectively detaching the connecting part at the root of the storage tank: the root parts of the storage tanks, such as a pneumatic valve, a gate valve, a check valve, a metal hose and the like, are dismantled and then transported to a storage yard for protection and storage;
adopting a protection measure for installing a temporary blind plate on the flange surface of the connected process pipeline;
and (3) protective dismantling of the fire pipeline: marking the lower ends of the vertical pipes around the tank wall, cutting the tank body to be lowered, sealing and protecting the tank body by using a plastic film, and conveying the cut pipe sections to a material storage yard for placement; the fire-fighting pipelines from the firewall to the periphery of the tank body are all protectively dismantled and marked to be transported to a material storage yard for storage;
cutting the coiling ladder and the high manhole ladder stand, and transporting to a material storage yard for storage;
4) dismantling accessories in the tank;
disconnecting the in-tank diffusion tube and the tank wall connecting tube, cutting the height of the tank body to be lowered by the lower ends of the oil measuring tube and the guided wave tube, and reinforcing the tank body according to design requirements before cutting;
step three: positioning the distribution positions of the cutting lines and the holding poles;
uniformly dotting positioning lines on the outer side of the tank at the positions of the T-shaped fillet welds of the wall plate and the bottom plate and the positions of the tank body with the reduced height of 300mm above the seam by using a level gauge; the position of the central point of the tank is measured by utilizing the intersection point of the two lines on the inner side of the tank, the central point is marked, and a line is positioned and drawn on the wall of the tank according to the distribution position diagram of the holding poles;
step four: replacing a tank bottom plate edge plate;
1) a circle of lap welding seam of the middle panel and the edge panel is cut by using a carbon arc gouging to protect the tar sand at the bottom;
2) the method comprises the following steps that a first batch of edge plates are formed by taking a single edge plate in the direction of 0 degree as a first plate, clockwise symmetrical cutting and replacement are carried out at intervals, the first batch of edge plates are cut at a position which is 100mm away from a weld joint of a short edge of the first edge plate, the edge plates are convenient to replace and install, the tank wall corresponding to the first edge plate is cut, a forklift is used for drawing out, the surface of asphalt sand is cleaned and repaired, a hydraulic ground is used for dragging the tank to assist the forklift to install the edge plates, a split stool is added on the edge plates along the lower opening of a tank wall slot after adjustment is finished, welding and fixing are carried out, and a first batch of lifting systems such as holding;
3) after the first batch of lifting systems are in place, checked and accepted, the residual edge plates are symmetrically replaced according to the first batch of modes, the split heads, the residual holding rods and the electric block are installed, and finally the tops of the holding rods are connected into a whole through pull rods;
4) welding the weld joint of 300mm at the outer end of the short side weld joint of the new edge plate, and carrying out ray detection on the weld joint according to the design requirement, wherein the detection cannot be carried out due to the limitation of the spatial position in transformation, so that TOFD (time difference diffraction) ultrasonic detection and penetration detection assistance are additionally adopted for innovatively adopting the surface of the weld joint of the edge plate;
step five: cutting the wallboard;
1) adjusting all electric hoists before cutting the wall plate to enable the electric hoists to be stressed uniformly, and carrying out test hoisting inspection;
2) cutting longitudinal seams of the bottom wall plate in blocks, cutting all longitudinal seams of each wall plate, radially and symmetrically cutting annular seams of the wall plates at intervals after welding lifting lugs, enabling a forklift to be in a supporting state when the cutting of the annular seams of each wall plate is about to finish, taking out the wall plates after the cutting is finished, transferring and carrying out centralized treatment, finishing the cutting operation in the same day, lowering the tank body onto a bottom plate, and fixing the tank body by spot welding to avoid strong wind weather at night;
step six: descending the tank body;
1) the PLC is used for controlling, and the console is used for operating in a unified way, so that the synchronous operation of the electric hoists is achieved;
2) the holding pole is used for making a striking mark every 300mm from the bottom for observing the synchronism of the tank body falling;
3) in the landing process, four persons are arranged to patrol the working states of the electric hoist, the expansion ring and the holding pole, the operation is immediately stopped and the power supply is cut off when the abnormality is found, and the operation can be continued after the potential safety hazard is eliminated until the electric hoist falls on the bottom plate;
4) a limiting block is arranged on the edge plate of the tank bottom before the tank body falls;
step seven: welding the tank body;
1) after the tank body is put in place by descending assembly, welding T-shaped fillet welds of the tank wall and the edge plate, welding two layers outside and two layers inside, in order to prevent welding deformation, firstly backing up the outside, then welding the inside fillet welds, finally welding the outside, uniformly distributing the inside and outside of the tank, wherein the welding workers in the tank should go beyond 500mm, and perform segmented welding along the same direction, and the welding bead of the initial layer should adopt a segmented back welding or skip welding method;
2) welding the residual welding seams of the edge plates after the T-shaped fillet welding seam is welded, and finally welding the contraction joint between the edge plates and the middle web plate;
3) opening a hole in the tank body according to design requirements, and installing a sewage drainage hole, a connecting pipe, a reinforcing ring, a manhole and a platform;
step eight: inspecting, testing and preserving;
1) carrying out nondestructive testing on the welding line according to the design requirement, carrying out a vacuum test on the welding line of the bottom plate, and checking the tightness test of the welding line by the reinforcing plate;
2) performing a water filling test on the sealing of the manhole and the flange surface of the connecting pipe of the tank body, and checking the tightness of the tank bottom, the strength and the tightness of the tank wall in the process, wherein the tank bottom and the tank wall are free of leakage and abnormal deformation and are qualified;
3) carrying out in-tank and out sand blasting anticorrosion painting according to design requirements;
step nine: restoring the installation of the accessories;
1) and (3) recovering and installing process pipelines: the pneumatic valve, the gate valve, the check valve and the metal hose are reinstalled according to the original design positions; the original positions of the nitrogen sealing pipeline and the oil expansion pipeline are recovered and installed; the original position of the gap bridge platform is restored and installed;
2) and (3) recovering and installing the fire pipeline: the fire-fighting water pipeline, the foam pipeline and the summer cooling spraying pipeline are reinstalled according to the original positions;
3) and (3) recovering and installing the inner floating disc: sequentially restoring and installing the edge plates, the edge pillars, the main beams, the floating pipes, the middle pillars, the paving plates, the pressing strips, the sealing devices and other accessories according to the typesetting layout;
4) the radar liquid level meter, the multi-point thermometer, the oil-water interface instrument, the servo, the automatic sampling instrument, the high-low level alarm instrument, the toxic gas alarm instrument and the like are reinstalled according to the original display positions; restoring the wiring of the instrument and the cable penetrating from the ground plane to the top of the tank and the lighting cable penetrating from the coiled ladder to the top of the tank; mounting the pneumatic valve air source pipe again;
step ten: performing an inner floating disc lifting test and overall acceptance inspection;
according to the design requirement, the inner floating disc is filled with water for a lifting test, the floating roof and the inner floating roof should stably lift in the lifting test, the guide mechanism, the sealing device and the automatic vent valve strut should not be jammed, the escalator should flexibly rotate, the floating roof and the accessories thereof should not interfere with other accessories on the tank body, the contact part of the floating roof and the liquid level should not leak, and the storage tank is integrally checked and accepted after the inspection is qualified.
2. The construction method for lowering the height and changing the bottom of the vertical storage tank according to claim 1, characterized in that: the lifting system component in the construction preparation of the first step comprises a holding pole, an electric hoist, an expansion ring and a lifting lug, and the lifting system component is based on the following steps: and calculating the quantity of the electric hoists by the upper load and the rated hoisting load of the electric hoists, and calculating the load of the electric hoists, analyzing the stress of the holding pole, and checking and calculating the lifting lugs and the welding lines.
3. The construction method for lowering the height and changing the bottom of the vertical storage tank according to claim 1, characterized in that: and the bottom electric instrument detached in the second step comprises a radar liquid level meter, a multi-point thermometer, an oil-water interface instrument, a servo and automatic sampling instrument, a high-low alarm instrument, a toxic gas alarm instrument and a pneumatic valve.
4. The construction method for lowering the height and changing the bottom of the vertical storage tank according to claim 1, characterized in that: set up the stopper on tank bottoms edge plate when step six jar bodies descend, the stopper specification is 200mm 150mm thickness and is 20mm, and interval 2 meters are evenly arranged, and the great region of wallboard ovality deviation, stopper encryption setting, the interval is not more than 0.5 meter, and stopper and wallboard atress friction face coat molybdenum disulfide are lubricated, and the stopper is demolishd to the group after accomplishing, polishes corresponding position.
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| CN112360182A (en) * | 2020-12-02 | 2021-02-12 | 中国二十冶集团有限公司 | Bottom changing construction method for oil tank in cave depot |
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