CN111005454A - Flue gas purification room net rack block hoisting construction method - Google Patents
Flue gas purification room net rack block hoisting construction method Download PDFInfo
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- CN111005454A CN111005454A CN201911252484.8A CN201911252484A CN111005454A CN 111005454 A CN111005454 A CN 111005454A CN 201911252484 A CN201911252484 A CN 201911252484A CN 111005454 A CN111005454 A CN 111005454A
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/342—Structures covering a large free area, whether open-sided or not, e.g. hangars, halls
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/35—Extraordinary methods of construction, e.g. lift-slab, jack-block
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Abstract
The invention discloses a construction method for hoisting a grid frame of a flue gas purification room in blocks, which comprises the following steps: the net frame of the flue gas purification room consists of an east net frame, a west net frame and a middle net frame. The invention adopts a construction method of hoisting, starting, spanning and high-altitude bulk loading in blocks, thereby avoiding the situation that a large crane station cannot be used due to the limitation of site conditions; the double-layer guy rope is arranged on the support frame which is temporarily supported, so that the integral stability of the support frame is ensured when the support frame is pressed; the temporary support for the circular tube and the temporary support for the tower crane standard knot ensure that the rod of the net rack unit is smoothly supplemented at high altitude, and the temporary support frame can be repeatedly used in later engineering after the engineering is finished, so that not only can social resources be saved to the maximum extent, but also the resource advantages can be fully exerted, and the optimal utilization of resources is achieved.
Description
The technical field is as follows:
the invention relates to a hoisting method of a grid frame of a flue gas purification room, in particular to a block hoisting construction method of the grid frame of the flue gas purification room, and belongs to the technical field of steel structures.
Secondly, background art:
due to the advantages of lightness, attractiveness, strong integrity, large space rigidity, high factory degree, short construction time and the like, the grid structure is widely applied to important places such as airports, waiting halls, stadiums, exhibition halls, movie theaters and the like. After the grid structure is built and used, the bearing capacity of the structure cannot meet the use requirement due to the reasons of change of use function, increase of load, damage of the structure and the like, and measures are needed to ensure the safety of the structure; if demolish the reconstruction, need consume a large amount of resources and time, cause the waste, and consolidate former spatial grid structure, then can satisfy under the safe prerequisite of structure, improve and improve the service function and the value of former structure, practice thrift the cost, reduce the investment. The invention carries out block hoisting on the net rack of the flue gas purification room, has reasonable scheme, standard, short construction period and high resource utilization rate, avoids safety accidents in the construction process and ensures the smooth installation and construction of the net rack of the flue gas purification room.
Thirdly, the invention content:
the technical problem to be solved by the invention is as follows: the construction method for hoisting the grid frame of the flue gas purification room in blocks is reasonable in scheme, safe, firm, short in construction period and high in resource utilization rate, and ensures smooth installation and construction of the grid frame of the flue gas purification room.
The technical scheme adopted by the invention for solving the technical problem is as follows:
a grid frame of a flue gas purification room comprises an east grid frame, a west grid frame and a middle grid frame, wherein the east grid frame consists of an east first walking-on grid frame and an east second starting-on grid frame, the west grid frame consists of a west first walking-on grid frame, a west second starting-on grid frame, a west third starting-on grid frame and a west fourth starting-on grid frame, and the middle grid frame consists of a high-altitude first splicing frame and a high-altitude first splicing frame; a circular tube temporary support is arranged below the east first starting spanning net rack and the east second starting spanning net rack starting spanning; the tower crane standard knot temporary support is arranged below the first western stepping net spanning frame and the second western starting net spanning frame, the second western starting net spanning frame and the third western starting net spanning frame, the third western starting net spanning frame and the fourth western starting net spanning frame in the starting span respectively.
The pipe supports temporarily and comprises pipe, base and channel-section steel, the bottom vertically welding of pipe is in the intermediate position of base, pass through channel-section steel and base fixed connection together around the pipe lower part.
The tower crane standard knot temporary support consists of a bottom steel plate, four main rods and horizontal web member inclined web members, wherein the four main rods are vertically welded on the bottom steel plate, and a rectangle is formed among the four main rods; the four main rods are connected together through horizontal web members, and inclined web members are arranged between the upper horizontal web member and the lower horizontal web member which are adjacent.
The construction method for hoisting the grid frame of the flue gas purification room in blocks comprises the following specific steps:
1) selection of slings and lifting points
Four-point hoisting is carried out by adopting a single-machine hoisting method, and each hoisting point is provided with a steel cable; 2) installation of net frame
2) Installation of temporary support for circular tube
a. After the east first starting span net rack and the east second starting span net rack are assembled on the ground, the net racks are hoisted in two sections, and a circular pipe temporary support is arranged below the starting span middle of each net rack, so that the net rack units can smoothly supplement poles at high altitude;
b. the section of the temporary support of the round pipe is 609mm multiplied by 16mm, the length of the section is 6.0m, the lower part of the support frame of the round pipe adopts HW250 with the specification as a base, the side length is 2m, the periphery is fixed by channel steel, the middle of the round pipe is respectively pulled and arranged at the quartering position by a cable rope and fixed on a rigid frame of the dust remover; the support frame is provided with a double-layer guy rope, so that the integral stability of the support frame is ensured when the support frame is pressed;
3) temporary support installation for tower crane standard knot
a. After a western first step-by-step net rack (2-A), a western second step-by-step net rack (2-B), a western third step-by-step net rack (2-C) and a western fourth step-by-step net rack (2-D) are assembled on the ground, the net racks are divided into four blocks which are hoisted in place by using a crawler crane;
b. the main rod specification of the tower crane standard knot temporary support adopts 135 × 10 square tubes, the horizontal web members adopt 50 × 4 square tubes, the inclined web members adopt 60 × 4 square tubes, the bottom support is fixed on a steel plate with the thickness of 25mm (4 m × 4 m), the standard knot size is 1.6m × 2.8m, and the temporary support frames are respectively provided with a wind-pulling rope at the seventh knot, the fourteenth knot and the eighteenth knot and fixed on a rigid frame of the dust remover; the support frame is provided with a double-layer guy rope, so that the integral stability of the support frame is ensured when the support frame is pressed;
4) net rack unit assembly
①, measuring and positioning
a. Leveling the bed-jig by adopting a leveling instrument, and releasing an orthographic projection line of a 'net rack' on the ground by using a theodolite for ground splicing and paying off to serve as a control line for ground splicing of the 'net rack';
b. the frame blocks are assembled at the radial position of the crawler crane, and the assembled site requires to lay broken stones which must be tamped and leveled and has smooth drainage;
② preparation of construction before installation of net rack
a. Assembling the bolt-ball joint: the bolt-ball joint is a joint consisting of parts such as a bolt ball, a high-strength bolt, a sleeve, a fastening screw, a cone, a head or a sealing plate and the like, and is connected with parts of each section by screwing in the high-strength bolt;
b. the performance of the high-strength bolt with the bolt ball joint is detected: during tensile test, the center of the high-strength bolt of M12-M36 is sampled, the diameter of a test piece is calculated according to 3/4 of the diameter of the bolt, the high-strength bolt of M39-M64 multiplied by 4 is eccentrically sampled, the sampling center is positioned at 1/4 of the diameter of the bolt, and the diameter of the test piece is calculated according to 3/8 of the diameter of the bolt;
c. placing bolt balls: the method of splicing the triangular cones is adopted for classified placement of the bolt balls, namely, the balls and the rod pieces at the positions are firstly assembled, one constructor finds the positions of the ball holes, the two web members are respectively butted, a sleeve bolt is screwed by a spanner or a pipe wrench, then one constructor holds an upper chord member, the other constructor rapidly aligns the bolt at the corresponding ball hole, the upper chord member is screwed in place by a spanner, and the web member constructor shakes the rod pieces during the screwing process so that the rod pieces and the balls are completely screwed in place; after the work is finished, another upper chord is arranged, the ball hole is aligned, and the bolt is screwed in place; finally, splicing the net rack rod pieces on the ground into small splicing units according to the mounting sequence, and placing the small splicing units according to the construction positions;
③ installation of net rack
a. Assembling the upper chord: the mounting sequence of the chord members is transmitted from inside to outside, and the screwing of the upper chord members and the balls is sequentially performed with the screwing of the web members and the lower chord balls;
b. assembling the web member and the upper chord ball: the web members and the upper chord sphere form a downward quadrangular pyramid, the web members and the upper chord sphere are connected by one-time screwing in place, the web members and the lower chord sphere cannot be connected by one-time screwing in place, and the web members are mainly used for loosening the upper chord;
c. assembling the chord and the ball: according to the number of the installation drawing, the plane for padding the lower chord ball is well padded, and the lower chord rod piece and the ball are connected and screwed in place at one time;
d. the mounting method of the triangular cone comprises the following steps: two constructors respectively find ball holes corresponding to the rod piece at the upper chord node and the lower chord node, quickly screwing bolts between the rod piece and the balls in place, simultaneously working by the four constructors, and finally installing the lower chord rod and the lower chord ball by the two constructors;
e. after all the net racks are installed, the positions of all the supports of the net racks are integrally adjusted, the net racks are finely adjusted to the designed positions by using jacks, and then all the supports are welded;
5) ball joint welding
a. Before welding, oil contamination and impurities at the welding part are cleaned, and the positioning welding line is checked to have no defect;
b. baking the welding rod before welding, wherein the baking temperature is between 100 and 150 ℃, and the baking time is two hours;
c. the welding sequence of the net rack is as follows: firstly, performing diffusion welding from the middle to two sides on a lower chord node and a higher chord node; after all the welding seams on each node are welded for the first time, welding for the second time is carried out to prevent welding stress from concentrating and deform the net rack; half of the welding seam is not allowed to be welded after being formed;
d. when the wall thickness of the rod piece is less than 4mm, the welding thickness is 1.2 times of the wall thickness, and when the wall thickness of the rod piece is more than 4mm, the welding thickness is 1.5 times of the wall thickness; when the wall thickness of the rod piece is less than 4mm, the whole welding line is formed on two sides, when the wall thickness of the rod piece is 4-8 mm, the whole welding line is formed in three times, when the wall thickness of the rod piece is 8-12 mm, the whole welding line is formed in four times, and when the wall thickness is more than 12mm, the whole welding line is formed in five times; the first pass is backing welding, which is necessary to be welded through and is not allowed to have the defects of slag inclusion, air holes and cracks; then, the second welding is carried out, and the last welding is forming welding.
The installation order of the net rack between the flue gas purification rooms is as follows: firstly, after an east first walking-on net rack (1-A) and an east second walking-on net rack (1-B) are assembled on the ground, the net racks are respectively hung in place by a truck crane, and then the net racks of a high-altitude first splicing rack (3-A) are assembled and installed in a scattered way in high altitude on the basis of the east first walking-on net rack (1-A) and the east second walking-on net rack (1-B); finally, after the high-altitude first scattered assembly frame (3-A) is scattered and assembled, the western first stepping net rack (2-A), the western second starting stepping net rack (2-B), the western third starting stepping net rack (2-C) and the western fourth starting stepping net rack (2-D) are respectively assembled on the ground and then are sequentially hoisted in place; and (3) carrying out high-altitude splicing and folding from two sides to the middle on the basis of the west-side starting piece and the high-altitude first splicing frame (3-A).
The grid structure combines a ring fixing method and a tack welding method; before tack welding, whether a pipe end is completely matched with a spherical surface or not and whether oil contamination exists on two sides of a groove or not are checked, spot welding can be carried out after the groove is cleaned, tack welding is required to be carried out thoroughly, and the length is generally 30 mm; the annular fixed welding seam is formed by dividing an annular welding opening into two symmetrical semicircular welding openings by the vertical center of the pipe, and forming two joints at the overhead welding position and the flat welding position according to the welding sequence of one vertical welding opening and one flat welding opening; in the first half of welding, the starting point of the overhead welding position and the welding point of the horizontal welding position must exceed the half circumference of the pipe and exceed the center line by 5-15 mm, when the welding rod reaches the joint of the positioning welding seam, the forward movement speed of the welding rod should be slowed down so that the joint part can be fully melted through, and when the strip is conveyed to the horizontal welding position (i.e. exceeds the center line), the arc can be extinguished after the arc pit is filled; the second half starts welding from the rear end of the cutting groove, when the bar is conveyed to the center of the joint, arc extinction is not allowed to be carried out immediately, and the welding rod is required to be pushed upwards to penetrate through the root which is not melted, so that the joint is completely fused; when a flat welding head is used for welding, the welding rod is conveyed to a slightly inclined vertical welding position, the welding rod is required to be inclined forward, top arc welding is kept and slightly transversely swung, when the welding rod is closed at a distance of 3mm from the joint, arc extinguishing cannot be immediately carried out, and the welding rod is required to be slightly pressed inwards; before arc quenching, the arc crater must be filled and the arc is then directed to the groove side for arc quenching.
After the net rack high-strength bolt is fastened, a small positioning bolt on the sleeve is screwed and locked; after the installation of the grid structure is finished and the bolts are screwed in place, redundant holes and pores are blocked and sealed, and then the antirust paint and finish paint are coated.
The invention has the following positive beneficial effects:
1. according to the invention, the temporary support of the circular tube and the temporary support of the tower crane standard knot are arranged, so that the high-altitude smooth rod supplement of the net rack unit is ensured, and the temporary support can be repeatedly utilized in later engineering after the engineering is finished, so that not only can social resources be saved to the maximum extent, but also the resource advantages can be fully exerted, and the optimal utilization of resources is achieved.
2. The invention adopts a construction method of hoisting, starting, spanning and high-altitude bulk loading in blocks, thereby avoiding the situation that a large crane station cannot be used due to the limitation of site conditions; the double-layer guy rope is arranged on the support frame which is supported temporarily, so that the overall stability of the support frame is ensured when the support frame is pressed.
3. The improvement of the welding method of the invention is as follows: the traditional welding process needs several positions such as overhead welding, vertical welding, horizontal welding and the like, so that the change angle of a welding rod is very large, the operation is difficult, molten metal has a vertical falling trend at the overhead welding position, welding beading is easy to generate, the molten metal has a tendency of dripping towards the inside of a steel pipe at the vertical welding position and when the molten metal is transited to the horizontal welding position, the phenomena of uneven fusion depth and irregular appearance are caused, two welding seam joints at the overhead welding position and the horizontal welding position are difficult to operate when welding roots, and the overhead welding joint is easy to indent usually, which is a special defect of overhead welding, and the root at the horizontal welding head is easy to generate incomplete penetration and welding beading; the annular fixed welding seam of the invention divides the annular welding opening into two symmetrical semi-circular welding openings by the vertical center of the tube, and performs upward vertical horizontal welding according to the welding sequence of upward vertical welding and horizontal welding, so as to form two joints at the upward welding position and the horizontal welding position, thereby ensuring that molten iron and slag are well separated, and the melting depth is easy to control; the welding defects of the overhead welding part and the flat welding part are prevented, when the welding is performed in the first half, the starting point of the overhead welding position and the welding point of the flat welding position need to exceed the half cycle of the pipe and exceed the central line by 5-15 mm, when the welding rod reaches the welding joint of the positioning welding, the forward movement speed of the welding rod needs to be reduced, the joint part can be fully melted through, and when the conveying rod reaches the flat welding part (namely, exceeds the central line), the arc extinguishing can be performed after the arc pit needs to be filled. In the latter half of welding, the bar conveying method is basically the same as that in the former half, but much attention must be paid when conveying the bar to the overhead welding and flat welding heads, and the overhead welding heads are easy to generate defects such as air holes, end penetration and the like during welding, so that a part (about 10mm in length) of the original welding line at the welding start position is cut by electric arc during joint, thereby not only cutting off the possible defective welding line, but also forming a gentle slope-shaped cutting groove to facilitate joint; starting welding from the rear end of the cutting groove, when the bar is conveyed to the center of the joint, arc extinction is not allowed to be carried out immediately, and the welding rod is required to be jacked upwards to penetrate through the root which is not melted, so that the joint is completely fused; when a flat welding joint is welded, proper current intensity is selected, when the welding rod is conveyed to a slightly inclined vertical welding position, the welding rod is inclined forward, top arc welding is kept and transversely swings slightly, when the welding rod is closed at a distance of 3mm to 5mm from the joint, arc can not be immediately extinguished, the welding rod needs to be pressed inwards slightly, at the moment, the arc can be heard to penetrate through the root to generate sound, and the welding rod swings back and forth at the joint to prolong the retention time, so that sufficient fusion is ensured; before arc quenching, the arc pit must be filled, and then the arc is led to one side of the groove to quench the arc; the strip conveying method for the second time and the third time is basically the same, and the welding method is mainly characterized in that a joint is welded by overlapping and stacking for 10-15 mm, so that the joint is in smooth transition and the size of a welding seam is ensured.
Fourthly, explanation of the attached drawings:
FIG. 1 is a schematic view of a grid structure of a flue gas purification room according to the present invention;
FIG. 2 is a schematic structural view of a temporary support for a round tube according to the present invention;
FIG. 3 is a schematic structural diagram of temporary support of the tower crane standard knot.
The fifth embodiment is as follows:
the invention will be further explained and explained with reference to the drawings, in which:
referring to fig. 1-3, a flue gas purification room net rack comprises an east net rack, a west net rack 2 and a middle net rack 3, wherein the east net rack 1 consists of an east first walking and spanning net rack 1-a and an east second walking and spanning net rack 1-B, the west net rack 2 consists of a west first walking and spanning net rack 2-a, a west second walking and spanning net rack 2-B, a west third walking and spanning net rack 2-C and a west fourth walking and spanning net rack 2-D, and the middle net rack 3 consists of a high-altitude first scattered rack 3-a and a high-altitude first scattered rack 3-B; a circular tube temporary support 4 is arranged below the east first starting step spanning net rack 1-A and the east second starting step spanning net rack 1-B in the starting step; tower crane standard joint temporary supports 5 are respectively arranged below the starting strides of the western first starting striding net rack 2-A, the western second starting striding net rack 2-B, the western third starting striding net rack 2-C and the western fourth starting striding net rack 2-D; wherein: the round tube temporary support 4 consists of a round tube 4-1, a base 4-2 and a channel steel 4-3, the bottom of the round tube 4-1 is vertically welded in the middle of the base 4-2, and the periphery of the lower part of the round tube 4-1 is fixedly connected with the base 4-2 through the channel steel 4-3; the tower crane standard knot temporary support 5 consists of a bottom steel plate 5-1, main rods 5-2, horizontal web members 5-3 and inclined web members 5-4, the number of the main rods 5-2 is four, the main rods 5-2 are vertically welded on the bottom steel plate 5-1, and a rectangle is formed among the four main rods 5-2; the four main rods 5-2 are connected together through horizontal web members 5-3, and inclined web members 5-4 are arranged between the upper and lower adjacent horizontal web members 5-3.
The block hoisting construction method of the grid frame of the flue gas purification room comprises the following specific steps:
1) selection of slings and lifting points
Four-point hoisting is carried out by adopting a single-machine hoisting method, and each hoisting point is provided with a steel cable; 2) installation of net frame
2) Installation of temporary support for circular tube
a. After the east first starting span net rack and the east second starting span net rack are assembled on the ground, the net racks are hoisted in two sections, and a circular pipe temporary support is arranged below the starting span middle of each net rack, so that the net rack units can smoothly supplement poles at high altitude;
b. the section of the temporary support of the round pipe is 609mm multiplied by 16mm, the length of the section is 6.0m, the lower part of the support frame of the round pipe adopts HW250 with the specification as a base, the side length is 2m, the periphery is fixed by channel steel, the middle of the round pipe is respectively pulled and arranged at the quartering position by a cable rope and fixed on a rigid frame of the dust remover; the support frame is provided with a double-layer guy rope, so that the integral stability of the support frame is ensured when the support frame is pressed;
3) temporary support installation for tower crane standard knot
a. Assembling a western first stepping net rack 2-A, a western second stepping net rack 2-B, a western third stepping net rack 2-C and a western fourth stepping net rack 2-D on the ground, and then dividing the net racks into four blocks to be hoisted in place by using a crawler crane;
b. the main rod specification of the tower crane standard knot temporary support adopts 135 × 10 square tubes, the horizontal web members adopt 50 × 4 square tubes, the inclined web members adopt 60 × 4 square tubes, the bottom support is fixed on a steel plate with the thickness of 25mm (4 m × 4 m), the standard knot size is 1.6m × 2.8m, and the temporary support frames are respectively provided with a wind-pulling rope at the seventh knot, the fourteenth knot and the eighteenth knot and fixed on a rigid frame of the dust remover; the support frame is provided with a double-layer guy rope, so that the integral stability of the support frame is ensured when the support frame is pressed;
4) net rack unit assembly
①, measuring and positioning
a. Leveling the bed-jig by adopting a leveling instrument, and releasing an orthographic projection line of a 'net rack' on the ground by using a theodolite for ground splicing and paying off to serve as a control line for ground splicing of the 'net rack';
b. the frame blocks are assembled at the radial position of the crawler crane, and the assembled site requires to lay broken stones which must be tamped and leveled and has smooth drainage;
② preparation of construction before installation of net rack
a. Assembling the bolt-ball joint: the bolt-ball joint is a joint consisting of parts such as a bolt ball, a high-strength bolt, a sleeve, a fastening screw, a cone, a head or a sealing plate and the like, and is connected with parts of each section by screwing in the high-strength bolt;
b. the performance of the high-strength bolt with the bolt ball joint is detected: during tensile test, the center of the high-strength bolt of M12-M36 is sampled, the diameter of a test piece is calculated according to 3/4 of the diameter of the bolt, the high-strength bolt of M39-M64 multiplied by 4 is eccentrically sampled, the sampling center is positioned at 1/4 of the diameter of the bolt, and the diameter of the test piece is calculated according to 3/8 of the diameter of the bolt;
c. placing bolt balls: the method of splicing the triangular cones is adopted for classified placement of the bolt balls, namely, the balls and the rod pieces at the positions are firstly assembled, one constructor finds the positions of the ball holes, the two web members are respectively butted, a sleeve bolt is screwed by a spanner or a pipe wrench, then one constructor holds an upper chord member, the other constructor rapidly aligns the bolt at the corresponding ball hole, the upper chord member is screwed in place by a spanner, and the web member constructor shakes the rod pieces during the screwing process so that the rod pieces and the balls are completely screwed in place; after the work is finished, another upper chord is arranged, the ball hole is aligned, and the bolt is screwed in place; finally, splicing the net rack rod pieces on the ground into small splicing units according to the mounting sequence, and placing the small splicing units according to the construction positions;
③ installation of net rack
a. Assembling the upper chord: the mounting sequence of the chord members is transmitted from inside to outside, and the screwing of the upper chord members and the balls is sequentially performed with the screwing of the web members and the lower chord balls;
b. assembling the web member and the upper chord ball: the web members and the upper chord sphere form a downward quadrangular pyramid, the web members and the upper chord sphere are connected by one-time screwing in place, the web members and the lower chord sphere cannot be connected by one-time screwing in place, and the web members are mainly used for loosening the upper chord;
c. assembling the chord and the ball: according to the number of the installation drawing, the plane for padding the lower chord ball is well padded, and the lower chord rod piece and the ball are connected and screwed in place at one time;
d. the mounting method of the triangular cone comprises the following steps: two constructors respectively find ball holes corresponding to the rod piece at the upper chord node and the lower chord node, quickly screwing bolts between the rod piece and the balls in place, simultaneously working by the four constructors, and finally installing the lower chord rod and the lower chord ball by the two constructors;
e. after all the net racks are installed, the positions of all the supports of the net racks are integrally adjusted, the net racks are finely adjusted to the designed positions by using jacks, and then all the supports are welded;
5) ball joint welding
a. Before welding, oil contamination and impurities at the welding part are cleaned, and the positioning welding line is checked to have no defect;
b. baking the welding rod before welding, wherein the baking temperature is between 100 and 150 ℃, and the baking time is two hours;
c. the welding sequence of the net rack is as follows: firstly, performing diffusion welding from the middle to two sides on a lower chord node and a higher chord node; after all the welding seams on each node are welded for the first time, welding for the second time is carried out to prevent welding stress from concentrating and deform the net rack; half of the welding seam is not allowed to be welded after being formed;
d. when the wall thickness of the rod piece is less than 4mm, the welding thickness is 1.2 times of the wall thickness, and when the wall thickness of the rod piece is more than 4mm, the welding thickness is 1.5 times of the wall thickness; when the wall thickness of the rod piece is less than 4mm, the whole welding line is formed on two sides, when the wall thickness of the rod piece is 4-8 mm, the whole welding line is formed in three times, when the wall thickness of the rod piece is 8-12 mm, the whole welding line is formed in four times, and when the wall thickness is more than 12mm, the whole welding line is formed in five times; the first pass is backing welding, which is necessary to be welded through and is not allowed to have the defects of slag inclusion, air holes and cracks; then, the second welding is carried out, and the last welding is forming welding.
The installation sequence of the net rack in the flue gas purification room in the above description is as follows: firstly, after an east first walking net rack 1-A and an east second starting net rack 1-B are assembled on the ground, the net racks are respectively lifted to the right by a truck crane, and then the net racks of a high-altitude first splicing rack 3-A are assembled and installed in a high-altitude way on the basis of the east first walking net rack 1-A and the east second starting net rack 1-B; finally, after the high-altitude first splicing frame 3-A is spliced in a scattered mode, the western first stepping net rack 2-A, the western second stepping net rack 2-B, the western third stepping net rack 2-C and the western fourth stepping net rack 2-D are respectively spliced on the ground and then sequentially hoisted in place; the high-altitude first splicing frame 3-B is spliced and folded from two sides to the middle on the basis of the west-side starting piece and the high-altitude first splicing frame 3-A;
the grid structure combines a formal welding method and a positioning welding method; before tack welding, whether a pipe end is completely matched with a spherical surface or not and whether oil contamination exists on two sides of a groove or not are checked, spot welding can be carried out after the groove is cleaned, tack welding is required to be carried out, and the length of a tack weld is generally 30 mm; the annular fixed welding seam is characterized in that an annular welding opening is divided into two symmetrical semi-circular welding openings by the vertical center of the pipe, upward vertical horizontal welding is respectively carried out according to the welding sequence of upward vertical horizontal welding, and two joints are formed at the upward welding position and the horizontal welding position; the welding defects of the overhead welding part and the flat welding part are prevented, when the welding is performed in the first half, the starting point of the overhead welding position and the welding point of the flat welding position need to exceed the half cycle of the pipe and exceed the central line by 5-15 mm, when the welding rod reaches the welding joint of the positioning welding, the forward movement speed of the welding rod needs to be reduced, the joint part can be fully melted through, and when the conveying rod reaches the flat welding part (namely, exceeds the central line), the arc extinguishing can be performed after the arc pit needs to be filled. In the latter half of welding, the bar conveying method is basically the same as that in the former half, but much attention must be paid when conveying the bar to the overhead welding and flat welding heads, and the overhead welding heads are easy to generate defects such as air holes, end penetration and the like during welding, so that a part (about 10mm in length) of the original welding line at the welding start position is cut by electric arc during joint, thereby not only cutting off the possible defective welding line, but also forming a gentle slope-shaped cutting groove to facilitate joint; starting welding from the rear end of the cutting groove, when the bar is conveyed to the center of the joint, arc extinction is not allowed to be carried out immediately, and the welding rod is required to be jacked upwards to penetrate through the root which is not melted, so that the joint is completely fused; when a flat welding joint is welded, proper current intensity is selected, when the welding rod is conveyed to a slightly inclined vertical welding position, the welding rod is inclined forward, top arc welding is kept and transversely swings slightly, when the welding rod is closed at a distance of 3mm to 5mm from the joint, arc can not be immediately extinguished, the welding rod needs to be pressed inwards slightly, at the moment, the arc can be heard to penetrate through the root to generate sound, and the welding rod swings back and forth at the joint to prolong the retention time, so that sufficient fusion is ensured; before arc quenching, the arc pit must be filled, and then the arc is led to one side of the groove to quench the arc; the bar conveying method for the second and third times is basically the same, and the welding method is mainly characterized in that a joint is welded by overlapping and stacking for 10-15 mm, so that the joint is in smooth transition and the size of a welding seam is ensured; the welding rod has the advantages that the traditional welding process needs to be performed through several positions such as overhead welding, vertical welding, horizontal welding and the like, the change angle of the welding rod is large, the operation is difficult, the molten metal has a vertical falling trend at the overhead welding position, the weld beading is easy to generate, the vertical welding position and the transition to the horizontal welding position have a tendency of dripping towards the inside of the steel pipe, the phenomena of uneven fusion depth and uneven appearance are caused, the two welding joints at the overhead welding position and the horizontal welding position are difficult to operate during welding of the root part, the inwards concave part is easy to generate at the overhead welding position, and the root part of the horizontal welding head is easy to generate the conditions of incomplete penetration and the weld beading.
After the net rack high-strength bolt is fastened, a positioning small bolt on the sleeve is screwed and locked; after the installation of the grid structure is finished and the bolts are screwed in place, redundant holes and pores are blocked and sealed, and then the antirust paint and finish paint are coated.
Claims (7)
1. The utility model provides a rack between gas cleaning, includes eastern rack (1), western rack (2) and middle rack (3), its characterized in that: the east net rack (1) consists of an east first walking net rack (1-A) and an east second walking net rack (1-B), the west net rack (2) consists of a west first walking net rack (2-A), a west second walking net rack (2-B), a west third walking net rack (2-C) and a west fourth walking net rack (2-D), and the middle net rack (3) consists of a high-altitude first scattered assembly rack (3-A) and a high-altitude first scattered assembly rack (3-B); a circular tube temporary support (4) is arranged below the east first starting step net rack (1-A) and the east second starting step net rack (1-B) in the starting step; and tower crane standard knot temporary supports (5) are respectively arranged below the first western stepping and spanning net rack (2-A), the second western stepping and spanning net rack (2-B), the third western stepping and spanning net rack (2-C) and the fourth western stepping and spanning net rack (2-D) in the starting and spanning process.
2. The flue gas cleaning room rack of claim 1, wherein: the temporary support (4) for the round pipe is composed of the round pipe (4-1), a base (4-2) and channel steel (4-3), the bottom of the round pipe (4-1) is vertically welded in the middle of the base (4-2), and the periphery of the lower portion of the round pipe (4-1) is fixedly connected with the base (4-2) through the channel steel (4-3).
3. The flue gas cleaning room rack of claim 1, wherein: the tower crane standard knot temporary support (5) consists of four bottom steel plates (5-1), main rods (5-2), horizontal web members (5-3) and inclined web members (5-4), the number of the main rods (5-2) is four, the main rods are vertically welded on the bottom steel plates (5-1), and a rectangle is formed among the four main rods (5-2); the four main rods (5-2) are connected together through horizontal web members (5-3), and inclined web members (5-4) are arranged between the upper horizontal web member (5-3) and the lower horizontal web member (5-3).
4. The flue gas purification room network frame of claim 1, wherein the construction method of block hoisting comprises the following steps:
1) selection of slings and lifting points
Four-point hoisting is carried out by adopting a single-machine hoisting method, and each hoisting point is provided with a steel cable; 2) installation of net frame
2) Installation of temporary support for circular tube
a. After the east first starting span net rack and the east second starting span net rack are assembled on the ground, the net racks are hoisted in two sections, and a circular pipe temporary support is arranged below the starting span middle of each net rack, so that the net rack units can smoothly supplement poles at high altitude;
b. the section of the temporary support of the round pipe is 609mm multiplied by 16mm, the length of the section is 6.0m, the lower part of the support frame of the round pipe adopts HW250 with the specification as a base, the side length is 2m, the periphery is fixed by channel steel, the middle of the round pipe is respectively pulled and arranged at the quartering position by a cable rope and fixed on a rigid frame of the dust remover; the support frame is provided with a double-layer guy rope, so that the integral stability of the support frame is ensured when the support frame is pressed;
3) temporary support installation for tower crane standard knot
a. After a western first step-by-step net rack (2-A), a western second step-by-step net rack (2-B), a western third step-by-step net rack (2-C) and a western fourth step-by-step net rack (2-D) are assembled on the ground, the net racks are divided into four blocks which are hoisted in place by using a crawler crane;
b. the main rod specification of the tower crane standard knot temporary support adopts 135 × 10 square tubes, the horizontal web members adopt 50 × 4 square tubes, the inclined web members adopt 60 × 4 square tubes, the bottom support is fixed on a steel plate with the thickness of 25mm (4 m × 4 m), the standard knot size is 1.6m × 2.8m, and the temporary support frames are respectively provided with a wind-pulling rope at the seventh knot, the fourteenth knot and the eighteenth knot and fixed on a rigid frame of the dust remover; the support frame is provided with a double-layer guy rope, so that the integral stability of the support frame is ensured when the support frame is pressed;
4) net rack unit assembly
①, measuring and positioning
a. Leveling the bed-jig by adopting a leveling instrument, and releasing an orthographic projection line of a 'net rack' on the ground by using a theodolite for ground splicing and paying off to serve as a control line for ground splicing of the 'net rack';
b. the frame blocks are assembled at the radial position of the crawler crane, and the assembled site requires to lay broken stones which must be tamped and leveled and has smooth drainage;
② preparation of construction before installation of net rack
a. Assembling the bolt-ball joint: the bolt-ball joint is a joint consisting of parts such as a bolt ball, a high-strength bolt, a sleeve, a fastening screw, a cone, a head or a sealing plate and the like, and is connected with parts of each section by screwing in the high-strength bolt;
b. the performance of the high-strength bolt with the bolt ball joint is detected: during tensile test, the center of the high-strength bolt of M12-M36 is sampled, the diameter of a test piece is calculated according to 3/4 of the diameter of the bolt, the high-strength bolt of M39-M64 multiplied by 4 is eccentrically sampled, the sampling center is positioned at 1/4 of the diameter of the bolt, and the diameter of the test piece is calculated according to 3/8 of the diameter of the bolt;
c. placing bolt balls: the method of splicing the triangular cones is adopted for classified placement of the bolt balls, namely, the balls and the rod pieces at the positions are firstly assembled, one constructor finds the positions of the ball holes, the two web members are respectively butted, a sleeve bolt is screwed by a spanner or a pipe wrench, then one constructor holds an upper chord member, the other constructor rapidly aligns the bolt at the corresponding ball hole, the upper chord member is screwed in place by a spanner, and the web member constructor shakes the rod pieces during the screwing process so that the rod pieces and the balls are completely screwed in place; after the work is finished, another upper chord is arranged, the ball hole is aligned, and the bolt is screwed in place; finally, splicing the net rack rod pieces on the ground into small splicing units according to the mounting sequence, and placing the small splicing units according to the construction positions;
③ installation of net rack
a. Assembling the upper chord: the mounting sequence of the chord members is transmitted from inside to outside, and the screwing of the upper chord members and the balls is sequentially performed with the screwing of the web members and the lower chord balls;
b. assembling the web member and the upper chord ball: the web members and the upper chord sphere form a downward quadrangular pyramid, the web members and the upper chord sphere are connected by one-time screwing in place, the web members and the lower chord sphere cannot be connected by one-time screwing in place, and the web members are mainly used for loosening the upper chord;
c. assembling the chord and the ball: according to the number of the installation drawing, the plane for padding the lower chord ball is well padded, and the lower chord rod piece and the ball are connected and screwed in place at one time;
d. the mounting method of the triangular cone comprises the following steps: two constructors respectively find ball holes corresponding to the rod piece at the upper chord node and the lower chord node, quickly screwing bolts between the rod piece and the balls in place, simultaneously working by the four constructors, and finally installing the lower chord rod and the lower chord ball by the two constructors;
e. after all the net racks are installed, the positions of all the supports of the net racks are integrally adjusted, the net racks are finely adjusted to the designed positions by using jacks, and then all the supports are welded;
5) ball joint welding
a. Before welding, oil contamination and impurities at the welding part are cleaned, and the positioning welding line is checked to have no defect;
b. baking the welding rod before welding, wherein the baking temperature is between 100 and 150 ℃, and the baking time is two hours;
c. the welding sequence of the net rack is as follows: firstly, performing diffusion welding from the middle to two sides on a lower chord node and a higher chord node; after all the welding seams on each node are welded for the first time, welding for the second time is carried out to prevent welding stress from concentrating and deform the net rack; half of the welding seam is not allowed to be welded after being formed;
d. when the wall thickness of the rod piece is less than 4mm, the welding thickness is 1.2 times of the wall thickness, and when the wall thickness of the rod piece is more than 4mm, the welding thickness is 1.5 times of the wall thickness; when the wall thickness of the rod piece is less than 4mm, the whole welding line is formed on two sides, when the wall thickness of the rod piece is 4-8 mm, the whole welding line is formed in three times, when the wall thickness of the rod piece is 8-12 mm, the whole welding line is formed in four times, and when the wall thickness is more than 12mm, the whole welding line is formed in five times; the first pass is backing welding, which is necessary to be welded through and is not allowed to have the defects of slag inclusion, air holes and cracks; then, the second welding is carried out, and the last welding is forming welding.
5. The flue gas purification room grid frame block hoisting construction method according to claim 4, characterized in that: the installation order of the net rack between the flue gas purification rooms is as follows: firstly, after an east first walking-on net rack (1-A) and an east second walking-on net rack (1-B) are assembled on the ground, the net racks are respectively hung in place by a truck crane, and then the net racks of a high-altitude first splicing rack (3-A) are assembled and installed in a high-altitude way on the basis of the east first walking-on net rack (1-A) and the east second walking-on net rack (1-B); finally, after the high-altitude first scattered assembly frame (3-A) is scattered and assembled, the western first stepping net rack (2-A), the western second starting stepping net rack (2-B), the western third starting stepping net rack (2-C) and the western fourth starting stepping net rack (2-D) are respectively assembled on the ground and then are sequentially hoisted in place; and (3) carrying out high-altitude splicing and folding from two sides to the middle on the basis of the west-side starting piece and the high-altitude first splicing frame (3-A).
6. The flue gas purification room grid frame block hoisting construction method according to claim 4, characterized in that: the grid structure is formed by combining a formal welding method and a positioning welding method; before tack welding, whether a pipe end is completely matched with a spherical surface or not and whether oil contamination exists on two sides of a groove or not are checked, spot welding can be carried out after the groove is cleaned, tack welding is required to be carried out thoroughly, and the length is generally 30 mm; the annular fixed welding seam is formed by dividing an annular welding opening into two symmetrical semicircular welding openings by the vertical center of the pipe, and forming two joints at the overhead welding position and the flat welding position according to the welding sequence of one vertical welding opening and one flat welding opening; in the first half of welding, the starting point of the overhead welding position and the welding point of the horizontal welding position must exceed the half circumference of the pipe and exceed the center line by 5-15 mm, when the welding rod reaches the joint of the positioning welding seam, the forward movement speed of the welding rod should be slowed down so that the joint part can be fully melted through, and when the strip is conveyed to the horizontal welding position (i.e. exceeds the center line), the arc can be extinguished after the arc pit is filled; the second half starts welding from the rear end of the cutting groove, when the bar is conveyed to the center of the joint, arc extinction is not allowed to be carried out immediately, and the welding rod is required to be pushed upwards to penetrate through the root which is not melted, so that the joint is completely fused; when a flat welding head is used for welding, the welding rod is conveyed to a slightly inclined vertical welding position, the welding rod is required to be inclined forward, top arc welding is kept and slightly transversely swung, when the welding rod is closed at a distance of 3mm from the joint, arc extinguishing cannot be immediately carried out, and the welding rod is required to be slightly pressed inwards; before arc quenching, the arc crater must be filled and the arc is then directed to the groove side for arc quenching.
7. The flue gas purification room grid frame block hoisting construction method according to claim 4, characterized in that: after the net rack high-strength bolt is fastened, a small positioning bolt on the sleeve is screwed and locked; after the installation of the grid structure is finished and the bolts are screwed in place, redundant holes and pores are blocked and sealed, and then the antirust paint and finish paint are coated.
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