CN217174896U - Bolt mounting distance support - Google Patents

Abstract

The utility model relates to a chemical plant cracking furnace, other engineering equipment of the same kind technical field such as gas furnace, especially, relate to a bolt installation distance support, characterized by, including stand, upper portion horizontal cross arm, lower part horizontal cross arm and horizontal pull rod, a plurality of to upper portion horizontal cross arm parallel arrangement, upper portion horizontal cross arm below sets up a plurality of lower part horizontal cross arm perpendicularly, and upper portion horizontal cross arm and lower part horizontal cross arm are connected through the horizontal pull rod respectively and are connected fixed stable space frame structure of formation with four stands, and upper portion horizontal cross arm and distance template accordant connection are equipped with a set of buried bolt's in advance installation locating hole in the distance template. The utility model has the advantages that: the bottom row of steel bars are adopted as a fixing measure of the lower part of the foundation bolt, an original bottom layer positioning die is replaced, the position precision, the section size and the concrete tamping performance of the bolt can be guaranteed, the forming quality of the bolt and the concrete can be guaranteed, the construction efficiency is improved by 30%, and the quality standard reaching rate is 100%.

Description

Bolt mounting distance support

Technical Field

The utility model relates to a chemical plant cracking furnace, other engineering equipment of the same kind technical field such as gas furnace install, especially relate to a bolt installation distance support.

Background

Along with the rapid development of economy in China, chemical plants, power plants and various large-scale novel industrial equipment are installed increasingly, embedded bolts of various foundations (especially equipment foundations) are adopted in a large number, compared with traditional buildings, the embedded bolts of the foundations of the buildings are large in specification and quantity and high in construction precision requirement, and once the embedded bolts generate large deviation, normal installation and debugging of the equipment are directly influenced, and the embedded bolts play a critical role in the whole project.

The method for fixing the embedded bolt mainly applied to the embedded bolt in the industrial building is an electric welding embedded bolt method. The method is mainly a technological mode that the embedded bolts are fixed on the steel bars of the foundation short column by welding means, and the steel structure is installed after pouring is finished, and the working efficiency is lower for occasions with large quantity, multiple specifications and higher construction precision requirement.

The application number 202121795343.3 discloses a positioning device for pre-embedded bolts at the top of a concrete column and a fixing structure for the pre-embedded bolts, wherein each pre-embedded bolt is suspended and fixed at the top of the concrete column by the positioning device, the positioning device comprises two positioning sleeves arranged at intervals, a connecting cross rod is detachably connected between the two positioning sleeves, and the connecting cross rod can horizontally move between the two positioning sleeves and is positioned; all be equipped with a terminal fastener that runs through the position sleeve and can fix the position sleeve on buried bolt or basic reinforcing bar in advance on every position sleeve. When the positioning device is used, the two positioning sleeves of each positioning device are respectively sleeved on one of the foundation steel bars and the embedded bolts, and the embedded bolts are supported through the connecting cross rods.

The Chinese utility model patent with the application number of 201910881628.X provides an auxiliary device for a pre-buried bolt and a fixing method for the pre-buried bolt, which comprises a pouring mold, wherein the pouring mold is provided with a pouring space; the fixing piece is connected to the pouring mold and provided with a plurality of through holes, and an embedded bolt penetrates through each through hole, so that the embedded bolt is fixed in the position of the embedded bolt in the pouring space in advance. The fixing method of the embedded bolts comprises the steps of firstly obtaining the installation positions of the embedded bolts, arranging an embedded bolt auxiliary device at each installation position, and pouring the embedded bolts.

In the foundation bolt construction process, the preformed hole method is complex and tedious in process. And the other method is a one-step pouring method, which adopts the mode of an upper layer of positioning template and a lower layer of positioning template for construction, after bolts are formed, the lower layer of positioning template is directly poured in concrete, on one hand, the manufacturing cost of the steel plate is higher, on the other hand, the size of the section of the concrete at the position of the lower layer of positioning template cannot be guaranteed, the concrete compactness under the lower layer of positioning template cannot be controlled, the construction quality cannot reach the expected effect, and certain hidden troubles are caused to the construction quality of the project.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a bolt installation distance support overcomes prior art's is not enough, through adopting bolt installation distance support when pre-buried bolt is under construction, replaces the pre-buried distance template in bolt bottom and the support braced system of traditional approach with end row reinforcing bar net, through constantly practising and technological improvement to summarize and refine, make its installation construction requirement that can adapt to the pre-buried bolt of capital high accuracy completely.

In order to achieve the above object, the utility model discloses a following technical scheme realizes:

bolt installation distance support, its characterized in that includes stand, upper portion horizontal cross arm, lower part horizontal cross arm and horizontal pull rod, and a plurality of to upper portion horizontal cross arm parallel arrangement, upper portion horizontal cross arm below sets up a plurality of lower part horizontal cross arm perpendicularly, and the interval is buried bolt diameter +2mm in advance between the adjacent cross arm, and upper portion horizontal cross arm and lower part horizontal cross arm are connected through horizontal pull rod respectively and are connected fixedly with four stands and form stable space frame structure, upper portion horizontal cross arm and distance template accordant connection, be equipped with a set of buried bolt's of advance installation locating hole on the distance template, the installation locating hole diameter is buried bolt diameter +2mm in advance.

The upper horizontal cross arm and/or the lower horizontal cross arm are of a double-steel-pipe structure, and the distance between the double steel pipes is +2mm of the diameter of the embedded bolt.

Compared with the prior art, the beneficial effects of the utility model are that: 1) the bottom row of steel bars are used as a fixing measure of the lower portion of the foundation bolt, an original bottom layer positioning die is replaced, the operation is simple and convenient, the position accuracy, the section size and the concrete tamping performance of the bolt can be guaranteed, and the quality of the bolt and the concrete forming can be guaranteed. 2) The installation speed is fast, saves material. Compared with the traditional construction method: in the traditional construction method, a bolt support system is embedded at the bottom of a foundation, and bolts are installed one by one; the utility model discloses a reinforcing bar net replaces the mounting system, whole group construction bolt. 3) The installation quality is high, and the position is accurate. 4) The method has the advantages of less required equipment, simple operation process, 30 percent improvement of construction efficiency and 100 percent of quality standard-reaching rate.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural view of an embodiment of the distance template of the present invention;

figure 2 is a plan view of a bolt mounted distance bracket according to an embodiment of the invention;

FIG. 3 is a perspective view of a spacer bracket for mounting a bolt according to an embodiment of the present invention;

FIG. 4 is a schematic view of the embodiment of the present invention illustrating the fabrication of bottom row steel bars;

fig. 5 is the utility model provides an in the embodiment of the utility model the installation of bolt bottom row reinforcing bar sketch map.

In the figure: 1-spacing template; 2-upper horizontal cross arm; 3-lower horizontal cross arm; 4-horizontal pull rod; 5-upright column; 6-bottom row of steel bars; 7-embedding bolts; 8-stirrup.

Detailed Description

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

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the position or positional relationship based on the position or positional relationship shown in the drawings, or the position or positional relationship which is usually placed when the product of the present invention is used, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention.

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

The components of the embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.

See fig. 1-fig. 5, is the embodiment of the distance bracket for fixing the distance template and the bolt according to the present invention, in order to ensure the rigidity of the mold, the distance template 1 is made of a steel plate with a thickness of 8 mm. The inner diameter of the hole in the plate surface of the distance template 1 is only 2mm larger than the outer diameter of the designed embedded bolt 7, the center of the hole is consistent with the design, when the embedded bolts 7 are sleeved in the hole, the maximum displacement deviation of each embedded bolt 7 can be 1mm, the maximum displacement deviation of any two embedded bolts 7 can be 2mm, and therefore the fact that the central displacement between any embedded bolts 7 of the same embedded bolt 7 group reaches the construction precontrol target is less than or equal to 2mm can be guaranteed.

Bolt installation distance support includes stand 5, upper portion horizontal cross arm 2, lower part horizontal cross arm 3 and horizontal pull rod 4, a plurality of 2 parallel arrangement to upper portion horizontal cross arm, upper portion horizontal cross arm below sets up a plurality of lower part horizontal cross arm 3 perpendicularly, the interval is buried bolt 7 diameter +2mm in advance between the adjacent cross arm, upper portion horizontal cross arm 2 and lower part horizontal cross arm 3 are connected through horizontal pull rod 4 respectively and are connected fixed formation stable space frame structure with four stands 5, upper portion horizontal cross arm 2 and distance template 1 accordant connection, be equipped with the installation locating hole of a set of buried bolt 7 on the distance template 1, the installation locating hole diameter is buried bolt 7 diameter +2mm in advance. The upper horizontal cross arm 2 and the lower horizontal cross arm 3 are both of a double-steel-pipe structure, and the distance between the double steel pipes is 7 mm +2mm of the embedded bolt.

The embodiment of the utility model provides a construction process flow and operating point

The method comprises the following steps:

distance template manufacturing → measurement and positioning → installation of embedded bolt bottom row reinforcing steel → erection of bolt installation distance bracket → installation of distance template and embedded bolt → adjustment of top elevation and verticality of embedded bolt → assembly welding → concrete pouring

Secondly, the operation key points are as follows:

1) the distance template 1 is manufactured, a manufacturer must strictly customize the distance template according to a design drawing, and the distance template 1 must meet the requirements of a drawing. The distance template 1 is the key for ensuring that the center displacement between any embedded bolts of the embedded bolts 7 in the same group is less than or equal to 2 mm;

2) and (4) measuring and positioning, namely measuring and confirming the elevation of the bottom position of the embedded bolt 7 and marking the corresponding positions of all the column main ribs. And (3) binding the stirrups 8 below the bottom positions of the embedded bolts 7, preferably, the distance between the stirrups 8 and the bottom positions of the embedded bolts 7 is not less than 50mm, and checking the column reinforcements and adjusting the verticality after binding.

3) Bottom row of steel bars 6 for installing embedded bolts

a. And manufacturing latticed bottom-row steel bars 6 according to the positions of the embedded bolts 7 and the cross-sectional sizes of the positions of the column bars. The bottom of the embedded bolt 7 can be ensured to be located at the upper row of steel bars of the grid bottom row of steel bars 6.

b. And fixing the bottom row of steel bars 6 at the corresponding positions of the column bars in a welding mode, and ensuring that the upper surface positions of the bottom plate steel bars are overlapped with the bottom positions of the embedded bolts 7.

c. The diameter of the steel bar adopted by the bottom row of steel bar 6 net is preferably more than or equal to phi 10mm

e. The bottom row of steel bars 6 net mainly plays a fixing role, and the embedded bolts 7 mainly bear the load and depend on the independent support system of the embedded bolts 7.

e. After the stirrups 8 at the upper parts of the column reinforcements are sleeved and gathered at the middle and upper parts, a top fixing system of the embedded bolts 7 is constructed.

4) Erecting a bolt mounting distance support:

i. 4 steel pipes are arranged as independent stable frame upright columns 5, the positions of the upright columns 5 are set according to the actual situation on site, but the distance between the upright columns 5 and the outer side of a foundation column is not more than 500mm, the steel pipes are used as horizontal pull rods 4 and cross braces outside the upright columns 5 to fix the distance between the upright columns 5 and ensure the stability of the upright columns 5, the steel pipes are connected and fixed by fasteners, the distance between the horizontal pull rods 4 and a foundation bearing platform in the first step is not more than 200mm, the distance is 1m above, and the height of the upright columns 5 is 300mm higher than the top of the foundation column;

ii. The upper end of the stabilizing frame body is provided with an upper horizontal cross arm 3 and a lower horizontal cross arm 3 in the longitudinal and transverse directions by steel pipes, the lower horizontal cross arm 3 and the uppermost horizontal pull rod 4 are in the same horizontal plane, and the horizontal cross arms are arranged by double steel pipes and used for clamping the foundation embedded bolts 7 and the fixed distance template 1;

iii, the height of the top surface of the upper horizontal cross arm 2 can be determined according to the actual conditions such as the height of a foundation column on a drawing, the height of a foundation column template with the screw thread leakage length of the foundation embedded bolt 7 and the like, but the top surface of the upper horizontal cross arm is not higher than the position 60mm below the top of the foundation embedded bolt 7;

iii, the top fixing system cannot be connected with the operation platform scaffold system and the foundation column template supporting system, and the independent stability of the system must be maintained;

5) installing a distance template 1 and embedded bolts 7:

(1) a single group of foundation embedded bolts 7 are fixed by a distance template 1, and the embedded bolts 7 are fixed up and down on the distance template 1 by nuts;

(2) and hoisting the fixed foundation embedded bolts 7 group to the corresponding foundation column by using a 25T crane, placing the foundation embedded bolts 7 group on the upper horizontal cross arm 2, installing the lower cross arm, clamping the embedded bolts 7 by using double steel pipes, correcting the positions, and fixing the cross arm and the horizontal pull rod 4. The cross arm and the horizontal pull rod 4 are fixed by steel strands, so that the position of the embedded bolt 7 can be conveniently adjusted. At the moment, the bottom of the embedded bolt 7 is just located on the installed bottom row of steel bars 6.

(3) A level is placed on each of the four sides of the distance form 1. And simultaneously observing the bubble of the level ruler, and finely adjusting the adjustable bracket by a specially-assigned person. And after the horizontal bubbles on each side are centered, adjusting the plane position of the distance template 1 again. After the adjustment is correct, the four corners are additionally provided with upright posts and cross rods. And (4) removing the adjustable support. The plane and horizontal displacement of the distance template 1 is re-checked again. If the error exists after rechecking, the positioning adjustment is carried out again.

6) Adjusting the top elevation and the verticality of the embedded bolt 7:

(1) and adjusting the top elevation of the embedded bolt 7, and after the embedded bolt 7 is in place, primarily adjusting the top elevation of the embedded bolt 7. One person observes that the gap between the embedded bolt 7 and the positioning hole is kept uniform and consistent at the upper opening of the embedded bolt 7, and the other person controls the elevation of the upper opening of the embedded bolt 7 by using a total station (or a level gauge) until the elevation is designed, and the other person rotates the nut at the upper opening of the embedded bolt 7 until the nut and the plane of the distance template 1 are gapless.

(2) After the initial adjustment is finished, the elevation of the upper opening of the embedded bolt 7 is rechecked by using a total station (or a level gauge) again, and if the elevation is deviated, the elevation is finely adjusted by rotating a nut of the upper opening of the embedded bolt 7 until the control precision requirement is met.

(3) The sequence of adjusting the embedded bolts 7 is that the elevation of the upper opening of the embedded bolt 7 on the top of the quadrangular column is adjusted, then the elevation of the upper opening of the embedded bolt 7 at the position of the middle column is adjusted, and the adjusting method is the same as the above.

(4) The elevation of the upper openings of the other column top embedded bolts 7 is based on the column top embedded bolts 7 which are adjusted in place. The steel wire drawing wire is used as a control line for marking the height of the upper opening of the embedded bolt 7 to adjust the rest of the embedded bolts 7.

(5) The position of the distance template and the verticality of the embedded bolt 7 are corrected by a measurer by using an instrument;

(6) after the position of the distance template is corrected, a horizontal cross rod and a horizontal pull rod of the fixing system are firmly fixed;

(7) and after the verticality of the embedded bolt 7 is corrected, welding and fixing the bottom of the embedded bolt 7 and the bottom row of reticular steel bars.

7) Assembling and welding: after the elevation and the verticality of the embedded bolt 7 are adjusted and checked to be correct, a professional welder fixes the distance template 1 and the upper horizontal cross arm 2 of the fixing system in a spot welding mode, the bottom of the embedded bolt 7 is welded with the upper horizontal cross arm 2 of the fixing system, and the embedded bolt 7 is fixed to be ensured to be space-invariant. And after the welding is finished, rechecking the elevation and the horizontal displacement again.

8) Pouring concrete:

(1) when concrete is poured and tamped, pump pipes, vibrating rods and the like are strictly forbidden to directly contact the embedded bolts 7 and the distance template 1, a worker looks at the template and focuses on strengthening the care of the embedded bolts at the top of the column, and the elevation and the axis dimension are measured in time in the pouring process.

(2) The embedded bolt is wrapped on the embedded bolt by adopting a thin foam adhesive tape, the embedded bolt is not in contact with the positioning hole of the distance template 1, the gap is uniform, the sleeve plate is convenient to remove, and the screw thread is not damaged.

(3) After the concrete pouring is finished, relevant personnel are organized by technical and quality inspection departments to recheck the axis and elevation of the embedded bolt in time, and corresponding measures are taken to adjust in time if the error range is exceeded.

(4) And when the strength of the concrete reaches 50%, the distance template 1 is removed and reused.

Material and equipment in the work progress, material, the utility model discloses distance template 1 adopts the mill customization, and specific quantity is decided according to the construction needs. The apparatus is shown in Table 1 below.

TABLE 1

Quality control in construction process

1) The variety, specification, performance and the like of the bolt meet the current national product standard and design requirements.

2) The construction tolerances should be as specified in table 2 below.

TABLE 2

Safety measures in construction process

According to relevant regulations of building installation safety operation rules, the following safety measures are made by combining the characteristics of construction:

1) the electric welding machine shell must be well grounded, the power supply needs to be disassembled and assembled by an electrician, and a separate switch needs to be arranged. The soldering pliers and the holding wire must be well insulated and firmly connected.

2) And fireproof measures are made, and fire hazard is avoided.

3) And carrying out detailed safety technology intersection on constructors and supervising and urging implementation.

4) Obvious safety signs are provided on the site. The scaffold, the support of the template and the upright post which are built on site can not be moved and dismantled by any person without permission.

5) Enough illumination is needed in night construction so as to ensure the safety of constructors.

6) The safety facilities are comprehensively checked after strong wind and rain, and construction can be continued after hidden dangers are eliminated. 9 environmental protection measures

The utility model discloses technical scheme does not have the environmental protection requirement of special explanation, mainly does well the clearance at any time of reinforcing bar head, welding electrode, accomplishes to have done work the material to the greatest extent, civilized construction.

Example benefit analysis

By adopting the distance template, the high precision of the embedded bolt is ensured. The total number of the engineering foundation columns is 417, the average size is 950 × 3800mm, the total number of the equipment foundation bolts is 3322, and the calculation is carried out according to the price of the information network and the journal of the manufacturing cost of Liaoning province:

the construction cost of a bolt bottom supporting system and a distance template in the traditional method is as follows:

a, each foundation column needs 4 upright columns phi 25 steel bars 2500mm long, the phi 25 steel bars are 4170m (2500 mm 4 x 417), cross arms phi 28 steel bars are 900mm long, and the phi 28 steel bars are 2627.1m (900 mm 7 x 417); the bottom spacer template was measured using a Q235B δ 8 steel plate 84.44m2 (450 × 450mm × 417 pieces).

And B, converting the weight of the steel, and summarizing the manufacturing cost:

4170m 0.00385t/m 3750 element/t +2627.1m 0.00483t/m 3800 element/t +84.44m2 element 0.0628t/m2 element/t =129103.23 element (two decimal places are reserved)

Secondly, the bottom row steel bar fixing method is adopted for manufacturing the steel bar:

each foundation column needs 950mm long 13 pieces of phi 10 steel bars on average, and the length of the phi 10 steel bars is 5149.95 m. Through steel weight conversion, the manufacturing cost is as follows:

5149.95m 0.000617t/m 3800/t =122074.57 (two reserved decimal places)

And thirdly, the construction cost of the bolts by the traditional method is as follows:

the traditional method calculates the required construction period according to 15 kinds of woodworking construction: the foundation of each cracking furnace is 40 columns and 292 bolts, 7 days are needed from bolt construction to concrete pouring of each cracking furnace, and 56 days are needed for 8 cracking furnaces; the gas furnace requires 22 days for 1000 bolts.

To sum up, the manufacturing cost is:

260 yuan/day (56 + 22) days =304200 yuan for 15 persons

Fourthly, the utility model discloses technical scheme construction bolt cost of labor:

calculating the required construction period according to 15 woodworking constructions: the foundation of each cracking furnace is 40 columns and 292 bolts, each cracking furnace needs 3 days from bolt construction to concrete pouring, and 8 cracking furnaces need 24 days; the gas furnace requires 10 days for 1000 bolts.

To sum up, the manufacturing cost is:

260 yuan/day (24 + 10) days =132600 yuan for 15 persons

In summary, the following steps: the material cost is saved to 117028.66 yuan (r-c)

The labor cost is saved to 171600 yuan (③ -fourthly)

Adopt the utility model discloses technical scheme saves the expense in total and does: 288628.66 yuan.

Adopt the utility model discloses technical scheme has not only guaranteed construction quality for construction speed, improved work efficiency, and saved manual work, material spending, great reduction engineering cost.

Application example 1

The Liaoning Baolai chemical project is located in the Liaodong Bay New district of Panjin, the general package unit: medium petrochemical fourth construction limited, design unit: china petrochemical engineering construction Co., Ltd. The number of embedded bolts of the engineering cracking furnace device reaches 2322, the number of gas furnace devices is 1000, the diameters are M42-M56, the method for constructing the bottom row of steel bars by adopting the distance templates and the method for constructing the bottom row of steel bars achieves high embedding precision and high construction speed, obtains good construction effect and is well praised by supervision and owners.

Application example two

The new 3# silo engineering of building of saddle thousand is located saddle thousand factories of choosing in Anshan city, and the construction unit: saddle steel group thousand mineral industry finial liability company, design unit: sedan Steel group mining design research Co., Ltd. The number of embedded engineering bolts is 1000, the diameters are M24-M42 different, distance template construction and bottom row steel bar construction methods are adopted, the quality is successfully guaranteed, the construction period is shortened, the cost is reduced, and the supervision and satisfaction and recognition of owners are obtained.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (2)

1. Bolt installation distance support, its characterized in that includes stand, upper portion horizontal cross arm, lower part horizontal cross arm and horizontal pull rod, and a plurality of to upper portion horizontal cross arm parallel arrangement, upper portion horizontal cross arm below sets up a plurality of lower part horizontal cross arm perpendicularly, and the interval is buried bolt diameter +2mm in advance between the adjacent cross arm, and upper portion horizontal cross arm and lower part horizontal cross arm are connected through horizontal pull rod respectively and are connected fixedly with four stands and form stable space frame structure, upper portion horizontal cross arm and distance template accordant connection, be equipped with a set of buried bolt's of advance installation locating hole on the distance template, the installation locating hole diameter is buried bolt diameter +2mm in advance.

2. Distance holder according to claim 1, wherein the upper horizontal cross arm and/or the lower horizontal cross arm is of double steel tube construction, the distance between the double steel tubes being +2mm of the diameter of the embedded bolt.

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