Modular installation method for large-diameter overhead pipeline

Abstract

The invention belongs to a modular installation method, and particularly relates to a modular installation method for a large-diameter overhead pipeline. According to the modular installation method for the large-diameter overhead pipeline, the pipeline is divided into about 12M pipe sections in advance, and the pipe sections are transported to a construction site after being prefabricated and subjected to corrosion prevention in a processing plant and hoisted to an installation position for assembly welding. The method has the remarkable effects that in the civil construction stage, the pipeline (comprising the reinforcing ring) is divided into about 12M pipe sections, the pipe sections are prefabricated in a processing factory, corrosion prevention (a welded junction position is reserved) is completed, and then the pipe sections are transported to a construction site to be modularly installed, so that the field installation amount can be reduced, and the installation time is shortened.

Description

Technical Field

[0001] The invention belongs to a modular installation method, and in particular relates to a modular installation method for a large-diameter overhead pipeline. Background Art

[0002] In the past, the installation method of overhead pipelines was to weld the purchased finished pipelines one by one (one section) along the pipeline direction. This method requires the erection of a large number of scaffolding along the pipeline direction, with many pipeline connection welds, and a large workload of non-destructive inspection and anti-corrosion, resulting in a long scaffolding time and a long construction period.

[0003] In actual work, the above methods still have problems such as long construction period and large working area. Specifically, the practice of large-diameter overhead pipeline installation in the installation project of the exhaust pipeline section II of a certain research institute's factory building. The non-standard air pressure pipeline of the overhead pipeline of this project is made of Q235B, with a pipeline diameter between 1020-1620mm and a maximum installation height of 11m (center elevation) from the ground. Since the overhead pipeline of this project is adjacent to the commissioned factory building and intertwined with the commissioned pipeline, the construction work surface is limited, and the project construction period is short. The use of traditional pipeline installation technology does not meet the needs of project construction. Therefore, a new installation method is needed. Summary of the invention

[0004] The present invention aims at the defects of the prior art and provides a modular installation method for large-diameter overhead pipelines.

[0005] The present invention is implemented as follows: a modular installation method for large-diameter overhead pipelines, wherein the pipelines are divided into 12M pipe sections in advance for prefabrication in a processing plant, and after anti-corrosion is completed, they are transported to the construction site and hoisted to the installation position for assembly and welding.

[0006] The modular installation method for a large-diameter overhead pipeline as described above includes the following steps, which are the pipe segment prefabrication construction process and the pipeline installation construction process executed in sequence.

[0007] In the above-mentioned modular installation method of a large diameter overhead pipeline, the pipeline section prefabrication construction process includes the following contents:

[0008] a) Construction preparation

[0009] Construction personnel should undergo on-site training and job skills training before taking up their posts; special operation personnel must hold a certificate before taking up their posts; construction personnel should be familiar with the drawings, construction technical requirements and relevant regulations and specifications.

[0010] The construction equipment and tools are in good working condition and meet the construction requirements. The measuring instruments are within the calibrated validity period and in good working condition.

[0011] According to the design requirements, check the quality certification documents of the construction materials to see if the specifications, models and materials meet the requirements of the drawings; the surface of the materials should be free of scratches and damage caused by external forces.

[0012] Before construction, complete the drawing review, draw the pipeline single-line diagram, divide the prefabricated pipe sections, mark the material information and quantity of pipes, pipe fittings, valves, flanges, etc., and mark the weld numbers according to the flow sequence of the medium; complete the review of the construction plan and quality plan, organize the construction safety and technical disclosure,

[0013] The workshop is well ventilated, the equipment is neatly arranged, and transportation is smooth; the electricity, lighting, and ventilation for construction meet the needs of prefabrication construction.

[0014] b) Cutting

[0015] According to the segmentation of the pipeline, layout and layout of each segment are carried out. The layout and numbering of materials should reserve welding shrinkage allowances during production and installation, as well as processing allowances such as cutting, planing and milling according to process requirements. The cutting of plates and pipes is carried out by plasma cutting and shearing machine cutting.

[0016] The plate cutting shall be carried out according to the size required by the layout drawing. The edge processing surface of the steel plate shall be smooth and free of defects such as delamination cracks and slag inclusions. When in doubt, the color penetrant flaw detection method shall be used for inspection. All slag and harmful impurities generated after material cutting shall be removed mechanically before the next manufacturing process or use.

[0017] After cutting, the cut end face of the pipe should be machined or polished. The oxidized surface produced by thermal cutting needs to be completely removed by metal brush or grinding to remove all traces of oxide scale. The cut surface should be flat, free of cracks, wrinkles, burrs, concave and convex shrinkage, slag, oxides, iron filings and other debris.

[0018] c) Prefabrication and welding of pipe sections and reinforcement rings

[0019] The prefabrication, welding and anti-corrosion of the pipe sections and reinforcement rings of this project are all completed in the processing plant.

[0020] The longitudinal welds of pipes and pipe fittings shall not exceed two. When welding pipes, pipes and pipe fittings, the distance between the two longitudinal welds shall be greater than 200mm. The verticality of the processed pipe joints, pipe fittings and tee branches shall be ≤3mm. The longitudinal deviation of the tee straight pipe shall be ≤1%. The ovality requirements of the pipe are: ≤4mm for DN≤1200 and ≤6mm for DN≥1400.

[0021] According to the transportation road conditions and on-site construction conditions, the single section of the prefabricated pipe segment is no longer than 12 meters. A single section of the pipe segment is welded together from two or more sections. In order to reduce the workload of on-site installation, the grooves at both ends of the spliced ​​pipe segment are transported to the site after the engineering processing is completed.

[0022] Take the 6-meter pipe section as an example for pipe segment prefabrication:

[0023] The reinforcement ring should avoid the girth weld and longitudinal weld of the pipeline. The axial distance between the edge of the reinforcement ring and the girth weld of the pipeline should not be less than 200mm. When intersecting with the longitudinal weld of the pipeline, a semicircular opening should be opened at the reinforcement ring to avoid it. The height of the weld leg of the remaining fillet welds is the thickness of the thin part of the welded part. The welding quality control requirements shall be implemented according to the welding construction plan.

[0024] The maximum spacing L of the reinforcement rings shall be evenly distributed according to the actual situation, provided that the requirements of the design drawings are met; the butt welds of the reinforcement rings shall be staggered with the longitudinal welds of the pipelines, and the spacing shall be ≥200mm.

[0025] Prefabrication of reinforcement ring, taking φ1620 pipe as an example:

[0026] The prefabricated pipe section should fully consider the control of ovality and have sufficient rigidity. If necessary, "M"-shaped anti-deformation support reinforcement can be added inside the pipe to ensure that no deformation occurs during storage, transportation and lifting.

[0027] d) Pipe section corrosion protection

[0028] The prefabricated pipe sections are anti-corrosive in the prefabrication plant.

[0029] The construction and acceptance of pipeline external anti-corrosion shall be carried out in accordance with the relevant provisions of the "Industrial Equipment and Pipeline Anti-Corrosion Engineering Construction Code" (GB50726-2011) and the "Industrial Equipment and Pipeline Anti-Corrosion Engineering Construction Quality Acceptance Code" (GB 50727-2011). Before applying primer to the pipeline, remove dust, dirt, rust spots and welding slag on the surface, and the welds should be treated to have no weld nodules, edges and corners, and no burrs.

[0030] Pipeline anti-corrosion requirements shall be implemented according to drawings and design documents.

[0031] When anti-corrosion, leave about 50mm of the grooves at both ends without painting, and then repaint after subsequent on-site welding.

[0032] e) Acceptance and handover

[0033] After the prefabrication of the pipe section is completed, a pre-handover inspection is carried out according to the construction drawings. The inspection content includes: whether the identification, structure and size of the pipe section are consistent with the design drawings; whether the appearance quality of the pipe section and the packaging and protection of the pipe mouth meet the requirements; whether the quality tracking documents formed by the prefabrication of the pipe section are complete, true and qualified.

[0034] The above-mentioned large diameter overhead pipeline modular installation method, wherein the pipeline installation construction process includes the following contents

[0035] a) Construction preparation

[0036] Personnel participating in the construction must undergo on-site training and possess the professional skills and physical fitness required for this project. Personnel with occupational contraindications such as high blood pressure and heart disease must not be assigned to work at heights. Special operations personnel must be certified before they can take up their posts.

[0037] The construction equipment and tools are in good working condition, and the measuring instruments are within the valid calibration period and meet the construction requirements.

[0038] The construction materials must be qualified, the quality certification documents must be authentic and complete, and they can only be used after being accepted by the supervisor and the owner. Before installation, the valves, compensators and other materials supplied by Party A must be unpacked and inspected, especially to check whether the compensator bellows is damaged. If there is any damage, it should be reported to the owner and supervisor immediately, and photos should be taken to witness and keep unpacking records.

[0039] After the finished pipe sections that have passed the prefabrication inspection are transported to the site, the appearance quality of the prefabricated pipe sections will be reviewed. The inspection contents include: pipe section identification, pipe body surface quality, prefabrication size, pipe end groove quality, manufacturing quality tracking documents, etc. Only after the inspection is qualified can the on-site installation be carried out. If there are any problems during the inspection, they will be handled on-site or returned to the factory according to the situation. Only after passing the inspection can the installation be carried out.

[0040] Before on-site construction, complete the drawing review, complete the pipeline installation construction plan and quality plan review, organize construction safety and technical disclosure,

[0041] Check whether the on-site environment meets the requirements for pipeline construction, whether the relevant civil engineering piers have been completed and passed the inspection, and whether they can ensure the full implementation of pipeline installation.

[0042] b) Line positioning

[0043] In order to shorten the pipeline installation period, after the arrival of pipelines and pipe fittings, positioning and laying out are carried out from the two highest expansion bends. The elbow is preferred for positioning, and the installation sequence is carried out synchronously from the middle to both sides. The positioning diagram is as follows:

[0044] c) Cutting and processing

[0045] According to the installation site layout, pipelines are mostly laid horizontally overhead. After the materials arrive at the site, they are prefabricated on site according to the pipeline layout requirements. The installation site prefabrication is roughly divided into the following types:

[0046] Leave an adjustment section at all interfaces with the original pipeline, and cut accurately after actual measurement. The cutting consumption and processing allowance must be considered when marking.

[0047] Carbon steel can be cut by plasma arc cutting, automatic or manual oxyacetylene cutting machine, or mechanical cutting. When thermal cutting is used, the scale, slag, spatter, etc. at the cut should be cleaned up, and the cut surface should be carefully checked for cracks in preparation for further production or use.

[0048] d) Support and hanger installation

[0049] Basic inspection, laying out and processing

[0050] The civil engineering foundation has been inspected and accepted, and should be re-inspected before installation: the geometric dimensions, plane position and elevation of the foundation should meet the design requirements; the surface appearance of the foundation should not have defects such as cavities, honeycombs, exposed reinforcement, cracks, etc.; there should be no water accumulation and debris in the reserved holes,

[0051] Pop out the center axis of the pipeline on the foundation surface, and pop out the installation positioning center line of the base based on the center axis. Transplant the elevation reference point on each side of the foundation and make obvious marks for installation measurement.

[0052] Before the support is in place, the foundation should be treated as follows: the surface in contact with the secondary concrete should be roughened and cleaned of oil stains and other debris; the concrete surface where the pad iron is placed should be chiseled flat and in close contact with the pad iron, and there should be no warping after the pad iron is placed.

[0053] Installation of supports and brackets

[0054] Draw the center line of the support on the top plate, and then use the hoisting equipment to hoist the prefabricated and qualified support and bracket into place as shown in the figure, and place temporary shims under the base to level and align the base.

[0055] Guide bracket or sliding bracket: The sliding surface is clean and flat, without skewness or jamming. Its installation position is offset from the center of the supporting surface in the opposite direction. The offset is 1 / 2 of the displacement value or meets the requirements of the design documents. The insulation layer shall not hinder its displacement.

[0056] e) Pipe section lifting

[0057] According to the construction site conditions, the factory prefabricated pipe sections and pipe fittings are prefabricated on site for secondary prefabrication. The dimensions of the secondary prefabrication on site refer to the following section diagrams for each area Fig.21 The crane is in place and can be flexibly adjusted on site according to the size and weight of the pipe section to be hoisted.

[0058] Some pipe sections are heavy, with a +11.01m expansion bend weighing about 20t. They need to be hoisted across the exhaust tower and the plant, and the maximum distance from the crane to the pipe installation location is 22m. To ensure construction quality and safety and improve construction efficiency, two 200t truck cranes were used on site to carry out hoisting operations from sections A1 and B1 to both sides.

[0059] Lifting area and segmentation:

[0060] Sling connection

[0061] The appropriate lifting sling should be selected according to the weight, size and position of the lifting lug of the pipe section;

[0062] The appearance of the slings should be inspected before connecting them;

[0063] Use slings to tie and directly hoist into place.

[0064] When lifting the valve, the valve's own lifting lugs should be used for lifting. It is strictly forbidden to use the valve stem or actuator for lifting.

[0065] (1) Trial lifting

[0066] Before the crane is officially lifted at the prefabrication site or on site, a trial lift should be conducted to check the stress of each part, with emphasis on the sinking of the crane legs and the change in the position of the rigging. If any abnormality is found, the crane should be suspended immediately and the trial lift should be conducted again after the problem is resolved. Only when all parts are normal can the formal lifting work be started.

[0067] (2) Lifting into place

[0068] After the trial lifting is completed, the truck crane continues to lift to the appropriate height;

[0069] The truck crane rotates in the direction of positioning and lifts the pipe section to the installation position;

[0070] The horizontal pipe module is placed directly on the pipe support according to the installation position;

[0071] Temporary fixing measures shall be taken between the vertical pipeline and the pipe sections connected to it;

[0072] The vertical pipe section and the steel support are connected and fixed with a fall chain.

[0073] (3) Removal of slings

[0074] The pipe section is hoisted into place and temporarily fixed;

[0075] After the pipe section is firmly fixed, remove the slings;

[0076] (4) Construction completed

[0077] After the pipe section is hoisted, the truck crane retracts the main arm;

[0078] The truck crane prepares to hoist the next pipe section according to the construction plan;

[0079] After the mobile crane construction is completed, it will leave the site;

[0080] Construction is finished.

[0081] f) Assembling welding and non-destructive testing

[0082] The welding of pipelines and supports and hangers shall be carried out according to the special construction plan for welding and non-destructive testing.

[0083] g) Valve and component installation

[0084] After the valves supplied by Party A arrive, we will organize the inspection and acceptance. Before installation, each valve will be filled with water for closing and sealing inspection, and the motor stroke test will be passed before it can be released for on-site installation.

[0085] Before installing the valve, you should carefully read the product manual to understand the installation technical requirements and installation precautions;

[0086] Before the valve is installed, its support has been completed according to the design requirements and passed the acceptance inspection.

[0087] Before installing the valve, check the valve model and determine its installation direction according to the flow direction of the medium; all valves are installed according to the design drawings and the manufacturer's installation guide.

[0088] The installation of the valve should be convenient for operation, inspection and maintenance. The valve stem of the valve on the horizontal pipeline should generally be installed within the upper semicircle.

[0089] The valve should be carefully handled and supported to avoid damage to the handwheel, motor and accessories. If there are lifting lugs on the valve, the lifting lugs should be used to lift it into place. It is not allowed to hang it on other parts. Before installation and final closure of the system, the inside of the valve should be checked as thoroughly as possible to ensure that no external impurities enter the valve. The valve opening should be sealed and maintained until the valve is installed. When the valve is connected to the pipeline by flange or thread, the valve should be installed in the closed state. The welding of flange and pipe shall be carried out according to the relevant procedures of the welding construction plan of this project. The flange connection shall be concentric with the pipe, and the bolts shall be allowed to penetrate freely. The installation direction shall be consistent. The flanges shall be kept parallel, and the deviation shall not exceed 1.5‰ of the outer diameter of the flange and shall not exceed 2mm. The skewness shall not be eliminated by strong tightening.

[0090] When installing the flange, check the sealing surface and sealing gasket. There should be no scratches, spots or other defects. The periphery of the soft gasket should be neat and the gasket size should match the flange sealing surface.

[0091] The flange connection should be concentric with the pipeline, and the bolts should be able to penetrate freely. The flange bolt holes should be arranged in the middle of the span. The flanges should be kept parallel. The deviation should not be greater than 0.15% of the flange outer diameter and should not be greater than 2mm. The skewness of the flange joint should not be eliminated by tightening the bolts.

[0092] Flange connections should use bolts of the same specification and the installation direction should be consistent. The bolts should be tightened evenly and symmetrically with a hydraulic torque wrench.

[0093] After the bolts are tightened, they should fit tightly against the flange without any wedge gaps. When washers are needed, no more than one should be used for each bolt. All nuts should be fully screwed into the bolts, and 2 to 3 threads of the nuts should be exposed after tightening.

[0094] h) Installation of bellows compensator

[0095] The wall of the bellows compensator pipe section is very thin and should be properly stored to prevent bumps and scratches. When installing, do not use iron chains or other lifting tools to hang directly on the surface of the bellows section.

[0096] The axis of the corrugated compensator should be aligned with the axis of the connected pipe. When there is a deviation in the installation of the pipe, in order not to affect the normal operation of the compensator, let the pipe find the compensator correctly. Do not use the method of deforming the compensator to adjust the installation deviation of the pipe.

[0097] Before installing and welding the compensator, the bellows of the compensator should be cleaned to prevent particles and debris from entering it and sealed with transparent tape. During the welding process, a baffle should be set on the bellows to prevent welding slag from splashing onto the surface of the corrugated shell;

[0098] After the pipeline is installed, the tie rods and auxiliary positioning mechanisms on the compensator used for transportation protection must be removed, and the large tie rods and nuts that restrict the internal thrust must not be removed;

[0099] Compensator pre-stretching requirements: If the manufacturer's compensator needs to be pre-stretched, except for the pre-stretched welds, all pipeline welds have been welded and passed the non-destructive inspection, the support and hanger in the pre-stretching area have been installed, the pipe and the fixed bracket have been fixed, and all bolts in the pre-stretching area have been tightened;

[0100] After installation, remove any debris from the outside of the compensator so that it does not hinder or limit the range of motion of the active parts of the compensator;

[0101] During installation, the compensator manufacturer should be notified and the on-site installation should be coordinated.

[0102] i) Cleanliness control during pipe section installation

[0103] Cleanliness control during pipe section installation is carried out according to the pipeline internal construction cleanliness control plan.

[0104] j) Pipeline pressure test

[0105] The construction of pipeline pressure test shall be carried out according to the pipeline pressure test plan.

[0106] k) Pipeline purging

[0107] The pipeline should be purged after passing the pressure test. Before purging, the instruments and valves installed on the pipeline should be removed and replaced with temporary short pipes. After the pipeline is purged and qualified, it should be reset. For the above valves and instruments connected by welding, protective measures such as bypass flow or removal of the valve head and valve seat and adding protective sleeves should be taken.

[0108] The order of purging should be the main pipe, branch pipe, and drainage pipe. The dirt purged out must not enter the pipes that have been purged.

[0109] Before pipeline purging, the firmness of pipeline supports and hangers should be carefully checked, and any objectionable parts should be reinforced.

[0110] When using air to purge, the purge pressure shall not exceed the design pressure of the pipeline, and the flow rate should not be less than 20m / s. The gas shall not contain oil during the purge. During the air purge process, a wooden target plate with white cloth or white paint should be set at the exhaust port for inspection. After 5 minutes, there is no rust, dust, moisture or other debris on the target plate, which is qualified.

[0111] l) Pipeline touch-up

[0112] The pipeline system is flushed and pressure tested to be qualified, and the carbon steel welds are repainted for anti-corrosion treatment. The specific construction and acceptance requirements are implemented in accordance with the pipeline anti-corrosion construction plan of this project.

[0113] m) Acceptance and handover

[0114] After the pipeline system construction is completed, the construction process records are organized according to the requirements of the handover documents, and the acceptance and handover procedures are carried out.

[0115] The significant effect of the present invention is that during the civil construction stage, the pipeline (including the reinforcement ring) is divided into about 12M pipe sections for prefabrication in a processing plant. After anti-corrosion (the weld position is reserved), it is transported to the construction site for modular installation, which can reduce the on-site installation volume and installation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0116] Figure 1 Overall schematic diagram of the pipeline;

[0117] Figure 2 Schematic diagram of pipeline segmentation a;

[0118] Figure 3 Schematic diagram of pipeline segmentation b;

[0119] Figure 4 Pipe segment prefabrication construction process;

[0120] Figure 5 Pipeline installation construction process;

[0121] Figure 6 Schematic diagram of a single pipe section;

[0122] Figure 7 Schematic diagram of splicing 12m pipe sections;

[0123] Figure 8a Schematic diagram of reinforcement ring;

[0124] Figure 8b yes Figure 8a A three-dimensional schematic diagram of

[0125] Figure 9a Schematic diagram of reinforcement ribs;

[0126] Figure 9b yes Figure 9a A three-dimensional schematic diagram of

[0127] Fig.10a Schematic diagram of the finished reinforcement ring;

[0128] Fig.10b yes Fig.10a A three-dimensional schematic diagram of

[0129] Fig.11a Schematic diagram of the “M” shaped anti-deformation support;

[0130] Fig.11b yes Fig.11a A three-dimensional schematic diagram of

[0131] Fig.12a Schematic diagram of pipe segment prefabrication product;

[0132] Figure 12b yes Fig.12a A three-dimensional schematic diagram of

[0133] Fig.13 Final schematic diagram of prefabricated pipe section a;

[0134] Fig.14a Final schematic diagram of prefabricated pipe section b;

[0135] Fig.14b yes Fig.14a A three-dimensional schematic diagram of

[0136] Fig.15 Schematic diagram of pipeline laying out and positioning a;

[0137] Fig.16 Schematic diagram of pipeline laying out and positioning b;

[0138] Fig.17a Compensation prefabrication (weighing about 3t);

[0139] Fig.17b yes Fig.17a A three-dimensional schematic diagram of

[0140] Fig.18a Prefabrication of expansion bend (weighing about 17t);

[0141] Fig.18b yes Fig.18a A three-dimensional schematic diagram of

[0142] Fig.19a Straight section with elbow;

[0143] Fig.19b yes Fig.19a A three-dimensional schematic diagram of

[0144] Fig.20a Flange prefabrication;

[0145] Fig.20b yes Fig.20a A three-dimensional schematic diagram of

[0146] Fig.21 General map of each area segment;

[0147] Fig. 22 This is the performance parameter table of 200t crane;

[0148] Fig.23 Schematic diagram of the section of area A;

[0149] Fig.24 Schematic diagram of the area B segment;

[0150] Fig.25 Schematic diagram of the area C segment;

[0151] Fig.26 Schematic diagram of sling installation (horizontal straight pipe section installation);

[0152] Fig. 27 Schematic diagram of sling connection (large valve hoisting);

[0153] Fig.28 Installation method of sling electric butterfly valve. DETAILED DESCRIPTION

[0154] The large diameter overhead pipeline is a long-distance air extraction pipeline, which starts from the original 2002 plant south end II extraction interface and ends at the original 3011ACF air extraction pipeline interface. The pipeline installation mainly includes various pipelines with a total length of about 370m, 3 valves, 1 compensator, and 36 pipe and pipe fitting supports and hangers. See below for details. Figure 1 Schematic diagram of the pipeline as a whole.

[0155] Due to the short installation period, in order to ensure the installation quality and progress, the pipeline needs to be segmented, including: 12 sections of φ1420×12 pipeline, 32 sections of φ1620×14 pipeline, and 1 section of φ1020×10 pipeline, which includes 14 adjustment sections. The corresponding reinforcement rings on the pipe sections are prefabricated at the same time as the pipelines, and only the expansion bends and some pipe sections need to be prefabricated on the construction site. Figure 2 , Figure 3 :

[0156] A modular installation method for a large diameter overhead pipeline comprises the following steps:

[0157] The pipe section prefabrication construction process and pipeline installation construction process are executed sequentially.

[0158] The pipe segment prefabrication construction process includes the following contents

[0159] f) Construction preparation

[0160] Construction workers should undergo on-site training and job skills training before taking up their posts; special operations personnel must be certified before taking up their posts; construction workers should be familiar with drawings, construction technical requirements and relevant regulations and specifications.

[0161] The construction equipment and tools are in good working condition and meet the construction requirements. The measuring instruments are within the calibrated validity period and are in good working condition.

[0162] According to the design requirements, check the quality certification documents of construction materials to see whether the specifications, models and materials meet the requirements of the drawings; the surface of the materials should be free of scratches and damage caused by external forces.

[0163] Before construction, conduct a review of the drawings, draw a single-line diagram of the pipeline, divide the prefabricated pipe sections, mark the material information and quantity of pipes, fittings, valves, flanges, etc., and mark the weld numbers in the order of medium flow; complete the review of the construction plan and quality plan, and organize construction safety and technical briefings.

[0164] The workshop is well ventilated, equipment is neatly arranged, and transportation is smooth; construction electricity, lighting, and ventilation meet the needs of prefabrication construction.

[0165] g) Cutting

[0166] According to the segmentation of the pipeline, layout and layout of each segment are carried out. The layout and numbering of materials should reserve welding shrinkage allowances during production and installation, as well as processing allowances such as cutting, planing and milling according to process requirements. The cutting of plates and pipes is carried out by plasma cutting and shearing machine cutting.

[0167] The plate cutting shall be carried out according to the size required by the layout drawing. The edge processing surface of the steel plate shall be smooth and free of defects such as delamination cracks and slag inclusions. When in doubt, the color penetrant testing method shall be used for inspection. All slag and harmful impurities produced after material cutting shall be removed mechanically before the next manufacturing process or use.

[0168] After cutting, the cut end of the pipe should be machined or polished. The oxidized surface produced by thermal cutting (if any) needs to be completely removed by metal brush or grinding to remove all traces of oxide scale; the cut surface should be flat, free of cracks, wrinkles, burrs, concave and convex shrinkage, slag, oxides, iron filings and other debris.

[0169] h) Prefabrication and welding of pipe sections and reinforcement rings

[0170] The prefabrication, welding and anti-corrosion of the pipe sections and reinforcement rings of this project are all completed in the processing plant.

[0171] The longitudinal welds of pipes and pipe fittings shall not exceed two. When welding pipes, pipes and pipe fittings, the distance between the two longitudinal welds should be greater than 200mm. The verticality of the processed pipe joints, pipe fittings and tee branches should be ≤3mm, the longitudinal deviation of the tee straight pipe should be ≤1%, and the ovality requirements of the pipe are: ≤4mm for DN≤1200, ≤6mm for DN≥1400.

[0172] According to the transportation road conditions and on-site construction conditions, the length of a single prefabricated pipe section is no more than 12 meters, and a single pipe section is welded together from two or more pipe sections. In order to reduce the workload of on-site installation, the grooves at both ends of the spliced ​​pipe section are transported to the site after the engineering processing is completed.

[0173] Take the 6-meter pipe section as an example for pipe segment prefabrication:

[0174] The reinforcement ring should avoid the circumferential weld and longitudinal weld of the pipeline. The axial spacing between the edge of the reinforcement ring and the circumferential weld of the pipeline shall not be less than 200mm. When intersecting with the longitudinal weld of the pipeline, a semicircular opening shall be opened at the reinforcement ring to avoid it. The weld leg height of the remaining fillet welds shall be the thickness of the thin part of the welded part. The welding quality control requirements shall be implemented according to the welding construction plan.

[0175] The maximum spacing L of the reinforcement rings shall be evenly distributed according to the actual situation, provided that the requirements of the design drawings are met; the butt welds of the reinforcement rings shall be staggered with the longitudinal welds of the pipelines, and their spacing shall be ≥200mm.

[0176] Prefabrication of reinforcement ring, taking φ1620 pipe as an example:

[0177] The prefabricated pipe section should fully consider the control of ovality and have sufficient rigidity. If necessary, "M"-shaped anti-deformation support reinforcement can be added inside the pipe to ensure that no deformation occurs during storage, transportation and lifting.

[0178] i) Pipe section corrosion protection

[0179] The prefabricated pipe sections (including reinforcement rings) are anti-corrosive in the prefabrication plant.

[0180] The construction and acceptance of pipeline external anti-corrosion shall be carried out in accordance with the relevant provisions of the "Industrial Equipment and Pipeline Anti-Corrosion Engineering Construction Specification" (GB50726-2011) and the "Industrial Equipment and Pipeline Anti-Corrosion Engineering Construction Quality Acceptance Specification" (GB 50727-2011). Before applying primer to the pipeline, remove dust, dirt, rust spots and welding slag on the surface, and the welds should be treated to have no weld bumps, no edges and corners, and no burrs.

[0181] Pipeline anti-corrosion requirements shall be implemented according to drawings and design documents.

[0182] During anti-corrosion, leave about 50mm of the groove at both ends without painting, and then repaint after subsequent on-site welding.

[0183] j) Acceptance and handover

[0184] After the prefabrication of the pipe section is completed, a pre-handover inspection is carried out according to the construction drawings. The inspection content includes: whether the identification, structure and size of the pipe section are consistent with the design drawings; whether the appearance quality of the pipe section and the packaging and protection of the pipe mouth meet the requirements; whether the quality tracking documents formed by the prefabrication of the pipe section are complete, true and qualified.

[0185] The pipeline installation construction process includes the following contents

[0186] n) Construction preparation

[0187] Personnel participating in the construction must undergo on-site training and possess the professional skills and physical fitness required for this project. Personnel with occupational contraindications such as high blood pressure and heart disease must not be assigned to work at heights. Personnel performing special operations must be certified before they can take up their posts.

[0188] The construction equipment and tools are in good working condition, and the measuring instruments are within the valid calibration period and meet the construction requirements.

[0189] The materials used for construction shall be accepted and the quality certification documents shall be authentic and complete. They can only be used after being accepted by the supervisor and the owner. Before installation, the valves and compensators supplied by Party A shall be inspected out of the box, especially to check whether the bellows of the compensator is damaged. If there is any damage, it shall be reported to the owner and supervisor immediately and photos shall be taken to witness and keep unpacking records.

[0190] After the finished pipe sections that have passed the prefabrication inspection are transported to the site, the appearance quality of the prefabricated pipe sections will be reviewed. The inspection contents include: pipe section identification, pipe body surface quality, prefabrication size, pipe end groove quality, manufacturing quality tracking documents, etc. Only after passing the inspection can the on-site installation be carried out. If there are any problems during the inspection, they will be handled on-site or returned to the factory according to the situation. Only after passing the inspection can the installation be carried out.

[0191] Before on-site construction, complete the drawing review, complete the pipeline installation construction plan and quality plan review, and organize construction safety and technical briefings.

[0192] Check whether the on-site environment meets the requirements for pipeline construction, whether the relevant civil engineering piers have been completed and passed the inspection, and whether they can ensure the full implementation of pipeline installation.

[0193] o) Line positioning

[0194] In order to shorten the pipeline installation period, after the materials (pipes and fittings) arrive, the positioning and laying out are carried out from the two highest expansion bends. The positioning location is preferentially selected at the elbow. The installation sequence is carried out synchronously from the middle to both sides. The positioning diagram is as follows:

[0195] p) Cutting and processing

[0196] According to the installation site layout, pipelines are mostly laid horizontally overhead. After the materials arrive at the site, they are prefabricated on site according to the pipeline layout requirements. The installation site prefabrication is roughly divided into the following types:

[0197] Leave an adjustment section (at the horizontal pipe) at all interfaces with the original pipeline, and cut accurately after actual measurement. The marking must take into account the cutting consumption and processing allowance.

[0198] Carbon steel can be cut by plasma arc cutting, automatic or manual oxyacetylene cutting machine, or mechanical cutting. When thermal cutting is used, the scale, slag, spatter, etc. at the cut should be cleaned up, and the cut surface should be carefully checked for cracks in preparation for further production or use.

[0199] q) Support and hanger installation

[0200] Basic inspection, laying out and processing

[0201] The civil foundation has been accepted and should be re-inspected before installation: the geometric dimensions, plane position and elevation of the foundation should meet the design requirements; the surface appearance of the foundation should not have defects such as voids, honeycombs, exposed reinforcement, cracks, etc.; there should be no water accumulation and debris in the reserved holes.

[0202] Pop out the central axis of the pipeline on the foundation surface, and use the central axis as the reference to pop out the installation positioning center line of the base. Transplant elevation reference points on each side of the foundation and make obvious marks for installation measurement.

[0203] The foundation should be treated as follows before the bearing is in place: the surface in contact with the secondary poured concrete should be roughened and cleaned of oil and other debris; the concrete surface where the shim is placed should be chiseled flat, and the contact with the shim should be close, and there should be no warping after the shim is placed.

[0204] Installation of supports and brackets

[0205] Draw the center line of the support on the top plate of the support. Then use the hoisting equipment to hoist the prefabricated and qualified support and bracket into place as shown in the figure, and place temporary shims under the base to level and align the base.

[0206] Guide bracket or sliding bracket: The sliding surface is clean and flat, without any skewness or jamming. Its installation position is offset from the center of the supporting surface in the opposite direction, and the offset is 1 / 2 of the displacement value or in accordance with the requirements of the design documents. The insulation layer shall not hinder its displacement.

[0207] r) Pipe section lifting

[0208] According to the construction site conditions, the factory prefabricated pipe sections and pipe fittings are prefabricated on site for secondary prefabrication. The dimensions of the secondary prefabrication on site refer to the following section diagrams for each area Fig.21 The crane can be flexibly adjusted on site according to the size and weight of the pipe section to be hoisted.

[0209] Considering that some pipe sections are heavy (+11.01m expansion bend is about 20t), they need to cross the exhaust tower and the factory building during hoisting, and the maximum distance from the crane position to the pipeline installation position is 22m. In order to ensure construction quality and safety and improve construction efficiency, two 200t truck cranes are used on site to carry out hoisting operations from sections A1 and B1 to both sides.

[0210] Lifting area and segmentation:

[0211] Sling connection

[0212] The appropriate lifting sling should be selected according to the weight, size and position of the lifting lug of the pipe section;

[0213] The appearance of the slings should be inspected before connecting them;

[0214] Use slings to tie and directly hoist into place (the sling connection diagram for the horizontal straight pipe section is as follows Fig. 22 ).

[0215] When hoisting the valve, the valve's own lifting lugs should be used for hoisting. It is strictly forbidden to use the valve stem or actuator for hoisting. The schematic diagram of the hoisting rigging connection is shown in Figure 27:

[0216] Trial lifting

[0217] Before the crane is officially lifted at the prefabrication site or on site, a trial lift should be conducted to check the stress of each part. Pay special attention to the sinking of the crane legs and the change of the rigging position. If any abnormality is found, the crane should be suspended immediately and the lifting should be tried again after the problem is solved. Only when all parts are normal can the official lifting work be started.

[0218] Lifting into place

[0219] After the trial lifting is completed, the truck crane continues to lift to the appropriate height;

[0220] The truck crane rotates in the direction of positioning and lifts the pipe section to the installation position;

[0221] The horizontal pipe module is placed directly on the pipe support according to the installation position;

[0222] Temporary fixing measures shall be taken between the vertical pipeline and the pipe sections connected to it;

[0223] The vertical pipe section and the steel support are connected and fixed using fall chains.

[0224] Sling removal

[0225] The pipe section is hoisted into place and temporarily fixed;

[0226] After the pipe section is firmly fixed, remove the slings;

[0227] Construction completed

[0228] After the pipe section is hoisted, the truck crane retracts the main arm;

[0229] The truck crane prepares to hoist the next pipe section according to the construction plan;

[0230] After the mobile crane construction is completed, it will leave the site;

[0231] Construction is completed.

[0232] s) Assembly welding and non-destructive testing

[0233] The welding of pipelines and supports and hangers shall be carried out in accordance with the special construction plan for welding and non-destructive testing.

[0234] t) Valve and component installation

[0235] After the valves supplied by Party A arrive, an acceptance inspection will be organized. Before installation, each valve will be filled with water for closing and sealing inspection, and the motor stroke test will be carried out before it can be released for on-site installation.

[0236] Before installing the valve, you should carefully read the product manual to understand the installation technical requirements and installation precautions;

[0237] Before the valve is installed, its support has been completed according to the design requirements and passed the acceptance.

[0238] Before installing the valve, check the valve model and determine its installation direction according to the medium flow direction; all valve installations are carried out according to the design drawings and the manufacturer's installation guide.

[0239] The installation of the valve should be convenient for operation, inspection and maintenance. The valve stem of the valve on the horizontal pipeline should generally be installed in the upper semicircle.

[0240] The valve should be handled and supported carefully to avoid damage to the handwheel, motor and accessories. As long as the valve is equipped with lifting lugs, the lifting lugs should be used to lift it into place. Hanging on other parts is not allowed.

[0241] Before installation and final closure of the system, the inside of the valve should be checked as thoroughly as possible to ensure that no external impurities enter the valve. The valve opening should be sealed and maintained until the valve is installed.

[0242] When the valve is connected to the pipeline with flange or thread, the valve should be installed in the closed state.

[0243] The welding of flange and pipe shall be carried out according to the relevant procedures of the welding construction plan of this project. The flange connection shall be concentric with the pipeline, and the bolts shall be allowed to penetrate freely and the installation direction shall be consistent. The flanges shall be kept parallel, and the deviation shall not exceed 1.5‰ of the outer diameter of the flange and shall not exceed 2mm. The skewness shall not be eliminated by tightening.

[0244] When installing the flange, the sealing surface and sealing gasket should be checked. There should be no defects such as scratches and spots. The periphery of the soft gasket should be neat and the gasket size should match the flange sealing surface.

[0245] The flange connection should be concentric with the pipeline and the bolts should be able to penetrate freely. The flange bolt holes should be arranged in the middle of the span. The flanges should be kept parallel, and the deviation should not exceed 0.15% of the flange outer diameter and should not exceed 2mm. The skewness of the flange joint should not be eliminated by tightening the bolts.

[0246] Flange connections should use bolts of the same specification and the installation direction should be consistent. The bolts should be tightened evenly and symmetrically with a hydraulic torque wrench.

[0247] After tightening, the bolts should fit tightly against the flange without any wedge gap. When a gasket is required, no more than one gasket should be added to each bolt. All nuts should be fully screwed into the bolts, and 2 to 3 threads of the nuts should be exposed after tightening.

[0248] u) Installation of bellows compensator

[0249] The wall of the bellows compensator pipe section is very thin and should be stored properly to prevent bumps and scratches. When installing, do not use iron chains or other lifting tools to hang directly on the surface of the bellows section.

[0250] The axis of the corrugated compensator should be aligned with the axis of the connected pipe. When there is a deviation in the installation of the pipeline, in order not to affect the normal operation of the compensator, let the pipe find the compensator correctly, and do not use the method of deforming the compensator to adjust the installation deviation of the pipeline;

[0251] Before installing and welding the compensator, the bellows of the compensator should be cleaned to prevent particles and debris from entering and sealed with transparent tape. During the welding process, a baffle should be set on the bellows to prevent welding slag from splashing onto the surface of the bellows shell;

[0252] After the pipeline is installed, the tie rod and auxiliary positioning mechanism (yellow painted parts) used for transportation protection on the compensator must be removed. The large tie rod and nut that restrict the internal thrust must not be removed;

[0253] Compensator pre-stretching requirements: If the manufacturer's compensator needs to be pre-stretched, except for the pre-stretched weld, all pipeline welds have been welded and passed the non-destructive inspection. The support and hanger in the pre-stretching area have been installed, and the pipe and the fixed bracket have been fixed. All bolts in the pre-stretching area have been tightened;

[0254] After installation, remove any debris from the outside of the compensator so that it does not hinder or limit the range of motion of the active parts of the compensator;

[0255] The compensator manufacturer should be notified during installation and cooperate with on-site installation.

[0256] v) Cleanliness control during pipe section installation

[0257] Cleanliness control during the pipe section installation process is carried out in accordance with the pipeline internal construction cleanliness control plan.

[0258] w) Pipeline pressure test

[0259] The construction of pipeline pressure test shall be carried out according to the pipeline pressure test plan.

[0260] x) Pipeline purging

[0261] The pipeline should be purged after passing the pressure test. Before purging, the instruments and valves installed on the pipeline should be removed and replaced with temporary short pipes. After the pipeline is purged and qualified, it should be reset. For the above valves and instruments connected by welding, protective measures such as bypass flow or removal of the valve head and valve seat and adding protective sleeves should be taken.

[0262] The order of purging should be the main pipe, branch pipe, and drainage pipe in sequence, and the dirt purged out must not enter the pipeline that has been purged and qualified.

[0263] Before pipeline purging, the firmness of the pipeline supports and hangers should be carefully checked, and any objectionable parts should be reinforced.

[0264] When using air to purge, the purge pressure shall not exceed the design pressure of the pipeline, and the flow rate should not be less than 20m / s. The gas shall not contain oil during the purge. During the air purge process, a wooden target board with white cloth or white paint should be set at the exhaust port for inspection. After 5 minutes, there is no rust, dust, moisture or other debris on the target board.

[0265] y) Pipeline touch-up

[0266] The pipeline system is flushed and pressure tested and passed, and the carbon steel welds are repainted for anti-corrosion treatment. The specific construction and acceptance requirements are implemented in accordance with the pipeline anti-corrosion construction plan of this project.

[0267] z) Acceptance and handover

[0268] After the pipeline system construction is completed, the construction process records are organized according to the requirements of the handover documents, and the acceptance and handover procedures are carried out.

Claims

1. A modular installation method for a large diameter overhead pipeline, characterized in that: The pipeline is divided into sections of about 12 meters in advance and prefabricated in the processing plant. After the anti-corrosion is completed, it is transported to the construction site and hoisted to the installation position for assembly and welding.

2. A modular installation method for a large diameter overhead pipeline according to claim 1, characterized in that: The invention comprises the following steps, which are executed in sequence: the pipe section prefabrication construction process and the pipeline installation construction process.

3. A modular installation method for a large diameter overhead pipeline according to claim 2, characterized in that: The construction process of pipe segment prefabrication includes the following contents: a) Construction preparation Construction personnel should undergo on-site training and job skills training before taking up their posts; special operation personnel must hold a certificate before taking up their posts; construction personnel should be familiar with the drawings, construction technical requirements and relevant regulations and specifications. The construction equipment and tools are in good working condition and meet the construction requirements. The measuring instruments are within the calibrated validity period and in good working condition. According to the design requirements, check the quality certification documents of the construction materials to see if the specifications, models and materials meet the requirements of the drawings; the surface of the materials should be free of scratches and damage caused by external forces. Before construction, complete the drawing review, draw the pipeline single-line diagram, divide the prefabricated pipe sections, mark the material information and quantity of pipes, pipe fittings, valves, flanges, etc., and mark the weld numbers according to the flow sequence of the medium; complete the review of the construction plan and quality plan, organize the construction safety and technical disclosure, The workshop is well ventilated, the equipment is neatly arranged, and transportation is smooth; the electricity, lighting, and ventilation for construction meet the needs of prefabrication construction. b) Cutting According to the segmentation of the pipeline, layout and layout of each segment are carried out. The layout and numbering of materials should reserve welding shrinkage allowances during production and installation, as well as processing allowances such as cutting, planing and milling according to process requirements. The cutting of plates and pipes is carried out by plasma cutting and shearing machine cutting. The plate cutting shall be carried out according to the size required by the layout drawing. The edge processing surface of the steel plate shall be smooth and free of defects such as delamination cracks and slag inclusions. When in doubt, the color penetrant flaw detection method shall be used for inspection. All slag and harmful impurities generated after material cutting shall be removed mechanically before the next manufacturing process or use. After cutting, the cut end face of the pipe should be machined or polished. The oxidized surface produced by thermal cutting needs to be completely removed by metal brush or grinding to remove all traces of oxide scale. The cut surface should be flat, free of cracks, wrinkles, burrs, concave and convex shrinkage, slag, oxides, iron filings and other debris. c) Prefabrication and welding of pipe sections and reinforcement rings The prefabrication, welding and anti-corrosion of the pipe sections and reinforcement rings of this project are all completed in the processing plant. The longitudinal welds of pipes and pipe fittings shall not exceed two. When welding pipes, pipes and pipe fittings, the distance between the two longitudinal welds shall be greater than 200mm. The verticality of the processed pipe joints, pipe fittings and tee branches shall be ≤3mm. The longitudinal deviation of the tee straight pipe shall be ≤1%. The ovality requirements of the pipe are: ≤4mm for DN≤1200 and ≤6mm for DN≥1400. According to the transportation road conditions and on-site construction conditions, the single section of the prefabricated pipe segment is no longer than 12 meters. A single section of the pipe segment is welded together from two or more sections. In order to reduce the workload of on-site installation, the grooves at both ends of the spliced ​​pipe segment are transported to the site after the engineering processing is completed. Take the 6-meter pipe section as an example for pipe segment prefabrication: The reinforcement ring should avoid the girth weld and longitudinal weld of the pipeline. The axial distance between the edge of the reinforcement ring and the girth weld of the pipeline should not be less than 200mm. When intersecting with the longitudinal weld of the pipeline, a semicircular opening should be opened at the reinforcement ring to avoid it. The height of the weld leg of the remaining fillet welds is the thickness of the thin part of the welded part. The welding quality control requirements shall be implemented according to the welding construction plan. The maximum spacing L of the reinforcement rings shall be evenly distributed according to the actual situation, provided that the requirements of the design drawings are met; the butt welds of the reinforcement rings shall be staggered with the longitudinal welds of the pipelines, and the spacing shall be ≥200mm. Prefabrication of reinforcement ring, taking φ1620 pipe as an example: The prefabricated pipe section should fully consider the control of ovality and have sufficient rigidity. If necessary, "M"-shaped anti-deformation support reinforcement can be added inside the pipe to ensure that no deformation occurs during storage, transportation and lifting. d) Pipe section corrosion protection The prefabricated pipe sections are anti-corrosive in the prefabrication plant. The construction and acceptance of pipeline external anti-corrosion shall be carried out in accordance with the relevant provisions of the "Industrial Equipment and Pipeline Anti-Corrosion Engineering Construction Code" (GB50726-2011) and the "Industrial Equipment and Pipeline Anti-Corrosion Engineering Construction Quality Acceptance Code" (GB 50727-2011). Before applying primer to the pipeline, remove dust, dirt, rust spots and welding slag on the surface, and the welds should be treated to have no weld nodules, edges and corners, and no burrs. Pipeline anti-corrosion requirements shall be implemented according to drawings and design documents. When anti-corrosion, leave about 50mm of the grooves at both ends without painting, and then repaint after subsequent on-site welding. e) Acceptance and handover After the prefabrication of the pipe section is completed, a pre-handover inspection is carried out according to the construction drawings. The inspection content includes: whether the identification, structure and size of the pipe section are consistent with the design drawings; whether the appearance quality of the pipe section and the packaging and protection of the pipe mouth meet the requirements; whether the quality tracking documents formed by the prefabrication of the pipe section are complete, true and qualified.

4. A modular installation method for a large diameter overhead pipeline according to claim 2, characterized in that: The pipeline installation construction process includes the following contents a) Construction preparation Personnel participating in the construction must undergo on-site training and possess the professional skills and physical fitness required for this project. Personnel with occupational contraindications such as high blood pressure and heart disease must not be assigned to work at heights. Special operations personnel must be certified before they can take up their posts. The construction equipment and tools are in good working condition, and the measuring instruments are within the valid calibration period. Meet construction requirements The construction materials must be qualified, the quality certification documents must be authentic and complete, and they can only be used after being accepted by the supervisor and the owner. Before installation, the valves, compensators and other materials supplied by Party A must be unpacked and inspected, especially to check whether the compensator bellows is damaged. If so, it should be reported to the owner and supervisor immediately, and photos should be taken to witness and keep unpacking records. After the finished pipe sections that have passed the prefabrication inspection are transported to the site, the appearance quality of the prefabricated pipe sections will be reviewed. The inspection contents include: pipe section identification, pipe body surface quality, prefabrication size, pipe end groove quality, manufacturing quality tracking documents, etc. Only after the inspection is qualified can the on-site installation be carried out. If there are any problems during the inspection, they will be handled on-site or returned to the factory according to the situation. Only after passing the inspection can the installation be carried out. Before on-site construction, complete the drawing review, complete the pipeline installation construction plan and quality plan review, organize construction safety and technical disclosure, Check whether the on-site environment meets the requirements for pipeline construction, whether the relevant civil engineering piers have been completed and passed the inspection, and whether they can ensure the full implementation of pipeline installation. b) Line positioning In order to shorten the pipeline installation period, after the arrival of pipelines and pipe fittings, positioning and laying out are carried out from the two highest expansion bends. The elbow is preferred for positioning, and the installation sequence is carried out synchronously from the middle to both sides. The positioning diagram is as follows: c) Cutting and processing According to the installation site layout, pipelines are mostly laid horizontally overhead. After the materials arrive at the site, they are prefabricated on site according to the pipeline layout requirements. The installation site prefabrication is roughly divided into the following types: Leave an adjustment section at all interfaces with the original pipeline, and cut accurately after actual measurement. The cutting consumption and processing allowance must be considered when marking. Carbon steel can be cut by plasma arc cutting, automatic or manual oxyacetylene cutting machine, or mechanical cutting. When thermal cutting is used, the scale, slag, spatter, etc. at the cut should be cleaned up, and the cut surface should be carefully checked for cracks in preparation for further production or use. d) Support and hanger installation Basic inspection, laying out and processing The civil engineering foundation has been inspected and accepted, and should be re-inspected before installation: the geometric dimensions, plane position and elevation of the foundation should meet the design requirements; the surface appearance of the foundation should not have defects such as cavities, honeycombs, exposed reinforcement, cracks, etc.; there should be no water accumulation and debris in the reserved holes, Pop out the center axis of the pipeline on the foundation surface, and pop out the installation positioning center line of the base based on the center axis. Transplant the elevation reference point on each side of the foundation and make obvious marks for installation measurement. Before the support is in place, the foundation should be treated as follows: the surface in contact with the secondary concrete should be roughened and cleaned of oil stains and other debris; the concrete surface where the pad iron is placed should be chiseled flat and in close contact with the pad iron, and there should be no warping after the pad iron is placed. Installation of supports and brackets Draw the center line of the support on the top plate, and then use the hoisting equipment to hoist the prefabricated and qualified support and bracket into place as shown in the figure, and place temporary shims under the base to level and align the base. Guide bracket or sliding bracket: The sliding surface is clean and flat, without skewness or jamming. Its installation position is offset from the center of the supporting surface in the opposite direction. The offset is 1 / 2 of the displacement value or meets the requirements of the design documents. The insulation layer shall not hinder its displacement. e) Pipe section lifting According to the construction site conditions, the factory prefabricated pipe sections and pipe fittings are prefabricated on site for secondary prefabrication. The dimensions of the secondary prefabrication on site refer to the following section diagram 21 of each area. The crane is in place and flexibly adjusted on site according to the size and weight of the hoisted pipe section. Some pipe sections are heavy, with a +11.01m expansion bend weighing about 20t. They need to be hoisted across the exhaust tower and the plant, and the maximum distance from the crane to the pipe installation location is 22m. To ensure construction quality and safety and improve construction efficiency, two 200t truck cranes were used on site to carry out hoisting operations from sections A1 and B1 to both sides. Lifting area and segmentation: Sling connection The appropriate lifting sling should be selected according to the weight, size and position of the lifting lug of the pipe section; The appearance of the slings should be inspected before connecting them; Use slings to tie and directly hoist into place. When lifting the valve, the valve's own lifting lugs should be used for lifting. It is strictly forbidden to use the valve stem or actuator for lifting. (1) Trial lifting Before the crane is officially lifted at the prefabrication site or on site, a trial lift should be conducted to check the stress of each part, with emphasis on the sinking of the crane legs and the change in the position of the rigging. If any abnormality is found, the crane should be suspended immediately and the trial lift should be conducted again after the problem is resolved. Only when all parts are normal can the formal lifting work be started. (2) Lifting into place After the trial lifting is completed, the truck crane continues to lift to the appropriate height; The truck crane rotates in the direction of positioning and lifts the pipe section to the installation position; The horizontal pipe module is placed directly on the pipe support according to the installation position; Temporary fixing measures shall be taken between the vertical pipeline and the pipe sections connected to it; The vertical pipe section and the steel support are connected and fixed with a fall chain. (3) Removal of slings The pipe section is hoisted into place and temporarily fixed; After the pipe section is firmly fixed, remove the slings; (4) Construction completed After the pipe section is hoisted, the truck crane retracts the main arm; The truck crane prepares to hoist the next pipe section according to the construction plan; After the mobile crane construction is completed, it will leave the site; Construction is finished. f) Assembling welding and non-destructive testing The welding of pipelines and supports and hangers shall be carried out according to the special construction plan for welding and non-destructive testing. g) Valve and component installation After the valves supplied by Party A arrive, we will organize the inspection and acceptance. Before installation, each valve will be filled with water for closing and sealing inspection, and the motor stroke test will be passed before it can be released for on-site installation. Before installing the valve, you should carefully read the product manual to understand the installation technical requirements and installation precautions; before installing the valve, its support has been completed according to the design requirements and passed the acceptance inspection. Before installing the valve, check the valve model and determine its installation direction according to the flow direction of the medium; all valve installations are carried out according to the design drawings and the manufacturer's installation guide. The installation of the valve should be convenient for operation, inspection and maintenance. The valve stem of the valve on the horizontal pipeline should generally be installed within the upper semicircle. The valve should be carefully handled and supported to avoid damage to the handwheel, motor and accessories. If there are lifting lugs on the valve, the lifting lugs should be used to lift it into place. It is not allowed to hang it on other parts. Before installation and final closure of the system, the inside of the valve should be checked as thoroughly as possible to ensure that no external impurities enter the valve. The valve opening should be sealed and maintained until the valve is installed. When the valve is connected to the pipeline by flange or thread, the valve should be installed in the closed state. The welding of flange and pipe shall be carried out according to the relevant procedures of the welding construction plan of this project. The flange connection shall be concentric with the pipe, and the bolts shall be allowed to penetrate freely. The installation direction shall be consistent. The flanges shall be kept parallel, and the deviation shall not exceed 1.5‰ of the outer diameter of the flange and shall not exceed 2mm. The skewness shall not be eliminated by strong tightening. When installing the flange, check the sealing surface and sealing gasket. There should be no scratches, spots or other defects. The periphery of the soft gasket should be neat and the gasket size should match the flange sealing surface. The flange connection should be concentric with the pipeline, and the bolts should be able to penetrate freely. The flange bolt holes should be arranged in the middle of the span. The flanges should be kept parallel. The deviation should not be greater than 0.15% of the flange outer diameter and should not be greater than 2mm. The skewness of the flange joint should not be eliminated by tightening the bolts. Flange connections should use bolts of the same specification and the installation direction should be consistent. The bolts should be tightened evenly and symmetrically with a hydraulic torque wrench. After the bolts are tightened, they should fit tightly against the flange without any wedge gaps. When washers are needed, no more than one should be used for each bolt. All nuts should be fully screwed into the bolts, and 2 to 3 threads of the nuts should be exposed after tightening. h) Installation of bellows compensator The wall of the bellows compensator pipe section is very thin and should be properly stored to prevent bumps and scratches. When installing, do not use iron chains or other lifting tools to hang directly on the surface of the bellows section. The axis of the corrugated compensator should be aligned with the axis of the connected pipe. When there is a deviation in the installation of the pipe, in order not to affect the normal operation of the compensator, let the pipe find the compensator correctly. Do not use the method of deforming the compensator to adjust the installation deviation of the pipe. Before installing and welding the compensator, the bellows of the compensator should be cleaned to prevent particles and debris from entering it and sealed with transparent tape. During the welding process, a baffle should be set on the bellows to prevent welding slag from splashing onto the surface of the corrugated shell; After the pipeline is installed, the tie rods and auxiliary positioning mechanisms on the compensator used for transportation protection must be removed, and the large tie rods and nuts that restrict the internal thrust must not be removed; Compensator pre-stretching requirements: If the manufacturer's compensator needs to be pre-stretched, except for the pre-stretched welds, all pipeline welds have been welded and passed the non-destructive inspection, the support and hanger in the pre-stretching area have been installed, the pipe and the fixed bracket have been fixed, and all bolts in the pre-stretching area have been tightened; After installation, remove any debris from the outside of the compensator so that it does not hinder or limit the range of motion of the active parts of the compensator; During installation, the compensator manufacturer should be notified and the on-site installation should be coordinated. i) Cleanliness control during pipe section installation Cleanliness control during pipe section installation is carried out according to the pipeline internal construction cleanliness control plan. j) Pipeline pressure test The construction of pipeline pressure test shall be carried out according to the pipeline pressure test plan. k) Pipeline purging The pipeline should be purged after passing the pressure test. Before purging, the instruments and valves installed on the pipeline should be removed and replaced with temporary short pipes. After the pipeline is purged and qualified, it should be reset. For the above valves and instruments connected by welding, protective measures such as bypass flow or removal of the valve head and valve seat and adding protective sleeves should be taken. The order of purging should be the main pipe, branch pipe, and drainage pipe. The dirt purged out must not enter the pipes that have been purged. Before pipeline purging, the firmness of pipeline supports and hangers should be carefully checked, and any objectionable parts should be reinforced. When using air to purge, the purge pressure shall not exceed the design pressure of the pipeline, and the flow rate should not be less than 20m / s. The gas shall not contain oil during the purge. During the air purge process, a wooden target plate with white cloth or white paint should be set at the exhaust port for inspection. After 5 minutes, there is no rust, dust, moisture or other debris on the target plate, which is qualified. l) Pipeline touch-up The pipeline system is flushed and pressure tested to be qualified, and the carbon steel welds are repainted for anti-corrosion treatment. The specific construction and acceptance requirements are implemented in accordance with the pipeline anti-corrosion construction plan of this project. m) Acceptance and handover After the pipeline system construction is completed, the construction process records are organized according to the requirements of the handover documents, and the acceptance and handover procedures are carried out.

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