Cold pre-tension installation method for high-temperature pipelines

Abstract

The present application belongs to the technical field of high-temperature pipeline installation, and particularly relates to a cold-state pre-tension installation method for high-temperature pipeline, comprising the following steps: S1, cold-state pre-tension stress calculation; S2, on-site anchor point condition confirmation; S3, preparation before construction; S4, pre-tension pipe opening measurement and cutting; S5, welding of hangers and guide plates; S6, cold-state pre-tension and group butt joint; S7, reinforcement of pipeline weld and removal of pre-tension device; S8, formal welding of pipeline weld; and S9, nondestructive testing and removal of reinforcement facilities. The present application can control the deformation of the pipeline under the heat state by pre-applying pre-tension to the pipeline, thereby reducing the thrust and moment of the pipeline on the equipment, reducing the stress level of the pipeline, and improving the safety and reliability of the pipeline. Meanwhile, the use of expansion joints and compensators is reduced, and the production cost of the enterprise is effectively reduced. Furthermore, the present application can be applied to compact construction sites, effectively reducing the construction difficulty and improving the construction efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-temperature pipeline cold-state pre-tension installation method, belonging to the technical field of high-temperature pipeline installation. BACKGROUND

[0002] High-temperature pipelines play a vital role in modern industrial production and are widely used in petrochemical, chemical, metallurgical, energy, aerospace, machinery, printing and dyeing, papermaking, power generation and other fields. In the application of high-temperature pipelines, the related equipment will usually undergo very large temperature changes (generally with a temperature difference of more than 400°C) during start-up, shutdown and production operation, which will cause the high-temperature pipeline system to produce a large thermal expansion stress and deformation, which will adversely affect the equipment and pipelines. In the prior art, stainless steel wave-shaped expansion joints, spherical compensators, π-shaped compensators and other compensation means are usually used to compensate the thermal expansion stress and deformation of the pipeline system. On the one hand, the procurement unit price of the above-mentioned components is high, which increases the production cost of enterprises; on the other hand, in the construction site where the pipelines are densely distributed and the equipment layout is compact, there is often insufficient space for setting, thereby causing construction difficulties and reducing construction efficiency. SUMMARY

[0003] In view of the above deficiencies in the prior art, the technical problem to be solved by the present application is to provide a high-temperature pipeline cold-state pre-tension installation method which can reduce the production cost of enterprises and improve the construction efficiency.

[0004] The high-temperature pipeline cold-state pre-tension installation method according to the present application comprises the following steps,

[0005] S1, cold-state pre-tension stress calculation, the maximum tension value during cold-state pre-tension is obtained by calculation;

[0006] S2, on-site anchor point condition confirmation, through on-site investigation, determine the anchor point that can withstand the maximum tension of cold-state pre-tension near the pre-tension operation point;

[0007] S3, preparation before construction, ensure that the cold-state pre-tension operation conditions are met;

[0008] S4, pre-tension pipe opening measurement and cutting, measure the distance dimension between the pre-tension pipe section end face and the fixed pipe section end face in the natural state, then measure the cold-state pre-tension amount from the pre-tension pipe section end face to the fixed pipe section and draw a cutting line, then cut off the pipe blank along the cutting line, and reestablish the bevel according to the welding process card;

[0009] S5, welding of lugs and guide plates, a plurality of pairs of lugs are welded on the fixed pipe section and the pre-tension pipe section away from the bevel respectively, which are used to connect the pre-tension device, a guide plate is welded on the outermost side of the pre-tension pipe section, and the other end of the guide plate is overlapped with the fixed pipe section;

[0010] S6, cold pre-tensioning and assembling the welding joint, from multiple positions connected to the pre-tensioning device, slowly and uniformly operate the pre-tensioning device according to the predetermined pre-tensioning direction and pre-tensioning amount to apply pre-tensioning force to the pipeline, and after pre-tensioning, the relevant dimensions of the pipeline joint should be adjusted immediately to ensure the accuracy of the pipeline installation position;

[0011] S7, reinforcing the pipeline joint and removing the pre-tensioning device, after confirming that the pre-tensioning amount and the pipeline state meet the requirements, the pre-tensioning point should be reliably fixed to maintain the pre-tensioning state of the pipeline, and after the joint and related pipeline are reinforced in place, the technical personnel should be checked and confirmed to be qualified before the pre-tensioning device near the joint can be removed;

[0012] S8, formal welding of the pipeline weld, clean the two sides of the pipeline groove in time, and after taking measures to prevent splashing, formal welding of the pipeline weld can be carried out, and the welding process should strictly follow the welding process card;

[0013] S9, non-destructive testing and removal of reinforcement facilities, the weld after welding should be polished and subjected to non-destructive testing in time, and after non-destructive testing is qualified, the reinforcement facilities should be removed slowly.

[0014] Further, the cold pre-tensioning operation conditions in S3 include the following requirements,

[0015] ① All welds (except pre-tensioning joints) between pipeline fixing points are welded, and all flanges connected by bolts in the main pipeline are tightened;

[0016] ② When measuring the reserved gap, the pipeline should be in a free state (except for weight support), and the pre-tensioning amount should be strictly reserved according to the design requirements.

[0017] ③ All types of supports and hangers on the pipeline are installed, the pipeline and the fixed support are fixed in place, and the hanger rods near the pre-tensioning joint should be reserved with sufficient adjustment allowance;

[0018] ④ The spring support and hanger have been installed and accepted according to the requirements, and the spring should be adjusted to the initial position of the design, so that the locking block of the spring can be freely pulled out, and the locking block should be removed (after the joint clamp is installed);

[0019] ⑤ Preparing pre-tensioning lugs;

[0020] ⑥ Complete the construction scaffold required at the work site in advance, and the scaffold should be inspected and hung with a green plate in time after it is erected.

[0021] Further, after the slope is rebuilt in S4, the inside and outside of the slope should be cleaned in time (if the pipeline material is stainless steel, a stainless steel special grinding wheel should be used to clean and polish the inside and outside of the slope).

[0022] Further, 2-8 pairs of lifting lugs are arranged on the fixed pipe section and the pre-tension pipe section in S5, and each pair of lifting lugs is uniformly distributed in a circle.

[0023] Further, the guide plate in S5 is welded at the most outer 9-point position direction of the pre-tension pipe section.

[0024] Further, the pre-tension device used in S6 is three groups of hand-operated hoists.

[0025] Further, the specific method for reliably fixing the pre-tension point in S7 includes the following two steps,

[0026] S71, the reinforcing plates made of steel plates of the same material as the pipe are fixed on the circumferentially symmetrical positions of the welding opening by spot welding, so that the pre-tension stress is directly applied to both sides of the weld, and the reinforcing plates are uniformly distributed in a circle.

[0027] S72, the rooting point is arranged by using the related column of the same platform, and the hand-operated hoist is used to apply a horizontal auxiliary force to the pipeline to ensure that the pipeline does not deviate after pre-tensioning.

[0028] Further, the isolation material is arranged between the guide plate and the outer wall of the fixed pipe section in S5, and is used to prevent scratching the outer wall of the fixed pipe section.

[0029] Further, the isolation material is a four-fluorine plate with a thickness of 2-3 mm.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The high-temperature pipeline cold-state pre-tension installation method can control the deformation of the pipeline under the hot state by pre-tensioning the pipeline, thereby reducing the thrust and torque of the pipeline on the equipment, reducing the stress level of the pipeline, improving the safety and reliability of the pipeline, reducing the use of expansion joints and compensators, effectively reducing the production cost of enterprises, and being applicable to compact construction sites, effectively reducing the construction difficulty and improving the construction efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a flowchart of an embodiment of the present application;

[0033] Figure 2 is a pre-tensioning schematic diagram of an embodiment of the present application. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be further described below in combination with the drawings:

[0035] Embodiment 1:

[0036] As Figure 1 , Figure 2As shown, the high-temperature pipeline cold pre-tensioning installation method of the present invention includes the following steps:

[0037] S1, Cold pre-tension stress calculation, which calculates the maximum tensile force value during cold pre-tension;

[0038] S2, On-site anchor point conditions confirmed: After on-site investigation, anchor points that can withstand the maximum cold pre-tension force were determined near the pre-tensioning operation point;

[0039] S3, Pre-construction preparations to ensure that the conditions for cold pre-tensioning operations are met;

[0040] S4, Measurement and cutting at the pre-tensioned pipe inlet, measurement of the end face of the pre-tensioned pipe section ( Figure 2 From position A in the middle to the end face of the fixed pipe section ( Figure 2 The spacing dimensions between the pipe sections in their natural state (position B) are determined. Then, the cold pre-tension amount is measured from the end face of the pre-tensioned pipe section to the fixed pipe section and a cutting line is drawn. The pipe material is then cut off along the cutting line, and the bevel is reconstructed with reference to the welding process card. The cold pre-tension amount is generally about half of the maximum displacement of the pipe in the operating state (hot state).

[0041] S5, welding lifting lugs and guide plates, welding multiple pairs of lifting lugs on the fixed pipe section and the pre-tensioned pipe section away from the bevel, respectively, for connecting the pre-tensioning device, welding a guide plate on the outermost side of the pre-tensioned pipe section, with the other end of the guide plate overlapping the fixed pipe section;

[0042] S6. Cold pre-tensioning and weld joint assembly: From multiple positions connected to the pre-tensioning device, operate the device slowly and evenly according to the predetermined pre-tensioning direction and amount to apply pre-tensioning force to the pipeline. During the pre-tensioning process, closely observe the deformation of the pipeline to avoid excessive pre-tensioning that could damage the pipeline or generate excessive additional stress. Use various measuring tools to monitor the displacement of the pipeline in real time until the conditions for weld joint assembly are met. After pre-tensioning, immediately adjust the relevant dimensions of the pipeline joint to ensure accurate pipeline installation. If the bevel gap deviation is large, external force can be applied horizontally to the left end of the pre-tensioned pipe section with the aid of the frame column for adjustment. If the assembly requirements are still not met, a small amount of grinding can be done on the end face of the pre-tensioned pipe section until the conditions for assembly are met. During the pipeline weld joint assembly process, check the position, elevation, slope, and verticality of the pipeline at any time to ensure they meet the design requirements and ensure accurate pipeline installation. At the same time, check the stress on the pipeline supports and hangers, and observe whether there are any abnormal deformations or displacements. If any deviations are found, adjust them in time.

[0043] S7, reinforce the pipe welding and remove the pre-tensioning device, after confirming that the pre-tensioning amount and the pipe state meet the requirements, the pre-tensioning point should be reliably fixed to maintain the pre-tensioning state of the pipe, after the welding and the related pipe are reinforced in place, the technical personnel should be accepted and confirmed to be qualified, then the pre-tensioning device near the welding can be removed, at this time the external force of the pipe pre-tensioning is borne by the reinforcement plate and the auxiliary hand hoist;

[0044] S8, formal welding of the pipe weld, clean the two sides of the pipe groove in time, after taking measures to prevent splashing, formal welding of the pipe weld can be carried out, and the welding process should strictly follow the welding process card;

[0045] S9, non-destructive testing and removal of reinforcement facilities, the weld after welding should be polished and non-destructively tested in time, and the reinforcement facilities should be slowly removed after the non-destructive testing is qualified.

[0046] Example 2:

[0047] As shown in Figure 1 , Figure 2 based on example 1,

[0048] Further, the cold pre-tensioning operation conditions in S3 include the following requirements,

[0049] ① All welds (except pre-tensioning openings) between pipe fixing points are welded, and all flanges connected by bolts in the main pipe are tightened;

[0050] ② When measuring the reserved gap, the pipe should be in a free state (except for weight support), and the pre-tensioning amount should be strictly reserved according to the design requirements.

[0051] ③ All kinds of supports and hangers on the pipe are installed, the pipe and the fixed support are fixed in place, and the hanger rod near the pre-tensioning opening should be reserved enough adjustment allowance;

[0052] ④ The spring support and hanger have been installed and accepted according to the requirements, and the spring should be adjusted to the initial position of the design, so that the locking block of the spring can be freely pulled out, and the locking block should be removed (after the facing clamp is installed);

[0053] ⑤ Pre-tensioning lugs are pre-fabricated, and the lug material should be the same as the pipe base material;

[0054] ⑥ The construction scaffold required at the operation point is completed in advance, and the scaffold should be inspected and hung with a green plate in time after it is erected.

[0055] Further, after the re-establishment of the groove in S4, the inside and outside of the groove should be cleaned in time (if the pipe material is stainless steel, the inside and outside of the groove should be cleaned and polished with a stainless steel special grinding wheel piece).

[0056] Further, 2-8 pairs of lifting lugs are arranged on the fixed pipe section and the pre-tension pipe section in S5, and each pair of lifting lugs is uniformly distributed in the circumference. In the embodiment, three pairs of lifting lugs are adopted, and the three pairs of lifting lugs are respectively located at the 12 o'clock, 4 o'clock and 8 o'clock positions.

[0057] Further, the guide plate is welded at the outermost 9 o'clock position of the pre-tension pipe section in S5, and the effect of the guide plate on the fixed pipe section is better.

[0058] Further, the pre-tension device adopted in S6 is three groups of hand-operated hoists.

[0059] Further, the specific method for reliably fixing the pre-tension point in S7 includes the following two steps.

[0060] S71, the reinforcing plates made of the steel plate of the same material as the pipe are fixed on the circumferentially symmetrical positions of the welding opening by spot welding, so that the pre-tension stress is directly applied to the two sides of the weld, and the reinforcing plates are uniformly distributed in the circumference. In the embodiment, three reinforcing plates are adopted, and the three reinforcing plates are uniformly distributed at an angle of 120°.

[0061] S72, the root point is set by using the related column of the same platform, and the hand-operated hoist is used to apply a horizontal auxiliary force to the pipeline, so as to ensure that the pipeline will not be deviated after pre-tension.

[0062] Further, the isolation material is arranged between the guide plate and the outer wall of the fixed pipe section in S5, and is used to prevent the outer wall of the fixed pipe section from being scratched.

[0063] Further, the isolation material is a four-fluorine plate with a thickness of 2-3 mm.

Claims

1. A method of cold pre-tensioned installation of high temperature pipework, characterised in that: It comprises the following steps, S1, cold pre-tension calculation, the maximum tension value of cold pre-tension is obtained by calculation; S2, on-site anchor point condition confirmation, through on-site investigation, the anchor point capable of bearing the maximum tension of cold pre-tension is determined near the pre-tension operation point; S3, preparation before construction, to ensure that the cold pre-tension operation condition is reached; S4, pre-tension pipe opening measurement and cutting, the interval size between the pre-tension pipe section end face and the fixed pipe section end face in the natural state is measured, then the cold pre-tension amount is measured from the pre-tension pipe section end face to the fixed pipe section and the cutting line is drawn, then the pipe blank is cut along the cutting line, and the bevel is rebuilt according to the welding process card; S5, welding of lugs and guide plates, a plurality of pairs of lugs are welded on the fixed pipe section and the pre-tension pipe section away from the bevel respectively, which are used for connecting the pre-tension device, and the guide plate is welded on the outermost side of the pre-tension pipe section, and the other end of the guide plate is overlapped with the fixed pipe section; S6, cold pre-tension and assembly of the welded joint, from the plurality of positions connected with the pre-tension device, the pre-tension device is slowly and uniformly operated according to the predetermined pre-tension direction and pre-tension amount, and the pre-tension force is applied to the pipe, after the pre-tension is in place, the pipe alignment related dimensions should be immediately adjusted to ensure the accuracy of the pipe installation position; S7, reinforcement of the pipe welded joint and removal of the pre-tension device, after confirming that the pre-tension amount and the pipe state meet the requirements, the pre-tension point should be reliably fixed to maintain the pre-tension state of the pipe, after the welded joint and the related pipe are reinforced in place, the technical personnel should check and confirm that it is qualified, and then the pre-tension device near the welded joint can be removed; the specific method for reliably fixing the pre-tension point comprises the following two steps, S71, the reinforcing plates made of the same material as the pipe are fixed on the circumferentially symmetrical positions of the welded joint by spot welding, so that the pre-tension stress is directly applied to the two sides of the welded joint, and the reinforcing plates are uniformly distributed in the circumference; S72, the root point is set by using the related column of the same platform, and the horizontal auxiliary force is applied to the pipeline by the chain hoist to ensure that the pipeline does not deviate after pre-tensioning; S8, formal welding of the pipe welded joint, the two sides of the pipe bevel are cleaned in time, after the anti-splashing measures are taken, the formal welding of the pipe welded joint can be performed, and the welding process is strictly performed according to the welding process card; S9, non-destructive testing and removal of the reinforcing facilities, the welded joint after welding should be polished and subjected to non-destructive testing in time, and the reinforcing facilities are slowly removed after the non-destructive testing is qualified.

2. The cold pre-tensioned installation method of high temperature piping according to claim 1, characterized in that: The cold pre-tension operation condition in S3 comprises, ① all the welded joints between the pipe fixing points are welded except the pre-tension joint, and all the flanges connected by bolts in the main pipe are fastened; ② when the reserved gap is measured, the pipe should be in a free state except for weight support, and the pre-tension amount should be strictly reserved according to the design requirements; ③ all kinds of supports and hangers on the pipe are installed, the pipe and the fixed support are fixed in place, and the hanger rod of the hanger near the pre-tension joint should be reserved with sufficient adjustment allowance; ④ the spring support and hanger are installed and checked according to the requirements, and the spring should be adjusted to the initial position of the design, so that the locking block of the spring can be freely pulled out, and the locking block is removed after the alignment clamp is installed; ⑤ pre-prepared pre-tension lugs; ⑥ the construction scaffold required by the operation point is completed in advance, and the scaffold should be checked and hung with a green card in time after the scaffold is erected.

3. The cold pre-tensioned installation method of high temperature piping according to claim 1, characterized in that: After the groove is reconstructed in S4, the oxide inside and outside the groove should be cleaned in time.

4. The cold pre-tensioned installation method of high temperature piping of claim 1, wherein: In S5, 2-8 pairs of lifting lugs are arranged on the fixed pipe section and the pre-tensioned pipe section, and each pair of lifting lugs is uniformly distributed in the circumference.

5. The cold pre-tensioned installation method of high temperature piping of claim 1, wherein: In S5, the guide plate is welded at the direction of the outermost 9-point position of the pre-tensioned pipe section.

6. The cold pre-tensioned installation method of high temperature piping of claim 1, wherein: In S6, the pre-tensioning device is three groups of hand-operated hoists.

7. The cold pre-tensioned installation method of high temperature pipes according to any one of claims 1 to 6, characterized in that: In S5, a separation material is arranged between the guide plate and the outer wall of the fixed pipe section to prevent scratching the outer wall of the fixed pipe section.

8. The cold pre-tensioned installation method of high temperature piping according to claim 7, characterized in that: The separation material is a four-fluorine plate with a thickness of 2-3 mm.

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