Cold-state pre-tensioning installation method for high-temperature pipeline

Abstract

The invention belongs to the technical field of high-temperature pipeline installation, and particularly relates to a high-temperature pipeline cold-state pre-stretching installation method which comprises the following steps: S1, cold-state pre-stretching stress calculation; s2, on-site anchor point condition confirmation; s3, preparation before construction; s4, measuring and cutting at a pre-stretching pipe orifice; s5, the lifting lug and the guide plate are welded; s6, cold-state pre-stretching is conducted, and welded junctions are assembled; s7, reinforcing the welded junction of the pipeline and dismantling the pre-tensioning device; s8, formally welding a pipeline welding seam; and S9, nondestructive testing is conducted, and reinforcing facilities are dismantled. Pretension force is applied to the pipeline in advance, so that deformation of the pipeline in a thermal state can be controlled to a certain degree, thrust and torque of the pipeline to equipment are reduced, the stress level of the pipeline is reduced, safety and reliability of the pipeline are improved, meanwhile, use of expansion joints and compensators is reduced, and the production cost of enterprises is effectively reduced; and moreover, the device can be suitable for construction sites with compact spaces, the construction difficulty is effectively reduced, and the construction efficiency is improved.

Description

Technical Field

[0001] The invention relates to a cold pre-tensioning installation method for a high-temperature pipeline, belonging to the technical field of high-temperature pipeline installation. Background Art

[0002] High-temperature pipelines play a vital role in modern industrial production. They are mainly used in petrochemical, chemical, metallurgical, energy, aerospace, machinery, printing and dyeing, papermaking, power generation and other fields, and are widely used. In the application of high-temperature pipelines, the relevant equipment usually experiences very large temperature changes (generally the temperature difference is above 400°C) during start-up, shutdown and production operation, which will cause the high-temperature pipeline system to produce large thermal expansion stress and deformation, which will have an adverse effect on the equipment and pipelines. In the prior art, compensation means such as stainless steel corrugated expansion joints, spherical compensators, and π-shaped compensators are usually used to compensate for the thermal expansion stress and deformation generated by the pipeline system. On the one hand, the purchase unit price of the above-mentioned components is expensive, which increases the production cost of the enterprise; on the other hand, in construction sites with dense pipelines and compact equipment layout, there is often no sufficient installation space, which makes construction difficult and reduces construction efficiency. Summary of the invention

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

[0004] The high-temperature pipeline cold pre-tensioning installation method of the present invention comprises the following steps:

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

[0006] S2, confirm the on-site anchor point conditions. After on-site investigation, determine the anchor point that can withstand the maximum tensile force of cold pre-tensioning near the pre-tensioning operation point;

[0007] S3, preparation before construction, ensuring that the cold pre-tensioning operation conditions are met;

[0008] S4, measure and cut at the pre-tensioned pipe mouth, measure the distance between the end face of the pre-tensioned pipe section and the end face of the fixed pipe section in the natural state, then measure the cold pre-tensioning amount to the fixed pipe section based on the end face of the pre-tensioned pipe section and draw a cutting line, then cut off the pipe raw material along the cutting line, and rebuild the groove according to the welding process card;

[0009] 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 groove, respectively, for connecting the pre-tensioning device, welding the guide plate on the outermost side of the pre-tensioned pipe section, and the other end of the guide plate overlaps the fixed pipe section;

[0010] S6, cold pre-tensioning and assembling welding joints, from multiple positions connected to the pre-tensioning device, operate the pre-tensioning device slowly and evenly according to the predetermined pre-tensioning direction and pre-tensioning amount, and apply pre-tensioning force to the pipeline. After pre-tensioning is in place, the relevant dimensions of the pipeline joints should be adjusted immediately to ensure the accurate installation position of the pipeline;

[0011] S7, reinforce the pipeline weld and remove the pre-tensioning device. After confirming that the pre-tensioning amount and pipeline status meet the requirements, the pre-tensioning point should be reliably fixed to maintain the pre-tensioning state of the pipeline. After the weld and related pipelines are reinforced in place, the pre-tensioning device near the weld can be removed after acceptance and confirmation by technical personnel;

[0012] S8, the formal welding of pipeline welds, timely clean both sides of the pipeline groove, and after taking anti-splash measures, the formal welding of pipeline welds can be carried out. The welding process strictly follows the welding process card;

[0013] S9, non-destructive testing and removal of reinforcement facilities. After welding is completed, the weld should be polished and non-destructive testing should be carried out in time. After the non-destructive testing is qualified, the reinforcement facilities should be slowly removed.

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

[0015] ① All welds between pipeline fixing points (except pre-tensioned joints) have been welded, and all flanges fastened by bolts in the main pipeline have been fastened;

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

[0017] ③ All kinds of supports and hangers on the pipeline have been installed, the pipeline and the fixed bracket have been fixed in place, and the hanger rod of the hanger near the pre-tensioning mouth should have sufficient adjustment margin;

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

[0019] ⑤ Prefabricated pre-tensioned lifting lugs;

[0020] ⑥ Complete the construction scaffolding required for the work site in advance. After the scaffolding is erected, it should be inspected and accepted in time and a green sign should be hung.

[0021] Furthermore, after the groove is rebuilt in S4, the oxides inside and outside the groove should be cleaned in time (for example, when the pipe material is stainless steel, a stainless steel special grinding wheel should be used to clean and grind the inside and outside of the groove).

[0022] Furthermore, 2 to 8 pairs of lifting ears are arranged on the fixed pipe section and the pre-tensioned pipe section in S5, and each pair of lifting ears is evenly distributed around the circumference.

[0023] Furthermore, the guide plate in S5 is welded at the 9 o'clock position on the outermost side of the pre-stretched pipe section.

[0024] Furthermore, the pre-tensioning device used in S6 is three sets of hand chain hoists.

[0025] Furthermore, the specific method for reliably fixing the pre-tensioning point in S7 includes the following two steps:

[0026] S71, fix the reinforcement plate made of the same material as the pipeline at a position symmetrical to the weld circumference by spot welding, so that the pre-tension stress acts directly on both sides of the weld and is evenly distributed around the circumference between the reinforcement plates;

[0027] S72, use the relevant columns on the same platform to set the rooting points, and use a hand winch to apply horizontal auxiliary force to the pipeline to ensure that the pipeline will not deviate after pre-tensioning.

[0028] Furthermore, in S5, an isolation material is provided between the guide plate and the outer wall of the fixed pipe section to prevent the outer wall of the fixed pipe section from being scratched.

[0029] Furthermore, the isolation material is a polytetrafluoroethylene plate with a thickness of 2-3 mm.

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

[0031] The high-temperature pipeline cold pre-tensioning installation method described in the present invention can control the deformation of the pipeline in a hot state to a certain extent by pre-applying a pre-tensioning force to the pipeline in advance, thereby reducing the thrust and torque of the pipeline on the equipment, reducing the stress level of the pipeline, and improving the safety and reliability of the pipeline. At the same time, it reduces the use of expansion joints and compensators, effectively reducing the production cost of the enterprise; and it can be applied to construction sites with compact space, effectively reducing the difficulty of construction and improving construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of an embodiment of the present invention;

[0033] Figure 2 Schematic diagram of pre-tensioning according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0035] Embodiment 1:

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

[0037] S1, cold pre-tension stress calculation, the maximum tension value during cold pre-tensioning is obtained by calculation;

[0038] S2, confirm the on-site anchor point conditions. After on-site investigation, determine the anchor point that can withstand the maximum tensile force of cold pre-tensioning near the pre-tensioning operation point;

[0039] S3, preparation before construction, ensuring that the cold pre-tensioning operation conditions are met;

[0040] S4, measure and cut at the pre-tensioned pipe mouth, measure the end face of the pre-tensioned pipe section of the pipeline ( Figure 2 A position in the middle) to the end face of the fixed pipe section ( Figure 2 The spacing size between the two pipes in the natural state (position B in the middle), and then measure the cold pre-tensioning amount to the fixed pipe section with the end face of the pre-tensioned pipe section as the reference and draw a cutting line, and then cut off the pipe raw material along the cutting line, and rebuild the groove with reference to the welding process card. The cold pre-tensioning amount is generally about half of the maximum displacement of the pipeline 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 groove, respectively, for connecting the pre-tensioning device, welding the guide plate on the outermost side of the pre-tensioned pipe section, and the other end of the guide plate overlaps the fixed pipe section;

[0042] S6, cold pre-tensioning and assembling the welds. From multiple positions connected to the pre-tensioning device, operate the pre-tensioning device slowly and evenly according to the predetermined pre-tensioning direction and pre-tensioning amount to apply pre-tensioning force to the pipeline. During the pre-tensioning process, the deformation of the pipeline should be closely observed to avoid damage to the pipeline or excessive additional stress caused by excessive pre-tensioning. A variety of measuring tools should be used to monitor the displacement of the pipeline in real time until the conditions for weld assembly are met. After pre-tensioning is in place, the relevant dimensions of the pipeline joints should be adjusted immediately to ensure the accurate installation position of the pipeline. If the groove gap deviation is large, the frame column can be used at the left end of the pre-tensioned pipe section to apply partial external force to the pipe section horizontally for adjustment. If the assembly requirements are still not met, the end face of the pre-tensioned pipe section can be slightly ground until the assembly conditions are met. During the process of pipe weld assembly, the position, elevation, slope, verticality and other indicators of the pipeline should be checked at any time to see if they meet the design requirements to ensure the accurate installation position of the pipeline. At the same time, the stress of the pipeline support and hanger should be checked to observe whether the support and hanger have abnormal deformation, displacement, etc. If deviation is found, it should be adjusted in time.

[0043] S7, reinforce the pipe weld and remove the pre-tensioning device. After confirming that the pre-tensioning amount and pipe status meet the requirements, the pre-tensioning point should be reliably fixed to maintain the pre-tensioning state of the pipe. After the weld and related pipes are reinforced in place, the pre-tensioning device near the weld can be removed after acceptance and confirmation by technical personnel. At this time, the external force of the pipe pre-tensioning is borne by the reinforcement plate and the auxiliary hand chain hoist at the same time;

[0044] S8, the formal welding of pipeline welds, timely clean both sides of the pipeline groove, and after taking anti-splash measures, the formal welding of pipeline welds can be carried out. The welding process strictly follows the welding process card;

[0045] S9, non-destructive testing and removal of reinforcement facilities. After welding is completed, the weld should be polished and non-destructive testing should be carried out in time. After the non-destructive testing is qualified, the reinforcement facilities should be slowly removed.

[0046] Embodiment 2:

[0047] like Figure 1 , Figure 2 As shown, based on Example 1,

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

[0049] ① All welds between pipeline fixing points (except pre-tensioned joints) have been welded, and all flanges fastened by bolts in the main pipeline have been fastened;

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

[0051] ③ All kinds of supports and hangers on the pipeline have been installed, the pipeline and the fixed bracket have been fixed in place, and the hanger rod of the hanger near the pre-tensioning mouth should have sufficient adjustment margin;

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

[0053] ⑤ Prefabricated pre-tensioned lifting lugs, the material of the lifting lugs used should be the same as the base material of the pipe;

[0054] ⑥ Complete the construction scaffolding required for the work site in advance. After the scaffolding is erected, it should be inspected and accepted in time and a green sign should be hung.

[0055] Furthermore, after the groove is rebuilt in S4, the oxides inside and outside the groove should be cleaned in time (for example, when the pipe material is stainless steel, a stainless steel special grinding wheel should be used to clean and grind the inside and outside of the groove).

[0056] Furthermore, 2 to 8 pairs of lifting ears are arranged on the fixed pipe section and the pre-tensioned pipe section in S5, and each pair of lifting ears is evenly distributed around the circumference. In this embodiment, three pairs of lifting ears are used, and the three pairs of lifting ears are respectively located at the 12 o'clock, 4 o'clock and 8 o'clock positions.

[0057] Furthermore, the guide plate in S5 is welded at the 9 o'clock position on the outermost side of the pre-stretched pipe section, where the effect of fixing the pipe section is better.

[0058] Furthermore, the pre-tensioning device used in S6 is three sets of hand chain hoists.

[0059] Furthermore, the specific method for reliably fixing the pre-tensioning point in S7 includes the following two steps:

[0060] S71, fix the reinforcing plate made of the same steel plate as the pipeline at a position symmetrical to the weld circumference by spot welding, so that the pre-tension stress acts directly on both sides of the weld, and the reinforcing plates are evenly distributed circumferentially. In this embodiment, three reinforcing plates are used, and the three reinforcing plates are evenly distributed at 120° to each other;

[0061] S72, use the relevant columns on the same platform to set the rooting points, and use a hand winch to apply horizontal auxiliary force to the pipeline to ensure that the pipeline will not deviate after pre-tensioning.

[0062] Furthermore, in S5, an isolation material is provided between the guide plate and the outer wall of the fixed pipe section to prevent the outer wall of the fixed pipe section from being scratched;

[0063] Furthermore, the isolation material is a polytetrafluoroethylene plate with a thickness of 2-3 mm.

Claims

1. A method for cold pre-tensioning and installing a high-temperature pipeline, characterized in that: The following steps are included: S1, cold pre-tension stress calculation, the maximum tension value during cold pre-tensioning is obtained by calculation; S2, confirm the on-site anchor point conditions. After on-site investigation, determine the anchor point that can withstand the maximum tensile force of cold pre-tensioning near the pre-tensioning operation point; S3, preparation before construction, ensuring that the cold pre-tensioning operation conditions are met; S4, measure and cut at the pre-tensioned pipe mouth, measure the distance between the end face of the pre-tensioned pipe section and the end face of the fixed pipe section in the natural state, then measure the cold pre-tensioning amount to the fixed pipe section based on the end face of the pre-tensioned pipe section and draw a cutting line, then cut off the pipe raw material along the cutting line, and rebuild the groove according to the welding process card; 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 groove, respectively, for connecting the pre-tensioning device, welding the guide plate on the outermost side of the pre-tensioned pipe section, and the other end of the guide plate overlaps the fixed pipe section; S6, cold pre-tensioning and assembling welding joints, from multiple positions connected to the pre-tensioning device, operate the pre-tensioning device slowly and evenly according to the predetermined pre-tensioning direction and pre-tensioning amount, and apply pre-tensioning force to the pipeline. After pre-tensioning is in place, the relevant dimensions of the pipeline joints should be adjusted immediately to ensure the accurate installation position of the pipeline; S7, reinforce the pipeline weld and remove the pre-tensioning device. After confirming that the pre-tensioning amount and pipeline status meet the requirements, the pre-tensioning point should be reliably fixed to maintain the pre-tensioning state of the pipeline. After the weld and related pipelines are reinforced in place, the pre-tensioning device near the weld can be removed after acceptance and confirmation by technical personnel; S8, the formal welding of pipeline welds, timely clean both sides of the pipeline groove, and after taking anti-splash measures, the formal welding of pipeline welds can be carried out. The welding process strictly follows the welding process card; S9, non-destructive testing and removal of reinforcement facilities. After welding is completed, the weld should be polished and non-destructive testing should be carried out in time. After the non-destructive testing is qualified, the reinforcement facilities should be slowly removed.

2. The high-temperature pipeline cold pre-tensioning installation method according to claim 1 is characterized in that: The cold pre-tensioning operation conditions in S3 include the following requirements: ① All welds between pipeline fixing points (except pre-tensioned joints) have been welded, and all flanges fastened by bolts in the main pipeline have been fastened; ② When measuring the reserved gap, the pipeline should be in a free state (except for weight support), and the pre-tensioning amount must be reserved strictly in accordance with the design requirements. ③ All kinds of supports and hangers on the pipeline have been installed, the pipeline and the fixed bracket have been fixed in place, and the hanger rod of the hanger near the pre-tensioning mouth should have sufficient adjustment margin; ④ The spring support and hanger have been installed and accepted as required, and the spring should be adjusted to the initial design position so that the locking block of the spring can be pulled out freely, and the locking block should be removed (after the matching fixture is installed); ⑤ Prefabricated pre-tensioned lifting lugs; ⑥ Complete the construction scaffolding required for the work site in advance. After the scaffolding is erected, it should be inspected and accepted in time and a green sign should be hung.

3. The method for cold pre-tensioning and installing a high-temperature pipeline according to claim 1, characterized in that: After the groove is rebuilt in S4, the oxides inside and outside the groove should be cleaned in time (if the pipe material is stainless steel, a stainless steel special grinding wheel should be used to clean and grind the inside and outside of the groove).

4. The method for cold pre-tensioning and installing a high-temperature pipeline according to claim 1, characterized in that: In the S5, 2 to 8 pairs of lifting ears are arranged on the fixed pipe section and the pre-tensioned pipe section, and each pair of lifting ears is evenly distributed around the circumference.

5. The high-temperature pipeline cold pre-tensioning installation method according to claim 1 is characterized in that: The guide plate in S5 is welded at the 9 o'clock position on the outermost side of the pre-stretched pipe section.

6. The method for cold pre-tensioning and installing a high-temperature pipeline according to claim 1, characterized in that: The pre-tensioning device used in S6 is three sets of hand chain hoists.

7. The high-temperature pipeline cold pre-tensioning installation method according to claim 1 is characterized in that: The specific method for reliably fixing the pre-tensioning point in S7 includes the following two steps: S71, fix the reinforcement plate made of the same material as the pipeline at a position symmetrical to the weld circumference by spot welding, so that the pre-tension stress acts directly on both sides of the weld and is evenly distributed around the circumference between the reinforcement plates; S72, use the relevant columns on the same platform to set the rooting points, and use a hand winch to apply horizontal auxiliary force to the pipeline to ensure that the pipeline will not deviate after pre-tensioning.

8. The method for cold pre-tensioning and installing a high-temperature pipeline according to any one of claims 1 to 7, characterized in that: In said S5, an isolation material is arranged between the guide plate and the outer wall of the fixed pipe section to prevent the outer wall of the fixed pipe section from being scratched.

9. The method for cold pre-tensioning and installing a high-temperature pipeline according to claim 8, characterized in that: The isolation material is a polytetrafluoroethylene plate with a thickness of 2-3 mm.

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