CN111331315A - Ethylene cracking furnace tube welding repair method - Google Patents
Ethylene cracking furnace tube welding repair method Download PDFInfo
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- CN111331315A CN111331315A CN202010322690.8A CN202010322690A CN111331315A CN 111331315 A CN111331315 A CN 111331315A CN 202010322690 A CN202010322690 A CN 202010322690A CN 111331315 A CN111331315 A CN 111331315A
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- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P6/00—Restoring or reconditioning objects
- B23P6/04—Repairing fractures or cracked metal parts or products, e.g. castings
Abstract
The invention discloses a welding repair method for an ethylene cracking furnace tube, which comprises the following steps: (1) cutting the old furnace tube: determining the damaged position of the old furnace tube, cutting off the damaged tube section, and cleaning and polishing the inner side and the outer side of the port of the residual old furnace tube; (2) cutting the new furnace tube: taking a new furnace tube with the same specification and the same length according to the length of the damaged tube section, cutting the new furnace tube into a long section and two short sections with the same length, and polishing the grooves of the ports of the long section and the short sections; (3) surfacing treatment of the old furnace tube: performing surfacing treatment on the surface of the groove of the old furnace tube to form a surfacing layer, and polishing the groove of the surfacing layer; (4) butt joint of new and old furnace pipes: firstly, the two short sections are respectively welded with the old furnace pipe with the surfacing layer, and then the long section is welded between the two short sections. The invention effectively solves the hot crack phenomenon generated by welding between new and old furnace pipes, and has the advantages of simple operation, high repair efficiency, good repair effect, high reliability, wide application range and the like.
Description
Technical Field
The invention relates to the technical field of welding of ethylene cracking furnace tubes, in particular to a welding repair method of an ethylene cracking furnace tube.
Background
Ethylene is one of the most important basic raw materials in the petrochemical industry in the world and is called as the mother material of the petrochemical industry, and an ethylene cracking furnace is a core device for producing ethylene and mainly used for processing various raw materials such as natural gas, refinery gas, crude oil, naphtha and the like into cracked gas. The radiation section of the ethylene cracking furnace mainly comprises a furnace tube, a furnace wall plate, a refractory lining, a combustor and the like, wherein the furnace tube is positioned in a lower hearth directly heated by flame radiation and is a key component of the radiation section, so the material of the furnace tube is usually a nickel-based alloy material with high temperature resistance, scouring resistance, thermal fatigue resistance, high creep strength, hydrogen corrosion resistance and carburization resistance, such as 25Cr-35Ni-Nb + MA and the like. However, because the working environment is severe, after long-term operation, the furnace tube still deforms, creeps, cracks, or even explodes, so the furnace tube with serious deformation or damage needs to be replaced regularly, and a great amount of welding problems between the new and old furnace tubes exist.
According to the detailed descriptions of the relevant documents, such as "welding of carburizing furnace tubes in radiation section of ethylene cracking furnace" published in journal 1992 in 1, welding process of Cr20Ni32Nb material in radiation section of furnace tube of ethylene cracking furnace "published in 2006-4-2 in 2006, welding of new and old furnace tubes in radiation section of ethylene cracking furnace" published in 2008 in Qilu petrochemical engineering journal 2008 in 1, and "discussion of common defects in welding of old cracking furnace tubes" published in 2017 in electric welding machine "in 5, the following documents are known: the old furnace tube after service has deteriorated quality and poor weldability, and is easy to generate hot cracking under the action of welding shrinkage stress or other tensile stress in the welding process with a new furnace tube, so the welding difficulty is higher. At present, various production enterprises generally adopt a mode of overlaying a transition layer, firstly carry out argon tungsten-arc welding on the groove surface of an old furnace tube to overlay high-nickel alloy, and then carry out butt welding with a new furnace tube to be replaced, thereby overcoming the technical problem that the new and old furnace tubes can not be directly welded.
However, after many times of practice, the heat affected zone of the old furnace tube welded by the method still has the phenomenon of thermal cracking, because the method cannot effectively reduce welding restraint force generated in the welding process, furnace tube self-gravity or forced assembly stress and other aspects of restraint stress, the weld metal can generate thermal cracking under the action of welding thermal cycle or reheat cracking is generated at a fusion line of high nickel alloy surfacing. Therefore, the method has certain limitation and cannot completely overcome the phenomenon of hot cracking caused by welding between the new furnace pipe and the old furnace pipe. Therefore, the welding repair method for the ethylene cracking furnace tube can effectively overcome the thermal cracking phenomenon.
Disclosure of Invention
The invention provides a welding repair method for an ethylene cracking furnace tube, which mainly aims to solve the problem that the existing welding repair method for the ethylene cracking furnace tube cannot completely overcome the phenomenon of hot cracks generated by welding between new and old furnace tubes and has certain limitations.
The invention adopts the following technical scheme:
a welding repair method for an ethylene cracking furnace tube comprises the following steps:
(1) cutting the old furnace tube: determining the damaged position of the old furnace tube, cutting off the damaged tube section, and cleaning and polishing the inner side and the outer side of the port of the residual old furnace tube;
(2) cutting the new furnace tube: taking a new furnace tube with the same specification and the same length according to the length of the damaged tube section, cutting the new furnace tube into a long section and two short sections with the same length, and polishing the grooves of the ports of the long section and the short sections;
(3) surfacing treatment of the old furnace tube: performing surfacing treatment on the surface of the groove of the old furnace tube to form a surfacing layer, and polishing the groove of the surfacing layer;
(4) butt joint of new and old furnace pipes: firstly, the two short sections are respectively welded with an old furnace pipe with a surfacing layer, and then the long section is welded between the two short sections.
Further, in the step (1), the cleaning length of the old furnace tube is 25mm respectively at the inner side and the outer side of the port, the bevel angle of the old furnace tube is 30 degrees, and the truncated edge is 1 mm.
Further, in step (2), the length of the two short sections is not less than 100mm, the bevel angles of the long section and the short sections are both 30 degrees, and the truncated edges are both 1 mm.
Further, in the step (3), the surfacing process is carried out in two layers, the fusion ratio of the first layer of surfacing is less than 20%, the interlayer temperature is less than 60 ℃, and the total thickness of the surfacing layers is more than 3 mm.
Further, in the step (4), the welding procedure between the short section and the surfacing layer firstly adopts butt-joint tack welding, and the butt-joint gap is smaller than 2 mm; then, layered welding is adopted, the thickness of the first layer is less than 2mm, and the interlayer temperature is less than 60 ℃.
Further, in the steps (3) and (4), the welding mode adopts manual argon tungsten-arc welding, and the welding wire is made of high-nickel alloy.
Further, in step (3), the wire is ERNiCr-3.
Furthermore, in the step (4), the welding wire brand adopted for welding the short section and the overlaying layer is ERNiCr-3, and the welding wire adopted for welding the long section and the short section is made of the same material as the new furnace tube.
Compared with the prior art, the invention has the beneficial effects that:
the invention innovatively adopts a mode of overlaying a transition layer and welding a new furnace tube in sections to weld and repair the ethylene cracking furnace tube, thereby overcoming the problems of deteriorated tube quality and poor weldability of the old furnace tube, effectively reducing the restraint stress in the welding process of the new and old furnace tubes, avoiding the generation of hot cracks, further solving the welding problem between the new and old furnace tubes, and having the advantages of simple operation, high repair efficiency, good repair effect, high reliability, wide application range and the like.
Drawings
FIG. 1 is a schematic view of the welding of the present invention.
In the figure, 1 is an old furnace pipe, 2 is a new and old furnace pipe connecting welding line, 3 is a new furnace pipe connecting welding line, 4 is a surfacing layer, 5 is a short section, 6 is a long section, delta is the thickness of the surfacing layer (delta = 3-5 mm), α is the angle of a welding line groove (α =60 degrees).
Detailed Description
The following describes embodiments of the present invention with reference to the drawings. Numerous details are set forth below in order to provide a thorough understanding of the present invention, but it will be apparent to those skilled in the art that the present invention may be practiced without these details.
In the production and operation of an ethylene cracking furnace of 3-month Fujian combined petrochemical engineering Limited company in 2020, 24 furnace tubes in the second pass of the radiation section of the 2# cracking furnace burst, and cracking raw materials in the furnace tubes leak and are injected into a hearth to burn, so that the 2# cracking furnace is emergently shut down and repaired.
The material of the furnace tube in the second pass of the radiation section of the 2# cracking furnace is 25Cr-35Ni-Nb + MA, the specification is phi 120 × 7mm, the furnace tube belongs to nickel-based materials, the specific material components are shown in Table 1. because the furnace tube runs in a high-temperature hearth at about 1000 ℃ for a long time, phenomena such as carburization, creep deformation, embrittlement and the like are easily generated, the hardness of the material is increased, the brittleness is enhanced, the strength, plasticity, toughness and the like are poor, the C content of the material of the inner wall of the furnace tube is increased from about 0.4% to about 2.84%, and the carbon equivalent is large, so the weldability is poor.
TABLE 1 old furnace tube Material composition (w,%)
| Chemical composition | C | Si | Mn | P | S | Cr | Ni | Nb | Mo | Al | Cu |
| Element content | 0.42 | 1.58 | 1.2 | 0.003 | 0.002 | 23.95 | 34.25 | 1.32 | 0.38 | 0.04 | 0.15 |
Referring to fig. 1, in order to overcome the deterioration of the quality of the old furnace pipe, poor weldability, reduce the restraint stress in the welding process of the new and old furnace pipes and avoid the generation of hot cracking phenomenon, the invention innovatively adopts a mode of surfacing transition layer and new furnace pipe sectional welding to weld and repair the burst ethylene cracking furnace pipe, and the specific process comprises the following steps:
(1) cutting the old furnace tube 1: firstly, determining the tube explosion position of the old furnace tube 1, cutting off the damaged tube section, checking the shape and wall thickness condition of the residual old furnace tube 1, if the condition of continuous use is satisfied after checking, cleaning the oxide layers on the inner side and the outer side of the port of the old furnace tube 1, and polishing the groove. Wherein, the cleaning length of the old furnace tube 1 is 25mm respectively inside and outside the port, the bevel angle of the old furnace tube 1 is 30 degrees, and the truncated edge is 1 mm.
(2) Cutting the new furnace tube: according to the length of the damaged pipe section, a new furnace pipe with the same length and the same specification is taken, the new furnace pipe is cut into a long section 6 and a short section 5 with the length of 100mm, the end openings of the long section 6 and the short section 5 are subjected to groove grinding, the groove angles of the long section 6 and the short section 5 are both 30 degrees, and the truncated edges are both 1 mm.
(3) Surfacing treatment of the old furnace tube 1: and (3) performing surfacing treatment on the high-nickel alloy on the surface of the groove of the old furnace pipe 1 by adopting manual argon tungsten-arc welding to form a surfacing layer 4, and polishing the groove of the surfacing layer 4 to meet the requirement of welding the groove with the short section 5. The grade of the welding wire adopted by surfacing welding is ERNiCr-3, the diameter of the welding wire is 2.4mm, and the specific components of the welding wire are detailed in Table 2. The surfacing process is carried out in two layers, the surfacing fusion ratio of the first layer is 18%, the temperature of each welding pass and the interlayer is 55 ℃, and the total thickness of the surfacing layers is 4 mm. The overlaying process is not allowed to swing, and the overlaying layer after overlaying is qualified through 100% PT detection. The specific process parameters of the surfacing process are detailed in table 4.
(4) Butt joint of new and old furnace pipes: the two short sections 5 are respectively welded with the old furnace tube 1 with the overlaying layer 4 by manual argon tungsten-arc welding, and then the long section 6 is welded between the two short sections 5. The welding wire used for welding the pup joint 5 and the overlaying layer 4 is ERNiCr-3 in the grade, the diameter of the welding wire is 2.4mm, and the specific components of the welding wire are detailed in a table 2; the welding wire adopted for welding the long section 6 and the short section 5 is made of the same material as a new furnace tube, the mark is WEL TIG 35CW, the diameter of the welding wire is 2.4mm, and the specific components of the welding wire are detailed in Table 3. The welding process between the short section 5 and the surfacing layer 4 and between the long section 6 and the short section 5 firstly adopts butt-joint tack welding, and the butt-joint gap is 1 mm; and then, adopting layered welding, wherein the interlayer temperature is 55 ℃, the layers cannot swing during welding, the thickness of a first layer welded between the short section 5 and the overlaying layer 4 is 2mm, and specific process parameters in the welding process are shown in a table 4.
TABLE 2 ERNiCr-3 welding wire composition (w,%)
TABLE 3 WEL TIG 35CW wire compositions (w,%)
TABLE 4 welding Process parameters
The welding method comprises the following steps: manual tungsten electrode argon arc welding
According to the welding repair technology, the new furnace tube is cut into a long section 6 and two short sections 5 with the length of 100mm, and when the short sections 5 are welded at the surfacing layer 4 of the old furnace tube 1, the self gravity and the forced assembly stress of the new furnace tube are greatly reduced, so that the welding restraint stress is very small, and the hot cracks generated by the connecting welding seams 2 of the new furnace tube and the old furnace tube can be avoided. And regarding the welding between the short section 5 and the long section 6, because the short section 5 and the long section 6 are both new uncontaminated furnace pipes, the impurity problem does not exist, the weldability is high, and therefore, even if large constraint stress exists between the short section 5 and the long section 6, the probability of hot cracks generated in the connecting welding seam 3 of the new furnace pipes is small. In addition, because there is 100 mm's interval between long section 6 and the old stove pipe 1, consequently when nipple 5 and long section 6 welding, the welding thermal cycle of new stove pipe joining weld 3 can not exert an influence to old stove pipe 1, consequently can not produce reheat crackle.
The welding repair technology effectively solves the problem of hot cracks generated when new and old furnace pipes are welded, so that 24 cracked furnace pipes in the second pass of the radiation section of the ethylene 2# cracking furnace are repaired in time, precious time is saved for the re-production of the ethylene cracking furnace, and the welding repair technology has the advantages of simplicity in operation, high repair efficiency, good repair effect, high reliability and the like. It should be noted that the welding repair method provided by the invention is not limited to the welding repair of the ethylene cracking furnace tube, and can also be applied to the welding repair of high-temperature alloy furnace tubes such as hydrogen production reforming furnace tubes.
The above description is only an embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any insubstantial modifications made by using the design concept should fall within the scope of infringing the present invention.
Claims (8)
1. The welding repair method for the ethylene cracking furnace tube is characterized by comprising the following steps: the method comprises the following steps:
(1) cutting the old furnace tube: determining the damaged position of the old furnace tube, cutting off the damaged tube section, and cleaning and polishing the inner side and the outer side of the port of the residual old furnace tube;
(2) cutting the new furnace tube: taking a new furnace tube with the same specification and the same length according to the length of the damaged tube section, cutting the new furnace tube into a long section and two short sections with the same length, and polishing the grooves of the ports of the long section and the short sections;
(3) surfacing treatment of the old furnace tube: performing surfacing treatment on the surface of the groove of the old furnace tube to form a surfacing layer, and polishing the groove of the surfacing layer;
(4) butt joint of new and old furnace pipes: firstly, the two short sections are respectively welded with an old furnace pipe with a surfacing layer, and then the long section is welded between the two short sections.
2. The ethylene cracking furnace tube welding repair method as set forth in claim 1, wherein: in the step (1), the cleaning length of the old furnace tube is 25mm respectively at the inner side and the outer side of the port, the bevel angle of the old furnace tube is 30 degrees, and the truncated edge is 1 mm.
3. The ethylene cracking furnace tube welding repair method as set forth in claim 1, wherein: in the step (2), the lengths of the two short sections are not less than 100mm, the bevel angles of the long section and the short sections are both 30 degrees, and the truncated edges are both 1 mm.
4. The ethylene cracking furnace tube welding repair method as set forth in claim 1, wherein: in the step (3), the surfacing process is carried out in two layers, the surfacing fusion ratio of the first layer is less than 20%, the interlayer temperature is less than 60 ℃, and the total thickness of the surfacing layer is more than 3 mm.
5. The ethylene cracking furnace tube welding repair method as set forth in claim 1, wherein: in the step (4), the welding procedure between the short section and the surfacing layer firstly adopts butt-joint tack welding, and the butt-joint gap is smaller than 2 mm; then, layered welding is adopted, the thickness of the first layer is less than 2mm, and the interlayer temperature is less than 60 ℃.
6. The ethylene cracking furnace tube welding repair method as set forth in claim 1, wherein: in the steps (3) and (4), the welding mode adopts manual argon tungsten-arc welding, and the welding wire is made of high-nickel alloy.
7. The ethylene cracking furnace tube welding repair method as set forth in claim 6, wherein: in step (3), the welding wire is ERNiCr-3.
8. The ethylene cracking furnace tube welding repair method as set forth in claim 6, wherein: in the step (4), the welding wire brand adopted for welding the short section and the overlaying layer is ERNiCr-3, and the welding wire adopted for welding the long section and the short section is made of the same material as that of the new furnace tube.
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Cited By (3)
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| CN114434031A (en) * | 2021-12-28 | 2022-05-06 | 青海中控太阳能发电有限公司 | Welding repair method for heat absorption pipe of fused salt heat absorber |
| CN114918633A (en) * | 2022-06-27 | 2022-08-19 | 宝武集团鄂城钢铁有限公司 | Method for repairing water leakage at root of copper pipe and copper cooling wall |
| CN116175079A (en) * | 2023-03-03 | 2023-05-30 | 中国核电工程有限公司 | Furnace tapping pipe repair system and method |
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