阅读说明：本技术 碳钢烟道/烟囱内衬不锈钢板结构及气密性检测方法 (Carbon steel flue/chimney lining stainless steel plate structure and air tightness detection method ) 是由 王道斌 于浩波 郑丽君 于 2020-08-25 设计创作，主要内容包括：本发明公开了一种碳钢烟道/烟囱内衬不锈钢板结构及气密性检测方法,不锈钢板结构为：若干块不锈钢板沿碳钢基板内壁周向和/或轴向,采用边沿搭接且焊接方式连接而成；上层不锈钢板边沿采用盖面焊焊接在下层不锈钢板上,焊缝为连续角焊缝；不锈钢板上均布若干个塞焊孔,在塞焊孔内依次经环形过渡焊和盖面满焊焊接在碳钢基板上。气密性检测方法为：先在碳钢烟道/烟囱靠两端端部的碳钢基板上开2个通气孔,通气孔位置须避开塞焊孔及不锈钢板过渡焊位置；再焊接不锈钢板衬里,碳钢烟道/烟囱靠两端端部不锈钢板外端需和碳钢基板连续焊；衬里焊接完毕后,进行外观检测,再以压缩空气法进行气密性试验。本发明烟道/烟囱强度高,耐温性能好,系统运行可靠,使用寿命长。(The invention discloses a carbon steel flue/chimney lining stainless steel plate structure and an air tightness detection method, wherein the stainless steel plate structure comprises the following components: the stainless steel plates are connected in a way of overlapping edges and welding along the circumferential direction and/or the axial direction of the inner wall of the carbon steel substrate; the edge of the upper stainless steel plate is welded on the lower stainless steel plate by adopting cover surface welding, and the welding seam is a continuous fillet welding seam; a plurality of plug welding holes are uniformly distributed on the stainless steel plate, and annular transition welding and cover surface full-weld welding are sequentially carried out in the plug welding holes on the carbon steel substrate. The air tightness detection method comprises the following steps: firstly, 2 vent holes are formed in a carbon steel substrate at the end part, close to two ends, of a carbon steel flue/chimney, and the positions of the vent holes need to avoid plug welding holes and transition welding positions of stainless steel plates; then welding a stainless steel plate lining, and continuously welding the outer ends of the stainless steel plates at the end parts close to the two ends of the carbon steel flue/chimney with the carbon steel substrate; after the welding of the lining is finished, appearance detection is carried out, and then an air tightness test is carried out by a compressed air method. The flue/chimney of the invention has high strength, good temperature resistance, reliable system operation and long service life.)

1. A structure of a carbon steel flue/chimney lining stainless steel plate is characterized in that the lining of the carbon steel flue/chimney is formed by connecting a plurality of stainless steel plates in a mode of edge lap joint and welding along the circumferential direction and/or the axial direction of the inner wall of a carbon steel substrate of the carbon steel flue/chimney; the edge of the upper stainless steel plate is welded on the lower stainless steel plate by adopting cover surface welding, the welding seam is a continuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate;

the edge of the lower stainless steel plate is welded on the carbon steel substrate by transition welding; wherein, the welding seam covered by the upper stainless steel plate is a discontinuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate; the welding seam which is not covered by the upper stainless steel plate is a continuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate;

the stainless steel plate is uniformly distributed with a plurality of plug welding holes, the stainless steel plate is welded on a carbon steel substrate in the plug welding holes by annular transition welding and cover full-face welding in sequence, the height of a welding seam of the annular transition welding is 0.6-0.85 times of the thickness of the stainless steel plate, and the welding seam is a continuous fillet welding seam; the highest position of the welding line of the cover surface full welding is not more than 1.8mm outside the stainless steel plate.

2. A carbon steel flue/stack liner stainless steel panel construction as claimed in claim 1 wherein the overlap width between the stainless steel panels is 20 mm.

3. The carbon steel flue/chimney lining stainless steel plate structure of claim 1, wherein the distance between two adjacent plug welding holes is 300mm, and the diameter of the plug welding hole is phi 8-16 mm.

4. The structure of the carbon steel flue/chimney lining stainless steel plate of claim 1, wherein the carbon steel substrate thickness H of the carbon steel flue/chimney is 6-20 mm, and the thickness of the stainless steel plate is 1.5-3 mm.

5. A carbon steel flue/chimney liner stainless steel plate structure according to claim 1, wherein when condensate water exists in the carbon steel flue/chimney, the stainless steel plates are laid along the axial direction of the carbon steel flue/chimney in a sequence that takes into account the flow direction of the condensate water in the carbon steel flue/chimney, and the former stainless steel plate overlaps the next stainless steel plate along the flow direction of the condensate water.

6. The structure of a stainless steel lining of a carbon steel flue/chimney as claimed in claim 1, wherein the stainless steel plate is 316L, 2205, 2507 or C276.

7. A method for detecting the air tightness of a carbon steel flue/chimney lining stainless steel plate comprises the following steps:

s1, before welding the stainless steel plate lining, 2 vent holes are formed in the carbon steel substrate at the end parts, close to the two ends, of the carbon steel flue/chimney, and the positions of the vent holes are required to be arranged in a mode of avoiding plug welding holes and transition welding positions of the stainless steel plate; the outer ends of the stainless steel plates at the end parts close to the two ends of the carbon steel flue/chimney need to be continuously welded with the carbon steel substrate;

and S2, after the welding of the carbon steel flue/chimney stainless steel plate lining is finished, firstly carrying out appearance detection on the lining, and then carrying out air tightness test on the lining by using a compressed air method.

8. The method for detecting the airtightness of a stainless steel plate for a carbon steel flue/chimney liner according to claim 7, wherein in step S2, the specific method for performing the airtightness test of the liner by a compressed air method is as follows:

(1) a first connecting pipe and a first ball valve are connected to the vent hole at one end of the carbon steel substrate to form an air outlet end; the vent hole at the other end is connected with a second connecting pipe and a second ball valve, and is finally connected to a compressed air source to form an air inlet end;

(2) compressed air is introduced between the sandwich layer of the stainless steel plate and the carbon steel substrate through the vent holes;

(3) the method comprises the steps of firstly opening the air outlet end ball valve, confirming that gas is sprayed out of the air outlet end ball valve, then closing the air outlet end ball valve, coating soapy water or diluted laundry detergent on all plug welding points and cover surface welding seams, judging whether bubbles emerge, and performing repair welding treatment on a stainless steel plate if yes until the stainless steel plate is qualified after no leakage is detected.

9. The method for detecting the air tightness of the carbon steel flue/chimney lining stainless steel plate according to claim 8, wherein the pressure of the compressed air is 0.01-0.07 MPa.

10. The method for detecting the air tightness of the stainless steel plate of the carbon steel flue/chimney liner according to claim 8, wherein a pressure reducing valve and an air filter are further connected to the second connecting pipe at the air inlet end.

Technical Field

The invention relates to the technical field of corrosion prevention in the chemical industry, in particular to a carbon steel flue/chimney lining stainless steel plate structure and an air tightness detection method.

Background

The flue gas related to the chemical industry is often flue gas with strong corrosivity, taking limestone-gypsum wet desulphurization process as an example, the flue gas after desulphurization is saturated wet flue gas with weak acidity, and a carbon steel flue and a carbon steel chimney behind the carbon steel flue must be subjected to antiseptic treatment before being put into use. The conventional anticorrosion treatment methods at present generally comprise two methods, namely carbon steel lining glass flakes or carbon steel lining glue. The two anticorrosion treatment methods have basically consistent defects, namely, the two anticorrosion treatment methods cannot resist high temperature, and the anticorrosion treatment can be damaged when the temperature exceeds 100 ℃; secondly, easy damage, the maintenance cost is very high.

In addition, currently, 4 common nondestructive testing methods are mainly used for welding seams of stainless steel plate structures of carbon steel flue/chimney linings, namely Ultrasonic Testing (UT), magnetic powder testing (MT), X-Ray Testing (RT) and liquid Penetration Testing (PT). Wherein the ultrasonic wave is applied to a part with a thickness of more than 5mm and a regular shape; magnetic powder detection cannot detect austenitic stainless steel materials and welding seams welded by austenitic stainless steel welding rods; the X-ray detection mainly qualitatively detects the defects of the welding seam, and is not suitable for a stainless steel sheet lined in a carbon steel substrate; fluid penetration testing is not suitable for inspecting workpieces having multiple plug weld holes.

Disclosure of Invention

The invention aims to provide a stainless steel plate structure for the lining of a carbon steel flue/chimney, and the lining of the stainless steel plate structure is adopted to replace the conventional anticorrosive treatment modes of carbon steel lining glass flakes or carbon steel lining glue and the like, so that the flue/chimney has high strength, good temperature resistance, reliable system operation and long service life.

The invention also aims to provide a method for detecting the air tightness of the carbon steel flue/chimney lining stainless steel plate.

The lining of the carbon steel flue/chimney is formed by connecting a plurality of stainless steel plates along the circumferential direction and/or the axial direction of the inner wall of a carbon steel substrate of the carbon steel flue/chimney in a mode of overlapping edges and welding; the edge of the upper stainless steel plate is welded on the lower stainless steel plate by adopting cover surface welding, the welding seam is a continuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate;

the edge of the lower stainless steel plate is welded on the carbon steel substrate by transition welding; wherein, the welding seam covered by the upper stainless steel plate is a discontinuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate; the welding seam which is not covered by the upper stainless steel plate is a continuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate;

the stainless steel plate is uniformly distributed with a plurality of plug welding holes, the stainless steel plate is welded on a carbon steel substrate in the plug welding holes by annular transition welding and cover full-face welding in sequence, the height of a welding seam of the annular transition welding is 0.6-0.85 times of the thickness of the stainless steel plate, and the welding seam is a continuous fillet welding seam; the highest position of the welding line of the cover surface full welding is not more than 1.8mm outside the stainless steel plate.

Preferably, the overlapping width between the stainless steel plates is 20 mm.

Preferably, the distance between two adjacent plug welding holes is 300mm, and the diameter of each plug welding hole is phi 8-16 mm.

Preferably, the thickness H of the carbon steel substrate of the carbon steel flue/chimney is 6-20 mm, and the thickness of the stainless steel plate is 1.5-3 mm.

Preferably, when condensed water exists in the carbon steel flue/chimney, the flow direction of the condensed water in the carbon steel flue/chimney needs to be considered in the laying sequence of the stainless steel plates along the axial direction of the carbon steel flue/chimney, and the previous stainless steel plate is lapped on the next stainless steel plate along the flow direction of the condensed water.

Preferably, the stainless steel plate may be 316L, 2205, 2507, C276 or other stainless steel plate as required.

A method for detecting the air tightness of a carbon steel flue/chimney lining stainless steel plate comprises the following steps:

s1, before welding the stainless steel plate lining, 2 vent holes are formed in the carbon steel substrate at the end parts, close to the two ends, of the carbon steel flue/chimney, and the positions of the vent holes are required to be arranged in a mode of avoiding plug welding holes and transition welding positions of the stainless steel plate; the outer ends of the stainless steel plates at the end parts close to the two ends of the carbon steel flue/chimney need to be continuously welded with the carbon steel substrate;

and S2, after the welding of the carbon steel flue/chimney stainless steel plate lining is finished, firstly carrying out appearance detection on the lining, and then carrying out air tightness test on the lining by using a compressed air method.

Preferably, in step S2, the specific method for performing the airtightness test of the liner by the compressed air method is as follows:

(1) a first connecting pipe and a first ball valve are connected to the vent hole at one end of the carbon steel substrate to form an air outlet end; the vent hole at the other end is connected with a second connecting pipe and a second ball valve, and is finally connected to a compressed air source to form an air inlet end;

(2) compressed air is introduced between the sandwich layer of the stainless steel plate and the carbon steel substrate through the vent holes;

(3) the method comprises the steps of firstly opening the air outlet end ball valve, confirming that gas is sprayed out of the air outlet end ball valve, then closing the air outlet end ball valve, coating soapy water or diluted laundry detergent on all plug welding points and cover surface welding seams, judging whether bubbles emerge, and performing repair welding treatment on a stainless steel plate if yes until the stainless steel plate is qualified after no leakage is detected.

More preferably, the pressure of the compressed air is 0.01 to 0.07 MPa.

Preferably, the second connecting pipe at the air inlet end is further connected with a pressure reducing valve and an air filter.

The invention has the following advantages and beneficial effects:

1. the carbon steel flue/chimney lining stainless steel plate structure adopts a brand new technical scheme, replaces the conventional anticorrosive treatment modes of carbon steel lining glass flakes or carbon steel lining glue and the like, and has the structural forms of plug welding and cover surface full welding, so that the carbon steel flue/chimney lining stainless steel plate structure has high strength, good temperature resistance, reliable system operation and long service life.

2. The method for detecting the air tightness of the carbon steel flue/chimney lining stainless steel plate can effectively ensure that the carbon steel flue/chimney is safely used at the working temperature and pressure.

3. The method for detecting the air tightness of the carbon steel flue/chimney lining stainless steel plate has the advantages of simple construction, visual display and strong operability.

4. The method for detecting the air tightness of the stainless steel plate of the carbon steel flue/chimney liner can detect all welding lines at one time, and is short in time consumption and low in detection cost.

Drawings

FIG. 1 is a diagram of a carbon steel flue/stack lining stainless steel panel layout according to an embodiment of the present invention;

FIG. 2 is a schematic illustration of a plug weld of stainless steel plates provided by an embodiment of the present invention;

FIG. 3 is a schematic view of a weld between stainless steel plates provided by an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a carbon steel substrate with open pores according to an embodiment of the present invention;

fig. 5 is a schematic view of a method for detecting airtightness after the stainless steel plate is welded according to an embodiment of the present invention.

In the figure: 1. a carbon steel substrate; 1-1, vent holes; 2. a stainless steel plate; 2-1, a first stainless steel plate; 2-2, a second stainless steel plate; 2-3, a third stainless steel plate; 3. plugging the welding hole; 4. annular transition welding; 5. fully welding the cover surface; 6. welding the cover surface; 7. transition welding; 8. a first steel pipe; 9. a first ball valve; 10. a second steel pipe; 11. a PU pipe; 12. a ball valve II; 13. a pressure reducing valve; 14. an air filter.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The embodiment of the invention provides a carbon steel flue/chimney lining stainless steel plate structure, wherein the lining of the carbon steel flue/chimney is formed by connecting a plurality of stainless steel plates 2 along the circumferential direction and/or the axial direction of the inner wall of a carbon steel substrate 1 of the carbon steel flue/chimney in a mode of overlapping and welding edges; the thickness H of the carbon steel substrate 1 of the carbon steel flue/chimney is 6-20 mm, the thickness of the stainless steel plate 2 is 1.5-3 mm, 2mm or 2.5mm is generally preferred, and the stainless steel plate 2 can be made of 316L, 2205, 2507 or C276 or other stainless steel plates according to needs. The lapping width between the stainless steel plates 2 is 20 mm; the edge of the upper stainless steel plate is welded on the lower stainless steel plate by adopting a cover surface welding 6, the welding seam is a continuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate;

the edge of the lower stainless steel plate is welded on the carbon steel substrate by transition welding 7; wherein, the welding seam covered by the upper stainless steel plate is a discontinuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate; the welding seam which is not covered by the upper stainless steel plate is a continuous fillet welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate;

a plurality of plug welding holes 3 are uniformly distributed in the stainless steel plate 2, the distance between every two adjacent plug welding holes 3 is 300mm, and the diameter of each plug welding hole 3 is phi 8-16 mm; the stainless steel plate 2 is welded on the carbon steel substrate 1 in the plug welding hole 3 sequentially by adopting annular transition welding 4 and cover surface full-weld 5, the height of a welding seam of the annular transition welding 4 is 0.6-0.85 times of the thickness of the stainless steel plate, and the welding seam is a continuous fillet welding seam; the highest position of the welding line of the cover surface full welding 5 is not more than 1.8mm outside the stainless steel plate 2.

Preferably, when condensed water exists in the carbon steel flue/chimney, the flow direction of the condensed water in the carbon steel flue/chimney needs to be considered in the laying sequence of the stainless steel plates along the axial direction of the carbon steel flue/chimney, and the previous stainless steel plate is lapped on the next stainless steel plate along the flow direction of the condensed water.

As shown in figure 1, the hole punching distance of the stainless steel plate 2 is 300x300mm, the diameter of the plug welding hole 3 is phi 8-16 mm, the material of the stainless steel plate 2 can adopt 316L, 2205, 2507, C276 and the like according to actual needs, the processed stainless steel plate 2 is sequentially laid and welded on the carbon steel substrate 1, and welding rods (cover surface welding) between the stainless steel plates 2 and welding rods between the carbon steel substrate 1 and the stainless steel plate 2 need to strictly adopt welding rods corresponding to the material of the stainless steel plate 2.

The specific scheme is as follows: firstly, laying a first stainless steel plate 2-1, plug-welding the first stainless steel plate 2-1 onto a carbon steel substrate 1 of a carbon steel flue/chimney according to the drawing 2, specifically, firstly, performing annular transition welding 4 in a plug welding hole 3, wherein the height of a welding seam is 0.6-0.85 times of the thickness of the stainless steel plate and is a continuous fillet welding seam, and then performing cover full welding 5 on the plug welding hole, wherein the highest position of the welding seam is not more than 1.8mm of the outside of the stainless steel plate; after the first stainless steel plate 2-1 is laid, the second stainless steel plate 2-2 is the same as the first stainless steel plate 2-1 in plug welding of the carbon steel substrate 1, the second stainless steel plate 2-2 is welded on the first stainless steel plate 2-1 in a cover surface welding 6 mode, the covering width is 20mm (see figure 3), specifically, a welding seam between the edge of the first stainless steel plate 2-1 and the carbon steel substrate 1 is a transition welding 7, the welding seam is a discontinuous angle welding seam, and the height of the welding seam is consistent with the thickness of the stainless steel plate; the part uncovered by the second stainless steel plate is a continuous fillet weld, and the height of the weld is consistent with the thickness of the stainless steel plate. The cover surface welding 6 between the second stainless steel plate 2-2 and the first stainless steel plate 2-1 is a continuous fillet welding, and the height of the welding seam is consistent with the thickness of the stainless steel plate. And sequentially paving a third stainless steel plate, a fourth stainless steel plate and a fifth stainless steel plate according to the mode. If condensed water (such as a desulfurization system) is generated in the carbon steel flue/chimney, the order of laying should take into consideration the flow direction of the condensed water in the carbon steel flue/chimney, and taking fig. 1 as an example, the third stainless steel plate 2-3 is covered on the first stainless steel plate 2-1, and the flow direction of the condensed water should be from the third stainless steel plate 2-3 to the first stainless steel plate 2-1.

The carbon steel flue/chimney lining stainless steel plate structure replaces the conventional anticorrosive treatment modes of carbon steel lining glass flakes or carbon steel lining glue and the like, and has the advantages of high strength, good temperature resistance, reliable system operation and long service life.

A method for detecting the air tightness of a carbon steel flue/chimney lining stainless steel plate comprises the following steps:

s1, before welding the lining of the stainless steel plate 2, as shown in FIG. 4, 2M 8 vent holes 1-1 need to be formed in the carbon steel substrate 1 at the end parts, close to the two ends, of the carbon steel flue/chimney, and the positions of the vent holes 1-1 need to be arranged in a way of avoiding the positions of the plug welding holes 3 and the stainless steel plate transition welding 7; welding stainless steel plates according to the welding requirements of the figures 1-3, wherein the outer ends of the stainless steel plates 2 at the end parts close to the two ends of the carbon steel flue/chimney need to be continuously welded with the carbon steel substrate 1;

and S2, after the welding of the carbon steel flue/chimney stainless steel plate lining is finished, firstly carrying out appearance detection on the lining, and then carrying out air tightness test on the lining by using a compressed air method.

Preferably, in step S2, the specific method for performing the airtightness test of the liner by the compressed air method is as follows:

(1) as shown in fig. 5, a steel pipe I8 (with a movable joint) of phi 8 and a ball valve I9 of phi 8 are sequentially connected to an M8 vent hole 1-1 at one end of the carbon steel substrate to form an air outlet end; the M8 vent hole 1-1 at the other end is sequentially connected with a phi 8 steel pipe II 10 (with a movable joint), a PU pipe 11, a ball valve II 12, a pressure reducing valve 13 and an air filter 14, and finally connected to a compressed air source to form an air inlet end;

(2) compressed air is introduced into the interlayer between the stainless steel plate 2 and the carbon steel substrate 1 through the vent holes 1-1, the pressure of the compressed air is 0.01-0.07 MPa, the pressure can be adjusted according to actual conditions, the welding line can be burst open when the pressure is too high, and the detection effect can be influenced when the pressure is too low.

(3) Firstly opening the first air outlet end ball valve 9, confirming that air is sprayed out of the first air outlet end ball valve 9, proving that the whole interlayer is communicated, then closing the first air outlet end ball valve 9, coating soap water or diluted laundry detergent on all plug welding points and cover surface welding seams, judging whether bubbles emerge, and performing repair welding treatment on a stainless steel plate if yes until the stainless steel plate is qualified after no leakage is detected.

The method for detecting the air tightness of the carbon steel flue/chimney lining stainless steel plate can effectively ensure that the carbon steel flue/chimney is safely used at the working temperature and pressure.

The method for detecting the air tightness of the carbon steel flue/chimney lining stainless steel plate has the advantages of simple construction, visual display and strong operability.

The method for detecting the air tightness of the stainless steel plate of the carbon steel flue/chimney liner can detect all welding lines at one time, and is short in time consumption and low in detection cost.

The details, features and advantages of a carbon steel flue/stack lining stainless steel plate structure and a method for detecting air tightness, etc. of the present invention will be specifically described below by way of examples, however, all the descriptions are for illustrative purposes only and should not be construed as forming any limitation on the present invention. Furthermore, any single feature described or implicit in an embodiment herein, or any single feature shown or implicit in each figure, may nevertheless be combined or subtracted between any of these features (or their equivalents) to arrive at still further embodiments of the invention that may not be directly mentioned herein. In addition, for the sake of simplicity, the same or similar features may be indicated in only one place in the same drawing.