WO2017133747A1 - Method for the maintenance of pipes/tubes of heat exchanges, coolers and condensers - Google Patents

Abstract

For locating a defect, that is, a leakage of pipes of heat exchangers and aircoolers via examination and engineering inspection, a sleeve of same metal with exact measurements is to be tailored via manual turning machine or CNC. The sleeve is designed to have a diameter equal to the inner diameter of the tube/pipe added to which is the ratio of displacement or overlapping. The thickness is that of original thickness or a little bit less. The said sleeve comprises the following: a sleeve having a cap or two halves; a sleeve with oil slot; a sleeve with two slots or two caps and sharp inclination angle; a straight sleeve used for fixing the defects in the U shape and a straight sleeve used in the helical shape. The tube is being entered such that the defect to be fixed shall be covered using hydraulic press and specific tools designed for fixing the sleeve in its right position. Regardless of the type of sleeve, it must be positioned under the defect directly such as low thickness, erosion, corrosion, pin holes besides all other defects causing leakage. The sleeve is considered as a solution allowing the continuously flowing of fluid in the tube and preventing the mixture of cold fluid. with the hot one from both sides (shell and tube sides) in addition to the outer diameter fixed on the inner diameter of the equipment such that the defected area is to be plugged/closed. In case of using the sleeve as a solution, it will promote the efficiency of equipment and increase the virtual lifetime thereof, whereas it allows the mixing of two fluids inside the tube without driving them out, thus increasing its temperature in comparison to the use of plug in the surrounding area of the defect, thus impacting other tubes and temperature of cooled fluid toward the shell side.

Description

METHOD FOR THE MAINTENANCE OF PIPES/TUBES OF HEAT EXCHANGES, COOLERS AND CONDENSERS

Technical Field

The Maintenance Of Pipes/Tubes Of Heat Exchanges, Coolers And Condensers

Background Art

The classification of heat exchangers is based on the transfer of heat between two or more various fluids, between solid surface and liquids or between solid particulates and a fluid, at different temperatures and in thermal contact.

The classification according to the production processes such as condensers transferring liquid into vapors; heaters/chillers heating /cooling liquids or fluids, taking into consideration the international TEMA standards as DIN 28 008 identifying the optimal method and clearance in all types of heat exchangers. That may include, for example, diameters, length ranges, spaces, thickness of tubes, support and plate baffles as well as pressures, temperatures together with all industrially applicable design specifications required for the best product with a desired quality.

Leakage of inner tubes wherein two liquids to be cooled is mixed with the coolant, i.e. two liquids from/to which the heat is being transferred, is a common defect. The practical solution thereto is the placement of a plug welded inside the tubes. Plug welding of tube bundle is consecutively performed, as an effective solution in many factories or facilities using such heat exchangers or air coolers.

Leakage typically occurs between the flange and tubes or between tubes only.

However, plug-welding in the flange and at the end of pipe/tube 1, as shown in fig. 1, may make the plug welding area be subject to excessive heat, causing some fractures in addition to the potential deactivation of pipe or tube. Whereby, the adjacent regions of the defected pipe would be impacted by the increase of heat and pressure.

Problems to be solved by the novel inventions

The negative impact resulted from the placement of a plug welded between the flange and the pipe/tube end (1), which solution undermines the efficiency of both heat exchanger and air air cooler, and thus that of final product, due to the higher temperature and pressure to extent that the fluid properties may be changed accordingly.

Whereas plugging for the defected tubes is only constricted to the ratio of approximately and not beyond 20%. The negative impact, from economy-related view; carmot"Be ignorable.

The welding may damage the flange face, affecting its mechanical properties and hardness and leading to fractures and cracks so difficult to fix.

Plug- welding tends to cancel the plugged tube and cause the two liquids therein to be blocked and gain high temperatures. This will lead to loss of thermal equilibrium and higher temperatures for the adjacent tubes. The more welding is performed, the higher the temperature becomes.

The shutdown of heat exchangers for cleaning and technical checking works definitely cause huge loss of money and time, given the value of time taken in case of any tube leakage.

This deficient solution; tube plug and welding method, has been widely used as the only available way with no improvement made thereon, despite all defects resulted from its application, its obvious technical disadvantages associated with less service life of heat exchange as the defected, leaking area are so difficult to access.

The placement of plug has bad effects in terms of quality and efficiency of heat exchangers and air coolers wherein temperature and pressure are not at levels required in the design

configuration.

Disclosure Of Invention :

The new invention is directed to the aim of averting the use of heat resulted from the welding process in a widely applied method via the fixation of metal plug onto the tube end. This presents a solution to a leakage problem; the mostly common defect of all used heat exchangers and air coolers.

Moreover, by a bypass of tube leakage, a liquid flow can be proceeded and a defected area in the tube, wherever located, be closed, since a outer diameter is to close the defect while the inner diameter allows the passage of liquid.

Whereby, a optimal use of tube can be achieved such that none of properties and features of heat exchangers and air coolers my be effected as shown in the figure 7 (15).

Whereas the sleeve 15 serves as a blockage for the defect 15 by the outer diameter of this sleeve while the inner diameter is open allowing the passage of liquid at same speed and direction. This helps the transfer of heat with no effect on the pressure generated from the liquid movement.

In addition, the tube ends are open from ingress /egress direction. Also, the bypass of tube leakage prevents the liquid serving as a coolant at shell side be mixed with the liquid to be cooled at tube side. This usually occurs in case of any defect causing leakage and the liquid most likely to pass from the defected point from the shell side to be mixed with the liquid or oil in the direction of tube side towards the inner of tube. Upon the use of a plug, the liquid would have been mixed inside the tube or pipe while the ends of said tube/pipe are sealed off and the mixed liquid inside which is of higher temperature than being in other tubes, causing lack of heat equilibrium. In contrast to all prior methods, the bypass of tube leakage employs a cold work in stead of hot work.

The new heatless design of the bypass of tube leakage impacts the metallurgical microstructure, noting that heat has a bad effect on the

mechanical properties such hardness, especially upon the exposure of a given point in the heat exchanger body to direct, irregular heat. Such difference is so obvious between the two methods. For example, for the bypass of tube leakage, there is no need to the withdrawal of heat exchanger, i.e. any defect can be immediately in-site fixable without making withdrawal and shutdown for the equipment, considering the time of maintenance is much less.

This method, the bypass of tube leakage, improves the efficiency of equipment, whereby no tube or pipe can be deactivated in case of any leakage in comparison to the weld-based method wherein a tube is blocked and deactivated, thus reducing the number of tubes. Deactivating a number of tubes will give rise to both temperature and pressure, which is conducive to terminate the service-life of the equipment. However, according to the bypass of tube leakage, all tubes are in operation and used to maximum level. Beside, it is cost-effective and high virtual life of the equipment up to 85%.

Via the bypass of tube leakage, heat transfer can be conducted as being configured by the designed together with achieving the ideal status while the inner diameter allows the passage of liquid to be cooled without having the two liquids mixed. It also allows the incessant passage of fluid, thus solving the above described problem with no consequent effect on heat transfer or pressure of the fluid.

Detailed Description

The present invention relates to the fixation or insertion of a sleeve inside a defected tube's inner diameter. Such defects include low thickness, pin holes, cracks, corrosion or others which may cause a tube leakage. The said sleeve is to be fixed onto a defected site (holes, cracks or corrosion), as shown in fig. 3 (5, 3, 2). These sleeves are designed for each position as defined in fig. 4 (7) wherein the sleeve is placed directly under the defect that has been located based on one of the following technical examination methods:

Inspection method approved by the international code and standard as UT, ECT, or any suitable methods Acoustic eye, MFL.

In fig. 8, the position of defect in relation to the sleeve is illustrated, while, in fig. 9, the said defect is fully covered in a form of U shape and the sleeve is also placed directly below it. As the said sleeve designed for such purpose is classified into: Straight sleeve and U-shaped sleeve which is divided irife various angles based on the position of defect. It is possible to be of a full U-shape, if required. It may be of less angle such as a fully U- shaped sleeve is of 180° and may also range from 10° to 180°. It may be spirally shaped. The sleeve is designed in a straight form to be subjected to a hydraulic press and formed inside the tube. It

is then to be pushed into a location where a leakage needs to be fixed (fig. 5, 10, 11). The said sleeve is to be inserted in the same manner as in tubes or pipes via drifting or hydraulic press and formed inside the tube of whatever shape or angle. However, in long distances, as in fig. 6, the said sleeve is to be cut by an acute angle. As it is shown in fig 6 (12) an overall shape of the sleeve and part designated as no. 13 representing the upper half while part no. 14 the lower part or vice-versa and illustrated from various angles.

The bypass of tube leakage is presented herein as a solution to the problem of leakage whether the tube of straight, spiral, U shape or of otherwise form used in the design of tubes for air coolers or heat exchangers.

The place of some defect, in terms of length and angle, should be taken into consideration. A defect-specific sleeve is designed as a permanent solution for blocking defects in the inner diameter by the insertion of sleeve therein. The inner diameter of sleeve is open to extent that it enables the passage of fluid while the outer diameter of which blocks the defect, the main idea of bypass of tube leakage method is illustrated in the fig 7, the number 17 & 18 are open ends for the entry and exit of liquid from the tube side, a defect of whatever type 16 is to be closed by a sleeve 15. Via such method, the liquid keeps flowing inside the tube and at the same time the defect 16 is to be closed from the outer diameter of sleeve 15, as shown in the fig. 7.

Applicability

The present invention/design-the bypass of tube leakage- applies on the inner diameters of heat exchangers, air cooler, condensers. It may be fitted and usable for inner diameters of any circular shape of whatever type or equipment, given that the type of metal used in the sleeve is the same metal of tubes or any metal specified according to TEMA, ASME, API, DIN, BS, or any alternative code or standards or equivalents thereto, vender specifications or any alternative ones applicable in the international industry for heating/cooling equipment.

The bypass of tube leakage can be employed for fixing leakage, corrosion and erosive thickness that hard to access or effect maintenance thereon as in the case of tubes/pipes used in the equipment referred to regarding the inner defects for heat exchanger tubes and inner diameters for all pipes and some valves. It should be noted that the said design depends on a sleeve of specific specifications as above indicated. Hereinafter described and illustrated are specifications defined for each type of sleeves:

• Straight cutting sleeve with two caps as shown figure no. 8 One side cutting sleeve as shown in the figure no. 9

Straight-shaped U tube as shown in the figure no. 10

Angle cut having different angles depending on tube lengths as shown in the figure no.6

In the applications illustrated, the respective method includes a sleeve to be inserted and fixed by hydraulic press whereas a lower or upper part is secured into a specific location directly under the defected area. It is then arranged to be subject to hydraulic press till the sleeve, with its lower and upper parts is stably mounted onto its specific place.

In conclusion, the main theme of the design is that the sleeve is to be directly fixed under a defect wherever it is inside the tube. Whereby, it is allowed a fluid to be flowed and a defect , at the same time, will be closed while maintaining the transfer of heat and pressure.

Brief description of the drawings :

Figure no. 1

1. Plug

It shows different locations of plugs fixed in place of welded plug in the flange of exchanger. It is a practical example for heat exchangers uses in the prior or present art.

Figure no. 2

It shows a side view of a number of plugs fixed onto the welding area in the flange. It presents the method applied in the prior or present art.

Figure no. 3

It shows a general concept of the bypass of tube leakage wherein sleeves are to secured onto potential defected areas

2. Straight sleeve

3. U-shaped less than 180 sleeve

4. Sleeve-free U tube

5. 180°-made, U-shaped sleeve

6. Open-ended, U-shaped sleeve Figure no. 4

7. Straight sleeve

8. An example defect covered by a tube in a straight tube

9. A tube sleeve with a defect fully covered

Figure no. 5

It shows the form of sleeve inside the exchangers with helical tubes.

10. Helical-shaped sleeve in the defected area

11. Helical-shaped sleeve in the defected area

Figure no. 6

It shows a sleeve of two parts. Angle cut with different angles depending on tube lengths.

12. Inclination angle of the upper and lower parts

13. A lower part of the sleeve - side view

14. A upper part of the sleeve - side view

Figure no. 7

It shows a general concept of the bypass of tube leakage

15. Sleeve location

16. Defect location

17. Open end

18. Open end

Figure no. 8 Straight cutting sleeve with upper and lower caps/part

19. Open end

20. Upper part/cap

21. Lower part/cap

22. Contact face Figure no. 9

It illustrates one side cutting sleeve having one part, one-way slot or cut.

23. Cutting edge one side

24. Sleeve with one cut

Figure no. 10

It shows U-shaped tube having various angles into which a straight sleeve is to be inserted by press till acquiring the shape of tube. It is of one part and 180 °.

25. U-shaped sleeve

26. U-shaped tube.

Claims

Claims

1- The bypass of tube leakage is applied for fixing defects causing leakages and resultant mixing of the tube side liquid to be cooled with the shell side liquid via the insertion of a inner sleeve inside the inner diameter of tube or pipe.

2- According to the claim no. 1 , the solution is that the leakage is to be blocked via inserting a sleeve in the inner diameter of the defected tube. Such leakage is resulted from holes, cracks, corrosion or other cause as in the fig. 3 ( 5, 3, 2) while number 6 represents open ends of tube. The figure no. 3 is a general description of the design idea.

3- According to the claim no. 2, the said sleeve is comprised of two parts or caps.

4- According to the claim no. 3, the said sleeve is classified into various types having given specifications depending on the location of defect.

5- According to the claim no. 4, the first type is one side cutting sleeve. Such sleeve has one slot and is based on strain/tension forces as shown in fig. no. 9.

6- According to the claim no. 4, the second type is straight cutting sleeve with two caps (as shown in fig. no. 8). It is based on the fixation .of two caps forming the inner diameter in addition to the measurement value which gives the sleeve the needed stability under pressure (drifting value). The said sleeve has an upper part 20 and a lower part 22.

7- According to the claim no. 4, the third type is a angle cut having different depending on the tube lengths. It consists of two parts of the integrated diameter required.

8- According to the claim no. 4, the fifth type is a helical-shaped sleeve to be inserted via special tools and form by hydraulic press inside the tube. It is intended to be entered in straight line till reaching the defected area then go in helical shape. In other words, the sleeve is to formed via press inside the tube. As shown in 10, 11, two sleeves are arranged into different places.

10- According to any of the previous claims 1-9, all shapes of sleeves are designed to do its function, that is, stopping the leakage caused by the defects above mentioned in the bypass of tube leakage design.

1 1- According to the claim 1 and 2, the installment and manufacturing method of the sleeve along with its shape, protection and maintenance and design of whatever type or form. There is difference in terms of dimensions, name as well as metal selection. As

previously described, a same or similar metal should be used so far it is approved according to TEMA, ASME, API, DIN, BS, or alternative code or standards or equivalents thereto. Having located the defects to be fixed via the said sleeve, the place of sleeve is to also selected.