MX2011005694A - High-frequency electrical soldering process for large diameter pipes. - Google Patents

Abstract

Currently there is no known process for manufacturing piping tubes having a diameter larger than 26 inches by using the HFW process Welding (ERW). It is worth mentioning that the process of the present invention may be used for an X80-graded steel and a maximum thickness of up to 0,750 inches. The process used for the manufacture of large diameter pipes is known as a continuous flow, which comprises several steps in order to obtain the final product, among which there are the following 14 main stages included : Reception of Raw Material, material inspection, acceptance or rejection thereof, edge cutting, roll storage, which may be also used with a plate, a harness, guides, ERW welding , pull out, heat treatment, cooling, sizer, pipe cutting and inner cleaning. The main feature of the process is that the main feed source is a steel roll, which in turn is cold worked through 4 stages, the main purpose being to narrow the material by a series of steps so as to obtain an O-shaped materia l. In order to obtain the final product, a series of processes are required including: reception of raw material, edge cutting, leveling, preform, guides, ERW welding, pull out, heat treatment, sizer, and inner cleaning, each of said steps being useful for manipulating the physical and mechanical properties of the material. It is worth mentioning that the weld appearance is very similar to that obtained by the manufacturing process of seamless steel pipes, due to the removal of excess material (this operation is performed at the inner and outer surfaces of the pipe) which allows smooth surfaces to be obtained, thereby ensuring that the pipe fulfills the preferred requirements. The main applications of the pipe of the present invention include transportation of liquids, as well as in the oil industry for gas conduction, in oil refineries, and oil drilling rigs, among others.

Description

HIGH FREQUENCY ELECTRIC WELDING PROCESS FOR SUPERIOR DIAMETERS DESCRIPTION OBJECT OF THE INVENTION The object of the present invention refers to an HFW High Frequency Electric Welding (ERW) process that is used for the manufacture of upper outer diameter pipe, which has applications such as: gas conduction, pipe for transportation of liquids , refineries, oil extraction in platforms, to name a few.

The main objective is to present a process capable of guaranteeing the production of pipes with more than 26 inches of outer diameter through the process of High Frequency Electric Welding HFW (High Frequency Welding) or "Electric Resistance Welding", using several phases inside of the process as they are: preforming, welding, heat treatment, cooling, roundness of the tube, etc. The realization of each one of the phases within the process guarantees the manufacture of high-diameter outer pipe with all the properties of the material and the highest quality standards.

BACKGROUND In the world market, various types of welding are used for the union of the pipe, currently, the HFW High Frequency Electric (ERW) welding process is not used in pipes larger than 26"in diameter. we can observe the manufacturing and welding processes that we can currently find, both processes must have a good relationship in order to guarantee the best application for the manufacture of the pipe.

The welding processes mentioned are described below for an analysis, in order to be able to compare and verify the differences obtained in each process.

The first welding process mentioned is the High Frequency Electric Welding HFW (ERW), in which metals are joined without the need for filler material, that is, they are joined by application of pressure and electric current on the area to be welded . The amount of heat to be supplied depends on the electrical resistance over said area. The main advantages that can be found in this process are the efficient use of energy, high production rates and do not need any filling material. Until now, only this process is known in pipes up to 26 inches in diameter.

The second process that we can find is known as Subed Arc Welding or SAW (Sumberged Are Welding) for its acronym in English, has as a characteristic feature the use of a continuous flow of protective material in powder or granulate, also called flux This substance protects the arc, the bath and the fusion of the atmosphere, so that both remain invisible during welding, part of the flux is melted, thereby protects and stabilizes the arc, generates slag that isolates the cord, and can even contribute to the alloy. The rest of the non-molten flux is collected for reuse.

The welding electrode SAW is consumable, so its chemical composition must be compatible with the steel of the pipe to be welded, the flux is a mixture of mineral compounds such as (SIO2, CaO, MnO, etc.) with certain characteristics that help to stabilize the arc when welding as well as possible chemical contributions to the welding mixture that complements the improvements in the physical properties of the pipe welded by this process. This process is quite versatile; It is used in general to join ferrous metals and alloys, also to coat materials against corrosion. The greatest limitation of this process is that it can only be applied in a horizontal position since otherwise it would spill the flux. This process has its greatest field of application in the manufacture of steel pipes and, in general, in the welding of almost any type of steel.

Among the advantages of this method, include: • High Productivity • Low cost in the preparation stage • The fact that it can be executed in a single step, even in very thick materials • It is very reliable for the control of the operation parameters.

• Very good quality of the process.

The third process that we can find is GMAW (gas metal are welding) or MIG (Metal Insert Gas) welding, where an electric arc is maintained between a solid wire that functions as a continuous electrode and the work piece. The arc and the molten solder are protected by an inert or active gas quantity. The process can be used in most metals and the range of wires in different alloys and applications is almost infinite.

MIG welding is a versatile process, with which welding can be deposited at a very high range and in any position. The process is widely used in steel sheets of low and medium caliber manufacturing, also on aluminum alloy structures particularly where there is a high requirement of manual work. What determines the correct application of this process is the fluidity of the molten solder, the shape of the weld bead and the spark or spatter it generates.

The fourth process we find is TIG Welding (Tungsten Inert Gas) is also known as Heliarc welding, it is a process in which a non-consumable solid tungsten electrode is used, the arc and the area around the molten solder are protected by atmospheres with a shield of inert gas, if any filler metal is necessary it is added to the welding. In TIG welding the zone is protected from the atmosphere by an inert gas that is fed through the torch, the gases used can be argon or helium that can be used successfully in this process, the argon is mainly used for its great versatility in the successful application of a wide variety of metals, in addition to its high performance allowing a welding with a low flow to carry out the process, in addition to the TIG welding is characterized by being stronger, more ductile and more resistant to corrosion than the welds made with the ordinary process of the manual arc. This process can be used with AC or DC current, as it is more adaptable to certain types of applications.

The fifth process that we can find is PLASMA welding, also known as PAW (Plasma Are Welding), and uses the same principles as TIG welding, so it can be considered as a development of that last process, however, both the energy density as the temperatures in this process are much higher due to the plasma state that is reached when a gas is heated to a temperature sufficient to achieve its ionization, thus separating the element of ions and electrons. The biggest advantage of the PAW process is that its impact zone is two or three times lower compared to TIG welding, which makes it an optimal technique for welding metals of small thickness.

The sixth process we find is welding by laser beam which uses the energy provided by a laser beam to melt and recrystallize the materials to be joined, obtaining the corresponding union between the elements involved. In laser welding, there is usually no contribution of any external material and welding is done by heating the area to be welded. By means of mirrors, all the energy of the laser is focused in a very small area of material, when a melting temperature is reached, the ionization of the mixture between the vaporized material and the protective gas occurs. (plasma formation). The energy absorption capacity of the plasma is even greater than that of the molten material, so that practically all laser energy is transmitted directly and without loss to the material to be welded.

The main advantages of the processing of materials by laser welding compared to conventional methods are the following: • Greater flexibility, that is, adaptation to applications with greater diversity in terms of geometric dimensions and type of material.

• The thermal effect on the piece is much lower • Processing quality is high • High production speed • Easy integration in robotic systems or tools integrated in a CNC The last process to be mentioned is the friction welding process (FSW), where a cylinder with a flat section and a profiled rotor, are softly approximated to the areas to be joined which are facing each other. The parties have to be secured to a support table to avoid being separated by force to which they are subjected. The heat of the friction of the rotary cylinder of high resistance to wear and the pieces to be welded cause that they soften without reaching the melting point allowing the rotary cylinder to follow the welding line through the pieces to be worked. The friction welding can be used to join sheets and plates without the need to use filler material or any type of gases and materials with a thickness of 1.6 to 30 mm can be welded with full penetration, without porosity or internal evasions.

These are the main welding processes that we can use. The following describes each of the manufacturing processes used for the manufacture of pipes. The first process is the continuous flow which is one of the main that we can find for the manufacture of pipe, has as its main source the receipt of raw material steel roll, this in turn is worked in cold through 4 stages which help us to close the material until we get the "U" shape and then go through another stage known as the Fin Pass, whose main function is to close the sheet completely until we get the "O" shape. Once the desired shape is obtained, the last step to conclude is the union of the material with the HFW High Frequency Welding (ERW) process.

The second process is the one of Roladora that is common for the manufacture of steel tubes regularly of high diameters and high thicknesses, it consists of a continuous process by means of which a sheet is submitted to the action of a series of 3 rollers that it provides to the steel plate a specific shape. The product obtained from the manufacture of tubes can be used in a wide variety of processes, in the rolling operation the most used materials are carbon steel and stainless steel, and the characteristics that define the product are the diameter of the tube and the Wall thickness. Once the tubular shape is obtained, the edges are welded to form a closed section.

After performing the welding operation, the required diameter is refined by passing the tube through another set of rollers. The bending of tubes can be done by automatic or manual machines, which use rollers to bend the tube while it is formed. The distribution of stresses around the circumference of the tube depends on the design of the rolling sequence.

The third process is that of forming with JCO press, whose action is carried out by means of a tool that is pressed against the material. It consists in shaping the steel plate in 3 steps. The first step has as main objective to apply load on one side of the plate (usually done in a series of repetitions) begins to visualize that the steel gets the shape of "J", then the second step is equal to the previous step, but it must be applied on the other side of the plate and now the "C" shape is obtained, and to finish the operation loads must be applied in the center of the plate and the material is completely closed, obtaining the shape of " Or "(in this operation, fewer repetitions are used because the part is already closed in its entirety).

The repetitions are restricted by several conditions, among which stand out: the thickness of the plate, the grade of steel, the conditions of the hydraulic press and the length of the steel plate.

The fourth process is formed by UO press, has the same principle as the process of forming with JCO press, but unlike this only, is done in 2 steps. We can also find the seamless or seamless steel tube, this form is the most common and consequently the most commercial. The pipe is manufactured from a solid cylindrical piece which is heated in an oven, prior to extrusion. Then it is deformed with rollers and then a hole is made through a penetrator. The seamless pipe is the best to contain the pressure due to its homogeneity in all its directions. Once the specified dimensions have been met, and according to the customer requirements, the tube goes through a heat treatment to achieve the required physical and mechanical properties.

We can also find pipe with longitudinal seam, which originates in a sheet and is bent to the desired shape and closed by a weld joining both ends.

BRIEF DESCRIPTION OF THE FIGURES Figure No. 1 is a block diagram of the high frequency electric welding process for higher diameters, where each of the phases is shown, as well as the interaction and monitoring of them.

Figure No. 2 is a graphic representation (front view) of the welding process, where the tube is held by tools called "Roles" that are mounted to a structure, which help us close the steel plates and this At the same time it helps us to adjust the material according to the required diameter. For this process, four roles are used, 2 in the upper part and another 2 in the lower part.

Figure No. 3 is a graphic representation (side view) of the welding process, which is very similar to Figure Nl but the difference is that you can see the necessary attachments for the formation of the pipe, in addition the head is illustrated mobile of the welding which is introduced inside both ends to make the union of the material.

Figure No. 4 is a graphic representation (top or side view) of the continuous forming, where we find the following stages: edge cutting, preforming, guides and ERW welding machine.

DETAILED DESCRIPTION OF THE INVENTION Below is detailed information, an essential part of the process for the manufacture of pipes with diameters greater than 26 inches, the manufacturing process used is known as continuous forming or also called "production mill" which is characterized in that the Main power supply is steel roll but can also be used with plate; This in turn is cold worked through 4 stages whose main purpose is to close the material until obtaining the "O" shape. In order to obtain the final product it is necessary to establish a series of steps, which are described below in more detail.

According to the block diagram that is illustrated in Figure No. 1, the first phase of the process is the receipt of raw material (1), where it is verified that the material to be used is the indicated, later the quality department takes care of perform the inspection test to the material (3), where various parameters are verified in order to ensure that it meets the requirements requested from the supplier, among which stand out: length, thickness, and width of the plate, as well as no marks and in the event that they are visualized, the tolerance of depth for acceptance must not be greater than +/- 10% of the thickness; If the material is not within the specification, it must be returned to the supplier through the adjustment phase (2), otherwise, if the material is accepted for manufacturing, the next process consists in cutting the edges ( 4) whose purpose is to adjust to the required width according to the diameter to be produced, for products with diameters greater than 26"it must be cut between 1" to 2"on both sides, then the material must be re-rolled and then fed into the "Production Mill" (5) to start the stage in the formation of the tube.

The process begins with the preforming phase (6), where the steel undergoes modifications in its physical properties because the material begins to bend and causes it to expand between 2 to 3 times its thickness (this is visualized in the width of the roll), this operation is carried out in a series of 4 steps until obtaining the "U" shape, later it is subjected to the process of guides (7), which consists of 3 castles with their respective roles each, which help us to compress the material up to 1/8"of its circumference, this is because in the previous process there is an increase in the width, then it can be concluded that the main function is as its name indicates to be guiding the material until closing almost in It is worth mentioning that at this point both ends are not completely closed.) At the end of the guide stage, the material is ready to be joined through the ERW process (8) ( high frequency electric welding Next, the welding process is specified, for which reference will be made to figure No. 2 and 3, which consists of 9 main parts, which are described below.

The welding process begins with the entrance of the plate to the welding machine, with the plate practically closed in the shape of "O". Once the plate is inserted, there is a pneumatic jack (15), located on the upper part of the machine, whose main function is to make necessary height adjustments to the assembly of angle roles. Subsequently there are contact adjusters (16), which are responsible for making the contact centering for the welding machine, that is, center the contact of the high frequency weld towards the tube.

Similarly, there is an assembly of angle roles (17), which consist of a plate that supports the 2 Roles and its main function is to adjust each of them.

The roles of angle (18) is the most important tool for the welding process, because it is designed to make the union of both ends of the roll, in this phase practically in the form of "O" and thus form the tube. This tool also helps us to apply pressure just when the tube is welding, thus reaffirming the weld and tube formation.

Subsequently we have the superior roles (19) and lower roles (20), which are tools that help us to put pressure on the material and support the circular shape of the tube.

In the middle part of the machinery and located below the angle roles, there is an external and internal cutting tool (21), whose purpose is to remove part of the welding generated in the process (excess material ). In the lower part of the machine there is a welding plate (22), which is the one that supports the pressure generated in the roles, and serves as support support in the higher roles (19) and lower roles (20) . Finally, it has adjustment screws for leveling (23), located below the welding plate, whose main function is to adjust the welding plate according to the requirements of the diameter to be produced.

Already described the main parts of the welding equipment, the values used are described below: a voltage between 28 to 38 Kvolts with an amperage between 28 to 38 ampers at a speed between 22 to 32 p / min. The average estimated time to weld is 2.20 min. considering an average length of 12.5 meters To conclude the welding stage, the capacity of the welding equipment is mentioned below, which helps us obtain diameters greater than 26 inches.

• Equipment capacity for the ERW welding process The welding machine works at a maximum of 16,000 Volts, the maximum current for the plate is 30 Ampers, also has a filament circuit that operates at 14.5 Volts at 450 Ampers with a power of 560 Kwatts.

Then the tube is in turn withdrawn from the "Production Mill" by means of a device called Puli Out, in the maintenance process (9), which main objective is to hold the tube and then start with the heat treatment process. (normalized) (10) which consists of heating the material between 30 to 50 degrees Celsius above the higher citric temperature, and whose general purpose is to produce a harder and stronger steel, it also benefits because the internal tensions are eliminated, the grain is refined, its internal structure changes and a uniform distribution of carbon is obtained. The ranges of temperatures applied are between 705 to 871 ° C, and the main factors that define the temperature for the treatment are the thickness of the material and the steel grade; When the treatment stage is concluded, it is essential to submit it to the cooling process (11), which is carried out at room temperature at a certain distance and then accelerates the cooling directly with a water-soluble mixture. Already to conclude the manufacture, the tube passes through a mechanical equipment that is known as "Sizer", in the phase of rounding (12), which has as main objective rounding the tube according to the required diameter and ensuring that it does not it is oval, then it is cut (13) according to the length requested by the client.

The last step observed in the block diagram is the cleaning in the inner part (14) this is longitudinally because in the welding operation excess material is removed, this in turn generates waste and / or burrs in the inside of the tube, so it must be completely cleaned.

Claims (2)

CLAIMS Having described my invention enough, I consider it as a novelty and therefore claim as my exclusive property, what is contained in the following clauses:

1. Process of high frequency electric welding for higher diameters, characterized by having, but not limited to, a series of phases for its realization, which are: receipt of raw material, inspection of material, phase of adjustment, phase of cutting of edges, unwinding, leveling, guillotine, feed to the production mill, preforming phase, guide process, high frequency electric welding phase, maintenance phase, thermal treatment phase, cooling phase, rounding phase, cutting phase and interior cleaning phase.

2. Process of high frequency electric welding for higher diameters, in accordance with claim 1, characterized in that the phase of the high frequency electric welding process starts at the moment of entering the "O" shaped plate, from the process of guides, and that said electric welding process has a pneumatic jack, located in the upper part of the machine, and whose main function is to make necessary height adjustments to the assembly of angle roles, later in the process it is counted on contact adjusters, which are responsible for contact centering for the welding machine, that is, center the contact of the high frequency weld towards the tube; once the centering is done, there is an assembly of angle roles, consisting of a plate that supports 2 roles and its main function is to adjust each of them, roll; After the rolls of angle is counted the superior and inferior roles help to make pressure in the material and support to give the circular shape to the tube; as well as the upper and lower roles, there is an external and internal cutting tool to remove part of the welding that is generated in the process and in the lower part it has a welding plate, which is the one that supports the pressure that it is generated in the roles, and it serves as support support in the superior and inferior roles; Finally, the process is aided by adjusting screws for leveling, located below the welding plate, whose main function is to adjust the plate according to the requirements of the diameter to be produced. Process of high frequency electric welding for higher diameters, in accordance with claim No. 2, characterized in that the phase of the high-frequency electric welding process employs, but does not limit, a voltage of 28 -38 kV, an amperage of 28 - 38 A and a speed of 22-32 feet / min. SUMMARY In summary, as mentioned, we can find various processes for the manufacture of pipe, but currently there is no known company in the industry which can provide pipes with a diameter greater than 26 inches using the HFW (ERW) welding process. It is worth mentioning that you have the ability to use this process with steel grades up to X80 in a maximum thickness of 0.750 inches. Next, the manufacturing process used in the manufacture of pipes for larger diameters is explained in a general manner. The operation is known as continuous flow, in which it is carried out through a series of steps, which helps us to obtain the final product. To carry out the process (pipe can be manufactured from roll and / or plate) as mentioned, the operation consists of 14 main activities among which stand out: Reception of Raw Material, Inspection of material (acceptance or rejection of the same), edge cutting, guillotine, bulldozer, roll storage, preforming, guides, ERW welding, polishing out, heat treatment, cooling, sizer, tube cutting and interior cleaning and each of them help us to manipulate the properties physical and mechanical aspects of the material. The main feature is that it works in cold through 4 stages whose main purpose is to close the material in a series of processes to obtain the circular shape, then the material is welded through the ERW welding process and then subjected to quality tests (material resistance, penetration of the weld, among others) in order to guarantee that the tube complies with the established standards It should be mentioned that the appearance of the weld is very similar to the seamless pipe manufacturing process, because the surplus material is removed (in this operation it must be made inside and outside the pipe) and the surface is completely smooth. Among the main applications are the transportation of liquids, also for petroleum uses such as: gas conduction, refineries and oil extraction in platforms to name a few.