CN107143703B - A kind of mechanical composite tube and its manufacturing method of 825 nickel-base alloy of liner - Google Patents

Abstract

The invention discloses a mechanical composite pipe lined with 825 nickel-based alloy and a manufacturing method thereof. The mechanical composite pipe is composed of an 825 nickel-based alloy inner pipe and a low-carbon steel outer pipe. After the equiaxial assembly of the carbon steel outer tube, use a mechanical expander to expand the diameter of the tube in sections or continuously. The amount of diameter expansion will cause plastic deformation of the 825 nickel-based alloy inner tube, while the deformation of the low-carbon steel outer tube is close to the maximum Elastic deformation; after the diameter expansion is completed, use a fixed diameter reducing machine to perform fixed diameter reduction on the outside of the pipe; inspect the mechanical composite pipe formed after internal diameter expansion and external diameter reduction, and cut off a certain size of the pipe end after passing the inspection. Welding, and groove processing on the pipe end, the manufacturing method of the present invention is not restricted by the strength of the inner and outer pipe materials, only need to change the external diameter reduction, the 825 nickel-based alloy inner pipe and the carbon steel outer pipe can be realized Effective combination.

Description

A mechanical composite pipe lined with 825 nickel-based alloy and its manufacturing method

Technical field:

The invention belongs to the manufacturing industry of steel pipes for oil and gas transportation, and in particular relates to a mechanical composite pipe lined with 825 nickel-based alloy and a manufacturing method thereof.

Background technique:

Statistics show that since 2000, my country's annual corrosion loss has exceeded 500 billion yuan, accounting for about 5% of the gross national product, and pipeline corrosion has accounted for a considerable proportion of it. The experience and statistical data of developed countries show that more than a quarter of the rust loss can be controlled by anti-corrosion means. As long as effective anti-corrosion measures are taken, the service life of equipment and equipment can be extended, and new anti-corrosion equipment, new technologies, new processes, and new materials can be actively promoted and used. Our country can at least reduce 30% of corrosion losses and recover hundreds of billions of losses. Yuan.

For a long time, people have studied various technologies to prevent the corrosion of pipelines by fluids, such as using corrosion-resistant metals and non-metallic materials, coating, plating, infiltrating, and lining corrosion-resistant layers in pipelines, adding corrosion inhibitors to fluids, and so on. Corrosion-resistant alloy pipes such as stainless steel, nickel-based alloys, and titanium alloys are widely used in corrosive environments such as petroleum, chemical, and marine industries because of their excellent anti-corrosion performance and processing performance. However, the cost of using a single corrosion-resistant alloy pipe is relatively high. For example, the wellhead gathering and transportation pipeline of the first line of West-to-East Gas Pipeline, because the gas source contains serious corrosive media, used 11 kilometers long duplex stainless steel gathering and transportation pipeline with a diameter of 508mm, all imported from abroad, and the total project cost was about 3.6 100 million.

Layered bimetallic composite materials can combine different metals with extremely different strengths, melting points, and thermal expansion coefficients. It integrates the advantages of different materials, gives full play to the characteristics of different materials, greatly saves rare and precious metal materials, and reduces the manufacturing cost of equipment. . If the steel pipe is made of stainless steel and pipeline steel, it is an effective method to solve the internal corrosion problem of the pipeline. The cost is also lower since the inner walls are only thinly clad. At the same time, the outer low carbon steel or pipeline steel can also provide the required strength and toughness requirements of the pipe body.

In the next few years, the market's demand for composite metal pipe products will increase rapidly. my country's oil industry alone consumes more than 1 million tons of petroleum steel pipes at a cost of more than 10 billion yuan, of which more than 50% of petroleum steel pipes are basically used in strong corrosion environments. That is, the market capacity of anti-corrosion pipelines in the oil industry exceeds 5 billion yuan per year. There are many oil and gas fields containing acid gas in my country. For example, many oil and gas fields in Xinjiang Tarim, Sichuan, and Central Plains are in the harsh environment of deep wells, high temperature, high pressure, and high corrosion. They need to import tens of thousands of tons of these high-alloy materials from Japan and Germany every year. If stainless steel composite pipes are used, imports can be stopped and a lot of money can be saved.

The general design principle of bimetallic composite pipe is that the base material meets the allowable stress of the pipe design, and the alloy resists corrosion or wear. The main manufacturing methods are divided into metallurgical bonding and mechanical bonding according to the degree of interface bonding. It is a flexible and low-cost method to manufacture layered bimetallic composite pipes by using metallurgically bonded layered composite plates as raw materials and welding after cold forming. It first heat-combines two slabs of different materials with a super-high-power hot rolling mill, then rolls them into tube blanks with UO or JCO technology, and then welds them longitudinally. Compared with expanded composite pipes and explosive composite pipes, layered bimetallic composite pipes prepared by welding have certain advantages over composite pipes manufactured by other processes in terms of secondary molding, welding and pipe body performance. However, since the clad layer is inside the steel pipe, there are special requirements for the groove processing, alignment accuracy, welding method and welding sequence in the manufacturing process. At the same time, different welding materials must be selected for different base materials. There are strict requirements on fusion ratio, heat input, interlayer temperature, etc., so manufacturing and processing are difficult and the yield is very low. In addition, because the steel pipe is processed by welding after forming, the selection of inner and outer pipe materials is limited. For example, titanium and steel, two immiscible materials, cannot be processed by welding. Also due to the influence of welding, the size of metallurgical composite pipe products is generally large. According to different manufacturing equipment, the minimum pipe diameter is generally not less than 508mm, which limits the application of metallurgical composite pipes in the field of oil and gas gathering and transportation pipelines.

Domestic research on composite pipes is mainly focused on small-diameter composite pipes, and the main means are diameter expansion and explosive compounding. Composite pipes through diameter expansion, explosive composite, etc. have certain defects in pipe performance and life, and their size is also limited. At the same time, its process has relatively large limitations, and it has high requirements for the strength matching of inner and outer tubes. Generally, the composite pipe manufactured by the internal diameter expansion process requires the outer pipe to be stronger than the inner pipe, while the composite pipe manufactured by the external diameter reduction process requires the outer pipe to be stronger than the inner pipe. However, techniques such as explosive compounding have special requirements for equipment and sites, which are not suitable for promotion, and their product quality cannot meet the requirements of oil and gas gathering and transportation pipes.

The composite pipe manufactured by using welded pipe or seamless steel pipe, coaxially assembling them according to the required size, pressurizing the inside to make them fit, and then reducing the diameter of the outer pipe is a mechanically combined composite pipe. The pipe manufacturing method is simple and the yield is high. Although it is not suitable for reheating due to the low degree of interface bonding, mechanical composite pipes can fully meet the needs of use when there is no deformation requirement for pipe fittings and no high-temperature environment.

The announcement number of the announcement on April 23, 2014 is CN203560610 U, and the name is a mechanical composite pipe with a corrosion-resistant alloy layer at the end of the pipe. The mechanical composite pipe includes a corrosion-resistant alloy inner pipe and a low-carbon steel outer pipe. The above-mentioned composite pipe combines the inner pipe, the outer pipe and the outer pipe together by means of mechanical diameter expansion. The disadvantage of this mechanical composite pipe is that when the mechanical composite pipe is manufactured by a single forming process such as internal expansion, there are special requirements for the strength of the raw material. The internal expansion process generally requires that the strength of the carbon steel outer tube is higher than that of the nickel-based alloy inner tube.

Invention content:

The object of the present invention is to provide a mechanical composite pipe lined with 825 nickel-based alloy and its manufacturing method. The manufacturing method is not limited by the strength of raw materials, and the effective combination of inner and outer pipes can be realized only by changing the amount of outer diameter reduction. , and the manufacturing method of the present invention is simple in process, and the performance of the prepared composite pipe product is reliable, which meets the construction needs of oil and gas gathering and transportation pipelines in severely corroded areas.

In order to solve the above technical problems, the technical solution adopted in the present invention is: a mechanical composite pipe lined with 825 nickel-based alloy, the mechanical composite pipe is composed of an 825 nickel-based alloy inner pipe and a low-carbon steel outer pipe, the The outer surface of the 825 nickel-based alloy inner tube is closely combined with the inner surface of the low-carbon steel outer tube through inner diameter expansion and outer diameter reduction.

The wall thickness of the 825 nickel-based alloy inner tube is 2mm-5mm, and the outer diameter is 20mm-590mm; the wall thickness of the low-carbon steel outer tube is 6mm-30mm, and the outer diameter is 25mm-610mm.

The 825 nickel-based alloy inner pipe is a seamless pipe or a welded pipe.

The low carbon steel outer pipe is a seamless pipe or a welded pipe.

The manufacturing method of the mechanical composite pipe lined with 825 nickel-based alloy includes: after assembling the 825 nickel-based alloy inner pipe and the low-carbon steel outer pipe equiaxially, adopting a mechanical diameter expanding machine to expand the diameter of the pipe in sections Or continuous diameter expansion, the diameter expansion will cause plastic deformation of the 825 nickel-based alloy inner tube, while the deformation of the low-carbon steel outer tube is close to the maximum elastic deformation; , when the strength of the 825 nickel-based alloy inner tube is smaller than that of the low-carbon steel outer tube, the inner diameter expansion is large, and the outer diameter reduction is small; when the 825 nickel-based alloy inner tube is stronger than the low-carbon steel outer tube, the inner expansion The diameter is small, and the external diameter reduction is large, so as to ensure that the inner and outer pipes can get better bonding strength under different strength matching conditions; the mechanical composite pipe formed after internal expansion and external diameter reduction is inspected and inspected. After qualified, the pipe end is cut off to a certain size for surfacing welding, and the pipe end is beveled.

The equiaxial assembly gap between the 825 nickel-based alloy inner tube and the low-carbon steel outer tube is 5-30mm.

The minimum yield strength of the low carbon steel outer tube is 360MPa-485MPa.

When the minimum yield strength of the low-carbon steel outer pipe is 360 MPa, the external diameter reduction is 1.2% of the outer diameter of the outer pipe.

When the minimum yield strength of the low-carbon steel outer pipe is 450 MPa, the external fixed diameter reduction is 0.3% of the outer diameter of the outer pipe.

Beneficial effects of the present invention:

1. At present, the composite pipe is manufactured by internal expansion or external extrusion process. The internal expansion process generally requires the strength of the carbon steel outer tube to be higher than the nickel-based alloy inner tube, while the external extrusion process requires the carbon steel outer tube to be stronger than the nickel-based alloy inner tube. tube, the manufacturing method of the present invention is not restricted by the material strength of the inner and outer tubes, and the effective combination of the inner and outer tubes can be realized only by changing the amount of outer diameter reduction, which breaks the limitation of material strength when this type of process is used to prepare composite tubes. When the strength of the outer tube When the strength of the outer tube is lower than that of the inner tube, reduce the amount of outer diameter reduction; when the strength of the outer tube is lower than that of the inner tube, increase the outer diameter reduction, so that the effective combination of the 825 nickel-based alloy inner tube and the carbon steel outer tube can be realized.

2. The dimensional accuracy of the composite pipe with externally fixed and reduced diameter is higher, which is more conducive to on-site welding installation, and greatly reduces the problems of misalignment and other alignment problems in traditional composite pipe welding. This method has no special requirements for site and technology, and is easy to promote .

Description of drawings:

The specific implementation manner of the present invention will be described in further detail below in conjunction with the accompanying drawings.

Fig. 1 is a structural schematic diagram of a composite pipe lined with a corrosion-resistant alloy according to the present invention.

Explanation of reference signs: 1-825 nickel-based alloy inner tube, 2-low carbon steel outer tube.

Detailed ways:

Referring to Figure 1, after the mechanical composite pipe is equiaxially assembled from the 825 nickel-based alloy inner pipe and the low-carbon steel outer pipe, a certain bonding force is generated between the inner and outer pipes to form a composite pipe fitting by adopting the method of first expanding the diameter inside and then reducing the diameter outside.

Both the 825 nickel-based alloy inner tube and the low-carbon steel outer tube of the present invention can be seamless tubes or welded tubes. The minimum yield strength of the outer tube is 360MPa or 450MPa.

The 825 nickel-based alloy inner tube is equiaxially assembled in the low-carbon steel outer tube, and the assembly gap is 5-30mm; The inner surface of the outer tube is tightly bonded, and the amount of diameter expansion causes the maximum elastic deformation of the low-carbon steel outer tube; after the mechanical expansion process is completed, the diameter reduction treatment is performed on the expanded composite tube; when the minimum yield strength of the outer tube B can be When the diameter is 360MPa or 450MPa, the external diameter reduction is 1.2% or 0.3% of the external diameter; the mechanical composite pipe after the diameter reduction process is processed and tested for the pipe end.

Other processes involved in the preparation of mechanical composite pipes in the present invention include.

(1) Low carbon steel outer tube preparation:

Cutting to length: Cut the base pipe to a certain length according to the product size specification requirements;

Inner surface inspection: Strictly check the quality of the inner surface of the base pipe to avoid defects that affect the bonding quality of the inner and outer pipes;

Inner surface treatment: shot blasting treatment on the inner surface;

Purge and dry: purge and dry the inner surface for later use.

(2) 825 nickel-based alloy inner tube preparation

Tube making: 825 nickel-based alloy steel strip is rolled into tube blank, welded by TIG or plasma welding method, the quality and shape of weld seam are strictly controlled, and grinding treatment is carried out when necessary;

Cutting to length: the qualified steel pipes are cut according to the length requirements;

Surface treatment: 825 nickel-based alloy steel pipes are pickled to ensure the quality of the outer surface;

Cleaning and drying: Clean the acid liquid on the surface of the steel pipe and dry it for later use;

(3) Assembly processing

Assembly of inner and outer tubes: put the inner tube into the outer tube, and seal and weld the ends of the tubes according to the process requirements;

Mechanical diameter expansion: The assembled pipe fittings are expanded in sections or continuously, and the diameter is expanded according to a certain amount of diameter expansion. After expanding to the predetermined deformation, it is kept for a certain period of time. The expansion amount should make the low carbon steel outer tube produce Maximum elastic deformation;

Fixed diameter reduction: Continuous sizing or reduction treatment is adopted for the expanded pipe fittings, and the fixed diameter reduction can be calculated according to the strength matching of inner and outer pipes. If the strength of the inner tube is greater than that of the outer tube, the diameter reduction amount is the maximum elastic deformation limit of the inner tube, and if the strength of the outer tube is greater than that of the inner tube, only a slight diameter reduction is performed;

Hydrostatic pressure test: test the pressure resistance of the steel pipe according to the standard;

Pipe end treatment: pipe end sealing welding and pipe end chamfering. Before sealing welding, the inner pipe is cut off to a certain length, and then special welding materials are used for surfacing welding from the inside, so that the inner and outer layers of the pipe end within a certain length range can achieve metallurgical bonding, which is the pipe end. Preparation for processing and subsequent installation and construction;

Dimensional inspection and marking: Check the appearance and size of the steel pipe, and mark it after meeting the standard requirements.

Example 1: The 825 nickel-based alloy inner tube and the X65 outer tube were mechanically composited according to the above method. Table 1 shows the chemical composition of the 825 nickel-based alloy and X65, and Table 2 shows the mechanical properties of the mechanically composited tube.

Embodiment 2: 825 nickel-based alloy inner tube and Q235 outer tube are mechanically compounded according to the above method, table 3 is the chemical composition of 825 nickel-based alloy and Q235, and table 4 is the mechanical properties of 825 nickel-based alloy and Q235 mechanical composite tube .

It can be seen from Table 2 and Table 4 that the mechanical composite pipe produced by the method of the present invention has a yield strength of >360MPa, a tensile strength of >490MPa, and an elongation of >=29%, which meets the construction needs of oil and gas gathering and transportation pipelines in severely corroded areas .

Table 1 Chemical composition of 825 nickel-based alloy and X65

steel number C Si mn P S Cr Ni Cu Mo Nb V Ti N X65 0.06 0.24 1.19 0.021 0.002 0.032 0.011 0.031 0.005 0.033 0.02 0.012 / 825 0.01 0.25 0.32 - 0.001 22.79 40.23 0.76 3.02 - - 0.71 -

Table 2 Mechanical properties of 825 nickel-based alloy and X65 mechanical composite pipe

YS(Rt0.5), MPa TS, MPa Elongation, % 470 560 39 465 565 40 460 565 43

Table 3 Chemical composition of 825 nickel-based alloy and Q235

steel number C Si mn P S Cr Ni Cu Mo Nb V Ti N Q345 0.16 0.45 1.22 0.017 0.003 / / / / / / / 825 0.01 0.25 0.32 - 0.001 22.79 40.23 0.76 3.02 - - 0.71 -

Table 4 Mechanical properties of 825 nickel-based alloy and Q235 mechanical composite pipe

YS(Rt0.5), MPa TS, MPa Elongation,% 365 505 31 370 495 29 365 500 33

Claims (6)

1. a kind of manufacturing method of the mechanical composite tube of 825 nickel-base alloy of liner, it is characterised in that:

The mechanical composite tube is made of 825 nickel-base alloy inner tubes and mild steel outer tube；

The inner surface of the outer surface of the 825 nickel-base alloy inner tube and mild steel outer tube it is interior expanding and it is outer determine tube reducing by way of It combines closely；

It include: by after 825 nickel-base alloy inner tubes and the isometric assembly of mild steel outer tube, using mechanical expansion equipment to being segmented in pipe Expanding or continuous expanding, expanding amount makes 825 nickel-base alloy inner tubes generate plastic deformation, and mild steel outer tube deflection is close maximum Flexible deformation；

After the completion of expanding, pipe is carried out outside using size-reducing mill to determine tube reducing processing, when 825 nickel-base alloy inner tube intensity are less than low-carbon When steel outer tube, then in expanding amount it is big, outer determine sizing reduction small, when 825 nickel-base alloy inner tube intensity are greater than mild steel outer tube, then interior Expanding amount is small, outer to determine that sizing reduction is big, to can obtain preferably combining in the case of guaranteeing the different strength matching of inner and outer pipes strong Degree；

To through it is interior it is expanding with it is outer determine tube reducing after the mechanical composite tube that is formed test, pipe end cuts off certain size after the assay was approved Built-up welding is carried out, and retaining wall on slope processing is carried out to pipe end.

2. a kind of manufacturing method of the mechanical composite tube of 825 nickel-base alloy of liner according to claim 1, feature exist In: the fit-up gap of the 825 nickel-base alloy inner tube and the isometric assembly of mild steel outer tube is 5~30mm.

3. a kind of manufacturing method of the mechanical composite tube of 825 nickel-base alloy of liner according to claim 1, feature exist In: the minimum yield strength of the mild steel outer tube is 360MPa~485MPa.

4. a kind of manufacturing method of the mechanical composite tube of 825 nickel-base alloy of liner according to claim 1, feature exist It is described outer determine sizing reduction for the 1.2% of outer pipe outside diameter when: the minimum yield strength of the mild steel outer tube is 360MPa.

5. a kind of manufacturing method of the mechanical composite tube of 825 nickel-base alloy of liner according to claim 1, feature exist It is described outer determine sizing reduction for the 0.3% of outer pipe outside diameter when: the minimum yield strength of the mild steel outer tube is 450MPa.

6. the mechanical composite tube based on claim 1,2,3,4 or the 5 manufacturing method manufactures, it is characterised in that: 825 nickel The wall thickness of based alloy inner tube is 2mm~5mm, and outer diameter is 20mm~590mm；The wall thickness of the mild steel outer tube is 6mm~30mm, Outer diameter is 25mm~610mm；The 825 nickel-base alloy inner tube is seamless pipe or welded pipe；The mild steel outer tube is seamless Pipe or welded pipe.