Natural gas cylinder liner for drawing process forming

Abstract

The invention discloses a natural gas cylinder liner for drawing process forming. The liner comprises a cylinder body (1) and an end enclosure (2). The liner is characterized in that the cylinder body (1) and the end enclosure (2) are matched by welding to form a closed annular inner cavity, wherein the cylinder body (1) and the end enclosure (2) are of an integral structure. The cylinder body (1) disclosed by the invention is improved to the integral structure through a middle rotating plate and a structure of being welded to a barrel in the prior art, so that the welding amount is reduced, the processing cost is lowered, and problems such as welding deformation and solder skips and the like of the cylinder body (1) caused by large-area welding are further avoided. Meanwhile, the key problems that the liner fails as fatigue cracks are generated weld joints in the prior art and the like are solved.

Description

[0001] Technical field: [0002] The invention belongs to the improved structure of the inner tank of the natural gas cylinder in the pressure vessel, and mainly relates to an inner tank of the natural gas cylinder adopting an integrated structure. [0003] Background technique: [0004] With the increase of the number of automobiles in our country, the air pollution caused by vehicle exhaust is becoming more and more serious. The promotion of gas vehicles is not only in line with the economic strategy of using natural gas resources. Like the developed countries in the world, it is a big issue for our country to develop natural gas instead of gasoline and diesel as the energy source of automobiles. trend. However, as a key equipment for the application of natural gas—compressed natural gas cylinders (Liqefied Natural Gas, LNG cylinders for short) have been produced and applied by some enterprises, and my country has also established the production and inspection standards of GB...

AI Technical Summary

Problems solved by technology

However, as a key equipment for the application of natural gas—compressed natural gas cylinders (Liqefied Natural Gas, LNG cylinders for short) have been produced and applied by some enterprises, and my country has also established the production and inspection standards of GB24159-2009 "Welded Insulated Gas Cylinders", such as Retrieve the document, the patent number is 201320187358.0, published "A Liquefied Natural Gas Cylinder Liner for Vehicles", the invention is provided with a safe gas phase space, which forms a vacuum space with the outer shell, which can better protect the inner tank and support the gas cylinder protective, but can be combined (attached figure 1 ) It can be seen that the production method of the liner is that the middle plate is turned, welded into a barrel, and two heads are welded at both ends. Due to the limitation of the production process, the quality of the three welds is difficult to guarantee, and safety accidents sometimes Occurrence, and the service life is short, in terms of a large number of analysis results, there are the following defects in its production and application:

[0005] (1) Welding quality is difficult to control, the yield of finished products is low, and the inspection cost is high. Automobile gas cylinders are thin-walled pressure vessels, which can only be welded on one side. Welding accumulation on the inner wall is unavoidable, especially for T-shaped welded seam joints. The parts where the defects are concentrated are also the weak links of pressure vessels such as gas cylinders. Defects caused by factors such as incomplete penetration, incomplete fusion, pores, slag inclusions, cold and hot cracks, and hydrogen embrittlement caused by arcs are difficult to detect by X-ray inspection. Inspect one by one, and at least 18 pictures should be taken for the inner tank of a gas cylinder. According to the inspection price in the current market, the inspection fee is 700 yuan, and the X-ray inspection is for macroscopic defects, that is, it can be detected according to the JB / T4730 standard The first-level standard still exists for small holes (air holes, slag holes), which affect the relevant technical indicators such as vacuum degree, leak rate, leak rate and static evaporation rate of the gas cylinder liner.

[0006] (2) Minor welding defects are often the source of fatigue failure. According to analysis reports on LNG cylinder accidents at home and abroad, except for the failure of cylinders exposed to severe fire conditions, all LNG cylinders that fail in use, Almost all of them appear during inflation or just after inflation. The pressure cycle of repeated inflation and deflation of the gas cylinder causes fatigue cracks to occur in small defects, resulting in failure, and fatigue cracks often occur in welds, fusion lines and heat-affected zones. Especially the longitudinal straight welds, the longitudinal welds are subjected to hoop stress (δ Q =PD / 2 δ ), while the longitudinal stress of the longitudinal straight weld is only 1 / 2 of the hoop stress (δm=PD / 4 δ )

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