CN2251088Y - Steel pipe lined with polypropylene composite acid pipe - Google Patents

Abstract

A steel pipe lined with polypropylene composite acid pipe, which is characterized in that a steel pipe 3 with a flange hole joint is set on a polypropylene plastic pipe 4, and the gap between the outer diameter of the polypropylene plastic pipe and the inner diameter of the steel pipe is δ, and each When connecting and installing section composite pipes, a sealing ring 2 is installed on the joint of the polypropylene pipe 4, and its steel pipe flange joint is connected with a bolt 1, and the joint of the polypropylene pipe 4 with the sealing ring 2 is clamped. The utility model has the advantages of simple structure, convenient manufacture, low cost, little loss in expansion joints and acid supply pipelines, and can be widely used in acid liquid delivery pipelines.

Description

Steel pipe lined with polypropylene composite acid pipe

The utility model belongs to the field of acid liquid conveying pipelines for hydrochloric acid washing units, and is especially suitable for high-temperature conveying hydrochloric acid solution pipelines.

The conveying pipeline of the existing hydrochloric acid shallow tank pickling unit is generally made of polypropylene plastic. Since the working temperature of the pipeline is as high as 90°C, the expansion coefficient of polypropylene is large and the deformation is also large, resulting in expansion joints and conveying pipes. The pipes were severely damaged. The outlet pipe of the graphite heater and the waste acid pipe in the trench often have acid leakage problems, and the pipes and expansion joints need to be replaced frequently, which not only increases the consumption of the pipes and expansion joints, but also seriously corrodes the structure of the unit and the structure of the underground acid ditch , the environment is polluted. Although there are many kinds of polypropylene composite plates, the process of making them into conveying pipes is complicated and costly.

The purpose of the utility model is to provide a steel pipe lined with polypropylene composite acid pipe with little damage to the expansion joint, long service life of the acid supply pipe and low cost.

The utility model is realized in that it is made up of steel pipe and polypropylene plastic pipe, and its key points are the steel pipe 3 with flange joint on the polypropylene plastic pipe 4, and the outer diameter of its polypropylene plastic pipe is the same as that of the steel pipe. The inner diameter of the clearance is given by the formula $\mathrm{\δ}=\sqrt{{\left(\frac{L+\mathrm{\Δ\; L}}{2f}\right)}^2-{\left(\frac{L}{2f}\right)}^2}$ Calculated, where L——the original standard length of steel pipe and polypropylene pipe,

ΔL=ΔL ₁ -ΔL ₂ ——expansion length difference,

ΔL ₁ ——length expansion of polypropylene pipe,

ΔL ₂ ——length expansion of steel pipe,

f - wave number. When installing each section of composite pipeline, install a sealing ring (2) on the joint of the polypropylene pipe (4), tighten the steel pipe flange joint with bolts (1), and place the polypropylene pipe with the sealing ring (2) (4) joint clamped.

The utility model has the advantage that, since the steel pipe 3 is used to control the expansion and elongation difference between the polypropylene pipe and the steel pipe, the difference is eliminated in the steel pipe, so that the expansion of the entire polypropylene pipeline is controlled within the design range of the steel pipe, ensuring that the expansion Nodes and pipelines are not damaged.

Below in conjunction with accompanying drawing, the utility model is further described.

Fig. 1 is a sectional view of the utility model.

Fig. 2 is a schematic diagram of a polypropylene pipe in a corrugated shape after being heated in a steel pipe inner sleeve of the present invention.

The gist of the present utility model is that the original polypropylene plastic pipe 4 is fitted with a steel pipe 3 with a flange joint. Considering that the polypropylene pipe will produce corrugated shapes in the steel pipe after being heated, the steel pipe is used to control the expansion of the polypropylene pipe and the steel pipe. Elongation difference, in order to make the expansion difference digest within the length of the steel pipe and ensure that the expansion joint and the pipeline are not damaged, the utility model is designed to have a clearance of δ between the outer diameter of the polypropylene plastic pipe and the inner diameter of the steel pipe during installation, using the formula $\mathrm{\δ}=\sqrt{{\left(\frac{L+\mathrm{\ΔL}}{2f}\right)}^2-{\left(\frac{L}{2f}\right)}^2}$ In the formula, L—the original standard length of steel pipe and polypropylene pipe,

ΔL=ΔL ₁ -ΔL ₂ ——expansion length difference,

ΔL ₁ ——length expansion of polypropylene pipe,

ΔL ₂ ——length expansion of steel pipe,

f - wave number.

The design standard pipe of the utility model is 1 meter, and the corrugated shape produced in the steel pipe after the polypropylene pipe is heated is 5 to 10 waves, and this design takes 7 waves.

The expansion coefficient of polypropylene is 1.49×10 ^-4 ·I/℃

The expansion coefficient of steel is 11.7×10 ^-6 ·I/℃

Expansion per standard meter:

ΔL ₁ =1.49×70×1000=10.43mm

ΔL ₂ =11.7×10 ^-6 70×1000=0.82mm

ΔL=10.43-0.82=9.61mm

f＝7L＝1000mm $\mathrm{\δ}=\sqrt{{\left(\frac{1000+9.61}{2\×7}\right)}^2-{\left(\frac{1000}{2\×7}\right)}^2}=9.92\mathrm{mm}$

That is, when the pipe length is 1 meter, after the polypropylene pipe (4) is heated, there are 7 waveforms generated in the steel pipe 3, and the optimum value of the installation gap δ can be 9.92mm. The average elongation of digestion swelling per wave was 1.41mm. Of course, its waveform can also be single-wave, double-wave or multi-wave. The gap between the length of other steel pipes and the number of waveforms after heating polypropylene can also be calculated according to the above formula. After the gap δ between the steel pipe 3 and the polypropylene pipe 4 is determined, it can be installed. Each section of the composite pipe is connected. During installation, a sealing ring 2 is installed at the joint of the polypropylene pipe, and the steel pipe is tightened with the bolt 1 through the corresponding flange. , and clamp the joint of polypropylene pipe 4 with sealing ring 2. In this way, the uniform gap can be ensured, the expansion of the entire pipeline can be controlled within the design range of the steel pipe, the loss of the expansion joint and the acid supply pipeline is very small, and there is no problem in transportation even at a high temperature of 90°C, and the service life of the pipeline is greatly improved Put an end to the occurrence of acid leakage and acid running. The utility model has the advantages of simple structure, convenient manufacture, low cost and good use effect, and can be widely used in acid liquid delivery pipelines of hydrochloric acid washing machines.

Claims (2)

1, the compound acid tube of a kind of inner lining of steel pipe polypropylene is made up of steel pipe and pp pipeline, it is characterized in that

A. go up the steel pipe (3) that suit has flanged joint at pp pipeline (4), its polypropylene plastics external diameter of pipe and pipe diameter the gap by formula $\mathrm{\δ}=\sqrt{{\left(\frac{L+\mathrm{\ΔL}}{2f}\right)}^2-{\left(\frac{L}{2f}\right)}^2}$ Calculate, L in the formula---steel pipe, polypropylene tube primary standard length,

Δ L=Δ L ₁-Δ L ₂---expansion length is poor,

Δ L ₁---polypropylene tube length expansion amount,

Δ L ₂---steel pipe length expansion amount,

F---wave number.

B. during every section compound acid tube connection, a seal ring (2) is installed in the joint of polypropylene tube, the flanged joint on its steel pipe is tightened with bolt (1), and the joint that will have a polypropylene tube (4) of seal ring (2) clamps.

2, the compound acid tube of a kind of inner lining of steel pipe polypropylene is characterized in that when pipe range is 1000mm, and the ripple that produces in steel pipe (3) after polypropylene tube (4) is heated is 7, and at this moment the optimum value of δ can be $\mathrm{\δ}=\sqrt{{\left(\frac{L+\mathrm{\ΔL}}{2f}\right)}^2-{\left(\frac{L}{2f}\right)}^2}=9.92\mathrm{mm}$ 。

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