JPS6264945A - Method for detecting damage sensitivity of heat transfer pipe of heat exchanger - Google Patents

Abstract

PURPOSE:To detect a pipe having possibility of corrosive damage even during a use period, by measuring the damage sensitivity of a heat transfer pipe by measuring the magnetic characteristics of the heat transfer pipe by a ferrite scope or a magnetic balance. CONSTITUTION:For example, a high nickel pipe within the standard component range of JIS Standard NCF 600 TB is used and a pipe having received corrosive damage by the addition of a minute amount of caustic soda is measured. Susceptibility is measured with respect to the pipe of which the corrosion was confirmed (damaged pipe) and a pipe of which the corrosion was not confirmed (healthy pipe). The susceptibility of the damaged pipe is low but that of the healthy pipe is high and difference is clearly confirmed between both pipes. Similarly, even if ferrite scope intensity is measured by a ferrite scope, difference is clearly shown between the damaged pipe and the healthy pipe. Because magnetic characteristics are measured, a heat transfer pipe having damage sensitivity can be detected and a pipe having possibility of the generation of corrosive damage can be replaced by periodic inspection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for detecting heat exchanger tubes that are likely to suffer corrosion damage from among heat exchanger tubes.

[The same point that the prior art and the invention are trying to solve] High nickel austenitic material, which is a corrosion-resistant alloy, is generally used in the as-annealed state for heat exchanger tube materials. Even in heat exchanger tubes made of such materials, corrosion damage may occur on the outer surface of the tube during its use. Although those with advanced corrosion damage are now plugged, heat transfer performance can be maintained if preventive measures are taken for heat exchanger tubes that are likely to be corroded or have slight a-corrosion damage. It is possible. However, conventionally, it has been difficult to detect heat exchanger tubes that are likely to suffer corrosion damage as described above during their use.

The present invention was made in view of the above circumstances, and its purpose is to provide a method for detecting damage susceptibility of heat exchanger heat exchanger tubes that can easily detect heat exchanger tubes that are likely to suffer G4 corrosion damage even during use. It is about providing.

[Means for solving problems]

The present invention focuses on the fact that there is a difference in magnetic properties between heat exchanger tubes that are prone to corrosion damage and heat exchanger tubes that are less susceptible to corrosion damage. The heat exchanger tube is characterized in that a heat exchanger tube having damage susceptibility is detected from the difference between the measured values.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings.

Figure 1 shows a simulation of an actual machine environment using 16 types of high nickel alloy heat exchanger tubes manufactured within the standard composition ratio of JIS standard NCF600TB shown in Table 1, under the condition of adding a small amount of caustic soda. This figure shows the results of measuring the magnetic susceptibility using a magnetic balance for heat exchanger tubes that were found to be damaged (hereinafter referred to as damaged tubes) and heat exchanger tubes that were not recognized (hereinafter referred to as healthy tubes). The figure shows that there is a difference in magnetic susceptibility between damaged tubes and healthy tubes, and from this it is possible to detect heat exchanger tubes that are susceptible to corrosion damage from among a large number of actual heat exchanger tubes by measuring their magnetic susceptibility. Can be done.

Figure 2 shows the results of measuring the ferrite scope strength of the damaged and healthy tubes using a ferrite scope (a device that measures the amount of ferrite in austenite or, in a broader sense, the amount of ferromagnetic material in non-magnetic materials). It is something that As can be seen from the figure, all of the damaged pipes have a ferrite scope strength of 0.09% or less, while the healthy pipes have a ferrite scope strength of 0.09% or more. Therefore, as in the case of magnetic susceptibility measurement, by measuring the ferrite scope strength of the heat exchanger tubes, it is possible to detect heat exchanger tubes that are likely to cause corrosion damage from among the actual heat exchanger tubes.

In this way, it can be seen that in order to detect a heat exchanger tube having a loss 1n sensitivity from among a large number of actual heat exchanger tubes, it is sufficient to measure the magnetic properties such as the ferrite scope strength and magnetic susceptibility of the actual heat exchanger tube. To specifically apply this method to an actual machine, for example, when measuring the strength of a heat exchanger tube in an actual machine with a ferrite scope, the probe 2 of the ferrite scope is inserted into the heat exchanger tube 3 as shown in Fig. 3. All you have to do is measure it. In addition, in FIG. 3, 1 is a tube support plate, and 4 is a tube plate.

〔Effect of the invention〕

As described above, according to the present invention, heat exchanger tubes susceptible to damage can be detected by measuring the magnetic properties of actual heat exchanger tubes. The heat transfer performance of the heat exchanger can be maintained.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams for explaining the method for detecting damage susceptibility of heat exchanger tubes according to the present invention. Figure 1 is a diagram showing the relationship between the presence or absence of corrosion damage and magnetic susceptibility, and Figure 2 is Diagram showing the relationship between the presence of corrosion damage and ferrite scope strength, Part 3
The figure shows a specific method for measuring ferrite scope intensity. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 10j) 5-QO9-0, 13-0, 197 Techniques 4 Ton Core 11 Degrees (''/,) Figure 2 Figure 3

Claims (1)

[Claims] A heat exchanger heat transfer tube characterized in that the magnetic properties of the heat exchanger heat transfer tube are measured using a ferrite scope or a magnetic balance, and heat transfer tubes susceptible to damage are detected from the difference in the measured values. Damage susceptibility detection method.