JPS6057383B2 - Corrosion prevention method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a butyl rubber-based sealing compound that can be heated and melted in order to prevent corrosion of complex parts such as connections of structures using iron and pipe structures to be laid. It is used to reliably cover especially complex shapes,
In order to completely adhere to the metal, the butyl rubber sealing compound is heated to lower its viscosity and then compacted onto the metal surface using an extrusion hand gun.

Here, we also learned that when the tannin in the butyl rubber sealing compound, which has been heated to reduce its viscosity, comes into contact with iron surfaces at high temperatures, it immediately forms iron tannate, forming a uniform corrosion-resistant oxide film layer. This relates to the characteristic corrosion prevention method. Conventionally, it is said that the corrosion of bolts and nuts at joints of steel pipes or cast iron pipes buried in soil is significantly more severe than that of the pipe bodies. Originally, the corrosion prevention method for bolts and nuts was to wrap the entire joint part of the pipe in a polyethylene sleeve or rubber sleeve, and fix both ends with vinyl tape or rubber bands. direct contact with can be prevented.

That is, methods are being used to completely cut off contact with the soil to prevent the generation of a contact potential difference and to prevent corrosion of local battery functions such as oxygen concentration batteries and salt concentration batteries. However, with this method, the pipe joint has many protrusions such as bolts and nuts, and has a complex shape, so the hollow polyethylene sleeve or rubber sleeve often breaks due to external pressure, and the pipe joint has a complicated shape. There is a large difference between the outer diameter of the main body and the maximum outer diameter of the joint, and the polyethylene sleeve or rubber sleeve does not fit tightly to the pipe at the fixed parts at both ends, making it difficult to completely isolate the joint from the soil. It has the drawbacks of being labor intensive and expensive. The corrosion prevention method according to the present invention is applied to structures using iron, but for a detailed explanation of the internal bolts and nuts of a pipe structure, a butyl rubber sealing compound is applied at the pipe joint construction site. The present invention provides a construction method that easily adheres to bolts and nuts, completely blocks corrosive soil, and prevents corrosion of bolts and nuts. The present invention is a construction method at a pipe joint construction site where the temperature is set at 120℃ to 1
Using a hand-type heated extrusion gun set at 80℃, inject a butyl rubber sealing compound that has been heated to a lower viscosity into a protective cup that is slightly larger than the shape of the bolts and nuts, and immediately cover the bolts and nuts with pressure. Consolidate by When heated, it has a low viscosity, so it easily fits into bolts and nuts with complex shapes, and can be crimped by applying a slight pressure, compacting into complex areas and entering gaps. After a few minutes, when the temperature reaches room temperature, it immediately exhibits its performance as a butyl rubber sealing compound, completely adhering without flowing, forming a thick insulating coating and exhibiting a corrosion-proofing effect. In addition, the reason why we used a butyl rubber sealing compound with tannins introduced here is that when the compound is heated to a low viscosity and consolidated, the tannins become highly reactive due to the high temperature. This is a construction method that generates iron oxide and forms a uniform corrosion-resistant oxide film layer along with a thick insulating coating layer of butyl rubber sealing compound. In addition, the present invention is generally applicable to parts with complex shapes of structures using iron.
Butyl rubber sealing compound 120, C~1
It is also possible to use a construction method that uses a hand-type heated extrusion gun set to 80 series C to heat and press-fit from the gap, and then immediately crimps with a protective material that fits the complex shape to completely adhere and form an insulating coating layer. be.

Furthermore, by introducing tannin into the butyl rubber sealing compound, it is also a construction method that simultaneously forms a uniform corrosion-resistant oxide film layer. Butyl rubber sealant used in the present invention. As a pound,
Although butyl rubber is the main ingredient, polyisobutylene rubber, natural rubber, polyisoprene rubber, ethylene-propylene rubber, polybutadiene rubber, styrene-butadiene block copolymer rubber, styrene-isoprene block copolymer rubber, etc. can be mixed.

Further, as the synthetic resin, polyethylene resin, polypropylene resin, monoethylene-vinyl acetate copolymer resin, etc. can be used. Furthermore, by mixing tackifiers, softening adhesives, softeners, fillers, anti-aging agents, pigments, antibacterial chemicals, tannins, etc. with the above polymer, a butyl rubber sealing compound with excellent corrosion resistance can be made. . If the amount of tannin used here is less than 0.05% by weight, it will not be possible to form a uniform corrosion-resistant oxide film layer of iron tannate, and if it is more than 5% by weight, water resistance and chemical resistance will deteriorate. It is no longer suitable as a corrosion-resistant material. Preferably, 0.1 to 2% by weight is appropriate. In addition, as an antibacterial drug, for example, metazol ゛■-1, which has extremely low toxicity and is highly safe.
00 (Merck, USA), Preventol A4 (
Merck & Co., Ltd. (USA), etc. can be used, and if the amount is less than 0.01% by weight, it will not be effective, and if it is more than 1% by weight, it will be economically problematic. Preferably 0.1-0
．． The heel volume % is appropriate. Furthermore, as the protective material used during construction, synthetic resin caps, rubber caps, etc. are preferable. Examples of the present invention will be shown below.

Prescription Example Example 1 No. 1 shown in Table-1. Approximately 20T wide of a butyl rubber sealing compound with a composition of l! r! n1 height 1h
This is made into a tape shape using a hand-type heated extrusion gun to a thickness of 1.0mm. , inner diameter 60m1 depth 4070
77! The mixture was extruded and filled into low-density polyethylene cups at a temperature of 150°C.

Immediately place this over the bolts and nuts of a 400φ cast iron pipe with a length of 1 m, including the joint part connected with bolts and nuts, and press it by hand until the end surface of the polyethylene cup comes into contact with the joint surface. It was created. Example 2 No. shown in Table-1. Instead of the formulation of NO. A specimen was prepared in the same manner as in Example 1 using a butyl rubber sealing compound having the composition of Example 2.

Comparative Example 1 A 400φ cast iron pipe with a length of 17TL including the joint part connected with bolts and nuts and a thickness of 0. theory, width 80i
1. A specimen was prepared by wrapping it in a polyethylene sleeve with an inner diameter of 640 m and fixing both ends with rubber bands.

When we observed the condition of the bolts and nuts of the specimens prepared in Examples 1 and 2 10 minutes after the work, we found that they were already at room temperature, and even when we tried to peel off the polyethylene cup, we could not peel it off easily. When peeled off, cohesive failure of the butyl rubber sealing compound occurred. Furthermore, when I wiped off the butyl rubber sealing compound remaining on the bolts and nuts using an organic solvent, I found that the areas in contact with the butyl rubber sealing compound were covered with a black oxide film. It was confirmed that iron tannate was produced. Next, Example 1,
The 400A cast iron pipes prepared in Example 2 and Comparative Example 1 were buried 1.5 m underground in soil with a resistivity of 900 Ω-d for one year, and the state of excavation was observed. The bolts and nuts of the test specimen did not change at all from their initial state and were able to withstand earth pressure satisfactorily.

However, the polyethylene sleeve of the specimen prepared in Comparative Example 1 had some defects due to earth pressure. Furthermore, when an attempt was made to forcibly remove each of the anticorrosive materials, the anticorrosive materials of Examples 1 and 2 were not easily removed, and when an attempt was made to remove the anticorrosive materials forcibly, cohesive failure of the butyl rubber sealing compound occurred. Next, we forcibly destroyed each anti-corrosion material and observed the condition of the bolts and nuts.
In the case of No. 2 and No. 2, although it was covered with a black oxide film, corrosion had not progressed. Moreover, in the case of Comparative Example 1, some corroded parts were observed. As described above, the construction method according to the present invention is a simple construction method that is effective for preventing corrosion in complex parts such as connections of structures using iron and pipe structures to be laid. , can be constructed safely and reliably,
In particular, it has the feature that it can be easily applied in any location, regardless of whether it is winter or summer, and it is a corrosion prevention method that has long-term safety in terms of performance.

Claims (1)

[Claims] 1. In a corrosion prevention method for complex-shaped parts of iron structures, tannin, which forms a protective film on the iron surface, is added in advance to a butyl rubber sealing material that melts and becomes low in viscosity when heated.
5 to 5 parts by weight of the soil antibacterial agent and 0.01 to 1 weight of the soil antibacterial agent. A corrosion prevention method characterized by compaction.