JPH034819Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] This invention relates to a corrosion-resistant bolt/nut, and more particularly to a corrosion-resistant bolt/nut used for connecting ductile pipes buried underground. [Prior Art] Underground pipes are relatively easily corroded by the influence of underground water and underground stray currents, and therefore, in order to eliminate these influences, they are usually provided with a strong anti-corrosion coating. However, when connecting pipes, if the connection part is strongly tightened with bolts and nuts, the corrosion-resistant coating may be destroyed by the tightening force, and corrosion may progress from there. The corrosion in this case is due to so-called galvanic corrosion, which is caused by the potential difference between the ductile pipe and the bolt nut, and therefore the bolt nut used in this part is generally made of a metal with a higher potential than the ductile pipe. [Problems with the prior art] However, although the above-mentioned means can slow down the progress of corrosion, they cannot prevent the corrosion itself and cannot prevent the expiration of their useful life. There is. In addition, in order to solve this problem, it has been proposed to form an extremely corrosion-resistant oxide film on the surface of the bolt nut to improve the corrosion resistance of the bolt nut itself, but the oxide film is destroyed by impact etc. For example, similar to the conventional example described above, there was a problem in that the progress of corrosion could not be prevented. [Problems to be solved by the invention] In view of the above-mentioned problems, this invention was made for the purpose of providing a corrosion-resistant bolt nut that is extremely corrosion resistant and can be used for a long period of time. [Technology to solve the problem] That is, the corrosion-resistant bolt nut of this invention has an oxide film with a porous structure formed on the surface of the bolt nut made of low-alloy ductile, and a synthetic resin is applied on the primer layer impregnated with the oxide film. It is characterized by the formation of a coating film. [Function] In this invention, low alloy ductile refers to an alloy made by adding 0.5% copper and 1% nickel to ductile. Therefore, the low-alloy ductile has a higher potential than the ductile pipe, and the material itself has corrosion resistance. By forming an oxide film with a porous structure on the surface of this material and impregnating it with a primer, a synthetic resin coating is formed, which improves the adhesion of the synthetic resin coating and eliminates interfacial peeling. By working together with the oxide film and synthetic resin coating, double
The substrate is triple protected, and even if these coatings are damaged, the potential difference in the low-alloy ductile prevents corrosion of the ductile pipe. [Example] Next, an example of this invention will be described. FIG. 1 is an enlarged sectional view of a main part of an embodiment of this invention. The corrosion-resistant bolt/nut 1 of this invention has an oxide film 2 with a porous structure formed on the surface of the bolt/nut 1A made of low alloy ductile made by adding 0.5% copper and 1% nickel to the ductile.

〔effect〕

As explained above, this idea is based on the fact that the bolt nut is double coated with a synthetic resin coating and an oxide coating, and the synthetic resin coating is firmly adhered by a primer impregnated with the porous oxide coating. Since the bolt nut is made of low-alloy ductile with a high potential, even if the coating film is destroyed, corrosion will not occur on the ductile. It has various practical effects, such as preventing it from progressing into the tube.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a main part of an embodiment of this invention.

Claims (1)

[Scope of utility model registration request] A corrosion-resistant bolt/nut comprising: an oxide film having a porous structure formed on the surface of the bolt/nut made of low-alloy ductile; and a synthetic resin coating film formed on a primer layer impregnated with the oxide film.