JPH02204539A - High corrosion resistant water-intake screen made of steel - Google Patents

Abstract

PURPOSE:To enhance the corrosion resisting function of the screen in the title by covering wires of different sectional shape with a galvanized layer containing high corrosion resistant aluminium, and providing the wires parallel to each other and at fixed intervals for water-intake on the outer surfaces of plural rods aligned parallel to each other. CONSTITUTION:A plurality of rods 1 are aligned parallel to each other. Next, a galvanized layer containing 1 to 8 parts by weight of aluminium is applied on the surface of a base material 2 made of low carbon steel and having isosceles triangular section so as to form wires 4. The wires 4 are provided parallel to each other and at fixed intervals for water-intake on the outer surfaces of the rods 1 so as to form a screen.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a highly corrosion-resistant steel screen for water intake that is buried in wells, riverbeds, etc., or installed in waterways or the sea.

(Prior Art) Steel screens for water intake are generally galvanized to provide corrosion resistance, and some are made of stainless steel.

In the case of galvanized steel, the composition of the plating layer is approximately 10% zinc.
0%, slightly 0.0 just for the purpose of improving surface gloss.
Approximately 5% aluminum is added.

(Problems to be Solved by the Invention) Conventional irregularly shaped galvanized wires have a plating layer that is essentially 100% zinc and have a circular cross-sectional shape.
It is made by gradually changing its shape by rolling with dies or rolls. Therefore, when finishing a screen with an isosceles triangular cross section, which is the optimal shape for a screen, the strongest force is applied around each vertex, causing the plating to peel off.

Since each intersection of the rod material and the wire material is electrical resistance welded, the plating layer at this welded portion is severely damaged by conventional zinc plating, which has a negative effect on the corrosion resistance after the product is manufactured.

Handling of the screen is quite rough, and the conventional galvanized layer is not very hard, so the screens rub against each other during transportation, collide with other objects during transportation or on-site work, and are prone to damage to well boreholes. When inserted, the galvanized layer is often damaged by contact with the hole wall or, in the case of a well, by collision with gravel filled around the hole after insertion. In this case as well, there remains the problem of loss of corrosion resistance.

According to the "Ministerial Ordinance on Water Quality Standards" for drinking water based on the Water Supply Act, zinc is stipulated to be 1.0 mg/Ω or less. For drinking water, conventional galvanizing does not have sufficient corrosion resistance, and depending on the quality of the water, it may not be able to meet this standard, and its use may be restricted.

There are screens that use stainless steel instead of zinc plating, but they cost four to five times more, leading to higher costs.

The present invention was devised to solve these problems.

(Means for Solving the Problems) The present invention consists of a plurality of rods arranged in parallel, the outer surfaces of which are coated with a highly corrosion-resistant aluminum-containing galvanized layer, and wires with irregular cross sections maintain a water intake gap between them. It is characterized by being arranged in parallel.

(Function) This screen is usually inserted into a well borehole, buried in a riverbed, etc., and further installed in a waterway etc., and used for water intake.

The profiled wire material, coated with a highly corrosion-resistant aluminium-containing galvanized layer, resists corrosive effects for a long time, extending the service life of the screen.

A galvanized layer containing 1 to 8% by weight of aluminum has great adhesion to the base material, so when drawing a round wire to make it into an isosceles triangular or other cross-sectional shape, the galvanized layer must be completely coated on the entire surface. Become thin. In particular, a large force is applied around the corners, but the plating layer does not peel off even in those areas and maintains a good plating layer.

These properties also prevent damage to the core layer during electrical resistance welding between rod material and wire material during the manufacturing process of the screen.

The higher the aluminum content, the higher the corrosion resistance in a general sense, but on the other hand, the price also increases, and
If it exceeds about % by weight, the sacrificial anticorrosion function will be reduced, and the plating surface will be easily damaged, making it undesirable as plating for water intake screens.

This plating layer also has a high surface hardness, so that the completed screen may rub against or collide with each other or other objects during transportation, or may come into contact with the hole wall when inserted into the borehole. Even if the gravel collides with the shell when it is filled with gravel after insertion, it can withstand these impacts and fulfill its covering function.

Furthermore, this plating layer is of course resistant to normal water use.
Even when used in harsh corrosive environments such as water with a high concentration of chlorine ions, including some seawater, and hot springs, the screen exhibits extremely good corrosion resistance compared to conventional screens plated with only zinc, and can be used for long periods of time. Allows for wide range of uses.

Furthermore, this plating layer has low zinc elution, and aluminum has low toxicity to the human body and is not a problem under water quality standards, so screens with this plating are suitable for use in wells for drinking water. be.

(Example) Figures 1 and 2 are cylindrical screens, Figures 3 and 4 are
The figure shows a flat screen, and FIG. 5 is a sectional view of a wire material. This flat screen can be made by cutting out the cylindrical screen shown in FIG. 1, but it may also be manufactured as a flat screen from the beginning.

1 is a rod material arranged in parallel. 2 is a base material of low carbon steel, and 3 is an aluminum 1 applied to the surface of this base material 2.
Wire material 4 of the invention with a galvanized layer containing ~8% by weight
It consists of This wire material 4 is connected to these rod materials 1
is placed parallel to the outer surface of the rod material L, and each intersection with the rod material L is electrically resistance welded.

The rod material 1 usually has a circular cross section. The wire material 4 is optimally one with an isosceles triangular cross section, but since the intersection with the rod material 1 is electrically resistance welded, the wire material 4 has a shape with a corner at that part, such as a T-shape, Piece shapes can also be adopted.

In addition, 11 is a short pipe for connection fixed to both ends of the rod material 1.

This screen is inserted into a well vertical hole, buried at a water intake point around a river, or installed in a waterway or the like.

This by-product plating N3 has extremely high corrosion resistance, and even when used in harsh corrosive environments such as water with high chlorine ion concentration or hot springs, the lifespan is several times longer than conventional zinc-only plating.

Furthermore, since there is little zinc elution, it is extremely advantageous for drinking water intake.

(Effects of the Invention) According to the present invention, the surface hardness of the plating layer is high and the adhesion to the base material is high. Therefore, the plating layer will not peel off locally at the corners of the wire during wire processing, and there will be less damage caused by electrodes during welding work, and there will be no scratches during transportation or installation of the screen. Provides stable anti-corrosion function over a long period of time.

This plating layer also allows use in more severe corrosive environments than before.

Furthermore, this plated layer has less zinc leaching, making this screen suitable for use in drinking water wells.

[Brief explanation of the drawing]

Fig. 1 is a side view of a cylindrical screen according to the present invention, Fig. 2 is a plan view of the same, Fig. 3 is a front view of the flat type screen, Fig. 4 is a side view of the same, and Fig. 5 is a wire FIG. 1. Rod material, 2. Base material, 3. Plating layer, 4.
Wire material, 11...Short pipe for connection.

Claims (4)

[Claims] (1) A wire material with irregular cross-sections coated with a highly corrosion-resistant aluminum-containing galvanized layer on the outer surface of a plurality of rod materials arranged in parallel is arranged side by side with a water intake gap maintained between each other. Highly corrosion resistant steel screen for water intake. (2) The highly corrosion-resistant steel screen for water intake according to claim 1, wherein the plating layer contains 1 to 8% by weight of aluminum. (3) The highly corrosion-resistant steel screen for water intake according to claim 1, wherein the wire material and the rod material are resistance welded at their intersection and at one corner in the cross section of the wire material. (4) The outer surfaces of multiple rods arranged in parallel are coated with a highly corrosion-resistant aluminum-containing galvanized layer, and wires with irregular cross sections are arranged side by side with a water intake gap between them, and are used exclusively for wells. A highly corrosion-resistant water intake steel screen characterized by its use.