JPH11226785A - Grooved backing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a grooved backing material to be used for water curtain wet type submerged welding in deep water by applying a water repellent treatment to a base material in which plural grooves are formed on the surface side facing to the rear side of a welding groove. SOLUTION: A backing martial 11 grooved in small pieces is made of a square ceramic plate 11a solidifying/forming a ceramic powdery body, one of a large groove 11c having a shallow dish-shaped cross section is provided extending in the longitudinal direction and further, over the surface side whole face including the large groove 11c surface, many small grooves 11b of triangle- shaped cross section are formed in the longitudinal direction. A water repellent treatment is applied to the backing material 11. As a coating method, a mothod in which a coating liquid which is adjusted beforehand so as to constitute a raggedness structure to keep water repellence and an air layer, is coated on the weld zone surface of a groove working part, etc., can be utilized. When a coating layer is submerged into water, an air film can bemaintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to underwater or waterborne facilities such as oil production facilities, cargo handling facilities, storage facilities, offshore airports, offshore storage bases, ships, submerged tunnels, wave power / tidal current / temperature difference power generation facilities, marine pastures, etc. In structures and onshore structures such as oil refineries, chemical plants, and bridges that are exposed to rainwater, water droplets, and splashes on land, joining members, repair welding,
The present invention relates to a grooved backing material suitable for use in maintenance and the like.

[0002]

2. Description of the Related Art Conventionally, in wet underwater welding, a backing material uses the same material (common metal) as a member to be welded, and is welded together with the member to be welded. As a removable backing material for wet type underwater welding, a method using a copper backing metal has only been studied so far. On the other hand, as a backing material for onshore welding, for example, there is a material made of ceramic. this is,
Usually, it is short and used by arranging a plurality of pieces along the welding line. This backing material is usually used after drying in a furnace and cannot be used in humid places or in the rain.

[0003]

When a co-metal backing is used as a backing material for wet-type underwater welding, the backing material remains after welding. Crevice corrosion which occurs in the gaps between the holes causes a problem. In addition, the welded joint with the co-metal backing material has a fatigue strength of about 80% compared to the completely penetration back-wave welding joint with the backing material that can be removed after welding such as a ceramic backing material. If the backing is used, there is a problem that both the material cost and the production cost increase.

[0004] When a copper backing material is used in wet underwater welding, it can be removed after welding, but the back beat surface formed has a slightly rough shape, and the fatigue strength of the welded portion is reduced. There is. The copper backing material is
Since the cooling water flow path is provided inside, it is usually long and has no flexibility, so that it is impossible to cope with misalignment or deformation of the welding groove, and the back beat shape is likely to be defective. Therefore, the accuracy of alignment between the members to be welded is strict, and it takes time and cost to prepare for construction.

[0005] When a commercially available backing material for land welding is used in wet underwater welding, a plurality of short ceramic-made backing materials close to a square plate are used. It is flexible, has good compatibility with molten metal, and has a good shape of the back bead, and is often used on land. However, since this type of backing material is porous, when used in water, it absorbs moisture, and the moisture absorbed inside decomposes due to welding arc heat to generate a large amount of hydrogen gas.

Japanese Unexamined Patent Publication (Kokai) No. 48-49 discloses "a backing flux for single-sided welding and a method for producing the same.
In order to improve the adhesion between the weld metal and the flux, 0.5 to 8 coal tar is contained in the flux component.
%. This has the effect of preventing moisture absorption during storage, but in rainy weather or places where water splashes, the degree of water repellency is low. Can not.

An object of the present invention is to provide a grooved backing material which can be used for wet underwater welding performed particularly in deep water, and which can form a good back beat.

[0008]

In order to achieve the above-mentioned object, a grooved backing material according to the present invention comprises a plurality of grooves formed on a surface side opposite to a back side of a welding groove by solidifying ceramic powder. The substrate formed in parallel is subjected to a water-repellent treatment, so that a coating layer capable of retaining an air film when immersed in water is formed on at least the surface side.

Since the grooved backing material of the present invention has a coating layer capable of retaining an air film when submerged in water, water adhering to the outer surface of the grooved backing material is blown off by the air film. And stay on the surface without penetrating the pores formed in the substrate. Also, when this grooved backing material is brought into the water from the atmosphere, the air that has accumulated near the outer surface of the grooved backing material in the air is brought in, forming an air film near the outer surface and holding it. Is done. And even if the grooved backing material comes into contact with water, the air that stays in multiple grooves is difficult to dissipate into the water, so a more stable air film is formed on the surface of the grooved backing material on average and thicker And will be retained. This air film, together with the shielding gas used in gas shield welding or the welding arc generated in covered arc welding, facilitates the elimination of water that tends to enter the welding groove.

Hereinafter, a method of forming a coating layer capable of retaining an air film when immersed in water and its operation will be described. It has been found that two conditions are required to maintain the air film. One is the water repellency of the material, and the other is a fine uneven structure on the surface for retaining the air film. The water repellency of the former is desirably 90 degrees or more in terms of the contact angle with water. If it is less than 90 degrees, the air film cannot be maintained for a long time. The fine irregularities on the surface of the latter are spaces necessary for retaining air when immersed in water. Due to the unevenness, when the surface comes into contact with water, air can be retained in this portion, and an air film can be retained on the surface. It has the function of preventing direct contact between the material and water.

The shape of the fine irregularities on the surface may be a projection or a depression having a triangular, hemispherical or irregular cross-section, which is arranged continuously or irregularly. As for the size of the unevenness, the interval between the concave portions or the interval between the convex portions (hereinafter simply referred to as the interval between the uneven portions) is preferably 2 nm to 200 μm.
More preferably, it is 20 nm to 50 μm. 20n
m or less, the size of the space that can hold air is small, and the volume of the air film becomes small when submerged in water. is there.

The height of the unevenness is preferably 20 nm or more.
Below this, there is a problem that the holding performance of the air film is poor. The upper limit is not particularly limited with respect to the formation of the air film, but is in a range where the work is not difficult to perform at the time of welding and the dimensional accuracy does not deteriorate. 1 mm or less is preferable.

As a specific coating method, a coating liquid that has been adjusted in advance so that the above-described water repellency and an uneven structure for retaining an air layer are formed after curing is applied to a welding portion such as a groove processing portion. A method of applying to the surface can be used.

As the coating liquid, a slurry in which hydrophobic particles and a resin are mixed and dispersed in a solvent, or a liquid of a surface treating agent having a hydrophobic group is used.

As the hydrophobic particles, those obtained by treating the surface of an inorganic oxide particle with a surface treating agent having a hydrophobic group or polytetrafluoroethylene particles of an organic material can be used.
Since the particles constitute a concavo-convex structure for holding an air film, the average particle size is preferably 2 nm to 200 μm. More preferably, the thickness is 20 nm to 50 μm. If it is less than 20 nm, the size of the space that can hold air is small, and the volume of the air film in water will be small. If it is more than 200 μm, the interval between the irregularities will be wide, and the retention of air in water will be poor. is there.

The types of the inorganic oxide particles to be treated include silica, alumina, titanium oxide, iron oxide and the like. In particular, among inorganic oxide particles, porous particles are preferable. As disclosed by the present applicant in Japanese Patent Application Laid-Open No. 7-17476 as a method of forming an air film on a submerged surface of a structure and a film structure of the submerged surface, the particle surface is porous. It has an excellent air retention function in water and exhibits super water repellency.

The surface treating agent having a hydrophobic group includes silane, chlorosilane, and the like having an alkyl group or a fluorine-substituted hydrophobic group.
So-called silane compounds of silazane, dimethylpolysiloxane, titanate coupling agents having an alkyl group, and aluminum-based coupling agents are used.

As the silane compound having an alkyl group,
Those having a methyl group, for example, methylmethoxysilane CH ₃ Si (OCH ₃ ) ₃ , dimethyldimethoxysilane (CH
₃ ) ₂ Si (OCH ₃ ) ₂ , trimethylmethoxysilane (CH ₃ )
₃ Si (OCH ₃ ), methyl triethoxysilane CH ₃ Si
(OC ₂ H ₅ ) ₃ , dimethyldiethoxysilane (CH ₃ ) ₂ Si
(OC ₂ H ₅ ) ₂ , trimethylethoxysilane (CH ₃ ) ₃ Si
(OC ₂ H _5), include hexamethyldisilazane, it is one having an ethyl group, ethyltrimethoxysilane C ₂
H ₅ Si (OCH ₃ ) ₃ , diethyldimethoxysilane (C
_{2 H 5) 2 Si (OCH} 3) 2, triethyl silane (C _{2
H 5) 3 Si (OCH 3} ), ethyl triethoxysilane C ₂ H ₅
Si (OC ₂ H ₅ ) ₃ , dimethyldiethoxysilane (C ₂ H ₅ ) ₂
Si (OC ₂ H ₅ ) ₂ , triethylethoxysilane (C ₂ H ₅ ) ₃
Si (OC ₂ H ₅ ) and the like having a propyl group, and propyltrimethoxysilane C ₃ H ₇ Si (OC
H ₃ ) ₃ , dipropyldimethoxysilane (C ₃ H ₇ ) ₂ Si (O
CH ₃ ) ₂ , tripropylmethoxysilane (C ₃ H ₇ ) ₃ Si
(OCH ₃ ), propyltriethoxysilane C ₃ H ₇ Si (O
C ₂ H ₅ ) ₃ , dipropyldiethoxysilane (C ₃ H ₇ ) ₂ Si
(OC ₂ H ₅ ) ₂ , tripropylethoxysilane (C ₃ H ₇ ) ₃
Si (OC ₂ H ₅ ) and the like, and n-octadecyltrimethoxysilane, n-dodecyltriethoxysilane and the like as long-chain alkylsilanes.

The above-mentioned alkoxysilane having 1 to 3 alkyl groups having 1 to 20 carbon atoms can be used alone or as a mixture of a plurality of chlorosilanes or silazanes. However, the metal alkoxide of the present invention is not limited to the above exemplified compounds (the same applies hereinafter).

Examples of the silane compound having a fluorine-substituted hydrophobic group include perfluorooctylethyltriethoxysilane CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ and perfluoroisopropylethyl triethoxy silane (CF ₃ ) ₂ C
In addition to F (CH ₂ ) ₂ Si (OC ₂ H ₅ ) _{3 and the} like, perfluoromethylethyltrimethoxysilane, perfluorobutylethyltrimethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethylmethyldimethoxysilane And alkoxysilane having a perfluoroalkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms.

As the titanate coupling agent, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate,
Examples thereof include tetraisopropyl bis (dioctyl phosphite) titanate and tetraoctyl bis (ditridecyl phosphite) titanate.

Examples of the aluminum-based coupling agent include acetoalkoxyaluminum diisopropylate.

The ceramic backing material treated as described above has such a property that it is not or almost not wetted by water. When submerged in water, it has the property of forming a thin film of air on the surface.
This air film can be confirmed by being reflected in silver when exposed to light. In addition, since the inside of the ceramic is also water-repellent, even if it is immersed in water, there is no intrusion of water into the inside and it is not completely wetted by water. In welding, in a local cavity immediately below the welding nozzle, water is completely removed by the shielding gas, and welding can be performed without water. Thus, stable welding and a good Uranami bead can be obtained.

Here, the property that the coating layer formed by each of the above surface treatment agents can retain an air film when immersed in water will be described with reference to FIGS. . As shown in FIG. 5, a flat plate 20 (a plate made of metal, ceramic, synthetic resin, or the like) having a coating layer 21 capable of retaining an air film when submerged in water is subjected to a water repellent treatment on a part of its surface. From the surface of the coating layer 21 is brought into the water while the air that has been in contact with the surface of the coating layer 21 is retained.
2 are formed. Then, for example, when a small amount of air is sent to the air film 22 through the thin tube 24, the air is taken into the air film 22 and the film 22 expands as shown by a dotted line. As described above, the coating layer 21 has a unique property of holding a thin air film 22 on the surface in water and taking in air supplied from the outside into the air film 22.

The property of taking in air will be further described with reference to FIGS. 6 (A) and 6 (B). First, FIG.
As shown in FIG. 5, when the flat plate 20 having the coating layer 21 formed on the entire surface is inclined in water and air is continuously supplied to the plate surface through the thin tube 24, the air retained on the coating layer 21 surface It is taken into the film 22 and the plate 2
It rises along the 0 inclined plane, and floats as bubbles 27 from the end of the air film 22. FIG. 6B is a view of the flat plate 20 in FIG. 6A as viewed from the front of the upward slope, and as shown, air 25 flows while spreading along the upward slope, and an air reservoir 26 at the upper end. Then, the air bubbles 27 emerge from the air. On the other hand, when the flat plate 20 without the coating layer, for example, with the cloth surface exposed is slightly inclined and immersed in water, and air is sent through the thin tube to the metal plate surface, as shown in FIG. When you touch the surface,
Immediately separates from the plate surface and floats as bubbles. In addition,
C on the coating layer, which is a shielding gas for welding
Each gas such as O ₂ , O ₂ , Ar, and He shows the same behavior as air, and these gases and air or their mixed gas are equivalent.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an underwater welding method using a grooved backing material of the present invention, that is, a water curtain type wet underwater welding method will be described with reference to FIG. The water curtain type wet underwater welding method is performed by using a gas metal arc welding method, and in principle, opposes a welding groove 2 formed between the members 1 to be welded and the longitudinal direction of the groove 2. The tip of the welding nozzle 3 to be moved in the direction has a double cylinder structure, and the inner and outer cylinders 3a,
Water is sprayed from the gap of 3b onto the member 1 to be welded including the welding groove 2 to form a trumpet-shaped water curtain 4, and the shielding gas 5 flows from the inner cylinder 3a to form a cavity 6 inside the water curtain 4.
Forming the welding wire 7 supplied through the contact tip 3c arranged at the axial center of the inner cylinder 3a.
In this method, the arc 8 generated between the workpiece and the member to be welded and the molten pool formed in the welding groove 2 by the arc 8 are protected from surrounding water and welded. Usually, a backing material 9 is attached to the butt groove 2 as shown in FIG. According to this method, even when the member to be welded is wet with water, water can be removed from the member to be welded by the water curtain and the shielding gas to form a local cavity filled with the shielding gas, Since a portion to be welded can be kept dry, stable welding can be performed. When used as a backing material for land, the welding method is a normal gas metal arc welding method. FIG. 2 is a view showing a state where the grooved backing material according to the present invention is attached to the back side of a welding groove. The backing material 10 uses a plurality of small-sized grooved backing materials 11 (or 12) arranged in the longitudinal direction.

Next, a grooved backing material according to an embodiment of the present invention will be described. Two types of grooved backing materials as shown in FIGS. 3 and 4 were prototyped. The small-piece grooved backing material 11 shown in FIG. 3 is composed of a square ceramic plate 11a formed by solidifying ceramic powder, and has a single large groove 11c having a shallow dish-shaped cross section (two-dot chain line) at the center on the surface side. Groove extending in the vertical direction, and a larger groove 11c is provided.
Many narrow grooves 11b having a triangular cross section are formed in the vertical direction over the entire surface including the surface. The longitudinal direction of the grooved backing material corresponds to the longitudinal direction of the welding groove. The size of the grooved backing material 11 is 32 mm long × 28 mm wide × 9 mm thick, similar to a commercially available land-based ceramic backing, and the narrow groove 11 that characterizes the present invention has a triangular shape and a narrow groove depth. Length: 0.5 mm, distance between adjacent grooves (narrow groove pitch) 1 mm. In addition, the depth of the narrow groove is 5 μm to 1 mm.
The fine groove pitch may be in the range of 5 μm to 2 mm, and the fine groove may have a size easily processed. The depth and pitch of the fine groove are determined by the water repellency of the water repellent to be applied, ie, the water repellency. The limit is determined by the contact angle. For example, in the case of a coating layer showing a super water repellency having a contact angle with water of 130 ° or more, both the depth and pitch of the narrow groove are allowed up to about 2 mm. The shape of the narrow groove is not limited to a triangle, but may be a trapezoid, a quadrangle, or a sine waveform. In addition, an uneven pattern in which vertical and horizontal grooves are provided instead of parallel grooves may be employed.

The grooved backing material 12 shown in FIG. 4 is a square plate 12a having the same dimensions in the vertical and horizontal directions. The surface side is flat, and many narrow grooves 12b having a triangular cross section are formed vertically over the entire surface side. It is formed in the direction. Grooved backing material 12
, The depth of the narrow groove and the pitch of the narrow groove are the same as those shown in FIG.

[0029]

According to the present invention, the grooved backing material can be provided with a narrow groove on the surface side opposite to the groove back surface, subjected to a water-repellent treatment, and can retain an air film when submerged in water. The coating layer has a thin coating layer on the surface, so a thicker air film can be formed in water, especially on the surface side with narrow grooves, compared to a backing material with a smooth surface. It can be used for underwater welding by the water curtain type wet underwater welding method. That is, a more stable cavity can be formed in the water curtain by the thick air film and the shielding gas for welding, and the weldability in the cavity can be improved.

[Brief description of the drawings]

FIG. 1 is a view for explaining in principle a water curtain type wet underwater welding method.

FIG. 2 is a view showing an arrangement of a grooved backing material of the present invention in a water curtain type wet underwater welding.

FIG. 3 is a view showing the shape of a grooved backing material of the present invention.

FIG. 4 is a view showing another shape of the grooved backing material of the present invention.

FIG. 5 is a diagram illustrating a coating layer that holds an air film on the surface in water.

FIG. 6 is a diagram illustrating that a coating layer formed on a plate surface holds an air film, and that air taken into the air film moves along the surface of the coating layer.

FIG. 7 is a diagram showing a state in which an untreated plate is immersed in water and air is immediately blown up as bubbles when air is sent to the plate surface.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 welded member 2 welding groove 3 welding nozzle 3a nozzle inner cylinder 3b nozzle outer cylinder 3c contact tip 4 water curtain 5 shielding gas 6 cavity 7 welding wire 8 arc 9 backing material 10 water repellent backing material 11 grooved backing Backing material 12 Backing material with groove 20 Flat plate 21 Coating layer 22 Air film

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhiro Fukuda 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Engineering & Shipbuilding Co., Ltd.

Claims (6)

[Claims] In a backing material to be attached to the back side of a welding groove of a member to be welded, a base material having a plurality of grooves formed on a surface side opposite to the back side of the welding groove is subjected to a water-repellent treatment. A grooved backing material, wherein a coating layer capable of retaining an air film when immersed in water is formed on at least the surface side. 2. A backing material to be attached to the back side of a welding groove of a member to be welded, wherein a hydrophobic particle and a resin are formed on a base material having a plurality of grooves formed on a surface side facing the back side of the welding groove. A grooved backing material characterized in that a coating layer capable of retaining an air film when immersed in water is formed on at least the surface side by coating the mixed and dispersed slurry on the surface. 3. The grooved backing material according to claim 2, wherein the hydrophobic particles are obtained by treating the surface of the inorganic oxide particles with a surface treating agent having a hydrophobic group. 4. The grooved backing material according to claim 3, wherein the inorganic oxide is silica, and the surface treatment agent is a silane compound having a hydrophobic group. 5. The grooved backing material according to claim 2, wherein the hydrophobic particles are made of an organic material, polytetrafluoroethylene (PTFE). 6. A backing material attached to the back side of a welding groove of a member to be welded, wherein a base material having a plurality of grooves formed on a surface opposite to the back side of the welding groove is used as a surface treatment agent having a hydrophobic group. Characterized in that a coating layer capable of retaining an air film when submerged in water is formed on at least the surface side by treating with water.