JPS59190823A - Method of coating pipe or cylindrical body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The subject of the invention is the extraction of a black or dark-colored conventional corrosion-resistant thermoplastic coating directly onto the external surface of a tube or cylinder, and the application of a white or light-colored or The metallic colored thermoplastic coating layer is extruded and applied directly. It is known that different materials are used by different systems to protect steel or prestressed concrete pipes or cylinders from gross corrosion. The most well-known of the Bao-Zhao coatings currently in use is the polyethylene coating.

Although there are many challenges to overcome in order to obtain a truly reliable and durable protective coating, the following key considerations can be made:

A) Materials for forming protective coatings for pipes and cylinders made of steel or prestressed concrete must have the following properties:

a) Resistance to the destructive effects of environmental chemicals and ultraviolet radiation of sunlight.

b) Resistance to the corrosive effects of all natural causes, including biological attack.

C) Waterproof.

d) Dielectric.

e) Multiple materials are mixed together to form a uniform single layer.
Bonding base and preferably gluing to the surface to be protected.

B) The covering layer or coating must remain robust over a long period of time without being damaged during handling, transport and transshipment of the tube or cylinder.

Certain additives, such as carbon black, are used to counteract the aging effects of the sun's ultraviolet rays.
This gives thermoplastic products a black or very dark color.

The dyes mentioned above counteract the undesirable effects of ultraviolet radiation, but due to their black color, membranes or layers of any type of thermoplastic material, including polyethylene, will heat up significantly if the tube is exposed to sunlight.

Tubes or cylinders made of steel or prestressed concrete1 may be stored in the open and unprotected for several months or for 1 to 2 years for technical or theoretical reasons before being finally buried underground. It is well known that this can happen.

Open storage of tubes or cylinders with thermoplastic corrosion-resistant coatings containing polyethylene coatings is carried out in coating plants, railyards, bays, or for other temporary storage. Following this, the coated tubes are laid in trenches where they are interconnected to form pipelines for transporting water, oil, power or other products.

Extreme heating due to exposure to sunlight, especially in the Mediterranean,
Alternatively, heating in the Sahara and Arabian desert regions results in a softening of the material forming the thermoplastic material layer. Moreover, the softening of the adhesive material placed between the surface to be protected and the thermoplastic '4 covering layer considerably reduces the adhesion between the covering layer and the tube or cylinder.

This reduction in adhesion creates serious problems with the integrity of the thermoplastic protective coating. Among these difficulties, mention may be made of partial peeling of the coating layer and/or its slipping on the tube to be protected. This can be difficult and expensive to locate and repair, and can result in rather severe cracking that destroys the coating.

OBJECTS OF THE INVENTION The present invention reduces the heating effect on black or dark-colored thermoplastic coatings when exposed to sunlight for 7" without altering the beneficial effects of carbon black. The purpose is to

(Structure of the Invention) This invention further provides a white or very light colored or metallic (white is most preferred) band that easily reflects sunlight on the outside of the black or dark-colored corrosion-resistant thermoplastic coating layer. It consists of applying.

A white or very pale or metallic thermoplastic band (hereinafter abbreviated as "lightfast" in this specification) I'i
, applied to closely and securely adhere to the underlying black or dark-colored thermoplastic protective layer.

The "lightfast" zone can be applied in a variety of ways, of which two methods considered by the inventors to be most appropriate will be described. These methods together with other methods constitute an essential part of this invention.

In a first example, a "lightfast" material is poured into an extrusion head along with carbon black added polyethylene or other corrosion resistant material.

In the second section 1, the "lightfast" material and the polyethylene (or other thermoplastic material) are transported through two separate extrusion heads. In this second example, the thickness of the "lightfast" guard band is completely independent of the thickness of the additional carbon black guard band.

Typically, a corrosion-resistant protective layer or membrane of polyethylene or other suitable thermoplastic material coating is applied in two or more strips around the circumference of the segment until the desired thickness of the protective layer is reached. It will be completed well. The thickness of the strip must be a divisor of the total thickness of the protective layer, and at the same time the strip is wound in a staggered manner according to the same divisor.

Example 1 Two associated extruders are provided in order to obtain a "lightfast" protective outer layer on top of the corrosion-resistant layer. One is used for the protective black or dark thermoplastic material and the other is used to extrude a single strip of the "lightfast" layer through a single extrusion head.

For example, the protective layer may be made up of three offset strips, and the total thickness of the protective layer may include a "lightfast" strip.

The sheathing tube or cylinder is moved under the extraction device while being rotated about the axis of the nine-point body.

The thermoplastic protective material is applied to the tube or cylinder immediately after receiving the adhesive to completely adhere the protective coating layer to the surface to be protected.

It should be noted that, like the black or dark band constituting the underlying layer, the white or light-colored "lightfast" band also has a protective function and corrosion resistance in itself. The "lightfast" zone is primarily distinguished by the absence of UV-resistant carbon black.

The layer covering the tube or cylinder consists of a ⅓-thick layer of white or light-colored or reflective material and a ⅔-thick black or dark-colored UV-resistant underlayer.

Example 2 Two separate extruders, each with an extrusion head, can be used to protect the outside of the underlying corrosion-resistant layer with a "lightfast" material. One of these is used for the carbon black-doped thermoplastic material and the other for the "lightfast" material. This device allows υ to vary the thickness of the two material layers.

In operation, the entire extrusion of the white or light-colored thermoplastic strip is carried out immediately after the extrusion of the black or dark-colored layer.

The width of the "lightfast" band should be a submultiple of the width of the black or dark thermoplastic material band and should be equal to the total thickness of the black protective coating and the offset width of the bands.

If the black layer is constructed by three layers of strips staggered by their width, the width of the "lightfast" strip should be the width of the black or dark-colored strip.

This is one of many embodiments of this invention, in which the corrosion-resistant protective layer consists of four layers: a black or dark inner triple layer with added carbon black and a white "lightfast" outer layer. It consists of an obi.

The "lightfast" zone will be of a different thickness than the Cargon Black 3-layer zone.

To promote adhesion of the "lightfast" strip to the black or dark colored underlayer, it is preferred to apply the "lightfast" strip onto the underlayer while the underlayer is still hot and pasty. It is preferred to roll the protective outer surface before the coating cools to completely smooth the surface of the coating and to promote adhesion between the dissimilar layers that make up the corrosion-resistant protective coating.

(Effects of the Invention) The importance of this invention is clear from the above description. This invention solves several problems with simple operation. That is, the present invention substantially reduces the effects of solar heat while continuing to use polyethylene and other suitable thermoplastic materials doped with carbon black or other pigments suitable to protect the tube or cylinder from ultraviolet radiation. Seshime,
The mechanical resistance of the protective covering layer or coating can thereby be substantially improved.

Although this invention' has been described in one embodiment, various modifications may be made within the scope of this invention. One such variation is to replace the "obi" system with "
It is conceivable that there is a "stocking" system all around.

[Brief explanation of the drawing]

FIG. 1 shows a schematic of the apparatus for carrying out Example 1, and FIG.
The figures are a cross-sectional view of a coated tube or cylinder, FIG. 3 is a longitudinal cross-section of a coated tube or cylinder, and FIG. 4 shows a schematic of the apparatus for carrying out Example 2. In Figure 1, A is the tube, B is the extruder or adhesive container, C is the extrusion head or other equipment for applying the entire adhesive, D is the adhesive layer for gluing the polyethylene to the tube, and E is the adhesive layer for gluing the polyethylene to the tube. Extruder for polyethylene added with carbon black, Fba2
Extrusion head for types of polyethylene, G is the extrusion part of polyethylene added with carbon black of the extrusion head,
H is the extruder for white, transparent or reflective polyethylene, ■ is the part of the extrusion head for white, transparent or reflective polyethylene, L is for direct extrusion onto the tube, and 2/3 of the carbon black-containing protective coating layer and white or very reflective 1/3 of the width (il-single strip of staggered polyethylene, M!-1: additives to promote adhesion of the protective coating to the tube) pressure roller, and N is a part of a tube with a corrosion-resistant underlayer and a white or very pale or reflective color coating layer, in Figure 2 1 is the inside of the tube or cylinder, 2 is the inside of the tube or cylinder. The thickness of the cylinder, 3 is the thickness of the adhesive layer, and 4 is the thickness of the corrosion-resistant coating layer.
3 are the same as those in FIG. 2, and 4 is a corrosion-resistant thermoplastic layer, in which a) is the thickness of the carbon black-containing inner layer of the thermoplastic coating layer, and h) is the thermoplastic The thickness of the carbon black-containing intermediate layer of the covering layer, C) indicates the thickness of the outer "lightfast" zone of the thermoplastic covering layer, A-E in FIG. 4 are similar to those in FIG. 1; F is the extrusion head for polyethylene containing carbine black, (d-j extruded directly onto the tube and 1/1/2 of the width to obtain the desired thickness.
3 is a staggered cargo roll, a polyethylene strip containing resin, H is a polyethylene extruder for white or light-colored "light-fast" materials, ■ is an extrusion head for white or light-colored "light-fast" polyethylene, L is carbon black a white or light-colored "lightfast" band completely surrounding the polyethylene underlayer and having one-third the width of the underlayer; M is a pressure roller to facilitate adhesion of the protective coating to the tube; and N indicates a portion of the tube coated with a white or light-colored or reflective layer. Margin below (11) Procedural amendment (method) August 1, 1980 - Thousand Days Commissioner of the Patent Office Kazuo Wakasugi Tono 1, Indication of the case 1982 Patent application No. 63104 2, Name of the invention Covering of a pipe or cylindrical body Method 3: Relationship with the case of the person making the amendment Patent applicant name: F, Knee, E, Full Anticorrosion Engineering Socheta Responsabilitari Mitte 4: Agent (3 others) 5: Date of amendment order: 1982 July 26th (shipment date) 6. Subject of amendment (1) “Representative of applicant” field in the application (2) Power of attorney (3) Drawings 7. Contents of amendment (11, (2 + as shown in the attached sheet) (3) Engraving of drawings (no changes in content) 8. List of attached documents (1) Request for correction 1 copy (2)
Power of attorney and translation 1 copy each (3) Engraved drawing 1 copy 01

Claims (1)

[Claims] 1. A white or light-colored thermoplastic or reflective coating layer is directly adhered onto a corrosion-resistant and UV-resistant black or dark-colored coating that is extruded directly onto the external surface of a tube or cylinder. A method 2 for coating a tube or cylindrical body characterized by extrusion, the method according to claim 1, wherein a white or light-colored thermoplastic or metallic coating layer is applied simultaneously with the application of the corrosion-resistant thermoplastic coating.