JPH0131078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lining pipe used in a mechanical joint.

[Conventional technology]

In a lined tube used for a mechanical joint, a lining layer must be provided over the entire inner surface, the front and rear end surfaces of the tube, and the portion of the outer surface following this end surface that corresponds to the joint portion.

In this case, the inner lining of the tube is formed by coating the metal surface of the tube with a synthetic resin etc. in order to protect the metal surface of the tube from the fluid flowing inside the tube, but the inner surface of the tube may be coated depending on the type of fluid flowing inside the tube. A synthetic resin is appropriately selected.

For example, the inner lining material may have excellent chemical resistance, water resistance or oil resistance, or durability (abrasion resistance, heat resistance, weather resistance, etc.)
Those with excellent quality are selected as appropriate.

On the other hand, the joint lining is formed on the end surface of the tube that is internally lined and a part of the outer surface of the tube that is continuous with that end surface, and it comes into contact with the fluid to some extent, but not as much as the inside surface of the tube, and is chemically resistant. In order to prevent corrosion of metal surfaces such as corrosion resistance, severe conditions such as those required for the inner lining of pipes, or material conditions compatible with different fluids are not required.

However, the lining material of the joint part
Ensure that fluid does not flow out from this part, that environmental stress cracks do not occur in the lining material due to external forces or internal stress applied perpendicularly to the lining pipe that is joined to other lining pipes, etc. It is required to have abrasion resistance and fatigue resistance when it is bonded to a material, etc., and different conditions are required from those required for the above-mentioned inner lining material.

[Problem to be solved by the invention]

In pipe lining processing for mechanical joints, where the inner surface of the pipe and the joint require different conditions for the lining layer, powdered resin is used as the lining material, and the entire inner surface of the pipe and a portion of the outer surface following it are processed using powder resin as the lining material. Separate lining with different lining materials would complicate and difficult the processing operations and would make it extremely difficult to obtain a satisfactory lining layer. This is because when the pipe is lined by heating and welding powdered resin, the temperature at both ends of the pipe tends to be lower than the other parts.
This is because a uniform lining layer cannot be obtained.

For this reason, when lining a pipe for a mechanical joint, powdered resin has not been used as a lining material. In order to seal the internal pressure applied to the joint surface of pipes for mechanical joints with other pipes, it is necessary to form a smooth lining layer on the joint surface. This is because a tube that does not have a uniform lining layer formed on a portion of the outer surface of the subsequent tube cannot meet this requirement.

[Means to solve the problem]

In view of the above-mentioned points, the present invention has been made with the object of providing a lining pipe for mechanical joints using powdered resin as the lining material. The metal tube has an inner lining layer formed by welding a powder resin to the entire surface, and a melt ink layer having a melting point lower than that of the powder resin is applied to the front and rear end surfaces of the metal tube and a part of the outer surface of the tube continuous to the end surfaces. It is characterized by having a lining layer of the joint part which is integrally joined to the inner lining layer by welding a powder resin which has a large thickness and is compatible or adhesive with the powder resin. It is something.

[Effect]

The lining tube for mechanical joints of the present invention has lining layer characteristics suitable for the joint portion on the front and rear end surfaces of the tube and a part of the outer surface continuous thereto, where the heating temperature tends to be low when heating the welded lining. In order to improve the internal pressure sealability of the front and rear end surfaces of the tube and part of the outer surface thereof, the tube was lined with a powder resin different from the inner lining material of the tube.

That is, in manufacturing the lining pipe for mechanical joints of the present invention, two types of powder resins that are mutually compatible or adhesive are used: a resin used to form the inner lining layer of the pipe; By separating the front and rear end surfaces of the tube and the resin used to form the lining layer on a part of the outer surface of the tube that is continuous with these end surfaces, and directly joining these two resins without creating cuts, a uniform and smooth joint can be achieved. A lining pipe for a mechanical joint having a lining layer of

〔Example〕

Generally, the lining layer formed on the outer surface of a lining pipe for mechanical joints is required to have the hardness and wear resistance required for the joint part, as well as to be smooth, since the joint is made at that part. be done.

Therefore, in the present invention, the inner lining material of the pipe and the lining material of the joint part are used properly, focusing on the fact that the heating temperature of the pipe to be lined with two types of powder resin differs depending on the part of the pipe, and the heating temperature is adjusted accordingly. By using a resin that can be welded to the resin to form the lining layer on the outer surface of the joint, which tends to be low, and that can be formed into a lining layer that satisfies the various conditions required for the joint, the inner surface of the pipe Lining layers with different characteristics are formed on the joint portions of the outer surface.

That is, as shown in FIG. 1, the lining pipe for a mechanical joint of the present invention is obtained by lining the entire inner surface of the pipe p with, for example, powder polyethylene by a conventional method to form an inner lining layer 1 on the inner surface of the pipe. Subsequently, the end face of the pipe p and the outer surface of the pipe up to the collar c are lined with a modified powder polyethylene different from the above-mentioned powder polyethylene by a conventional method to form a lining layer for the joint portion.

The inner lining layer 1 can be formed by pumping powder resin onto the inner surface of the heated pipe p, by spraying powder resin, by sprinkling powder resin, or by filling powder resin. heated tube p
A resin is welded to the inner surface of the tube, and the lining layer 2 on the end surface and the joint portion of the outer surface of the tube is formed using a powder resin that has a lower melting point and a wider processing temperature range than the powder resin used for the inner lining. It is welded to a required portion of the pipe p by a spraying method, an electrostatic coating method, a sprinkling method, a fluidized dipping method, a thermal spraying method, or the like.

Note that the lining process can be performed on the end of a curved lining tube as shown in FIG. 2 in the same manner as that shown in FIG. 1.

Next, an example of manufacturing the lining pipe of the present invention will be explained.

Manufacturing example 1 Collar c for mechanical joint was provided
After blasting the inner surface of the 8B steel pipe, we heated it to approximately 280℃, placed it on a rotary table and rotated it, and then pumped polyethylene powder into the pipe to line the inner surface of the pipe. The end surface of the tube and its outer surface up to the collar were lined with powder-modified polyethylene with a large melt index, and when the lining material was completely melted and cooled, about 1.2 mm of the inner surface of the tube was formed. A lined tube was obtained in which a smooth lining layer of approximately 0.7 mm was formed on the end face and part of the outer surface following it.

Production Example 2 A bent pipe equipped with a collar c for a mechanical joint is heated to approximately 300°C and set in a lining machine, and the inside of the pipe is filled with powdered polypropylene and the inner surface of the pipe is lined. , Both end surfaces of the tube and the outer surface up to the collar were immersed in a fluidized bath in which powdered nylon flows, lining was applied around the tube ends, and the lining material was completely melted and then cooled. , on the inner surface of the tube approx.
1.2mm, approximately 0.6mm on the end face and part of the outer surface following it
A lined tube with a smooth lining layer was obtained.

〔effect〕

In the mechanical joint lining tube obtained in the above two examples, following the lining of the inner surface of the tube, the end of the tube and a part of the outer surface of the tube following this end surface have a lower melting point and melt index than the inner lining material. Since the lining is integrally melted and bonded with the inner lining layer using large resin powder, there is no joint between the inner lining layer and the lining layer at the joint, and the joint is smooth. The lining layer is formed into a solid lining layer, and in these respects, it is a product of far superior quality to conventional products in terms of corrosion resistance, durability, and reliability.

Furthermore, in the lining layer in the above two examples, the melting temperature of at least the powder resin lining the inner surface of the tube and the powder resin lining the end surface of the tube and a part of the outer surface following it, Since different melt indexes are used for tubes heated at approximately the same time,
It has the following characteristics:

In other words, in conventional pipes for mechanical joints in which a single type of powdered resin is brought into contact with a heated pipe to form a welded lining layer, the end of the pipe is bonded to other parts during heating for lining. Because the temperature tends to be lower than that, it is not only difficult to form a uniform lining layer, but also the sealing surface on the outer surface of the tube end for sealing the internal pressure is not necessarily formed into a smooth lining layer due to the low temperature. As a result, the disadvantage of often not being able to exhibit sufficient sealing performance has become apparent, so lining pipes for mechanical joints using a single powdered resin as a lining material have not been widely used.

However, in the present invention, when the inner surface of the tube is lined with, for example, powdered polyethylene as a lining tube for a mechanical joint, a powdered resin such as modified polyethylene having a higher melt index than the powdered resin for the inner lining is used. By forming the joint lining layer by lining the tube end surface and part of the outer surface following it, even if the heating temperature at the tube end is lower than other parts, it is possible to achieve specific characteristics required for each of the inner and outer surfaces. A lined tube with a uniform lining layer was obtained. Moreover, as a result, the sealing surface for sealing the internal pressure on the outer surface became smooth, and the sealing performance was also satisfactory.

Furthermore, the lining pipe for mechanical joints of the present invention uses a powder resin mixed with a drug or pigment for improving light resistance in the powder resin for lining the pipe end, that is, the joint part. Therefore, it is possible to provide a lining pipe for a mechanical joint that does not easily deteriorate even when left outdoors for a long period of time.

As described above, in the lining pipe for a mechanical joint of the present invention, the lining layer of the joint portion formed on the end surface and the outer surface continuous to this end surface is smooth and has sufficient hardness for the joint portion. Therefore, it is suitable as a metal tube for mechanical joints, and by using two types of resin, not only can the lining processing conditions be varied widely, but the outer and inner surfaces can have different required characteristics. In addition, if resins of different colors are used for the lining material of the end surface of the pipe and the outer surface following this, identification during piping becomes easier.

[Brief explanation of drawings]

The drawings show an embodiment of the lining pipe of the present invention, and FIG. 1 is a vertical cross-sectional view of a portion of one example, and FIG. 2 is a vertical cross-sectional view of a portion of another example. p... Metal tube, 1... Inner lining layer, 2...
...Pipe end and outer lining layer, c...Color for mechanical joint.

Claims (1)

[Claims] 1. An inner lining layer is formed by welding a powdered resin to the entire inner surface of a heated metal tube, and at least the powder is applied to the front and rear end surfaces of the metal tube and a part of the outer surface of the tube that is continuous with this end surface. A lining of a joint part that is integrally joined to the inner lining layer by welding a powder resin that has a lower melting point than a resin, a larger melt index, and is compatible or adhesive with the powder resin. A lining pipe for a mechanical joint characterized by having a layer.