CA1232428A - Method for the centrifugal casting of pipes - Google Patents
Method for the centrifugal casting of pipesInfo
- Publication number
- CA1232428A CA1232428A CA000462892A CA462892A CA1232428A CA 1232428 A CA1232428 A CA 1232428A CA 000462892 A CA000462892 A CA 000462892A CA 462892 A CA462892 A CA 462892A CA 1232428 A CA1232428 A CA 1232428A
- Authority
- CA
- Canada
- Prior art keywords
- molten metal
- filler material
- pipe
- pipes
- nickel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D13/00—Centrifugal casting; Casting by using centrifugal force
- B22D13/02—Centrifugal casting; Casting by using centrifugal force of elongated solid or hollow bodies, e.g. pipes, in moulds rotating around their longitudinal axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/14—Casting in, on, or around objects which form part of the product the objects being filamentary or particulate in form
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/18—Measures for using chemical processes for influencing the surface composition of castings, e.g. for increasing resistance to acid attack
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Continuous Casting (AREA)
- Rigid Pipes And Flexible Pipes (AREA)
- Powder Metallurgy (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A molten metal is introduced into a rotating ingot mold during the centrifugal casting of pipes. Before or during the introduction of the molten metal, a metal powder containing 80 wt% or more nickel is fed in, which contains a small amount of further alloying elements. The metal powder has a higher specific weight than that of the molten metal. If the melting point is also made lower than the casting temperature of the molten metal, an alloyed outer skin of the pipe of austenitic cast iron with 21 to 24% nickel is formed. As a result, the pipe, which is manufactured at lower costs, has the same corrosion resistance as an applied protective layer while reliably preventing damage to the outer skin which, in the case of known protective layers, form points of increased corrosion.
A molten metal is introduced into a rotating ingot mold during the centrifugal casting of pipes. Before or during the introduction of the molten metal, a metal powder containing 80 wt% or more nickel is fed in, which contains a small amount of further alloying elements. The metal powder has a higher specific weight than that of the molten metal. If the melting point is also made lower than the casting temperature of the molten metal, an alloyed outer skin of the pipe of austenitic cast iron with 21 to 24% nickel is formed. As a result, the pipe, which is manufactured at lower costs, has the same corrosion resistance as an applied protective layer while reliably preventing damage to the outer skin which, in the case of known protective layers, form points of increased corrosion.
Description
2 :3 SLY
BACKGROUND OF THE INVENTION
The present invention relates to a method for the centrifugal casting of pipes, wherein a molten cast iron is introduced into a rotating metallic ingot mold with a filler material being fed in before or during the introduction of the molten metal.
The manufacture of pipes by centrifugal casting has long been known. In this method, a predetermined quantity of a molten metal is poured via a runner into a rotating ingot mold for forming the casting. The casting process must take place within a predetermined time, so that the desired characteristics of the material are achieved. It is widely known to cast a molten cast iron for the centrifugal casting of pipes and this can either be a cast iron with nodular graphite or with lamellar graphite.
Pipes manufactured by centrifugal casting have numerous possible uses. A particularly important and extensive field of use is or the transportation of liquids of all types. The pipelines produced for this purpose are often laid in the ground, so that they are in immediate contact with the soil.
As a result of this contact, there is a possibility of chemical or electrochemical reaction between the pipe material and its surroundings, which can lead to the destruction of the pipe material.
The occurrence of chemical and/or electrochemical reactions on such pipes laid in the ground can be counteracted by adopting various measures; however, known measures require an additional treatment of the finished pipe, for which corresponding equipment is required. These measures include ~-2~6 123~2~3 the tarring of pipes by immersing the pipes in a tar bath.
Other known measures involve the wrapping of a loose plastic foil around the pipe or galvanization by spraying or extruding on the pipe a polyethylene coating. The application of a glass fiber-reinforced additional coating is also known. Despite the considerable expenditure involved in applying such protective coatings, a completely reliable protection cannot be ensured, because such protective coatings can become damaged, particularly during storage, transportation and laying.
However, even if there is no damage to the protective coating prior to the laying of the pipes, it can certainly take place afterwards, such as when filling trenches due to loading caused by traffic and as a result of earth movements, such as subsidence and the like.
If the aforementioned protective coatings have damaged points, it has been found that they are particularly at risk.
Corrosion concentrates at these points and then rapidly advances therefrom. The corrosion starts at the outer circumferential surface of the pipe and then advances from the outside towards the inside.
SUMMARY OF THE INVENTION
The object of the present invention is to develop a method for centrifugal casting of pipes wherein protection against chemical and/or electrochemical reactions of the pipe material with its surroundings and damage to the protection of the pipe is reliably prevented.
According to the present invention, the foregoing object is achieved wherein filler material forms a corrosion-proof 1~3~8 layer constituting an alloy with the pipe on the outer surface of the pipe which is to be centrifugally cast.
It is admittedly known to use filler materials during the centrifugal casting of pipes at the time of pouring the molten metal into the notating ingot mold and said filler materials are introduced either before or during the introduction into the ingot mold. These filler materials include flux (DOS
BACKGROUND OF THE INVENTION
The present invention relates to a method for the centrifugal casting of pipes, wherein a molten cast iron is introduced into a rotating metallic ingot mold with a filler material being fed in before or during the introduction of the molten metal.
The manufacture of pipes by centrifugal casting has long been known. In this method, a predetermined quantity of a molten metal is poured via a runner into a rotating ingot mold for forming the casting. The casting process must take place within a predetermined time, so that the desired characteristics of the material are achieved. It is widely known to cast a molten cast iron for the centrifugal casting of pipes and this can either be a cast iron with nodular graphite or with lamellar graphite.
Pipes manufactured by centrifugal casting have numerous possible uses. A particularly important and extensive field of use is or the transportation of liquids of all types. The pipelines produced for this purpose are often laid in the ground, so that they are in immediate contact with the soil.
As a result of this contact, there is a possibility of chemical or electrochemical reaction between the pipe material and its surroundings, which can lead to the destruction of the pipe material.
The occurrence of chemical and/or electrochemical reactions on such pipes laid in the ground can be counteracted by adopting various measures; however, known measures require an additional treatment of the finished pipe, for which corresponding equipment is required. These measures include ~-2~6 123~2~3 the tarring of pipes by immersing the pipes in a tar bath.
Other known measures involve the wrapping of a loose plastic foil around the pipe or galvanization by spraying or extruding on the pipe a polyethylene coating. The application of a glass fiber-reinforced additional coating is also known. Despite the considerable expenditure involved in applying such protective coatings, a completely reliable protection cannot be ensured, because such protective coatings can become damaged, particularly during storage, transportation and laying.
However, even if there is no damage to the protective coating prior to the laying of the pipes, it can certainly take place afterwards, such as when filling trenches due to loading caused by traffic and as a result of earth movements, such as subsidence and the like.
If the aforementioned protective coatings have damaged points, it has been found that they are particularly at risk.
Corrosion concentrates at these points and then rapidly advances therefrom. The corrosion starts at the outer circumferential surface of the pipe and then advances from the outside towards the inside.
SUMMARY OF THE INVENTION
The object of the present invention is to develop a method for centrifugal casting of pipes wherein protection against chemical and/or electrochemical reactions of the pipe material with its surroundings and damage to the protection of the pipe is reliably prevented.
According to the present invention, the foregoing object is achieved wherein filler material forms a corrosion-proof 1~3~8 layer constituting an alloy with the pipe on the outer surface of the pipe which is to be centrifugally cast.
It is admittedly known to use filler materials during the centrifugal casting of pipes at the time of pouring the molten metal into the notating ingot mold and said filler materials are introduced either before or during the introduction into the ingot mold. These filler materials include flux (DOS
3,105,145), which is used for forming a sealing slag on the inner surface of the pipe and which takes up any impurities incorporated into the molten metal.
Filler materials can also be introduced in order to influence, slow down the cooling of the molten metal in the ingot mold, in order thereby to improve the structure and consequently the pipe quality (DAY 2,460,510).
In connection with the centrifugal casting of bimetallic pipes, it is known (DOS 2,852,030) to successively introduce different molten charges for forming different layers in the rotating ingot mold. The next layer is only introduced when the primary layer has reached a temperature which is below the solids temperature. The internal layer can be a plating layer containing nickel as the alloying element.
Unlike in the case of the hitherto known uses of filler materials in the centrifugal casting of pipes, the invention is based on the idea that the solution of the aforementioned problem is only achieved if there is no formation of an additional protective layer on the outer surface of the pipe and instead the protective layer is formed as part of the metal pipe wall, accompanied by a corresponding modification to the structure.
~-?36 i2;~2A2~3 DETAILED DESCRIPTION
It has now been surprisingly found that the formation of such a protective layer can be achieved in a relatively simple manner during the introduction of the molten metal, if a suitable filler material is lea in before or during the introduction of the molten metal into the ingot mold. A nickel alloy with a nickel content of 80 wt.% or more has proved particularly suitable. Further alloying elements can be selected from the group consisting of boron, silicon, chrome and copper. Such alloys are known as corrosion and heat-resistant materials and are commercially available. This alloy is introduced into the centrifugal casting mold in powder form with a particle size of approximately 0.1 to 1 mm. The specific weight of such alloys is well above the specific weight of the molten cast iron and is approximately 7.8 g/cm .
The melting point of such nickel alloys should be lower than 1300C and consequently lower than the casting temperature of the molten cast iron of approximately 1350 to 1380C.
Particularly favorable conditions are obtained if the melting point of the nickel alloy is below the liquids temperature of the molten cast iron, that is below approximately 1150C.
Hereinafter are given exemplified embodiments of pipes manufactured by centrifugal casting from cast iron and nodular graphite using the above-described method.
Example 1 Into the steel ingot mold of a centrifugal casting machine was introduced a metal powder carrying the trade name Hostile ~1--236 ~.Z32~28 D and having the following chemical analysis: 85 wt.% Nix 10 wt.% So and 3 wt.% Cu. This material was introduced via the runner in powder form and at the same time as the molten cast iron. The metal powder has a melting point of 1120C and a specific weight of 7.8 g/cm .
So that the powder with an introduced cast iron forms an alloy with the outer wall area of the pipe to be centrifuged, it must be introduced in a quantity such that an alloyed outer wall area of 0.1 to 1.0 mm and preferably 0.4 mm is formed from austenitic nodular cast iron (21 to 24% No).
Example 2 Into a rotating steel ingot mold of a centrifugal casting machine was introduced a metal powder with the chemical composition 94 wt.% Nix 3 wt.% B and 3 wt.% So and having a melting point of 1050C. Introduction took place in a uniform manner, that is using a screening means, over the entire inner surface of the ingot mold The metal powder quantity was metered in the same way as in Example 1.
Following the introduction of the metal powder, the molten iron was introduced into the mold in a second operation. Once again, an alloyed outer skin of the pipe of austenitic nodular cast iron was formed.
The aforementioned method is in no way limited to the centrifugal casting of pipes using lamellar or nodular graphite and it can be used in the same way in fact for other molten metal charges. The metal powders used must have a lower melting point and a higher specific gravity than the charges.
~3~-~36 1~3~4~8 This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
Filler materials can also be introduced in order to influence, slow down the cooling of the molten metal in the ingot mold, in order thereby to improve the structure and consequently the pipe quality (DAY 2,460,510).
In connection with the centrifugal casting of bimetallic pipes, it is known (DOS 2,852,030) to successively introduce different molten charges for forming different layers in the rotating ingot mold. The next layer is only introduced when the primary layer has reached a temperature which is below the solids temperature. The internal layer can be a plating layer containing nickel as the alloying element.
Unlike in the case of the hitherto known uses of filler materials in the centrifugal casting of pipes, the invention is based on the idea that the solution of the aforementioned problem is only achieved if there is no formation of an additional protective layer on the outer surface of the pipe and instead the protective layer is formed as part of the metal pipe wall, accompanied by a corresponding modification to the structure.
~-?36 i2;~2A2~3 DETAILED DESCRIPTION
It has now been surprisingly found that the formation of such a protective layer can be achieved in a relatively simple manner during the introduction of the molten metal, if a suitable filler material is lea in before or during the introduction of the molten metal into the ingot mold. A nickel alloy with a nickel content of 80 wt.% or more has proved particularly suitable. Further alloying elements can be selected from the group consisting of boron, silicon, chrome and copper. Such alloys are known as corrosion and heat-resistant materials and are commercially available. This alloy is introduced into the centrifugal casting mold in powder form with a particle size of approximately 0.1 to 1 mm. The specific weight of such alloys is well above the specific weight of the molten cast iron and is approximately 7.8 g/cm .
The melting point of such nickel alloys should be lower than 1300C and consequently lower than the casting temperature of the molten cast iron of approximately 1350 to 1380C.
Particularly favorable conditions are obtained if the melting point of the nickel alloy is below the liquids temperature of the molten cast iron, that is below approximately 1150C.
Hereinafter are given exemplified embodiments of pipes manufactured by centrifugal casting from cast iron and nodular graphite using the above-described method.
Example 1 Into the steel ingot mold of a centrifugal casting machine was introduced a metal powder carrying the trade name Hostile ~1--236 ~.Z32~28 D and having the following chemical analysis: 85 wt.% Nix 10 wt.% So and 3 wt.% Cu. This material was introduced via the runner in powder form and at the same time as the molten cast iron. The metal powder has a melting point of 1120C and a specific weight of 7.8 g/cm .
So that the powder with an introduced cast iron forms an alloy with the outer wall area of the pipe to be centrifuged, it must be introduced in a quantity such that an alloyed outer wall area of 0.1 to 1.0 mm and preferably 0.4 mm is formed from austenitic nodular cast iron (21 to 24% No).
Example 2 Into a rotating steel ingot mold of a centrifugal casting machine was introduced a metal powder with the chemical composition 94 wt.% Nix 3 wt.% B and 3 wt.% So and having a melting point of 1050C. Introduction took place in a uniform manner, that is using a screening means, over the entire inner surface of the ingot mold The metal powder quantity was metered in the same way as in Example 1.
Following the introduction of the metal powder, the molten iron was introduced into the mold in a second operation. Once again, an alloyed outer skin of the pipe of austenitic nodular cast iron was formed.
The aforementioned method is in no way limited to the centrifugal casting of pipes using lamellar or nodular graphite and it can be used in the same way in fact for other molten metal charges. The metal powders used must have a lower melting point and a higher specific gravity than the charges.
~3~-~36 1~3~4~8 This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
Claims (15)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the centrifugal casting of pipes characterized by a corrosion resistant alloy formed on the outer surface of the cast pipe wherein molten metal is introduced into a rotating metallic ingot mold comprising feeding a filler material to said mold such that said filter material forms with said molten metal a corrosion-resistant alloy on the outer surface of the cast pipe.
2. A method according to claim 1 wherein said filler material comprises a nickel alloy consisting of at least 80 wt.% nickel.
3. A method according to claim 2 wherein said nickel alloy comprises an alloying element selected from the group consisting of boron, silicon, chromium, copper and mixtures thereof.
4. A method according to claim 1 wherein said filler material is a powder.
5. A method according to claim 4 wherein the particle size of the powder filler material is from about 0.1 to 1.0 mm.
6. A method according to claim 1 wherein said filler material has a specific weight which is greater than the molten metal.
7. A method according to claim 6 wherein the specific weight of the filler material is about 7.8 g/cm3 .
8. A method according to claim 1 wherein the melting point of the filler material is less than 1300°C.
9. A method according to claim 1 wherein the melting point of the filler material is less than 1150°C.
10. A method according to claim 1 wherein the liquidus temperature of the molten metal is less than 1300°C.
11. A method according to claim 1 including feeding said filler material to said mold prior to the introduction of said molten metal.
12. A method according to claim 1 including feeding said filler material to said mold with said molten metal.
13. A method according to claim 2 wherein said filler material is a powder.
14. A method according to claim 2 wherein the particle size of the powder filler material is from about 0.1 to 1.0 mm.
15. A method according to claim 1 wherein said molten metal is molten cast iron.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH5082/83-2 | 1983-09-19 | ||
| CH5082/83A CH660856A5 (en) | 1983-09-19 | 1983-09-19 | METHOD FOR SPIN CASTING PIPES. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232428A true CA1232428A (en) | 1988-02-09 |
Family
ID=4287638
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000462892A Expired CA1232428A (en) | 1983-09-19 | 1984-09-11 | Method for the centrifugal casting of pipes |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0141966B1 (en) |
| JP (1) | JPS6087965A (en) |
| AT (1) | ATE33352T1 (en) |
| CA (1) | CA1232428A (en) |
| CH (1) | CH660856A5 (en) |
| DE (1) | DE3470288D1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| UA29555C2 (en) * | 1999-12-20 | 2000-11-15 | Дочірнє Підприємство "Нексус - Виробничо-Комерційна Компанія " | method of centrifugal casting of billets of rollers of machines for continuous casting of billets |
| CN102274951B (en) * | 2011-08-04 | 2013-03-06 | 广东新劲刚超硬材料有限公司 | Method for synthesizing titanium carbide-base hard alloy coating on surfaces of castings in situ |
| DE102015111096B4 (en) * | 2015-07-09 | 2018-04-26 | Benteler Steel/Tube Gmbh | Process for producing a seamless, multi-layer pipe product |
| DE102020200034A1 (en) * | 2020-01-03 | 2021-07-08 | Sms Group Gmbh | Process for producing a composite pipe and composite pipe |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2139880A1 (en) * | 1971-08-09 | 1973-02-22 | Apv Paramount Ltd | Bi metallic tubes - with specified properties of inner or outer layers |
| JPS4852630A (en) * | 1971-11-05 | 1973-07-24 | ||
| JPS4918696A (en) * | 1972-06-15 | 1974-02-19 | ||
| IN154618B (en) * | 1980-12-22 | 1984-11-17 | Abex Corp | |
| JPS59220266A (en) * | 1983-05-27 | 1984-12-11 | Kawasaki Heavy Ind Ltd | Production of composite steel pipe by centrifugal casting |
-
1983
- 1983-09-19 CH CH5082/83A patent/CH660856A5/en not_active IP Right Cessation
-
1984
- 1984-09-11 CA CA000462892A patent/CA1232428A/en not_active Expired
- 1984-09-12 DE DE8484110897T patent/DE3470288D1/en not_active Expired
- 1984-09-12 EP EP84110897A patent/EP0141966B1/en not_active Expired
- 1984-09-12 AT AT84110897T patent/ATE33352T1/en not_active IP Right Cessation
- 1984-09-19 JP JP59194937A patent/JPS6087965A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| CH660856A5 (en) | 1987-05-29 |
| ATE33352T1 (en) | 1988-04-15 |
| JPS6087965A (en) | 1985-05-17 |
| DE3470288D1 (en) | 1988-05-11 |
| EP0141966A1 (en) | 1985-05-22 |
| EP0141966B1 (en) | 1988-04-06 |
| JPH0520184B2 (en) | 1993-03-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |