GB1588819A - Creation of Inventions and Patents with Artificial Intelligence

GB1588819A – Method of manufacturing tubes having no residual circumferential tensile stresses
– Google Patents

GB1588819A – Method of manufacturing tubes having no residual circumferential tensile stresses
– Google Patents
Method of manufacturing tubes having no residual circumferential tensile stresses

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Publication number
GB1588819A

GB1588819A
GB46908/77A
GB4690877A
GB1588819A
GB 1588819 A
GB1588819 A
GB 1588819A
GB 46908/77 A
GB46908/77 A
GB 46908/77A
GB 4690877 A
GB4690877 A
GB 4690877A
GB 1588819 A
GB1588819 A
GB 1588819A
Authority
GB
United Kingdom
Prior art keywords
tubes
tube
elongation
detensioned
tensile stresses
Prior art date
1976-11-12
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

Application number
GB46908/77A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Vallourec SA

Original Assignee
Vallourec SA
Priority date (The priority date 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 date listed.)
1976-11-12
Filing date
1977-11-10
Publication date
1981-04-29

1977-11-10
Application filed by Vallourec SA
filed
Critical
Vallourec SA

1981-04-29
Publication of GB1588819A
publication
Critical
patent/GB1588819A/en

Status
Expired
legal-status
Critical
Current

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Classifications

B—PERFORMING OPERATIONS; TRANSPORTING

B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL

B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL

B21D3/00—Straightening or restoring form of metal rods, metal tubes, metal profiles, or specific articles made therefrom, whether or not in combination with sheet metal parts

B21D3/12—Straightening or restoring form of metal rods, metal tubes, metal profiles, or specific articles made therefrom, whether or not in combination with sheet metal parts by stretching with or without twisting

C—CHEMISTRY; METALLURGY

C21—METALLURGY OF IRON

C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING

C21D7/00—Modifying the physical properties of iron or steel by deformation

C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working

Description

PATENT SPECIFICATION
( 11) Co ( 21) Application No 46908/77 ( 22) Filed 10 Nov 1977 ( 19) ( 31) Convention Application No 7 634 179 ( 32) Filed 12 Nov 1976 in = ( 33) France (FR)
00 ( 44) Complete Specification published 29 April 1981
1 J’ ( 51) INT CL B 21 D 3/12 ” ( 52) Index at acceptance B 3 E 14 K 8 FB ( 54) METHOD OF MANUFACTURING TUBES HAVING NO RESIDUAL CIRCUMFERENTIAL TENSILE STRESSES ( 71) We, VALLOUREC (Us IN Es A TUBES DE LORRAINE-ESCAUT ET VALLOUREC REUNIES) a French Body Corporate of 7, Place du Chancelier Adenauer-75016 Paris, France do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-
The present invention relates to a method for the manufacture of detensioned tubes which, within the meaning of the present invention, means metal tubes having no residual circumferential tensile stresses or only a very low level of such stresses The invention applies more particularly to tubes made from steel or alloys having characteristics identical to steel, but can also be applied to tubes made from other metals.
Advantageously the invention can be applied to very long tubes with thin walls.
The tubes obtained are intended for a variety of uses but the invention is of particular interest in the case of manufacturing tubes for use under conditions where the corrosion resistance is important, such as for example in the field of heat exchangers or tubes intended for the chemical or petroleum industry.
It is well known in the metal tubes industry and particularly the steel tubes industry that tubes manufactured by whatever method and which have undergone whatever treatment fail to a greater or lesser extent to be straight and are in fact virtually never straight Due to the requirements of use which call for straight tubes most metal tubes undergo straightening on straightening machines, whereof numerous types exist but those most frequently used comprise rotary rollers with a hyperbolic profile.
The straightening operation induces in the tubes, starting from their outer surface, residual circumferential tensile stresses whose average value is relatively high, as well as possibly residual compression stresses at the inner surface of the tube.
The term circumferential tensile stress is understood to mean tensile stress directed in a transverse sectional plane of the tube in a direction tangential to the circle passing through the considered point of the tube.
However, the existence’ of such tensile stresses promotes the appearance of stress corrosion, which it is hardly possible to 55 prevent under certain conditions of use and assembly of tubes Obviously corrosion riks reduce the possible uses of tubes and lead to serious economic disadvantages.
Moreover, in certain cases such circumfer 60 ential tensile stresses may result from processes other than straightening, but the resulting disadvantages are the same.
The invention aims at obviating these disadvantages and at providing a method 65 permitting the production of tubes in which said circumferential tensile stresses are eliminated or significantly reduced, together with the corrosion risks corresponding thereto.
Moreover, the invention aims at providing 70 a method which is particularly economic and simple to perform.
According to the present invention in a method for the production of detensioned tubes the tube to be detensioned at least 75 once undergoes an axial tension greater than or equal to the value corresponding to an elongation of 02 % for a period which is sufficient to cause the desired decrease or elimination of the stresses This value 80 corresponds to the value of the conventional elastic limit for an elongation of 02 %.
It has already been proposed to place the tubes under axial tension, but under conditions differing from those of the present 85 invention and with different aims, for example to bring about a permanent and significant elongation of the tubes or, in the case of rigid thick tubes, to make said tubes straight by a straightening action The invention 90 leads to completely different results.
According to a first preferred embodiment of the invention the tensioning of the tube causes an elongation thereof which can reach 1 %, said elongation value being that 95 undergone by the tube at the time when it is under tension.
According to the invention the tube is not then subject to any treatment such as straightening or the like which is liable to 100.
1 588 819 1,588,819 cause the appearance of new circumferential tensile stresses.
The invention particularly relates to a method in which the tube is straightened by means of straightening machines with hyperbolic rollers, after which the abovementioned axial tensioning is carried out.
The tube tensioning period is dependent on the nature of the tube.
In general manner a sufficient stress can immediately be applied to the tube and the tube is maintained under tension for a period of several minutes, for example 2 to 3 minutes.
As a variant slow and progressive tensioning can be performed, whereby the values laid down in the invention are reached in a period of a few minutes, for example 2 to 4 minutes.
In general manner the method according to the invention is applicable both to welded tubes and to tubes produced by processes not involving welding.
It is generally preferable to carry out tensioning leading to a smaller elongation in the case of cold rolled tubes than in the case of drawn tubes.
The invention also relates to tubes detensioned by the method according to the invention.
Other advantages and features of the invention can be gathered from reading the following description with reference to a non-limitative example.
Weldless stainless steel tubes with a diameter of 2222 mm, a thickness of 1 27 mm and a length up to 30 m are manufactured.
These tubes, on arriving from the straightening process, have circumferential tensile stresses of approximately 20 to 25 HB, which can be demonstrated by the longitudinally split ring method.
The two ends of the tube are gripped by the vices of a tensioning machine and the machine is started up The displacement of the movable vice takes 4 minutes and reaches a value of 340 mm at the end of this period, corresponding to 08 % of the length of the tube and a stress on the machine of approximately 3 5 tonnes After removing the tube from the machine it has a residual elongation of 065 %.
The magnesium chloride corrosion tests and the split ring measurements show that the residual circumferential tensile stresses have disappeared.
The method according to the invention has been described relative to the manufacture of tubes which have undergone straightening As a variant, however, it is possible to use the method of the invention for tubes having circumferential tensile stresses caused by processes other than straightening, obviously provided that said tubes are not again straightened after performing the method of the invention.

Claims (7)

WHAT WE CLAIM IS:-

1 A method for the production of detensioned tubes, wherein the tube to be detensioned at least once undergoes an axial tension greater than or equal to a value corresponding to an elongation of 002 % for a period which is sufficient to cause the desired decrease or elimination of the stresses.

2 A method according to claim 1, wherein the tube is straightened, after which it undergoes axial tensioning.

3 A method according to either of the claims 1 and 2 wherein the tube is tensioned so as to cause an elongation thereof up to 1 %.

4 A method according to any one of the claims 1 to 3, wherein the tube is maintained under tension corresponding to an elongation at least 02 % for a few minutes.

A method according to any one of the claims 1 to 4, wherein the tube is slowly and progressively tensioned and the value of a tension corresponding to an elongation of at least 02 % is reached after a few minutes.

6 Detensioned tubes produced by the method according to any one of claims 1 to 5.

7 A method for producing detensioned tubes substantially as described hereinbefore.
For the Applicants, G F REDFERN & CO, High Holborn House, 52/54 High Holborn, London WC 1 V 6 RL.
Printed for Her Majestlys Stationery Office by Burgess & Son (Abingdon), Ltd -1981.
Published at The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

GB46908/77A
1976-11-12
1977-11-10
Method of manufacturing tubes having no residual circumferential tensile stresses

Expired

GB1588819A
(en)

Applications Claiming Priority (1)

Application Number
Priority Date
Filing Date
Title

FR7634179A

FR2370793A1
(en)

1976-11-12
1976-11-12

PROCESS FOR MANUFACTURING DETENSIONED TUBES, DEVICE FOR IMPLEMENTING THIS PROCESS AND EXPANDED TUBES OBTAINED

Publications (1)

Publication Number
Publication Date

GB1588819A
true

GB1588819A
(en)

1981-04-29

Family
ID=9179839
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

GB46908/77A
Expired

GB1588819A
(en)

1976-11-12
1977-11-10
Method of manufacturing tubes having no residual circumferential tensile stresses

Country Status (8)

Country
Link

US
(1)

US4156360A
(en)

JP
(1)

JPS5361550A
(en)

BE
(1)

BE860702A
(en)

DE
(1)

DE2750096A1
(en)

FR
(1)

FR2370793A1
(en)

GB
(1)

GB1588819A
(en)

IT
(1)

IT1114667B
(en)

SE
(1)

SE439021B
(en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

DE3030598C2
(en)

1980-08-11
1982-07-29
Mannesmann AG, 4000 Düsseldorf

Process for the production of pipes resistant to stress corrosion cracking

FR2521883B1
(en)

1982-02-19
1985-08-30
Sacilor

METHOD FOR DRESSING A RAILWAY RAIL AND DRESSE RAILWAY RAIL

JPS60187663A
(en)

1984-03-01
1985-09-25
Nippon Steel Corp
Electric welded oil well pipe having low hardness and high yield strength and its production

WO2018037421A1
(en)

2016-08-22
2018-03-01
Siddhi Engineers
Process for manufacturing steel cheese tubes/jumbo tubes/pipes for woven-sacks and cops/bobbins/pirns for synthetic yarn

WO2019123485A1
(en)

2017-12-23
2019-06-27
Siddhi Engineers
A process of induction hardening treatment at steel cheese tube edge for high impact resistance

Family Cites Families (4)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

US2336524A
(en)

1940-11-01
1943-12-14
Nat Tube Co
Combination straightener and tester for pipes

US3031750A
(en)

1958-02-14
1962-05-01
Rods Inc
Method of producing steel bars

US3469425A
(en)

1968-03-20
1969-09-30
Allegheny Ludlum Steel
Apparatus for stretching tubing

US3678727A
(en)

1970-08-27
1972-07-25
Robert G Jackson
Stretch-draw tubing process

1976

1976-11-12
FR
FR7634179A
patent/FR2370793A1/en
active
Granted

1977

1977-11-09
DE
DE19772750096
patent/DE2750096A1/en
not_active
Ceased

1977-11-10
GB
GB46908/77A
patent/GB1588819A/en
not_active
Expired

1977-11-10
US
US05/850,426
patent/US4156360A/en
not_active
Expired – Lifetime

1977-11-10
BE
BE182524A
patent/BE860702A/en
not_active
IP Right Cessation

1977-11-11
SE
SE7712779A
patent/SE439021B/en
not_active
Application Discontinuation

1977-11-11
JP
JP13614777A
patent/JPS5361550A/en
active
Pending

1977-11-11
IT
IT29596/77A
patent/IT1114667B/en
active

Also Published As

Publication number
Publication date

SE7712779L
(en)

1978-05-13

US4156360A
(en)

1979-05-29

IT1114667B
(en)

1986-01-27

FR2370793B1
(en)

1979-03-02

DE2750096A1
(en)

1978-05-24

BE860702A
(en)

1978-05-10

JPS5361550A
(en)

1978-06-02

SE439021B
(en)

1985-05-28

FR2370793A1
(en)

1978-06-09

Contact information