CA1182183A - Device for improving the resistance and the stiffness of a subsea conduit - Google Patents
Device for improving the resistance and the stiffness of a subsea conduitInfo
- Publication number
- CA1182183A CA1182183A CA000389813A CA389813A CA1182183A CA 1182183 A CA1182183 A CA 1182183A CA 000389813 A CA000389813 A CA 000389813A CA 389813 A CA389813 A CA 389813A CA 1182183 A CA1182183 A CA 1182183A
- Authority
- CA
- Canada
- Prior art keywords
- thickness
- conduit
- resistance
- increased
- stiffness
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L57/00—Protection of pipes or objects of similar shape against external or internal damage or wear
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L57/00—Protection of pipes or objects of similar shape against external or internal damage or wear
- F16L57/02—Protection of pipes or objects of similar shape against external or internal damage or wear against cracking or buckling
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Rigid Pipes And Flexible Pipes (AREA)
- Pipeline Systems (AREA)
- Materials For Medical Uses (AREA)
Abstract
DEVICE FOR IMPROVING THE RESISTANCE
AND THE STIFFNESS ON A SUBSEA CONDUIT.
ABSTRACT
Device for improving the resistance and the stiffness of a subsea conduit, consisting of a section of pipeline having a increased thickness but with the same inside diameter, there being provided at the conduit and a length equal to from 2 to 5 times the increased for 0.5 to 10 times the nominal outside diame-ter of the conduit.
AND THE STIFFNESS ON A SUBSEA CONDUIT.
ABSTRACT
Device for improving the resistance and the stiffness of a subsea conduit, consisting of a section of pipeline having a increased thickness but with the same inside diameter, there being provided at the conduit and a length equal to from 2 to 5 times the increased for 0.5 to 10 times the nominal outside diame-ter of the conduit.
Description
The present invention relates to a device for improving the resistance an~ the stiffness of a subsea conduit.
In particular, the present invention xelates to subsea conduits and more particularly to the subsea conduits laid at a considerable depth.
Subsea conduits are subjected to stresses and loads of a different nature, both during the pipelayin~ operations and during practical use. ~hese stresses are originated by the external pressure, the internal pressure, the influence of the environment and the irregular configuration of the sea bed.
Moreover, unforeseen conditions may occur, such as defects in the material, subsea landslides, bumps, and scraping by anchors.
More particularly, in the case of a pipe blow, the breakage can be propagated, under certain conditions, even for len~ths of several kilometers. A similar propagation of the damage may occur, due to the effect of a pressure from the outside, in the case of an accidental kink of a pipe section.
It is thus important to insert, in the pipeline, at regularly spaced apart intervals, some devices which, by increasing the resistance, are capable of stopping ~he propa~ation of -the damage so as to res-trict it -to a sl)ort section.
In the conventional art it ;s provided to e~3uip the pipeline at longer or shorter intervals with col-lars or outer ring which are positioned on the pipelineupon assemb].ing and which are secured by means of worii-ing spots. Another approach which has been sug~ested is to insert sleeves in the interior o-f the pipe].ine after that the latter has been assembled.
Lastly another approach is to insert duri.ng a~s-sembly a-f tlle pi.peline short plpe sections haviny the same outsie diameter as the remainder of the p;.peline but thicker. These approaches havc qui.te remarkable defects. The method which adop-ts cxternal collars 2p-plied to the pi.peline already assembied involves supple-mentary operations to be effec-ted beyond the laying raMp because the collars so app].ied would not permi-t a con-venient slidirl~ along the layin~ ramp ancl thro~1gh ti1e tensioning (lev:ice for thc pipeline.
~0 To inscrt intcrnal sleeves ir1 thc already asscm-bled pipeline llas -the defects that the pressure drops are increased. the clean.ing operat:iorls o~ the pipelire are made harder and tha-t the method is inoperati~e in the case that the unexpected stress is an internal over-pressure such as bursts shock waves Ol water-hammer.
To in.sert sections havin~ the same outside di.a-mc-ter 2S the remainder of the conduit but wlth 2n in-creased thickness does not cause an~ di~+`f3.culty uncJer 3.
the respect of the assembling and laying operations, but has the same defects recalled above in connection with the increase of the pressure drops and the difficulties of pipe cleaning. There are, moreover, difficulties as to the internal alignment in correspondence with the welding seals and, in addition, there are shortcomings originated by the fact that sections of different thicknesses are to be welded:
under working conditions, there is an irregular distribution of the stresses in the welded area due to the effect of the abrupt thickness variation.
As regards the internal cleaning, it is common practice to carry out such an operation by specially provided devices which are commonly callde pigs. These latter, in the most widely adopted version, are essentially composed of plugs, equipped with brushes or like implements for removing the incrustations and deposits, such devices being introduced in the pipes and pushed on by a fluid.
The variations of the inside diameter, as limited as they may be, but repeated many times along the line, may damage the gaskets of such pigs and hinder their forward motion.
According to the present invention, there is pro-vided a device for improving the resistance and the stiffness of subsea conduits comprising a pipe sectiorl having a central section with an increased thickness but the same inside diameter and having at the ends two end sections with a thickness equal to that of the remainder of the conduit, the total length of said pipe section being equal to a value of from 0.5 times to 10 times the nominal outside diam~ter of the conduit and the length of the end sections being equal to at least 1.5 times the increased wall thickness.
Preferably, the length of the end sections is equal ~.
to 2 to 5 times the increased wall thickness.
~ preferred embodiment of the present invention, will now be described as example, without limitative manner, having reference the attached drawing, wherein the single figure shows the main elements of the present invention.
The total leng-th is divided into two e~ual sections, a, placed at the ends, and a central section, 1.
In the section 1 an increased thickness sl is adopted, whereas, in the sections a the same thickness s is maintained as for the other sections of the conduit. The increased thickness sl is comprised between 1.1 times and 3 times the thickness s of the other sections of the conduit. The adoption of the section a is an expedient dictated by the fact, recalled above, that the variations of the thickness ori~inate a considerable local increase of the stresses in the steel mass. One thus obtains the effect that the area in which the stresses are irregularly distributed is kept far away of the welded joint. The length a of the end portions must be, at least, more than 1.5 times the thickness sl and it is preferred that it is from 2 times to 5 times as much. The area in which there is a thickness .
variation is radiussed with a rad:ius of curvature which preferably exceeds 5 millimeters. Such an expedient limits the local ,accumulation of stresses.
In addition, the gradual transition from s to sl facilitates the pipelaying operations.
When assessiny the advantages of the device according to the present invention lt should be borne in mind, moreover, that the standard specifications stipulate for the pipelines the outside diameter as the characteristic diameter so that, for a certain nominal diameter, there are different inside diameters consistently with -the thickness.
5.
In addition, it should be taken in-to account that the constructional allowances, in their turn, have a bearing on the inside diameter.
In -the present invention, the reference diameter shall be the inside diameter and the thickness increase will influence the outside diameter only.
The pipeline assemblage operations are not altered, in the slightest, inasmuch as no supplernentary operations or tools are required.
A very satisfactory internal alignment is obtained in correspondence with the welding seam. This fact, which does away with internal level ~lnevennesses due to the working allowance for the thickness, makes it possible to effect the weld:ing operations better and more reliably, too.
There are no difficulties for cleaning nor any hindrances to the fluid flow by whirls and pressure drops.
An improvement, of the resistance of the pipeline to tangential stresses is obtained in that the thickness increase sl reduces the specific tangential stress which is expressed in terms of:
6~- ~P D
2sl wherein ~ indicates the stress, ~P the difference between the internal and the external pressures, D is the diameter and sl the thickness.
Such a thickness increase permits, obviously, to -,_ _ ~.
stop the propagation of a possiblc~ ]ongitudinaI fissure.
Likewise, a loca] împrovemtllt is ob-tained as -to the resistance of the conduit to ovalization, that which stops the propagation of a posslble kink The stiffness against ovalization of a conduit section having a certain length is proportiona1 to the parameter K = s~3 It is apparent that the -thickness increase consi-derably improves the resistance to ovalization and stops the propagatiorl o~ such a phenomenon.
In additiorl to solving in a simple and cheap way the technical problem of locally increasing the res;-stance of the pipeline botll to kinli and to break by pre venting the propagation of brealcs to adJoinillg pipe sections7 the device accordlny to the invention is charac~
terized by the fo110wing allvalltages -- its installation is easy since thc devlce is weldetl lilcc a conventional pipe length antl no Junction problem exists, th pipelaying and launchintJ operations bcins unaltertd;
- it does not costruct the fluid l`lo~v;
- it does not hinder cleaning ;
it limits the local exaltation of the stresses and loca]izes these to an area whi~h is far from the ~velding seam.
The length of t e conduit sections between the devices according to the invention as it is obvious varies consistellt~y with the depth of the sca bed and other paraMeters of tlle installatioll.
As an inclicati.on however the deviccs are spa-ced part from about 30 me-ters to about 1000 meters from each other. Since these devices afford a considerable benefit a].so in communicati.on w;.-th the stiffness of the pipeline and i.ts resistance to long;tudillal bends it should be prov.ided that -they are installed at closer spaci.ng where the sea bed has a rmore irregular out].ine or e~hibits more difficult environme-ltal conditions.
In particular, the present invention xelates to subsea conduits and more particularly to the subsea conduits laid at a considerable depth.
Subsea conduits are subjected to stresses and loads of a different nature, both during the pipelayin~ operations and during practical use. ~hese stresses are originated by the external pressure, the internal pressure, the influence of the environment and the irregular configuration of the sea bed.
Moreover, unforeseen conditions may occur, such as defects in the material, subsea landslides, bumps, and scraping by anchors.
More particularly, in the case of a pipe blow, the breakage can be propagated, under certain conditions, even for len~ths of several kilometers. A similar propagation of the damage may occur, due to the effect of a pressure from the outside, in the case of an accidental kink of a pipe section.
It is thus important to insert, in the pipeline, at regularly spaced apart intervals, some devices which, by increasing the resistance, are capable of stopping ~he propa~ation of -the damage so as to res-trict it -to a sl)ort section.
In the conventional art it ;s provided to e~3uip the pipeline at longer or shorter intervals with col-lars or outer ring which are positioned on the pipelineupon assemb].ing and which are secured by means of worii-ing spots. Another approach which has been sug~ested is to insert sleeves in the interior o-f the pipe].ine after that the latter has been assembled.
Lastly another approach is to insert duri.ng a~s-sembly a-f tlle pi.peline short plpe sections haviny the same outsie diameter as the remainder of the p;.peline but thicker. These approaches havc qui.te remarkable defects. The method which adop-ts cxternal collars 2p-plied to the pi.peline already assembied involves supple-mentary operations to be effec-ted beyond the laying raMp because the collars so app].ied would not permi-t a con-venient slidirl~ along the layin~ ramp ancl thro~1gh ti1e tensioning (lev:ice for thc pipeline.
~0 To inscrt intcrnal sleeves ir1 thc already asscm-bled pipeline llas -the defects that the pressure drops are increased. the clean.ing operat:iorls o~ the pipelire are made harder and tha-t the method is inoperati~e in the case that the unexpected stress is an internal over-pressure such as bursts shock waves Ol water-hammer.
To in.sert sections havin~ the same outside di.a-mc-ter 2S the remainder of the conduit but wlth 2n in-creased thickness does not cause an~ di~+`f3.culty uncJer 3.
the respect of the assembling and laying operations, but has the same defects recalled above in connection with the increase of the pressure drops and the difficulties of pipe cleaning. There are, moreover, difficulties as to the internal alignment in correspondence with the welding seals and, in addition, there are shortcomings originated by the fact that sections of different thicknesses are to be welded:
under working conditions, there is an irregular distribution of the stresses in the welded area due to the effect of the abrupt thickness variation.
As regards the internal cleaning, it is common practice to carry out such an operation by specially provided devices which are commonly callde pigs. These latter, in the most widely adopted version, are essentially composed of plugs, equipped with brushes or like implements for removing the incrustations and deposits, such devices being introduced in the pipes and pushed on by a fluid.
The variations of the inside diameter, as limited as they may be, but repeated many times along the line, may damage the gaskets of such pigs and hinder their forward motion.
According to the present invention, there is pro-vided a device for improving the resistance and the stiffness of subsea conduits comprising a pipe sectiorl having a central section with an increased thickness but the same inside diameter and having at the ends two end sections with a thickness equal to that of the remainder of the conduit, the total length of said pipe section being equal to a value of from 0.5 times to 10 times the nominal outside diam~ter of the conduit and the length of the end sections being equal to at least 1.5 times the increased wall thickness.
Preferably, the length of the end sections is equal ~.
to 2 to 5 times the increased wall thickness.
~ preferred embodiment of the present invention, will now be described as example, without limitative manner, having reference the attached drawing, wherein the single figure shows the main elements of the present invention.
The total leng-th is divided into two e~ual sections, a, placed at the ends, and a central section, 1.
In the section 1 an increased thickness sl is adopted, whereas, in the sections a the same thickness s is maintained as for the other sections of the conduit. The increased thickness sl is comprised between 1.1 times and 3 times the thickness s of the other sections of the conduit. The adoption of the section a is an expedient dictated by the fact, recalled above, that the variations of the thickness ori~inate a considerable local increase of the stresses in the steel mass. One thus obtains the effect that the area in which the stresses are irregularly distributed is kept far away of the welded joint. The length a of the end portions must be, at least, more than 1.5 times the thickness sl and it is preferred that it is from 2 times to 5 times as much. The area in which there is a thickness .
variation is radiussed with a rad:ius of curvature which preferably exceeds 5 millimeters. Such an expedient limits the local ,accumulation of stresses.
In addition, the gradual transition from s to sl facilitates the pipelaying operations.
When assessiny the advantages of the device according to the present invention lt should be borne in mind, moreover, that the standard specifications stipulate for the pipelines the outside diameter as the characteristic diameter so that, for a certain nominal diameter, there are different inside diameters consistently with -the thickness.
5.
In addition, it should be taken in-to account that the constructional allowances, in their turn, have a bearing on the inside diameter.
In -the present invention, the reference diameter shall be the inside diameter and the thickness increase will influence the outside diameter only.
The pipeline assemblage operations are not altered, in the slightest, inasmuch as no supplernentary operations or tools are required.
A very satisfactory internal alignment is obtained in correspondence with the welding seam. This fact, which does away with internal level ~lnevennesses due to the working allowance for the thickness, makes it possible to effect the weld:ing operations better and more reliably, too.
There are no difficulties for cleaning nor any hindrances to the fluid flow by whirls and pressure drops.
An improvement, of the resistance of the pipeline to tangential stresses is obtained in that the thickness increase sl reduces the specific tangential stress which is expressed in terms of:
6~- ~P D
2sl wherein ~ indicates the stress, ~P the difference between the internal and the external pressures, D is the diameter and sl the thickness.
Such a thickness increase permits, obviously, to -,_ _ ~.
stop the propagation of a possiblc~ ]ongitudinaI fissure.
Likewise, a loca] împrovemtllt is ob-tained as -to the resistance of the conduit to ovalization, that which stops the propagation of a posslble kink The stiffness against ovalization of a conduit section having a certain length is proportiona1 to the parameter K = s~3 It is apparent that the -thickness increase consi-derably improves the resistance to ovalization and stops the propagatiorl o~ such a phenomenon.
In additiorl to solving in a simple and cheap way the technical problem of locally increasing the res;-stance of the pipeline botll to kinli and to break by pre venting the propagation of brealcs to adJoinillg pipe sections7 the device accordlny to the invention is charac~
terized by the fo110wing allvalltages -- its installation is easy since thc devlce is weldetl lilcc a conventional pipe length antl no Junction problem exists, th pipelaying and launchintJ operations bcins unaltertd;
- it does not costruct the fluid l`lo~v;
- it does not hinder cleaning ;
it limits the local exaltation of the stresses and loca]izes these to an area whi~h is far from the ~velding seam.
The length of t e conduit sections between the devices according to the invention as it is obvious varies consistellt~y with the depth of the sca bed and other paraMeters of tlle installatioll.
As an inclicati.on however the deviccs are spa-ced part from about 30 me-ters to about 1000 meters from each other. Since these devices afford a considerable benefit a].so in communicati.on w;.-th the stiffness of the pipeline and i.ts resistance to long;tudillal bends it should be prov.ided that -they are installed at closer spaci.ng where the sea bed has a rmore irregular out].ine or e~hibits more difficult environme-ltal conditions.
Claims (6)
1. A device for improving the resistance and the stiffness of subsea conduits comprising a pipe section having a central section with an increased thickness but the same inside diameter and at the ends two end sections with a thickness equal to that of the remainder of the conduit, the total length of said pipe section being equal to a value of from 0.5 times to 10 times the nominal outside diameter of the conduit and the length of the end sections being equal to at least 1.5 times the increased wall thickness.
2. A device according to claim 1, characterized in that the length of the end sections is equal to 2 to 5 times the increased wall thickness.
3. A device according to claim 1, characterized in that the increased thickness is comprised between 1.1 times and 3 times the thickness of the conduit.
4. A device according to claim 1, 2 or 3, charac-terized in that the zone in which there is a variation of the thickness is gently radiussed with a radius of curvature.
5. A device according to claim 1, 2 or 3, charac-terized in that the zone in which there is a variation of the thickness is radiussed with a radius of curvature longer than 5 millimeters.
6. A device according to claim 1, 2 or 3, charac-terized in that the specific tangential stress of the conduit is given by the formula:
wherein:
.DELTA.P = is the difference between internal and external pres-sures, D = is the diameter of the conduit, sl = is the increased thickness.
wherein:
.DELTA.P = is the difference between internal and external pres-sures, D = is the diameter of the conduit, sl = is the increased thickness.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT26259A/80 | 1980-11-27 | ||
| IT26259/80A IT1134476B (en) | 1980-11-27 | 1980-11-27 | DEVICE TO IMPROVE THE STRENGTH AND RIGIDITY OF SUBMARINE DUCTS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1182183A true CA1182183A (en) | 1985-02-05 |
Family
ID=11219080
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389813A Expired CA1182183A (en) | 1980-11-27 | 1981-11-10 | Device for improving the resistance and the stiffness of a subsea conduit |
Country Status (22)
| Country | Link |
|---|---|
| JP (1) | JPS57116993A (en) |
| AR (1) | AR227340A1 (en) |
| AU (1) | AU546604B2 (en) |
| BE (1) | BE891263A (en) |
| BR (1) | BR8107347A (en) |
| CA (1) | CA1182183A (en) |
| DE (2) | DE3146979A1 (en) |
| DK (1) | DK513981A (en) |
| ES (1) | ES270030Y (en) |
| FI (1) | FI813612L (en) |
| FR (1) | FR2494807A1 (en) |
| GB (1) | GB2088513B (en) |
| IN (1) | IN155419B (en) |
| IT (1) | IT1134476B (en) |
| MA (1) | MA19343A1 (en) |
| NL (1) | NL8105359A (en) |
| NO (1) | NO814009L (en) |
| NZ (1) | NZ198814A (en) |
| OA (1) | OA06980A (en) |
| PT (1) | PT74037B (en) |
| SE (1) | SE8107104L (en) |
| TR (1) | TR21667A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2914979B1 (en) * | 2007-04-12 | 2009-07-10 | Saipem S A Sa | METHOD FOR PRODUCING AN UNDERWATER DRIVING COMPRISING THE DRYING OF ASSEMBLY WELDS WITHIN THE DRIVING |
| NL2007386C2 (en) * | 2011-09-09 | 2013-03-12 | Heerema Marine Contractors Nl | Improved method of gripping a pipeline. |
| DE102014102621A1 (en) * | 2014-02-27 | 2015-08-27 | Doege Beteiligungs Gmbh | Large-tube arrangement and method for producing such |
| CN114131226B (en) * | 2020-09-04 | 2023-08-22 | 中国石油天然气集团有限公司 | Manufacturing method of tee joint |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1383527A (en) * | 1972-05-26 | 1974-02-12 | British Petroleum Co | Pipelines |
| FR2428782A1 (en) * | 1978-06-13 | 1980-01-11 | Pont A Mousson | STEEL TUBULAR ELEMENTS FOR PIPES AT SEA |
-
1980
- 1980-11-27 IT IT26259/80A patent/IT1134476B/en active
-
1981
- 1981-10-29 NZ NZ198814A patent/NZ198814A/en unknown
- 1981-11-04 AU AU77092/81A patent/AU546604B2/en not_active Expired - Fee Related
- 1981-11-04 GB GB8133257A patent/GB2088513B/en not_active Expired
- 1981-11-04 IN IN1226/CAL/81A patent/IN155419B/en unknown
- 1981-11-10 CA CA000389813A patent/CA1182183A/en not_active Expired
- 1981-11-10 BR BR8107347A patent/BR8107347A/en unknown
- 1981-11-16 FI FI813612A patent/FI813612L/en not_active Application Discontinuation
- 1981-11-17 TR TR21667A patent/TR21667A/en unknown
- 1981-11-19 DK DK513981A patent/DK513981A/en not_active Application Discontinuation
- 1981-11-20 AR AR287535A patent/AR227340A1/en active
- 1981-11-20 FR FR8121809A patent/FR2494807A1/en not_active Withdrawn
- 1981-11-22 OA OA57554A patent/OA06980A/en unknown
- 1981-11-24 ES ES1981270030U patent/ES270030Y/en not_active Expired
- 1981-11-25 NO NO814009A patent/NO814009L/en unknown
- 1981-11-25 PT PT74037A patent/PT74037B/en unknown
- 1981-11-26 JP JP56188522A patent/JPS57116993A/en active Pending
- 1981-11-26 BE BE0/206666A patent/BE891263A/en not_active IP Right Cessation
- 1981-11-26 DE DE19813146979 patent/DE3146979A1/en not_active Withdrawn
- 1981-11-26 DE DE19818134555U patent/DE8134555U1/en not_active Expired
- 1981-11-26 NL NL8105359A patent/NL8105359A/en not_active Application Discontinuation
- 1981-11-27 MA MA19547A patent/MA19343A1/en unknown
- 1981-11-27 SE SE8107104A patent/SE8107104L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| AU7709281A (en) | 1982-06-03 |
| IT8026259A0 (en) | 1980-11-27 |
| OA06980A (en) | 1983-07-31 |
| GB2088513A (en) | 1982-06-09 |
| GB2088513B (en) | 1984-05-23 |
| IN155419B (en) | 1985-01-26 |
| FR2494807A1 (en) | 1982-05-28 |
| NZ198814A (en) | 1985-07-12 |
| NL8105359A (en) | 1982-06-16 |
| IT1134476B (en) | 1986-08-13 |
| MA19343A1 (en) | 1982-07-01 |
| DE8134555U1 (en) | 1983-09-08 |
| AU546604B2 (en) | 1985-09-12 |
| PT74037A (en) | 1981-12-01 |
| ES270030Y (en) | 1985-02-16 |
| PT74037B (en) | 1983-05-23 |
| FI813612L (en) | 1982-05-28 |
| DE3146979A1 (en) | 1982-07-08 |
| JPS57116993A (en) | 1982-07-21 |
| AR227340A1 (en) | 1982-10-15 |
| DK513981A (en) | 1982-05-28 |
| TR21667A (en) | 1985-09-13 |
| BE891263A (en) | 1982-05-26 |
| ES270030U (en) | 1984-08-01 |
| BR8107347A (en) | 1982-08-03 |
| SE8107104L (en) | 1982-05-28 |
| NO814009L (en) | 1982-05-28 |
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Legal Events
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