NO853543L - PROCEDURE FOR SURFACE CURRENCY OF THE CIRCUIT BANDS IN A CONNECTION BETWEEN PARTS OF A DRILL STRING. - Google Patents
PROCEDURE FOR SURFACE CURRENCY OF THE CIRCUIT BANDS IN A CONNECTION BETWEEN PARTS OF A DRILL STRING.Info
- Publication number
- NO853543L NO853543L NO853543A NO853543A NO853543L NO 853543 L NO853543 L NO 853543L NO 853543 A NO853543 A NO 853543A NO 853543 A NO853543 A NO 853543A NO 853543 L NO853543 L NO 853543L
- Authority
- NO
- Norway
- Prior art keywords
- coupling
- band
- zone
- internal threads
- pipe
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 8
- 230000008878 coupling Effects 0.000 claims description 30
- 238000010168 coupling process Methods 0.000 claims description 30
- 238000005859 coupling reaction Methods 0.000 claims description 30
- 229910000831 Steel Inorganic materials 0.000 claims description 5
- 239000010959 steel Substances 0.000 claims description 5
- 230000001680 brushing effect Effects 0.000 claims description 4
- 238000005488 sandblasting Methods 0.000 claims description 4
- 230000007704 transition Effects 0.000 claims description 4
- 230000005855 radiation Effects 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 230000001939 inductive effect Effects 0.000 claims description 2
- 239000000463 material Substances 0.000 description 5
- 239000002344 surface layer Substances 0.000 description 4
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 4
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- 238000005553 drilling Methods 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000009931 harmful effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000013532 laser treatment Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
Classifications
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
- C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
- C21D9/14—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes wear-resistant or pressure-resistant pipes
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/22—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for drills; for milling cutters; for machine cutting tools
Description
Foreliggende oppfinnelse angår en fremgangsmåte som mulig-gjør overflateherding av koblinger mellom deler av en bore-streng uten at overflaten blir ru. The present invention relates to a method which enables surface hardening of connections between parts of a drill string without the surface becoming rough.
Oppfinnelsen angår også et borerør som er behandlet på denne måte. The invention also relates to a drill pipe that has been treated in this way.
Ved boring av brønner er det kjent å benytte borekroner anbragt på den nedre ende av en rekke borerør som er sammen-føyd etter hverandre for oppnåelse av en bestemt lengde. When drilling wells, it is known to use drill bits placed on the lower end of a series of drill pipes which are joined one after the other to achieve a specific length.
Hvert av rørene består av et sylindrisk stålelement som på endene har henholdsvis en tappdel med utvendige gjenger og en muffedel med innvendige gjenger. Each of the pipes consists of a cylindrical steel element which, at the ends, respectively has a pin part with external threads and a socket part with internal threads.
Ytterflatene av koblingene rager nødvendigvis utenfor rørene, som de er sammenføyd med via koniske overganger, og ytterflatene til koblingene vil først komme i kontakt med innsiden av brønnen, og utsettes således for gnidning mot veggene i brønnen eller mot en eventuell foring i brønnen. The outer surfaces of the couplings necessarily protrude outside the pipes, to which they are joined via conical transitions, and the outer surfaces of the couplings will first come into contact with the inside of the well, and thus be exposed to rubbing against the walls of the well or against any lining in the well.
Rotasjon av borestrengen i brønnen vil derfor bevirke en kontinuerlig slitasje av koblingene, og dette nedsetter bruks-tiden til borerørene i for stor grad, idet de høye omkost-ninger ved utskiftning av borerør i stor grad påvirker den totale økonomi for boreoperasjonen. Rotation of the drill string in the well will therefore cause continuous wear of the couplings, and this reduces the service life of the drill pipes to a large extent, as the high costs of replacing drill pipes greatly affect the overall economy of the drilling operation.
I henhold til kjent teknikk unngås denne ulempe ved at muffedelen av koblingen overflateherdes, ettersom denne del er mest utsatt for slitasje. Nærmere bestemt herdes bare et omkretsbånd på koblingsdelen som ligger mellom det gjengede parti og det koniske parti, og som har en bredde på omtrent 60 - 80 mm, ettersom det gjengede parti ikke kan herdes, fordi det må være så mykt at det oppnås pålitelig griping ved hjelp av skrue-verktøy, og den koniske sone trenger ikke å herdes. According to known technology, this disadvantage is avoided by surface-hardening the sleeve part of the coupling, as this part is most exposed to wear. Specifically, only a circumferential band of the coupling part located between the threaded portion and the conical portion, and having a width of approximately 60 - 80 mm, is hardened, as the threaded portion cannot be hardened, because it must be so soft that reliable gripping is achieved using screw tools, and the conical zone does not need to be hardened.
Den herdemetode som vanligvis benyttes består i at det på omkretsbåndet påføres et hardt material, slik som wolframkarbid, som er i form av små partikler med uregelmessig form eller kuleform, ved fastsmelting. På grunn av smeltingen vil det tilsetningsmateriale som wolframkarbidet er blandet med sammenføyes med det smeltede stålet i koblingsdelens overflate, og herdematerialet vil således bli festet i ytter-flaten av koblingsdelen. The hardening method that is usually used consists of applying a hard material, such as tungsten carbide, which is in the form of small particles with an irregular shape or spherical shape, to the circumferential band, by solidification. Due to the melting, the additive material with which the tungsten carbide is mixed will be joined with the molten steel in the surface of the coupling part, and the hardening material will thus be fixed in the outer surface of the coupling part.
Denne kjente metode innebærer imidlertid alvorlige ulemper, ved at, selv om herdeelementene har små dimensjoner, den dannede overflate har øket hardhet, men er også meget ru, og skader foringen i brønnen. However, this known method entails serious disadvantages, in that, even though the hardening elements have small dimensions, the formed surface has increased hardness, but is also very rough, and damages the lining in the well.
Vanligvis er bare en liten del av brønnen uten foring, og det meste av brønnen er således foret og utsatt for den skadelige virkning av den herdede kobling, og denne ulempe er mere alvorlig enn den ovenfor nevnte ulempe, idet det tidligere oppsto stor slitasje på borerørene, slik at disse etter kort brukstid ikke kunne benyttes uten å skade brønnen, mens de herdede koblinger gir forholdsvis lang brukstid for bore-rørene, mens derimot foringen i brønnen blir skadet, og kan ikke repareres, etter som foringen er et permanent element i brønnen, og det kan ikke tolereres skade eller slitasje av noe slag når det gjelder foringen. Usually only a small part of the well is unlined, and most of the well is thus lined and exposed to the harmful effect of the hardened coupling, and this disadvantage is more serious than the above-mentioned disadvantage, as previously there was a lot of wear on the drill pipes , so that after a short period of use these could not be used without damaging the well, while the hardened connections provide a relatively long service life for the drill pipes, while on the other hand the liner in the well is damaged and cannot be repaired, as the liner is a permanent element in the well , and damage or wear of any kind cannot be tolerated when it comes to the lining.
Formålet med den foreliggende oppfinnelse er å unngå de nevnte ulemper, og å komme frem til en fremgangsmåte for overflateherding av et omkretsbånd på muffedelen av koblinger for borerør som ikke bevirker ru overflate, slik at koblingene ikke bevirker skade på foringen i brønnen. Dette oppnås hovedsakelig ved at det benyttes stråling fra CO^genera-torer, også kjent som laserstråler, for å danne en strøm av energi langs omkretsbåndet på koblingsdelen som skal herdes, for å oppvarme denne til under smeltetemperaturen, i et tynt overflatelag med en tykkelse på 1 mm, til austenitiseringstemperaturen. På grunn av den begrensede mengde varme som kreves for dette formål overføres denne varme ved å ledes til de underliggende kaldere lag så hurtig at det behandlede overflatelag i båndet omdannes fra austenittstruktur til martensittstruktur, og således blir meget hardt (herdet stål). Fordelene med en slik type herding vil umiddelbart fremgå av det oppnådde resultat, den praktiske brukbarhet og omkost-ningene. Det oppnås en eksepsjonell hardhet nøyaktig i de ønskede områder, fordi laserstrålen består av elektromagnetisk stråling som er lett å kontrollere og å innrette i samsvar med optiske lover. På den annen side er det ikke noe behov for kostbare herdematerialer slik som wolframkarbid eller for det kompliserte utstyr som er nødvendig for sliping, smelting og påføring av slike materialer, ettersom behandlingen utføres ved innbyrdes bevegelse mellom koblingen og den fokuserte stråle, idet laserstrålen ikke virker under vakuum og danner ikke forbrenningsprodukter eller gasser slik som ved påføring av wolframkarbid. The purpose of the present invention is to avoid the aforementioned disadvantages, and to come up with a method for surface hardening of a circumferential band on the sleeve part of couplings for drill pipes which does not cause a rough surface, so that the couplings do not cause damage to the casing in the well. This is mainly achieved by using radiation from CO^ generators, also known as laser beams, to form a stream of energy along the circumferential band of the coupling part to be hardened, to heat this to below the melting temperature, in a thin surface layer with a thickness of 1 mm, to the austenitizing temperature. Due to the limited amount of heat required for this purpose, this heat is transferred by being conducted to the underlying colder layers so quickly that the treated surface layer in the strip is converted from an austenite structure to a martensite structure, and thus becomes very hard (hardened steel). The advantages of this type of curing will be immediately apparent from the result achieved, the practical usability and the costs. Exceptional hardness is achieved precisely in the desired areas, because the laser beam consists of electromagnetic radiation that is easy to control and to align in accordance with optical laws. On the other hand, there is no need for expensive hardening materials such as tungsten carbide or for the complicated equipment necessary for grinding, melting and applying such materials, as the treatment is carried out by mutual movement between the coupling and the focused beam, the laser beam not acting under vacuum and does not form combustion products or gases as when applying tungsten carbide.
Det er også funnet 'at for at behandlingen skal være mest effektiv må omkretsbåndet på muffedelen av koblingen som skal overflateherdes rengjøres ved å børstes eller sandblåses før behandlingen, for å lette absorpsjonen av laserstråleenergien, og båndet bør også forvarmes induktivt for å hindre dannelsen av brister som kan danne utgangspunkt for brudd i overgangs-sonen mellom det behandlede overflatelag og det indre av koblingen som har hovedsakelig uendret struktur. It has also been found that in order for the treatment to be most effective, the circumferential band of the sleeve portion of the coupling to be surface hardened must be cleaned by brushing or sandblasting prior to the treatment, to facilitate the absorption of the laser beam energy, and the band should also be inductively preheated to prevent the formation of cracks which can form the starting point for breakage in the transition zone between the treated surface layer and the interior of the coupling, which has an essentially unchanged structure.
Fremgangsmåten for overflateherding av et omkretsbånd på en muffedel av en kobling for borerør av stål der båndet ligger mellom en sone med innvendige gjenger i koblingsdelen, og en konisk sone i overgangen mellom koblingen og det sylindriske rør, kjennetegnes i henhold til oppfinnelsen ved de følgende trinn: Rengjøring av omkretsbåndet ved børsting og/eller sandblåsing, induktiv forvarming av båndet, og oppvarming av et overflatelag i båndet med en tykkelse i området 1 mm til austenitiseringstemperatur ved hjelp av en energistrøm dannet ved stråling fra en CC^lasergenerator. The method for surface hardening of a circumferential band on a sleeve part of a coupling for steel drill pipe where the band lies between a zone with internal threads in the coupling part, and a conical zone in the transition between the coupling and the cylindrical pipe, is characterized according to the invention by the following steps : Cleaning of the circumferential band by brushing and/or sandblasting, inductive preheating of the band, and heating of a surface layer in the band with a thickness in the region of 1 mm to austenitizing temperature by means of an energy flow generated by radiation from a CC^laser generator.
Ettersom det således herdede omkretsbånd på muffedelen av koblingen ikke bare er meget hardt men også meget sprøtt, utføres, for å minske faren for sprekkdannelse til et minimum og således gjøre koblingen mere motstandsdyktig mot de for-skjellige påkjenninger under bruk, i henhold til en fore-trukket utførelsesform av oppfinnelsen, herdingen av båndet ikke i hele bredden av båndet, men bare i parallelle strimler, for å kompensere for den meget lave elastisitet i de herdede soner eller strimler ved hjelp av den uendrede elastisitet i de uherdede, mellomliggende strimler. As the circumferential band thus hardened on the sleeve part of the coupling is not only very hard but also very brittle, in order to reduce the risk of cracking to a minimum and thus make the coupling more resistant to the various stresses during use, it is carried out according to a -drawn embodiment of the invention, the hardening of the tape not over the entire width of the tape, but only in parallel strips, to compensate for the very low elasticity in the hardened zones or strips by means of the unchanged elasticity in the uncured, intermediate strips.
Oppfinnelsen skal i det følgende beskrives nærmere under hen-visning til den vedlagte tegning, som illustrerer en fore-trukket utførelsesform av et borerør i henhold til oppfinnelsen. The invention will be described in more detail below with reference to the attached drawing, which illustrates a preferred embodiment of a drill pipe according to the invention.
Tegningen viser et sylindrisk borerør 1 av stål idet den nedre ende av røret går over i en konisk sone 2 og en tappdel 3 av en kobling, utstyrt med utvendige gjenger 4, og den øvre ende av røret går over i en konisk sone 5 og en muffedel 6 av koblingen, utstyrt med innvendige gjenger 7. Omkretsbåndet F til muffekoblingsdelen 6 som ligger mellom sonen 7 med innvendige gjenger og den koniske sone 5 er herdet langs parallelle strimler 8^, 8^og 83, ved hjelp av en laserstråle som hever temperaturen i et ytre lag av strimlene med en tykkelse i området 1 mm til austenitiseringstemperaturen. The drawing shows a cylindrical drill pipe 1 made of steel, the lower end of the pipe passing into a conical zone 2 and a spigot part 3 of a coupling, equipped with external threads 4, and the upper end of the pipe passing into a conical zone 5 and a sleeve part 6 of the coupling, equipped with internal threads 7. The circumferential band F of the sleeve coupling part 6 lying between the zone 7 with internal threads and the conical zone 5 is hardened along parallel strips 8^, 8^ and 83, by means of a laser beam which raises the temperature in an outer layer of the strips with a thickness in the region of 1 mm to the austenitizing temperature.
Før laserstrålen benyttes rengjøres strimlene ved børsting og/eller sandblåsing, og forvarmes induktivt, idet laser-behandlingen av strimlene utføres ved innbyrdes bevegelse mellom koblingsdelen og laserstrålen ved hjelp av kjente midler som muliggjør at koblingsdelene kan rotere og beveges langs sin akse mens laserstrålen er ubevegelig, eller som holder koblingsdelene ubevegelige og bevirker at laserstrålen utfører bevegelser i form av passende rotasjon og rettlinjede bevegelser av refleksjonsflåtene. Before the laser beam is used, the strips are cleaned by brushing and/or sandblasting, and preheated inductively, as the laser treatment of the strips is carried out by mutual movement between the coupling part and the laser beam using known means which enable the coupling parts to rotate and move along their axis while the laser beam is motionless , or which keep the coupling parts immobile and cause the laser beam to perform movements in the form of appropriate rotation and rectilinear movements of the reflection rafts.
Claims (2)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT22647/84A IT1176705B (en) | 1984-09-13 | 1984-09-13 | PROCEDURE PERFECTED FOR SURFACE HARDENING OF THE JOINTS OF THE DRILLING AUCTIONS AND AUCTIONS SO OBTAINED |
Publications (1)
Publication Number | Publication Date |
---|---|
NO853543L true NO853543L (en) | 1986-03-14 |
Family
ID=11198819
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
NO853543A NO853543L (en) | 1984-09-13 | 1985-09-11 | PROCEDURE FOR SURFACE CURRENCY OF THE CIRCUIT BANDS IN A CONNECTION BETWEEN PARTS OF A DRILL STRING. |
Country Status (15)
Country | Link |
---|---|
JP (1) | JPS6179725A (en) |
AU (1) | AU576383B2 (en) |
BE (1) | BE903227A (en) |
BR (1) | BR8504550A (en) |
CA (1) | CA1253054A (en) |
DE (1) | DE3532451A1 (en) |
DK (1) | DK413185A (en) |
ES (1) | ES8609491A1 (en) |
FR (1) | FR2570084A1 (en) |
GB (1) | GB2164358B (en) |
IT (1) | IT1176705B (en) |
NL (1) | NL8502505A (en) |
NO (1) | NO853543L (en) |
NZ (1) | NZ213327A (en) |
PT (1) | PT81120B (en) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SE450151B (en) * | 1985-11-21 | 1987-06-09 | Ffv Transmission Ab | DEVICE WITH CONTROLLED FRICTION AND PROCEDURE TO RECEIVE CONTROL FRICTION BY SUCH A DEVICE |
US4708752A (en) * | 1986-03-24 | 1987-11-24 | Smith International, Inc. | Process for laser hardening drilling bit cones having hard cutter inserts placed therein |
CA2038378C (en) * | 1991-03-25 | 1998-08-18 | Irvin Joseph Laporte (Bud) | Stabilized drill tube |
GB2257163B (en) * | 1991-07-02 | 1995-04-05 | Res & Dev Min Def Gov In | A process for improving fatigue crack growth resistance |
EP1045958B1 (en) * | 1998-01-05 | 2008-05-14 | Weatherford U.S., L.P. | A drill pipe and method of forming and reconditioning a drill pipe |
WO2005001234A1 (en) * | 2003-06-30 | 2005-01-06 | Todd Andrew Haines | Sub-assembly for drill strings |
DE102007044696A1 (en) * | 2007-06-29 | 2009-01-08 | Ks Kolbenschmidt Gmbh | Melt-treated bowl rim of a piston combustion bowl |
JP4790767B2 (en) * | 2008-07-16 | 2011-10-12 | 川崎重工業株式会社 | Swash plate type hydraulic rotating machine |
SE535814C2 (en) | 2011-05-20 | 2013-01-02 | Atlas Copco Secoroc Ab | Threading device, threaded joint and drill string component for striking rock drilling |
FR3015546B1 (en) | 2013-12-20 | 2015-12-25 | Vallourec Drilling Products France | DRILL LINING ELEMENT HAVING AN IMPROVED REFILL LAYER |
CN106761460A (en) * | 2017-03-15 | 2017-05-31 | 吉林大学 | Graphene shaped wear-resistant belt of drill pipe joint prepared by a kind of laser melting coating |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE920135C (en) * | 1951-06-22 | 1954-11-15 | Rheinische Roehrenwerke Ag | Process for the production of wear-resistant linkage pipe connectors and sleeves for oil field pipes |
US3489620A (en) * | 1967-03-01 | 1970-01-13 | United States Steel Corp | Method of processing sucker rods and resulting article |
DE1783058A1 (en) * | 1968-09-26 | 1971-02-18 | Gerd Hoeptner | Process for hardening cutting and chipping tools with higher cutting edge hardness |
GB1496377A (en) * | 1974-11-26 | 1977-12-30 | Nippon Steel Corp | Method of heat-treatment of welded pipe and apparatus therefor |
CA1063439A (en) * | 1976-09-28 | 1979-10-02 | Torrington Company (The) | Textile element and method of making same |
DE3343783C1 (en) * | 1983-12-03 | 1984-07-05 | M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8900 Augsburg | Process for the production of wear-resistant cylinder running surfaces of internal combustion engines |
-
1984
- 1984-09-13 IT IT22647/84A patent/IT1176705B/en active
-
1985
- 1985-08-30 AU AU46906/85A patent/AU576383B2/en not_active Ceased
- 1985-09-02 NZ NZ213327A patent/NZ213327A/en unknown
- 1985-09-02 GB GB08521740A patent/GB2164358B/en not_active Expired
- 1985-09-10 CA CA000490381A patent/CA1253054A/en not_active Expired
- 1985-09-11 FR FR8513461A patent/FR2570084A1/en not_active Withdrawn
- 1985-09-11 DK DK413185A patent/DK413185A/en not_active Application Discontinuation
- 1985-09-11 DE DE19853532451 patent/DE3532451A1/en active Granted
- 1985-09-11 NO NO853543A patent/NO853543L/en unknown
- 1985-09-12 NL NL8502505A patent/NL8502505A/en not_active Application Discontinuation
- 1985-09-12 PT PT81120A patent/PT81120B/en not_active IP Right Cessation
- 1985-09-12 BE BE0/215578A patent/BE903227A/en not_active IP Right Cessation
- 1985-09-12 JP JP60200689A patent/JPS6179725A/en active Pending
- 1985-09-13 BR BR8504550A patent/BR8504550A/en unknown
- 1985-09-13 ES ES547703A patent/ES8609491A1/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
DE3532451C2 (en) | 1987-10-22 |
GB2164358B (en) | 1988-08-03 |
IT8422647A0 (en) | 1984-09-13 |
ES547703A0 (en) | 1986-09-01 |
DE3532451A1 (en) | 1986-03-20 |
IT1176705B (en) | 1987-08-18 |
GB8521740D0 (en) | 1985-10-09 |
AU576383B2 (en) | 1988-08-25 |
DK413185D0 (en) | 1985-09-11 |
BE903227A (en) | 1986-03-12 |
PT81120B (en) | 1992-05-29 |
CA1253054A (en) | 1989-04-25 |
ES8609491A1 (en) | 1986-09-01 |
GB2164358A (en) | 1986-03-19 |
AU4690685A (en) | 1986-03-20 |
BR8504550A (en) | 1986-07-15 |
PT81120A (en) | 1985-10-01 |
DK413185A (en) | 1986-03-14 |
NL8502505A (en) | 1986-04-01 |
NZ213327A (en) | 1987-05-29 |
FR2570084A1 (en) | 1986-03-14 |
JPS6179725A (en) | 1986-04-23 |
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