SE7910020L - Elsvetsmuff av termoplastiskt material - Google Patents

Elsvetsmuff av termoplastiskt material

Info

Publication number
SE7910020L
SE7910020L SE7910020A SE7910020A SE7910020L SE 7910020 L SE7910020 L SE 7910020L SE 7910020 A SE7910020 A SE 7910020A SE 7910020 A SE7910020 A SE 7910020A SE 7910020 L SE7910020 L SE 7910020L
Authority
SE
Sweden
Prior art keywords
spirals
winding
thermoplastic material
resistance wire
electric welding
Prior art date
Application number
SE7910020A
Other languages
English (en)
Other versions
SE457556B (sv
Inventor
W Sturm
Original Assignee
Sturm Werner
Von Roll Ag
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.)
Filing date
Publication date
Application filed by Sturm Werner, Von Roll Ag filed Critical Sturm Werner
Publication of SE7910020L publication Critical patent/SE7910020L/sv
Publication of SE457556B publication Critical patent/SE457556B/sv

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29DPRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D23/00Producing tubular articles
    • B29D23/001Pipes; Pipe joints
    • B29D23/003Pipe joints, e.g. straight joints
    • B29D23/005Pipe joints, e.g. straight joints provided with electrical wiring
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C61/00Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor
    • B29C61/06Making preforms having internal stresses, e.g. plastic memory
    • B29C61/0608Making preforms having internal stresses, e.g. plastic memory characterised by the configuration or structure of the preforms
    • B29C61/0625Preforms comprising incorporated or associated heating means
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/34Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
    • B29C65/3404Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint
    • B29C65/342Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint comprising at least a single wire, e.g. in the form of a winding
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/34Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
    • B29C65/3472Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
    • B29C65/3476Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/66Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by liberation of internal stresses, e.g. shrinking of one of the parts to be joined
    • B29C65/68Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by liberation of internal stresses, e.g. shrinking of one of the parts to be joined using auxiliary shrinkable elements
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/01General aspects dealing with the joint area or with the area to be joined
    • B29C66/05Particular design of joint configurations
    • B29C66/10Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/11Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/112Single lapped joints
    • B29C66/1122Single lap to lap joints, i.e. overlap joints
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/50General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/52Joining tubular articles, bars or profiled elements
    • B29C66/522Joining tubular articles
    • B29C66/5221Joining tubular articles for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/50General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/52Joining tubular articles, bars or profiled elements
    • B29C66/522Joining tubular articles
    • B29C66/5229Joining tubular articles involving the use of a socket
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/50General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/63Internally supporting the article during joining
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/90Measuring or controlling the joining process
    • B29C66/91Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
    • B29C66/914Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
    • B29C66/9161Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux
    • B29C66/91651Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/68Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts by incorporating or moulding on preformed parts, e.g. inserts or layers, e.g. foam blocks
    • B29C70/82Forcing wires, nets or the like partially or completely into the surface of an article, e.g. by cutting and pressing
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16LPIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L47/00Connecting arrangements or other fittings specially adapted to be made of plastics or to be used with pipes made of plastics
    • F16L47/02Welded joints; Adhesive joints
    • F16L47/03Welded joints with an electrical resistance incorporated in the joint
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/34Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
    • B29C65/3468Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the means for supplying heat to said heated elements which remain in the join, e.g. special electrical connectors of windings
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/01General aspects dealing with the joint area or with the area to be joined
    • B29C66/347General aspects dealing with the joint area or with the area to be joined using particular temperature distributions or gradients; using particular heat distributions or gradients
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00General aspects of processes or apparatus for joining preformed parts
    • B29C66/50General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/52Joining tubular articles, bars or profiled elements
    • B29C66/522Joining tubular articles
    • B29C66/5229Joining tubular articles involving the use of a socket
    • B29C66/52291Joining tubular articles involving the use of a socket said socket comprising a stop
    • B29C66/52294Joining tubular articles involving the use of a socket said socket comprising a stop said stop being heated

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Branch Pipes, Bends, And The Like (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)
  • Shaping Of Tube Ends By Bending Or Straightening (AREA)
SE7910020A 1978-05-02 1979-12-05 Foerfarande foer framstaellning av en elsvetsmuff SE457556B (sv)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH476078A CH630162A5 (de) 1978-05-02 1978-05-02 Elektro-schweissmuffe aus thermoplastischem material.

Publications (2)

Publication Number Publication Date
SE7910020L true SE7910020L (sv) 1979-12-05
SE457556B SE457556B (sv) 1989-01-09

Family

ID=4282034

Family Applications (1)

Application Number Title Priority Date Filing Date
SE7910020A SE457556B (sv) 1978-05-02 1979-12-05 Foerfarande foer framstaellning av en elsvetsmuff

Country Status (12)

Country Link
EP (1) EP0015958B1 (sv)
JP (1) JPS6340993B2 (sv)
AT (1) AT360293B (sv)
BE (1) BE875992A (sv)
CA (1) CA1118011A (sv)
CH (1) CH630162A5 (sv)
DE (2) DE2947583D2 (sv)
GB (1) GB2036518B (sv)
IT (1) IT1112585B (sv)
NL (1) NL7903215A (sv)
SE (1) SE457556B (sv)
WO (1) WO1979001018A1 (sv)

Families Citing this family (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH644054A5 (de) * 1980-03-31 1984-07-13 Fischer Ag Georg Schweissmuffe fuer thermoplastische materialien, verfahren und vorrichtung zu deren herstellung.
JPS6142160B2 (sv) * 1980-08-22 1986-09-19 Esudan Pty Ltd
GB2090558B (en) * 1981-01-06 1984-08-30 British Gas Corp Method of manufacture of a heat sealable fitting and fitting made by such method
FR2503020A1 (fr) * 1981-04-02 1982-10-08 Rech Applic Plastiques Et Raccord electrosoudable en matiere thermoplastique et procede de fabrication
FR2516439A1 (fr) * 1981-11-13 1983-05-20 Armosig Procede de soudage electrique de pieces en matiere plastique, en particulier pour canalisations de fluides et manchons de raccordement pour de telles canalisations
DE3204681C2 (de) * 1982-02-11 1986-02-06 Friedrichsfeld Gmbh, Steinzeug- Und Kunststoffwerke, 6800 Mannheim Verfahren und Vorrichtung zum Einbetten eines elektrischen Heizdrahtes in einem muffenartigen Kunststoffteil
CH657907A5 (de) * 1982-06-23 1986-09-30 Von Roll Ag Muffe aus thermoplastischem material zum verbinden von leitungselementen.
DE3272031D1 (en) * 1982-10-05 1986-08-21 Rech Et D Applic Des Plastique Electrical plastic welding sleeve and method for its manufacture
US4626308A (en) * 1983-02-18 1986-12-02 The Victaulic Company Plc Method of making welded pipe joints
GB8719430D0 (en) * 1987-08-17 1987-09-23 Glynwed Tubes & Fittings Manufacturing electrofusion coupler
GB8910070D0 (en) * 1989-05-03 1989-06-21 Fusion Plastics Ltd Electro-fusion fittings
JP2736805B2 (ja) * 1989-05-19 1998-04-02 日本鋼管継手株式会社 合成樹脂管継手
JPH03793U (sv) * 1989-05-26 1991-01-08
GB2235740B (en) * 1989-08-22 1992-12-23 British Gas Plc Grouted pipe joint for polyolefin-lined pipes
FI87318C (sv) * 1991-06-14 1992-12-28 Kwh Pipe Ab Oy Förfarande för skarvning av spirallindade termoplaströr
JPH0715602A (ja) * 1993-06-15 1995-01-17 Toshiba Corp 画像データ処理装置
GB2299047A (en) * 1995-03-21 1996-09-25 Uponor Ltd Manufacture of electrofusion fittings
DE19628916A1 (de) * 1995-10-12 1997-04-17 Fischer Georg Rohrleitung Muffe zum Verbinden von Rohrleitungsteilen
FR2748415B1 (fr) * 1996-05-09 1998-06-26 Etex De Rech Tech Soc Element de raccord pour un assemblage de pieces en materiaux thermoplastiques par soudage et procede de fabrication d'un tel element
CN113580588A (zh) * 2021-08-10 2021-11-02 安徽杰蓝特新材料有限公司 一种挤出型rtp复合压力管件的加工工艺

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL236188A (sv) * 1958-02-17
CH515449A (de) * 1970-09-08 1971-11-15 Rollmaplast Ag Elektrisch schweissbare Rohrmuffe aus Kunststoff mit Berührungsschutz
CH544906A (de) * 1971-11-12 1974-01-15 Gerbert & Cie Elektrisch heizbare Schweissmuffe und Verfahren zu deren Herstellung
US4117311A (en) * 1976-03-22 1978-09-26 Von Roll Ag. Electric welding muff
CH622870A5 (sv) * 1977-06-03 1981-04-30 Werner Sturm

Also Published As

Publication number Publication date
BE875992A (fr) 1979-11-05
SE457556B (sv) 1989-01-09
ATA320779A (de) 1980-05-15
EP0015958B1 (de) 1983-11-09
DE2947583D2 (en) 1980-11-13
WO1979001018A1 (en) 1979-11-29
EP0015958A1 (de) 1980-10-01
CA1118011A (en) 1982-02-09
JPS6340993B2 (sv) 1988-08-15
AT360293B (de) 1980-12-29
GB2036518A (en) 1980-06-25
JPS55500479A (sv) 1980-07-31
DE2947583C1 (de) 1987-04-23
NL7903215A (nl) 1979-11-06
IT7922232A0 (it) 1979-04-27
CH630162A5 (de) 1982-05-28
IT1112585B (it) 1986-01-20
GB2036518B (en) 1982-11-03

Similar Documents

Publication Publication Date Title
GB2036518B (en) Thermoplastic welding sleeve
US4436988A (en) Spiral bifilar welding sleeve
ES257226Y (es) Manguito para soldadura
GB2036225A (en) Welding sleeve of thermoplastic material
FI831306L (fi) Svetsmuff.
NL7114535A (sv)
GB2282201A (en) Thermoplastic welding sleeve
SE8105690L (sv) Forfarande och anordning for lindning av skruvlinjeformade foremal
US2423021A (en) Resistor ballast
FR2452048A1 (fr) Manchon en matiere synthetique pouvant etre soude au moyen d'une resistance electrique dont les spires entourent le manchon
ES2043653T3 (es) Accesorios para tubos soldables por calor.
JPS57193276A (en) Production of finned tube
JPS57171655A (en) Production of spring made of shape memory alloy
JPS5716788A (en) Manufacture of heat pipe
SU733235A1 (ru) Гибкий дорн дл игз рукавных изделий
FR2658692B1 (fr) Generateur electrothermique pour le chauffage de liquide, avec un ruban electriquement resistant spirale sur un tube traverse par le liquide.
KR880004529A (ko) 전자기 편향 유닛 제조 방법
JPS56134464A (en) Electrode for electric-discharge lamp
GB1139912A (en) Improvements in or relating to extensible coils
JPS5570015A (en) Manufacture of resin molded coil
JPS57163540A (en) Manufacture of spraying pipe for agricultural chemical
JPH0751296B2 (ja) 溶着継手の製造方法
JPS5527692A (en) High voltage bushing for distributing transformer
GB580489A (en) Improvements in or relating to protective waterproof coverings of electrical condensers and resistances and other objects of irregular prismatic shape
JPS5788987A (en) Production of small diameter pipe

Legal Events

Date Code Title Description
NUG Patent has lapsed

Ref document number: 7910020-2

Effective date: 19911209

Format of ref document f/p: F