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Title: Thermally insulated pipe with electrically conducting portions for dissipating static electricity
Claims: What is claimed is: 1. A thermally insulated pipe, in particular a pipe for mining industries, comprising a plastic outer pipe and an inner pipe, the pipes being concentrically positioned with respect to each other, and a thermally insulating layer of heat resistant material between the inner and the outer pipe, said outer pipe having an electrically conductive outer surface layer which is electrically conductively connected with the inner pipe. 2. A pipe as claimed in claim 1, wherein the inner pipe is made of metal and includes metal support flanges spaced from the end zones of the pipe, said flanges cooperate conductingly with said electrically conductive surface layer on the outside of the plastic pipe, and said electrically conductive surface layer extends into the inside of the plastic pipe at least to the point where the flanges are positioned. 3. A pipe according to claim 1, wherein said inner pipe includes support flanges spaced from the end zones of the pipe, said electrically conductive surface layer extending to the inside of said plastic outer pipe at least up to the point at which the flanges are positioned and defining a conductive inner layer adjacent said end zones. 4. A pipe according to claim 3, wherein the support flanges and the conductive inner layer cooperate conductively and sealingly with the plastic outer pipe. 5. A pipe according to claim 3, wherein at least one of the support flanges includes a circumferential groove, a sealing ring of conductive material accommodated in said circumferential groove between the outer pipe and said one support flange. 6. A pipe according to claim 3, wherein the inner pipe is made of plastic and each support flange is made of a conductive elastomer and the outside surface of the inner pipe is provided with a conductive surface layer. 7. A pipe according to claim 3, wherein each support flange is provided with at least one closeable opening. 8. A pipe according to claim 7, wherein the inside of one of the flanges has a layer of filter material covering said at least one opening. 9. A pipe according to claim 8, wherein the layer of filter material is a fibrous layer, a woven layer or an asbestos layer. 10. A pipe according to claim 3, wherein at least one of the flanges comprises two flat parts which clampingly cooperate with a resilient circular ring, which ring clampingly cooperates with the inside of the outer pipe. 11. A pipe according to claim 10, wherein the circular ring constitutes a flat disc, the inside circumference of the disc clampingly cooperating with the outside of the inner pipe owing to the clamping cooperation of the flat parts. 12. A pipe according to claim 11, wherein the flat disc is constructed of circular segments, the separation lines of the circular segments being juxtaposed. 13. A pipe according to claim 1, wherein the insulating layer consists of thermally insulating filling particles covered with an electrically conductive layer. 14. A pipe according to claim 1, wherein the outer pipe constitutes shells which cooperate sealingly, the inside of the shells being provided with an insulating layer. 15. A pipe according to claim 1, wherein the conductive layer is a thermosetting resin with soot particles. 16. A pipe according to claim 1, further including an electrically conductive rubber ring positioned between the outer and inner pipes, said outer and inner pipes having inner and outer electrically conductive layers respectively arranged adjacent said ring, said ring extending from the electrically conductive inner layer on the outer pipe up to the electrically conductive outer layer of the inner pipe. 17. A pipe according to claim 1, wherein said electrically conductive layer comprises a resinous material admixed with electrically conductive particles. Other info: Inventors: de Putter, Warner Jan (Hardenberg, NL) Application Number: 743658 Filing Date: 1976-11-22 Publication_date: 1978-07-25 Assignee: Wavin B. V. (Zwolle, NL) Primary Class(es): 361/215 138/103, 138/149, 174/47 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Askin, Laramie E. Assistant Examiner: Attorney: Wigman & Cohen |
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