PIPELINE FOR CONVEYING FLUIDS OR SOLIDS

Abstract

A pipeline for conveying fluids or solids has a metallic pipe on which a tubular lining made of plastic is arranged on an inner wall. The wall structure with the lining and the metallic pipe are designed to be electrically conductive and the electrical resistance of the wall structure being less than 10.sup.8Ω. This allows the electrostatically charged bulk material or fluid to discharge reliably when passing through the pipe.

Claims

1. A pipeline for conveying fluids or solids, comprising a metallic pipe having an inner wall and a tubular lining made of plastic arranged on the inner wall, wherein a wall structure with the lining and the metallic pipe is configured to be electrically conductive, and a specific volume resistance R.sub.v of the pipeline is less than 10.sup.8 Ωm.

2. The pipeline according to claim 1, wherein the volume resistance R.sub.v of the pipeline is between 1.5×10.sup.6 Ωm and 2.8×10.sup.6 Ωm,

3. The pipeline according to claim 1, wherein the volume resistance R.sub.v of the pipeline is between 2.0×10.sup.6 Ωm and 2.3×10.sup.6 Ωm.

4. The pipeline according to claim 1, wherein the lining of plastic comprises a polyurethane, a polyester and/or diphenylmethane.

5. The pipeline according to claim 1, wherein the lining is fixed to the metallic pipe by mechanical fastening means made of metal.

6. The pipeline according to claim1, wherein the lining is bonded to the metallic pipe.

7. The pipeline according to claim 1, wherein the lining is held in a clamping manner in the metallic pipe without mechanical fastening means.

8. The pipeline according to claim 1, wherein the contact force of the lining on the metallic pipe at all measuring points is between 200N and 400N.

9. The pipeline according to claim 1, wherein the lining has a surface resistance between 2×10.sup.−7Ω and 50×10.sup.−7Ω measured with a ring electrode according to EN ISO 284:2004 at a measuring voltage of 1,000 V according to IEC 60079.-32-2:2015.

10. The pipeline according to claim 1, wherein the lining has a thickness in a radial direction of between 3 mm and 10 mm.

11. The pipeline according to claim 10, wherein the lining has a thickness in the radial direction of between 5 mm and 8 mm.

12. The pipeline according to claim 1, wherein an insert made of metal is arranged in the lining.

13. The pipeline according to claim 12, wherein the insert is formed as an expanded metal.

14. The pipeline according to claim 1, wherein the metallic pipe is made of stainless steel.

15. The pipeline according to claim 1, wherein the lining has a specific surface resistance smaller than 8×10.sup.8Ω.

16. The pipeline according to claim 1, wherein the lining has a contact resistance R.sub.v according to DIN 54345-1:1992 at a measuring voltage of 1,000 V according to IEC 60079-32-2:2015 between 0.5×10.sup.7Ω and 15×10.sup.7Ω.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention is explained in more detail below by means of an example of an embodiment with reference to the accompanying drawings, wherein:

[0022] FIG. 1 shows a section through a pipeline according to the invention;

[0023] FIG. 2 shows a detailed view of the pipeline of FIG. 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] A pipeline 1 comprises a metallic pipe 2 in which an inner tubular lining 3 made of plastic is arranged. The lining 3 is inserted into the metallic pipe 2 and is clamped to an inner wall of the pipe by a metallic fastening means 4, for example a screw. Several fastening means 4 can be provided distributed over the circumference.

[0025] FIG. 2 shows in detail the lining 3 and the pipe 2, which are spaced apart without fastening means and between which a gap (d) is formed which can form a condenser. To avoid such gaps, the lining 3 is preferably in clamping contact with the inner wall of the metallic pipe 2. Alternatively or additionally, the lining 3 can also lie against the metallic pipe 2 in a clamping manner without fastening means 4 or be bonded to the metallic pipe 2, in particular via a conductive adhesive.

[0026] According to the invention, the pipeline 1 with the wall structure of lining 3 and metallic pipe 2 is designed to be conductive, with the volume resistivity R.sub.v of the pipeline 1 formed in this way being less than 10.sup.8 Ωm.

[0027] For this purpose, the plastic lining can comprise polyurethane or be made of polyurethane and have a specific surface resistance of less than 8×10.sup.8 Ωm. Optionally, a metallic insert, such as an expanded metal mesh, can also be arranged in the lining. However, such an insert can also be dispensed with for greater elasticity.

[0028] Bulk materials are preferably conveyed through the pipeline 1, for example sand, gravel, grain, soybeans, corn or flour, which have a high abrasive effect when conveyed, wherein the metallic pipe 2 is protected by the inner lining made of plastic. The metallic pipe 2 may have a diameter between 80 and 1000 mm, in particular 150 and 350 mm, the thickness of the metallic pipe 2 being for example 1 mm to 3 mm and the thickness of the lining being for example between 3 mm to 12 mm, in particular 5 mm to 10 mm.

[0029] To produce the lining, a preferably plate-shaped material is cut to size and then formed into a tubular body, which is then inserted into the outer metallic pipe 2. The lining 3 is then fixed to the metallic pipe 2 via fastening means 4 and/or adhesives.

[0030] To measure the electrostatic chargeability, a metallic tube made of stainless steel with a diameter of 200 mm and a wall thickness of 2 mm was internally covered with a lining made of plastic, which was fixed to the metallic tube via fasteners in the form of screws. The test specimen thus obtained was examined at a relative humidity of 25 to 30% and a temperature of 23° C.

[0031] A strip electrode with a length/distance ratio of 10:1 at a measurement voltage of 1000V was placed on the lining in accordance with IEC 60079-32-2:2015 to perform measurements to determine the volume resistivity. The volume resistivity is calculated from the measured volume resistance, the effective electrode area of the strip electrode and the material thickness.

[0032] The volume resistivity R.sub.v for different samples ranged from 1.5×10.sup.6 Ωm to 2.8×10.sup.6 Ωm, in particular 2.0×10.sup.6 Ωm and 2.3×10.sup.6 Ωm. The product of volume resistivity R.sub.v and electrode area ranged from 0.9×10.sup.4 Ωm.sup.2 to 1.8×10.sup.4 Ωm.sup.2, in particular 1.1×10.sup.4 Ωm.sup.2 to 1.6×10.sup.4 Ωm.sup.2.

[0033] This allows the lined pipeline to be used for conveying combustible dusts, flammable liquids and gases.

LIST OF REFERENCE NUMERALS

[0034] 1 Pipeline [0035] 2 Pipe [0036] 3 Lining [0037] 4 Fastening means [0038] d Gap