US 5,867,883 A · Extruded multiple plastic layer coating bonded to the outer surface of a metal tube having an optional non-reactive inner layer and process for making the same

Abstract

A multi-layer tube having a metal tube having an outer surface and a zinc layer bonded to the metal tube outer surface. The zinc layer being selected from the group consisting of zinc plating, zinc nickel alloys, zinc cobalt alloys, zinc aluminum alloys, and mixtures thereof. A surface treatment layer is bonded to the zinc layer, wherein the surface treatment layer is selected from the group consisting of a zinc/aluminum/rare earth alloy, phosphate, chromate and mixtures thereof. A first polymeric layer is bonded to the surface treatment layer, wherein the first polymeric layer is selected from the group consisting of a thermoplastic elastomer, an ionomer, a nylon, a fluoropolymer, and mixtures thereof. A second polymeric layer is bonded to the first polymeric layer, wherein the second polymeric layer is selected from the group consisting of a nylon, a thermoplastic elastomer, a fluoropolymer, and mixtures thereof. The tube also has a continuous interior layer made of non-reactive material which is preferably made of a polymeric material which is substantially non-reactive in the presence of short chain alcohols. The process for manufacturing the multi-layer tubing of the present invention also includes the steps of positioning a length of non-reactive tubing into the interior of unsealed metal tube, sealing the metal tube with the non-reactive tubing contained within and extruding multiple layers of a melt-processible thermoplastic onto the external surface metal tube the external surface can be pretreated with at least a zinc based coating and a sealant coating on top of the zinc based coating.

Claims22

Dependent claims

A process for manufacturing a metal tube having an interior surface resistant to interaction with materials to be conveyed therethrough, the method comprising:

positioning a length of preformed non-reactive tube composed of essentially solidified material having an external surface and a predetermined outer diameter within an inner diameter of a metal tube of essentially corresponding length, the metal tube having an unsealed side seam, wherein the inner diameter of the metal tube is greater than said outer diameter of the non-reactive tube;
sealing the side seam and reducing the metal tube to an outer diameter essentially equal to the predetermined outer diameter of said preformed non-reactive tube after said length of non-reactive tubing has been positioned within said inner diameter of the metal tube;
and
extruding multiple layers of a melt-processible thermoplastic including at least a first polymeric layer and a second polymeric layer onto the external surface of the reduced metal tube, wherein the first polymeric layer is selected from the group consisting of a thermoplastic elastomer, an ionomer, a nylon, a fluoropolymer, and mixtures thereof, and the second polymeric layer is selected from the group consisting of a nylon, thermoplastic elastomer, a fluoropolymer, and mixtures thereof.

1 more element

A process for manufacturing a lined metal tube comprising the steps of:

inserting a length of preformed tube composed of essentially solidified polymeric material having a predetermined outer diameter into an inner diameter of a metal tube of essentially corresponding length, the metal tube having an external surface having a zinc-based coating present thereon, an unsealed side seam, and an inner diameter at least 30% greater than the predetermined outer diameter of the polymeric tube, the metal tube travelling at a first rate and the polymeric tube being inserted travelling at a second rate greater than the first rate;
after insertion of the preformed polymeric tube into the metal tubing, welding the unsealed side seam while maintaining the preformed polymeric tube at a location within the metal tube distant from the side seam during the welding step;
and
reducing the metal tube after welding to an outer diameter essentially equal to the predetermined outer diameter of the polymeric tube;
and
extruding multiple layers of a melt-processible thermoplastic to the external surface of the metal tube;
wherein the polymeric tube is maintained in tension relative to the metal tube during the sealing step, the tension being sufficient to orient said polymeric tubing material relative to the metal tube.

4 more elements

A process for manufacturing a lined metal tube comprising the steps of:

coating at least the external surface of a metal tube having an inner diameter and an unsealed side seam with a zinc based coating material selected from the group consisting of zinc, zinc-nickel alloy, zinc-cobalt alloy, zinc-aluminum alloy, and mixtures thereof;
sealing the zinc based coating on the metal tube with at least one sealant coating selected from the group consisting of a phosphate surface treatment, a chromate surface treatment, a zinc-aluminum alloy surface treatment, and combinations thereof;
inserting a length of preformed polymeric tube having a predetermined outer diameter into the inner diameter of the metal tube of essentially corresponding length, the metal tube having an unsealed side seam and an inner diameter at least 30% greater than the predetermined outer diameter of the polymeric tube, the metal tube travelling at a first rate and the preformed polymeric tube being inserted at a second rate greater than the first rate;
after insertion of the preformed polymeric tube into the metal tube, welding the unsealed side seam while maintaining the preformed polymeric tube at a location within the metal tube distant from the side seam during the welding step;
and
reducing the metal tube to an outer diameter essentially equal to the predetermined outer diameter of the preformed polymeric tube;
and
extruding multiple layers of a melt-processible thermoplastic to the external surface of the metal tube;
wherein the preformed polymeric tube is maintained in tension relative to the metal tube during the sealing step, the tension being sufficient to orient said polymeric tubing material relative to the metal tube.

6 more elements

Dependencies are inferred from the claim text.

Extruded multiple plastic layer coating bonded to the outer surface of a metal tube having an optional non-reactive inner layer and process for making the same

Life of this patent

Extruded multiple plastic layer coating bonded to the outer surface of a metal tube having an optional non-reactive inner layer and process for making the same

Life of this patent

Abstract

Claims22