Pipe coating

• US 4,589,275 A
• Filed: 07/13/1984
• Issued: 05/20/1986
• Est. Priority Date: 04/16/1982
• Status: Expired due to Term

• Current Assignee: The Kendall Company (Colgate-Palmolive Company)
• Original Assignee: The Kendall Company (Colgate-Palmolive Company)
• Inventors: Thomas, Samuel J., Robich, James M., Hayes, Robert L.
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): WILLIAMS, HEZRON
• Application Number:
  US06/630,439
• Time in Patent Office: 676 Days
• Field of Search: 73/40.5 R, 73/40.5 A, 73/592, 73/40, 73/49.1, 340/605, 138/103, 138/104, 138/149, 138/36, 174/11 R, 174/47, 285/47, 285/93
• US Class Current: 73/40.50R
• CPC Class Codes: G01R 31/1263 of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
• CPC Class Codes: G01R 31/58 Testing of lines, cables or conductors testing of electric windings G01R31/72

Abstract

Pipe coating having a thermal insulating layer of polymeric material and an outer barrier layer is provided with an additional layer between the two layers to facilitate testing of the latter for discontinuities. The intermediate layer can be electroconductive, smooth-surfaced, or of color contrasting to that of the barrier layer.

Claims

1. In a pipe coated with a thermal insulating layer of foamed plastic polymeric material having an irregular outer surface and an outer barrier layer of non-foamed plastic polymeric material,

the improvement comprising an intermediate layer interposed between and bonded to said insulating layer and said outer barrier layer to facilitate detection of pinholes and other discontinuities in said outer barrier layer, said intermediate layer having an inner face which mates with the irregularities of said insulating layer and an outer face smooth and substantially free from said irregularities.

2. A coated pipe as claimed in claim 1 in which said intermediate layer is electroconductive.

3. In the method of detecting pinholes and other discontinuities in the outer barrier layer of metal pipe coated with a thermal insulating layer of foamed polymeric material having an irregular outer surface and an outer barrier layer of polymeric material which comprises measuring ultrasonic characteristics of said barrier layer,

the improvement which comprises interposing between and bonding to said insulating layer and said outer barrier layer a layer of mastic which fills the irregularities of the surface of said insulating layer and which presents a substantially smooth even outer surface.