Pipe inspection apparatus and process
AssigneeUnion Oil Company of California
InventorMitchel A. Stark
Life of this patent
Estimating the term…
Abstract
An openable ring assembly is externally centered around and moved parallel to the centerline of a stationary pipe. As a low-frequency EM source signal is applied to the ring assembly, the time and/or frequency shifts of a detected EM signal from the source signal can be correlated to pipe wall thickness without removal of external pipe insulation and metal cladding, if present. The ring assembly may be opened or expandably segmented to allow pipe thickness detection around obstructions or larger diameter pipe. Centering is preferably accomplished by using rollers circumferentially attached to the ring assembly.
Claims22
An apparatus for inspecting the wall of a pipe having an external surface that is substantially covered by an insulation system, said apparatus comprising:
- an electromagnetic element capable of forming at least a partial loop around said insulation system;
- means for centering said electromagnetic element around said insulation system, wherein said means for centering contacts said insulation system;
- means for traversing said electromagnetic element along said insulation system in a direction substantially coaxial with the centerline of said pipe;
- means for generating a low-frequency EM source signal connected to said electromagnetic element;
- means for detecting a resultant EM signal in or near said electromagnetic element;
- and
- means for correlating said resultant EM signal with the thickness of the wall of said pipe proximate to said electromagnetic element.
An apparatus for detecting thinning of the wall of a stationary pipe, said apparatus comprising:
- an openable, electromagnetic element capable of at least partially enclosing said stationary pipe;
- means for traversing said electromagnetic element in a direction coaxial with the centerline of said stationary pipe;
- means for centering said electromagnetic element around said stationary pipe as said electromagnetic element is traversing said stationary pipe;
- means for generating a periodic electromagnetic source signal proximate to said stationary pipe;
- and
- means for detecting a pipe-induced electromagnetic signal in said electromagnetic element, wherein said pipe-induced electromagnetic signal is dependent upon the wall thickness of said stationary pipe.
An apparatus for detecting thinning in the wall of an externally insulated pipe comprising:
- an openable electromagnetic element capable of partially closing around the outside of said externally insulated pipe;
- a roller device attached to said openable element, wherein said roller device centers said element around the outside of said externally insulated pipe while said element traverses said pipe in a direction coaxial with the centerline of said pipe;
- an electromagnetic source signal generator electrically connected to said openable element;
- a detector for detecting a pipe-induced electromagnetic signal in said openable element;
- and
- a signal processor for correlating said detected electromagnetic signal with the thickness of said externally insulated pipe.
A process for inspecting the wall of an externally insulated, EM conductive pipe, said process comprising:
- placing a loop-like electromagnetic element around at least a portion of said externally insulated pipe;
- moving said loop-like element over said externally insulated pipe in a direction substantially parallel to the centerline of said pipe;
- generating a low-frequency EM source signal proximate to said externally insulated pipe;
- detecting a resulting EM signal;
- and
- correlating said resulting EM signal with the wall thickness of said pipe.
Dependencies are inferred from the claim text.