Welded Pipe Threaded Connection With Uniform ID Seam Patch
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Solution Overview
Problem
Welded pipes used in oil and gas drilling often have non-uniform inner and outer diameters due to longitudinal seams, leading to weakened threaded connections that may leak, and existing methods to enhance these connections, such as swaging, are unreliable as they can cause the pipe to split or yield excessively.
Innovation Solution
A method involving the application of a weld patch on the interior surface of the pipe to cover the welded seam, machining it to achieve a uniform inside diameter, and optionally adding threads, which includes using a heat input not exceeding 50 kilo-Joules per inch of weld length and selecting a material with yield strength exceeding that of the pipe to enhance the structural integrity of the tubular member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If welded pipe is formed from a plate with longitudinal seam, then manufacturing is easier and cost is lower, but the pipe has non-uniform inside diameter and weakened threaded connections
Solution Approach 1:
The patent applies a weld patch specifically at the location of the longitudinal seam on the interior surface of the pipe. This local reinforcement addresses the non-uniformity and weakness at the seam location without requiring the entire pipe to be manufactured differently, thus maintaining ease of manufacture while improving local precision and strength
Solution Approach 2:
The patent creates a composite structure by applying a weld patch (additional material layer) over the longitudinal seam of the welded pipe. This composite approach combines the base pipe material with the weld patch material to create a reinforced zone that compensates for the non-uniformity and weakness at the seam location
2Strength
If swaging is applied to increase connector cross section, then tensile strength increases, but welded pipe may split or yield excessively
Solution Approach 1:
The weld patch creates a localized reinforcement zone at the seam location, providing additional material and strength where needed without subjecting the entire pipe to the high-stress swaging process that causes splitting or excessive yielding
Solution Approach 2:
The weld patch is applied to the pipe interior surface before threading or connector formation. This preliminary reinforcement strengthens the seam area in advance, preventing the pipe from splitting or yielding when subsequent operations or service loads are applied
3Ease of manufacture
If threaded connection is formed on welded pipe with non-uniform ID, then connection may leak and cannot achieve gas-tight or liquid-tight seal
Solution Approach 1:
The weld patch is positioned to cover the longitudinal seam and extend into the threaded connection zone, providing local reinforcement that ensures uniform ID and adequate wall thickness at the critical threading location, enabling reliable gas-tight or liquid-tight seals
Solution Approach 2:
The weld patch is applied before threading to pre-reinforce the seam area and establish a uniform ID profile. This preliminary action ensures that when threads are formed, the underlying structure is sufficiently strong and uniform to achieve reliable sealing without leakage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach strengthens the tubular connections, enabling them to achieve gas-tight or liquid-tight seals and withstand significant compressive forces, similar to seamless pipes, while maintaining uniform elasticity and preventing pipe splitting.
Implementation Method 1
applying a patch of material to the interior surface, such that the patch covers an arcuate segment of the interior surface that includes the welded seam
Implementation Method 2
machining the patch such that the interior surface of the tubular member from the tube end to the axially spaced first location has a uniform inside diameter
Data Source
AI summary
A tubular member includes a tube body, a tube end, an exterior surface, an interior surface, a nominal wall thickness, a longitudinal axis, a welded seam, and a patch of material. The welded seam forms an arcuate portion of the interior surface, and the patch covers a portion of the interior surface that includes a portion of the welded seam, extending from the tube end to an axially spaced first location. The resulting interior surface from the tube end to the axially spaced first location has a uniform inside diameter.