OCTG Pipe Strength Gradient via Differential Annealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing oil country tubular goods (OCTG) pipe systems face challenges in maintaining strength and reducing material usage in connection regions, leading to increased production costs and outer diameter enlargement due to the need for upsetting and thread cutting, which weakens the pipe.
Innovation Solution
A seamless OCTG pipe system with connection ends made from a hardenable steel alloy, where the yield strength of the connection end is higher than the pipe body, achieved through differential annealing to set varying strength gradients, allowing for reduced or omitted upsetting and smaller outer diameters, while maintaining or increasing strength and load capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pipe end is upset to compensate for thread cutting weakness, then the strength of the pipe end is improved, but the outer diameter is enlarged and production costs increase
Solution Approach 1:
The patent applies local quality by creating a strength gradient within the pipe structure. The connection end region is heat-treated to achieve higher yield strength (600-1300 MPa) compared to the pipe body (500-900 MPa), allowing the connection end to withstand thread cutting without requiring upset processing that would enlarge the outer diameter.
Solution Approach 2:
The patent changes the physical parameter of yield strength through controlled heat treatment (annealing) of the connection end region. By adjusting heat treatment parameters (temperature, time, cooling rate), the connection end achieves optimized strength properties that eliminate the need for upset processing while maintaining adequate strength for threading.
2Strength
If the pipe end is upset to compensate for thread cutting weakness, then the strength of the pipe end is improved, but production costs increase due to additional processing
Solution Approach 1:
The patent applies local quality by creating a strength gradient within the pipe structure. The connection end region is heat-treated to achieve higher yield strength (600-1300 MPa) compared to the pipe body (500-900 MPa), allowing the connection end to withstand thread cutting without requiring upset processing that would enlarge the outer diameter.
Solution Approach 2:
The patent changes the physical parameter of yield strength through controlled heat treatment (annealing) of the connection end region. By adjusting heat treatment parameters (temperature, time, cooling rate), the connection end achieves optimized strength properties that eliminate the need for upset processing while maintaining adequate strength for threading.
3Strength
If higher strength is achieved in the connection region through heat treatment, then load capacity is improved, but energy expenditure increases
Solution Approach 1:
The patent applies segmentation by dividing the heat treatment process into two distinct stages: (1) homogeneous heating of the entire pipe to hardening temperature followed by quench hardening, and (2) selective reduced-intensity annealing only of the connection end region. This segmented approach concentrates energy expenditure only where needed to achieve the strength gradient, rather than uniformly treating the entire pipe.
Solution Approach 2:
The patent applies local quality by creating a strength gradient within the pipe structure. The connection end region is heat-treated to achieve higher yield strength (600-1300 MPa) compared to the pipe body (500-900 MPa), allowing the connection end to withstand thread cutting without requiring upset processing that would enlarge the outer diameter.
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
The OCTG pipe system achieves higher strength and load capacity in connection regions with reduced material usage and energy expenditure, enabling cost savings and improved handling and flexibility during drilling operations.
Implementation Method 1
The pipe is composed of a hardenable steel alloy, is homogeneously warmed to a hardening temperature, and is quench hardened
Implementation Method 2
During subsequent annealing after the hardening treatment, targeted setting of the strength is realized. The higher strength in the pipe ends is achieved by virtue of the intensity of the annealing of the pipe end being reduced in relation to the pipe body
Data Source
AI summary
A pipe system for oil country tubular goods (OCTG) and a method of manufacturing the OCTG pipe system is disclosed. The pipe system includes at least one OCTG pipe having a pipe body, the pipe body having at least one connection end formed in unipartite and materially integral manner with the pipe body for coupling to a second OCTG pipe. The OCTG pipe is formed in seamless fashion from a hardenable steel alloy, and the connection end has a yield strength higher than the yield strength of the pipe body.