Weld-Zone Metal Coating for Corrosion-Resistant Oil and Gas Pipe
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Metal pipes used for conveying oil and gas face corrosion and abrasion issues in the heat-affected zone during welding, leading to incomplete protection and increased costs or reduced service life, especially in larger diameters where re-coating is uneconomical.
Innovation Solution
A metal pipe with a weldable, stainless steel coating applied in the transition region, covering the heat-affected zone and extending to the pipe joint, providing a continuous anti-corrosion and anti-abrasion layer that retains protection during welding without additional coating, and featuring a variable thickness to minimize edges and pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pipe is coated with a base coating on the inner surface, then protection against corrosion and abrasion is provided, but the base coating peels off or becomes perforated in the heat-affected zone during welding
Solution Approach 1:
The coating system is segmented into two distinct layers: a metal coating applied to the transition region (heat-affected zone) and a base coating applied to the pipe body. This segmentation allows each layer to perform its specific function - the metal coating provides heat and corrosion resistance at the weld zone, while the base coating provides abrasion resistance in the pipe body, eliminating the conflict between heat resistance and abrasion resistance that causes peeling.
Solution Approach 2:
Different coating materials and thicknesses are applied to different regions of the pipe. The transition region receives a metal coating with specific properties for heat and corrosion resistance, while the pipe body receives a base coating optimized for abrasion resistance. This local differentiation ensures that each region has the appropriate protective properties for its specific operational conditions.
2Reliability
If the base coating is reapplied subsequently in large pipe diameters, then protection is restored, but pipe laying speed decreases and system costs increase
Solution Approach 1:
The metal coating is applied to the transition region during the initial pipe manufacturing process, before the pipe is put into service. This preliminary action ensures that the heat-affected zone is pre-protected against corrosion and abrasion, eliminating the need for subsequent re-coating operations and maintaining high pipe laying speeds.
Solution Approach 2:
The metal coating is applied in advance to prevent the harmful effects of heat and corrosion at the transition region. By providing this preliminary protection, the base coating remains intact during welding operations, preventing the need for corrective re-coating and maintaining production efficiency.
3Reliability
If the metal coating thickness is increased, then protection against corrosion and abrasion is improved, but material costs and weight increase
Solution Approach 1:
The metal coating is applied selectively only to the transition region where heat-affected corrosion and abrasion occur, rather than coating the entire pipe. This localized application provides necessary protection at the critical zone while minimizing additional weight and material costs.
Solution Approach 2:
The metal coating thickness is optimized to provide sufficient protection against heat and corrosion at the transition region without excessive thickness. The coating thickness is tailored to the specific requirements of the heat-affected zone, providing adequate protection while avoiding unnecessary material usage and weight increase.
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 solution ensures a continuous protective layer on the inner surface of the pipe, reducing material and system costs, improving wear resistance, and maintaining pipeline efficiency by preventing corrosion and abrasion in welded connections, thus enhancing both service life and laying speed.
Implementation Method 1
Stainless materials used as a coating are, for example, very resistant to chemical attacks from oils or gases
Implementation Method 2
metal material with anti-corrosion and/or anti-abrasion properties
Data Source
AI summary
A metal pipe and a system of pipes, and a method of producing the same. The pipe is for conveying oil and gas. The pipe includes a metal coating in a transition region. The metal coating of the transition region obviates a subsequent coating of the inner surface of the transition region after connecting two pipes using a welding process in order to form a pipeline.