Stainless Steel Pipe Weld Pitting Resistance Evaluation
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Solution Overview
Problem
Current methods for evaluating the pitting resistance of stainless steel pipe welds are inaccurate and costly, particularly for marine industrial oil and gas pipes, due to welding defects and incomplete slag removal, which affect the critical pitting temperature and service life prediction.
Innovation Solution
A rapid and comprehensive method involving the collection of multiple weld samples to determine surface oxide inclusion density, followed by a critical pitting temperature test, and fitting function formula derivation to predict the pitting resistance of stainless steel pipe welds, allowing for the evaluation of different welding processes and heat input methods without additional testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional critical pitting temperature testing is performed on each weld sample, then measurement precision is improved, but loss of time and experimental cost increase significantly
Solution Approach 1:
The patent performs preliminary action by measuring oxide inclusion density and establishing a fitting function formula beforehand. This allows the critical pitting temperature to be predicted directly from oxide inclusion density without performing time-consuming critical pitting temperature tests on each sample, thus resolving the contradiction between measurement precision and testing time
Solution Approach 2:
The patent creates a mathematical model (fitting function formula) that copies the relationship between oxide inclusion density and critical pitting temperature. This model serves as a substitute for actual physical testing, enabling rapid prediction of pitting resistance while maintaining evaluation accuracy
2Reliability
If multiple weld samples are tested to improve evaluation comprehensiveness, then reliability is improved, but experimental cost increases
Solution Approach 1:
The patent uses a mathematical model to copy the complex relationship between multiple welding parameters and pitting resistance. Once the fitting function is established through initial testing, it can predict results for multiple samples at low cost, resolving the contradiction between evaluation reliability and testing cost
Solution Approach 2:
The patent changes the measurement parameter from critical pitting temperature (which requires expensive and time-consuming tests) to oxide inclusion density (which can be measured quickly and cheaply). This parameter substitution maintains evaluation reliability while significantly reducing testing cost
Data Source
AI summary
The disclosure relates to a rapid and comprehensive method for evaluating pitting resistance of stainless steel pipe welds. Weld samples are collected from different positions of one or more welds on the stainless steel pipe to obtain the surface oxide inclusion density and critical pitting temperature of each weld sample, the surface oxidation inclusion density is taken as an independent variable and the critical pitting temperature is taken as a dependent variable to obtain a fitting function formula between the surface oxidation inclusion density and the critical pitting temperature. The surface oxide inclusion density obtained by adopting the same welding process on the stainless steel pipe to be tested is substituted into the fitting function formula to obtain a standard critical pitting temperature of the weld to be tested. The pitting resistance of the weld of the stainless steel pipe to be tested can be evaluated rapidly, accurately, and comprehensively.