Power End Frame Welds with Residual Compressive Stress
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Solution Overview
Problem
Conventional well stimulation pumps face damage from tensile stresses, leading to stress cracks and fractures at welds, causing leakage and potential failure, with existing solutions focusing on repairing or replacing the fluid end but not addressing the power end's stress issues effectively.
Innovation Solution
The method involves forming a power end frame with a face plate and housing, creating a weld, and applying laser shock peening to induce residual compressive stresses on the welds and surfaces, enhancing the pump's resistance to tensile loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional welding is used to assemble power end components, then manufacturing simplicity is maintained, but stress cracks and fractures occur at welds under tensile loads
Solution Approach 1:
The patent applies laser shock peening to fundamentally change the stress state parameters at the weld, transforming the stress profile from tensile to compressive. This parameter change in residual stress prevents stress crack initiation and propagation while maintaining the original welding process, thus resolving the contradiction between manufacturing simplicity and weld reliability
Solution Approach 2:
Laser shock peening is applied as a preliminary treatment to induce compressive residual stresses before the pump operates under tensile loads. This preliminary anti-action counteracts the harmful tensile stresses that would otherwise cause stress cracks at the weld, preventing damage before it occurs while keeping the welding process simple
2Reliability
If stress cracks are welded to prevent leakage, then leakage is reduced, but additional stress concentration points are created
Solution Approach 1:
Instead of simply welding stress cracks (which creates new stress concentration points), the patent uses laser shock peening to convert the harmful tensile stress environment into a beneficial compressive stress environment. This transforms the problematic condition into an advantageous state that prevents future cracking while maintaining leak-free operation
Solution Approach 2:
The patent changes the stress parameter from tensile to compressive through laser shock peening treatment. This parameter change addresses both leakage prevention and stress concentration issues simultaneously, as the compressive stress field prevents crack propagation without creating additional stress concentration points
3Reliability
If the entire power end is replaced when damaged, then reliability is restored, but downtime and waste increase
Solution Approach 1:
Laser shock peening is applied as a preliminary protective action during manufacturing or maintenance, creating compressive residual stresses that prevent stress crack development. This preliminary action extends the service life of the power end, delaying the need for replacement and reducing downtime and waste associated with frequent replacements
4Strength
If laser shock peening is applied to welds, then resistance to tensile loads increases, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical stress relief methods with laser shock peening, which uses optical energy (laser) to induce compressive residual stresses. This substitution achieves superior tensile load resistance while actually simplifying the overall manufacturing process by eliminating the need for complex mechanical pre-stressing or over-engineering
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 extends the life of the power end by counteracting tensile stresses, reducing the likelihood of stress fractures and improving the pump's operational performance and longevity.
Implementation Method 1
laser shock peening at least one of the weld or a surface proximate the weld to form a treated surface at the at least one of the weld or the surface proximate the weld. The treated surface has a residual compressive stress resulting from the laser shock peening.
Data Source
AI summary
A power end frame includes a housing and a face plate secured to the housing. During use, components of the power end frame, including the housing and the face plate, are subjected to large tensile stresses. This disclosure describes a method of imparting compressive stresses in the power end frame to resist these large tensile stresses.