Pump Body Pre-Compression Fatigue Crack Inhibition
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Solution Overview
Problem
Reciprocating pumps used for fracturing operations experience fatigue failure due to stress cycles, which can lead to premature failure of the fluid end, despite autofrettage processes aimed at inducing residual compressive stresses.
Innovation Solution
Applying pre-compressive forces to raised surfaces on pump bodies through a method involving connecting pump bodies side by side with fasteners and end plates, which compresses the pump bodies to inhibit fatigue crack initiation, and optionally autofrettaging the pump bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If autofrettage process is applied to induce residual compressive stresses, then fatigue resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies pre-compressive forces to the pump body before the pump undergoes its service life, creating a preliminary state of compression that counteracts the tensile stresses that would otherwise cause fatigue cracks. This preliminary action (pre-compression) is achieved through the autofrettage process or alternative methods described in the patent, establishing a residual stress state that protects against future fatigue damage without requiring continuous intervention during operation.
2Manufacturing precision
If pump bodies are made as single monoblock structure, then manufacturing precision is improved, but ease of repair deteriorates
Solution Approach 1:
The patent divides the pump body into separate, replaceable components (such as the fluid end assembly that can be removed and replaced as a unit, or individual cylinders/pistons that can be serviced independently). This segmentation allows damaged components to be replaced without replacing the entire pump body, significantly improving ease of repair and maintenance while maintaining adequate manufacturing precision through proper joining methods and design.
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 pre-compressive force reduces stress concentrations and extends the operational life of the pump assembly by delaying fatigue crack initiation, allowing for easier maintenance and replacement of failed components.
Implementation Method 1
a pre-compressive force is applied to raised surfaces on the pump bodies. The raised surfaces on the pump bodies may engage with an adjacent end plate or an adjacent pump body to apply a pre-compressive force at the raised surfaces
Implementation Method 2
The effectiveness of the autofrettage process depends on the extent of the residual stress on the inner walls and their magnitude
Implementation Method 3
tightening the fasteners to compress the pump bodies between the end plates. In this manner, a pre-compressive force can be applied at the raised surfaces on each of the pump bodies
Data Source
AI summary
A multiplex fluid pump assembled from a plurality of pump bodies connected side by side between opposing end plates with a plurality of fasteners tightened to compress the pump bodies between the end plates. Raised surfaces on opposite exterior side surfaces of each pump body are engaged with an adjacent end plate or an adjacent pump body to apply a pre-compressive force at the raised surfaces and thereby inhibit the initiation of fatigue cracks.