Fluid End Tension Members for Plunger Pump Stress Reduction
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Solution Overview
Problem
High-pressure reciprocating plunger pumps with intersecting horizontal and vertical cylinder bores experience high stress regions at the intersection, leading to fatigue failures and costly repairs or replacements, as existing stress reduction techniques like autofrettage and shot peening have shown limited success.
Innovation Solution
Incorporating tension members that extend parallel to the longitudinal axis of the fluid end body, providing compressive loads to counteract tensile stresses at the high-stress intersection regions, thereby reducing the need for labor-intensive autofrettage and other ineffective methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If intersecting horizontal and vertical cylinder bores are used to reduce pump profile, then compactness is improved, but high stress regions develop at the intersection leading to fatigue failure
Solution Approach 1:
The invention applies preliminary compressive stress to the fluid end body through tension members extending through the intersecting bores. This pre-compression counteracts the tensile stresses that develop during pump operation at the high-stress intersection region, preventing fatigue failure before it occurs.
Solution Approach 2:
The invention changes the stress state parameter of the fluid end body by introducing compressive stress through tension members. This transforms the stress regime from predominantly tensile (which causes fatigue) to a balanced state with compressive pre-stress, thereby improving fatigue resistance while maintaining the compact intersecting bore design.
2Reliability
If traditional stress reduction techniques like autofrettage are used, then some stress relief is achieved, but they are labor-intensive and show limited success
Solution Approach 1:
The invention extracts the stress management function from complex manufacturing processes like autofrettage and shot peening, and implements it through a simple structural addition - tension members that provide continuous compressive stress. This simplifies the manufacturing process while maintaining or improving stress reduction effectiveness.
3Reliability
If tension members are added to reduce stress, then fatigue resistance is improved, but device complexity increases
Solution Approach 1:
The tension members serve multiple functions: they structurally connect the intersecting bores, provide the necessary compressive stress to counteract fatigue, and maintain the compact profile of the pump. This multi-functionality justifies the added structural elements by consolidating several requirements into a single solution.
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
Significantly reduces stress at the intersection regions, prolonging the service life of the fluid end and minimizing the frequency and cost of repairs and replacements, while offering a cost-effective solution to fatigue failures.
Implementation Method 1
the tension member provides a compressive load on the body reducing the tensile stresses encountered in the region during operation of the fluid end
Data Source
AI summary
A fluid end for a reciprocating pump including a body having a base, a side and a longitudinal opposing side, a cylinder bore formed horizontally through the body and a vertical bore intersecting the cylinder bore defining a high stress region proximate the intersection, and a tension member extending through the body substantially parallel to the longitudinal axis of the body, wherein the tension member provides a compressive load on the body reducing the stresses encountered in the region during operation of the fluid end.