Displacement Pump Valve Seal Geometry for Inner-Diameter Stress Relief
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Solution Overview
Problem
Displacement pumps, particularly well service pumps, experience seal deterioration due to excessive displacement volume at the inner diameter of the contact surface, leading to elevated heat, stress, and strain, which reduces the operational life of the seals.
Innovation Solution
The design of durable valves for displacement pumps incorporates an annular seal with a geometry that minimizes the displacement volume near the inner diameter and redistributes it towards the outer diameter, using a radially inner frustoconical surface and a radially outer convex surface to reduce stress and strain on the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seal has a conventional geometry with uniform displacement volume, then the valve can maintain a simple structure, but the seal experiences excessive heat, stress, and strain at the inner diameter leading to deterioration
Solution Approach 1:
The seal geometry is modified to have non-uniform displacement volume distribution, with specifically controlled cumulative displacement ratios at different radial locations. The inner diameter portion has reduced displacement volume (cumulative ratio ≤0.20 at 40% from ID) while the outer diameter portion has increased displacement volume (cumulative ratio ≤0.45 at 65% from ID), creating local quality variations that reduce stress concentration and extend seal life
Solution Approach 2:
The seal geometry parameters are optimized by controlling the cumulative displacement ratio at specific radial locations. The design specifies cumulative displacement ratios of at most 0.20 at 40% from ID, at most 0.35 at 55% from ID, and at most 0.45 at 65% from ID, changing the geometric parameters to redistribute displacement volume and reduce harmful stress
2Reliability
If the displacement volume is concentrated at the inner diameter, then the seal structure can be simpler, but heat and stress concentration reduces seal durability
Solution Approach 1:
The seal is designed with spatially varying displacement volume characteristics, where the inner diameter region has minimized displacement volume (cumulative ratio ≤0.20 at 40% from ID) to reduce heat generation, while the outer diameter region has maximized displacement volume (cumulative ratio ≤0.45 at 65% from ID) to compensate for volume loss, creating local quality optimization that addresses both thermal and mechanical stress distribution
Data Source
AI summary
A valve for a displacement pump includes a valve body having an annular strikeface and defining an annular receptacle, and an annular seal received in the receptacle of the valve body, the seal including an annular contact surface, wherein the seal defines a cumulative displacement ratio of (i) at least one of at most 0.20 at a location that is spaced 40% from an inner diameter (ID) of the contact surface of the seal moving towards an outer diameter (OD) of the contact surface, (ii) at most 0.35 at a location that is spaced 55% from the ID of the contact surface moving towards the OD of the contact surface, and (iii) at most 0.45 at a location that is spaced 65% from the ID of the contact surface moving towards the OD of the contact surface.