Pump Fluid End Toroidal Surface for Stress Cracking Resistance

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Solution Overview

Problem

Positive displacement pumps experience significant material stress at the intersection of bores within the fluid end block, leading to potential material failure such as stress cracking.

Innovation Solution

Incorporating a toroidal surface along the bore intersection rim to distribute stress over a larger area, reducing material stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional cylindrical bores are used in the fluid end block, then the manufacturing process is simple, but material stress concentrates at the bore intersection rim leading to potential failure

Engineering Contradiction:

Improveresistance to stress crackingVSAvoidbore intersection rim geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies curvature by forming a toroidal surface at the bore intersection rim instead of using a sharp edge or flat surface. This curved geometry distributes stress over a larger area, preventing stress concentration and reducing the risk of cracking while maintaining structural integrity.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The toroidal surface is applied locally at the bore intersection rim where stress concentration occurs, rather than modifying the entire fluid end block. This localized approach addresses the specific problem area while keeping the rest of the structure simple and easy to manufacture.

Inventive Principle:

Principle #3Local quality

2Strength

If a toroidal surface is added to the bore intersection rim, then material stress is reduced by up to 25%, but manufacturing complexity increases

Engineering Contradiction:

Improvematerial stress distributionVSAvoidbore intersection rim fabrication

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The toroidal surface provides a curved geometry that naturally distributes stress over a larger area, reducing peak stress by up to 25% compared to traditional designs. This curvature is achieved through standard machining operations such as forming or milling, making it feasible to manufacture.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent modifies the geometric parameters of the bore intersection rim by introducing a toroidal surface with specific dimensions and curvature radii. These parameter changes optimize stress distribution while remaining compatible with conventional manufacturing capabilities.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250290506A1Pump fluid end with toroidal surface

Publication Date: 2025.09.18 NAT OILWELL VARCO LP

AI summary

A positive displacement pump system can include a fluid end block, which can be configured to provide a pumping chamber and control a flow of a fluid through the positive displacement pump system. The fluid end block can include a first cylindrical wall defining a plunger bore extending partially through the fluid end block and a second cylindrical wall defining a fluid conveying cross bore that intersects the plunger bore defining a bore intersection rim. A portion of the first bore intersection rim can include a first toroidal surface.