Tie Rod Sleeve Design for Pump Assembly Thread Fatigue
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Solution Overview
Problem
Reciprocating pumps used for high-pressure fracturing fluids face potential failure and safety risks due to weaknesses in tie rods, particularly at the threaded connections, which require frequent inspection and replacement to prevent defects and injuries.
Innovation Solution
A pump assembly design featuring a tie rod with a rod portion and a sleeve portion, where the sleeve surrounds the rod and abuts the power end and fluid end, distributing the load and reducing stress on the threads, thereby enhancing the reliability and maintainability of the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional tie rods with threaded connections are used to connect power end and fluid end, then the pump assembly can be assembled and operated, but the threads are susceptible to fatigue and require frequent inspection and replacement
Solution Approach 1:
The tie rod is divided into two separate components: a sleeve portion and a rod portion. The sleeve portion is threaded and connects to the power end, while the rod portion connects to the fluid end. This segmentation eliminates the need for threaded connections between the tie rod components, as they are joined through a simple insert fit, thereby preventing thread fatigue and extending service life.
Solution Approach 2:
The tie rod assembly uses a composite structure combining a sleeve portion with an insert and a rod portion. This composite design allows the threaded sleeve to be replaced independently if needed, while the main rod structure remains intact, improving reliability without requiring complete tie rod replacement.
2Strength
If conventional tie rod design with threaded ends is used, then connection between power end and fluid end is achieved, but stress concentration occurs at the threads leading to potential failure
Solution Approach 1:
By separating the threaded connection (sleeve portion) from the load-bearing rod portion, the design isolates the stress concentration to the sleeve insert interface rather than propagating through the entire tie rod. This segmentation protects the main structural integrity from stress concentration effects.
Solution Approach 2:
The sleeve portion acts as an intermediary element between the power end and the rod portion. It absorbs and distributes the connection stresses through its interface with the power end, preventing direct stress transmission to the rod portion and eliminating thread-related stress concentration in the main load-bearing path.
Data Source
AI summary
A pump assembly having a power end and a fluid end, wherein the fluid end includes 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. The power end and at least one of the plurality of pump bodies being connected together by a tie rod having a rod portion and a sleeve portion, wherein the sleeve portion surrounds the rod portion and abuts the power end at an end and at least one of the pump bodies of the fluid end at an opposite end.