Bellows Guide Rings Reduce Wear in Submersible Pump Seals
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Solution Overview
Problem
The existing seal sections in electrical submersible well pumps experience wear due to the sliding movement of corrugated metal bellows, which reduces their fatigue life as they extend and contract to equalize motor lubricant and hydrostatic well fluid pressures.
Innovation Solution
Incorporating a guide ring with a wear-resistant element, such as a coating or insert, and axially extending grooves on the guide ring and guide member surfaces to reduce friction and prevent direct contact between the bellows and the guide surfaces, along with using separate flexible corrugated wall segments joined by guide rings to distribute the axial movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bellows extend and contract to equalize pressure, then the pressure equalization function is achieved, but wear of the corrugated wall increases due to sliding contact with guide surfaces
Solution Approach 1:
A guide ring is introduced as an intermediary component between the bellows corrugated wall and the guide tube. The guide ring has a contacting surface that engages with the guide tube, while the bellows wall remains closely spaced but non-contacting. This mediator transfers the sliding contact function from the thin corrugated wall to a more durable guide ring structure, eliminating direct wear on the bellows while maintaining the pressure equalization function through continued axial movement.
2Adaptability or versatility
If the axial travel range of the floating ends increases, then the pressure equalization capability is improved, but the extent of sliding contact and wear increases
Solution Approach 1:
The guide ring serves as a protective intermediary that enables increased axial travel range without proportionally increasing wear. By providing a dedicated contacting surface on the guide ring rather than the bellows wall, the system can accommodate larger floating end displacements for improved pressure equalization while the wear is concentrated on the guide ring's contacting surface, which is designed to handle such sliding contact.
3Force
If the corrugated wall is made thinner to reduce friction, then the sliding resistance is reduced, but the wear resistance decreases
Solution Approach 1:
The guide ring acts as an intermediary bearing surface that allows the bellows corrugated wall to maintain optimal thickness for flexibility and pressure equalization without needing to be excessively thin for friction reduction. The guide ring's contacting surface provides the low-friction sliding interface, while the bellows wall can be sufficiently thick to maintain wear resistance and structural integrity.
Solution Approach 2:
The guide ring may incorporate wear-resistant materials or coatings (such as PTFE, PEEK, or other low-friction materials) to provide both low sliding resistance and high wear resistance in a single component. This composite approach allows the contacting surface to simultaneously reduce friction during axial movement while maintaining durability against repeated sliding contact.
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 solution significantly reduces wear and increases the fatigue life of the seal section by minimizing friction and distributing the axial movement effectively, thereby maintaining the pressure equalization functionality over a longer operational period.
Implementation Method 1
the seal section has a first bellows and a second bellows that are coaxial with each other and that equalize a pressure difference between motor lubricant pressure and hydrostatic well fluid pressure
Implementation Method 2
The guide ring has a contacting surface protruding slightly from the wall and slidingly engaging the guide surface as the bellows contracts and extends
Data Source
AI summary
A well pump assembly has a pump driven by an electrical motor. A seal section reduces a pressure difference between a dielectric lubricant in the motor and a hydrostatic well fluid pressure. The seal section has a housing containing a guide tube concentric with the axis. Contractible and extensible inner and outer bellows surround the guide tube. An inner bellows guide ring is secured to the inner bellows between ends and has an inner surface with an inner diameter smaller than a minimum inner diameter of the inner bellows for sliding engagement with an outer surface of the guide tube as the inner bellows lengthens and contracts. The outer bellows has a guide ring secured between ends and having an outer surface with an outer diameter larger than a maximum outer diameter of the outer bellows for sliding engagement with an inner surface of the housing.