Scraper Ring Assembly With Camming Seal Against Abrasive Debris
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Solution Overview
Problem
Conventional sealing arrangements in high pressure reciprocating pumps are ineffective in maintaining seals against abrasive debris, leading to reduced lifespan and increased maintenance needs, especially in extreme conditions like fracking operations.
Innovation Solution
An annular scraper ring assembly with multiple rings of varying resiliencies, featuring a camming mechanism and sharp leading edges to enhance sealing forces and debris removal, is integrated into the packing arrangement to improve seal longevity and debris control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing arrangements are used in high pressure reciprocating pumps, then the structure is simple, but the sealing effectiveness against abrasive debris is poor and lifespan is reduced
Solution Approach 1:
The packing arrangement is divided into multiple sequential rings with distinct functions: a resilient ring for primary sealing, a scraper ring for debris removal, and a junk ring for debris containment. This segmentation allows each component to specialize in its specific function, improving overall sealing effectiveness against abrasive debris while managing complexity through functional modularity
Solution Approach 2:
The scraper ring acts as an intermediary element between the resilient sealing ring and the junk ring. It actively removes debris from the plunger surface before debris can compromise the primary seal, thereby protecting the resilient ring and extending its lifespan without requiring fundamental changes to the overall packing structure
2Duration of action of stationary object
If conventional sealing rings are used, then the device complexity is low, but the lifespan of the packing arrangement is reduced due to debris damage
Solution Approach 1:
The scraper ring performs preliminary debris removal action before the fluid pressure can force debris against the resilient sealing ring. By proactively scraping the plunger surface and directing debris into the junk ring, the system prevents premature wear and damage to the primary sealing elements, thereby extending packing arrangement lifespan
Solution Approach 2:
The scraper ring and junk ring are designed as sacrificial components that can be easily replaced. The scraper ring wears from contact with abrasive debris, and the junk ring collects and contains this debris. These shorter-lived components protect the more expensive resilient sealing rings, reducing overall maintenance costs and extending the effective service life of the critical sealing elements
3Reliability
If the first ring is made from resilient material to form a seal, then sealing capability is improved, but the ring is vulnerable to damage from abrasive debris
Solution Approach 1:
The scraper ring serves as a protective intermediary that intercepts abrasive debris before it can contact the resilient first ring. By scraping the plunger surface and directing debris into the junk ring, the scraper ring shields the resilient sealing material from abrasive wear, maintaining sealing capability while protecting against damage
Solution Approach 2:
The scraper ring is designed as a sacrificial component that absorbs abrasive wear instead of the resilient first ring. This shorter-lived scraper element protects the more valuable resilient sealing material, allowing the first ring to maintain its sealing function for longer periods without direct exposure to abrasive damage
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 scraper ring assembly significantly enhances sealing forces and extends the lifespan of the packing arrangement by effectively removing debris and preventing 'nibbling' phenomena, thereby reducing maintenance frequency and ensuring continuous operation in harsh conditions.
Implementation Method 1
The second ring defines a camming surface configured to engage the upstream face of the first ring and cam the inner surface of the first ring inwards when the first ring is compressed against the second ring
Implementation Method 2
The first ring includes an upstream face and an inner surface and is formed from a resilient material configured to form a seal against a plunger
Data Source
AI summary
An annular scraper ring assembly for a packing arrangement that can form a seal with a plunger included in a fluid end of a reciprocating pump includes a first ring having an upstream face and an inner surface cooperatively forming an edge and a second ring having a downstream face configured to engage the upstream face of the first ring and urge the edge of the first ring inwards so that the edge of the first ring is positioned inwardly beyond the second ring.