Modular Suction Gland Assembly Thread Failure
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Solution Overview
Problem
Conventional positive displacement pumps used in hydraulic fracturing experience pressure loss and thread failure due to cyclic loading, requiring scrapping of the entire fluid end block when retainer nut threads fail, leading to inefficiencies and increased maintenance costs.
Innovation Solution
A modular suction gland assembly is introduced, where the retainer nut is secured to a modular suction gland using a threaded connection, allowing for easy replacement and enhanced thread engagement by extending the threaded interface beyond the fluid end block, utilizing bolts or screws for secure fastening and providing additional sealing with annular and face seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the retainer nut is directly threaded into the fluid end block, then the structure is simple, but the threads are prone to failure under cyclic loading
Solution Approach 1:
The suction gland is divided into modular components: a body portion with external threads that engages the fluid end block, and a retainer nut with internal threads that secures the suction cover. This segmentation isolates the threaded connections from the critical sealing surfaces, so that thread failure does not compromise the seal or require scrapping of the entire fluid end block.
2Reliability
If the threaded connection is extended beyond the fluid end block, then thread engagement is enhanced, but the device complexity increases
Solution Approach 1:
The threaded connection is extended in the axial dimension beyond the face of the fluid end block. The suction gland body has external threads that engage the fluid end block, and the retainer nut extends axially beyond the block face to provide additional threaded engagement length. This dimensional extension strengthens the thread connection without adding radial or lateral complexity.
3Ease of manufacture
If the entire fluid end block is scrapped when threads fail, then manufacturing simplicity is maintained, but maintenance cost and time increase
Solution Approach 1:
The suction gland assembly is designed as a disposable or replaceable component that can be removed and replaced without scrapping the expensive fluid end block. When the suction gland or retainer nut threads fail, only the suction gland assembly needs to be discarded and replaced, while the fluid end block is recovered and reused. This dramatically reduces maintenance costs and downtime.
4Device complexity
If conventional sealing methods are used, then the structure remains simple, but pressure loss occurs due to seal failure
Solution Approach 1:
The suction gland incorporates sealing elements (such as O-rings or packing) in advance at the interface between the suction gland body and the fluid end block, and between the suction cover and the suction gland. These seals provide beforehand cushioning against pressure leakage, preventing pressure loss and maintaining system integrity under cyclic loading conditions.
Data Source
AI summary
A positive displacement pump includes a suction cover disposed in a suction access bore defined in the fluid end and housing, where the suction cover is configured to cover the suction access bore. A retainer nut is configured for abutting against the suction cover and retaining the suction cover within the suction access bore. A suction gland has an inner circumferential threaded interface configured to engage an external circumferential threaded interface defined on the retainer nut, and the suction gland has a plurality of threaded openings configured to receive a plurality of threaded fasteners that can be used for securely fastening the suction gland to the fluid end housing.