Hose Crimp Fitting with Reverse Threaded Lock Nut
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Solution Overview
Problem
Existing hose crimp fittings with 37 degree JIC sealing technology are prone to leaks due to hydraulic shock and vibrations, causing the JIC swivel nut to loosen and disconnect, which is particularly problematic in subsea applications with high pressures and constant vibrations.
Innovation Solution
A hose fitting assembly featuring a tubular hose stem with two left-handed threaded sections, a JIC/swivel nut with internal right-hand threads, and a left-hand threaded lock nut that prevents the JIC/swivel nut from rotating under vibration, utilizing a conical washer and ferrule for secure engagement and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a JIC swivel nut is used for hose crimp fittings, then the connection can be made with standard 37 degree JIC sealing technology, but the nut is prone to loosening and leaking due to hydraulic shock and vibrations
Solution Approach 1:
The connection system is divided into two separate nuts: a standard JIC swivel nut for sealing and a reverse-threaded lock nut for anti-loosening. This segmentation allows each component to perform its specialized function - the JIC nut provides the metal-to-metal seal while the reverse-threaded lock nut prevents loosening under vibration and hydraulic shock.
Solution Approach 2:
A reverse-threaded lock nut (left-handed threads) is introduced to counteract the loosening tendency of the standard right-handed JIC swivel nut. The opposite threading direction creates opposing rotational forces that prevent the JIC nut from backing off during vibration and hydraulic shock events.
2Ease of operation
If standard JIC threading is used, then the fitting can be easily assembled, but vibrations cause the nut to progressively rotate and loosen the connection
Solution Approach 1:
The reverse-threaded lock nut creates opposing rotational forces that counteract the loosening tendency of the standard JIC swivel nut under vibration. As the system vibrates, the reverse threading prevents progressive rotation in the loosening direction, maintaining connection stability while preserving ease of initial assembly.
Solution Approach 2:
The reverse-threaded lock nut acts as a countermeasure against the loosening force generated by vibration. The opposing thread direction provides a counteracting mechanical force that balances and neutralizes the destabilizing vibratory effects on the connection.
3Reliability
If a lock mechanism is added to prevent nut loosening, then connection stability improves, but device complexity increases
Solution Approach 1:
The anti-loosening function is separated into a distinct reverse-threaded lock nut component rather than integrating complexity into the JIC swivel nut itself. This segmentation maintains the simplicity and standardization of the original JIC connection while adding a separate, dedicated lock mechanism for vibration resistance.
Solution Approach 2:
The reverse-threaded lock nut serves multiple functions: it acts as a vibration-resistant lock mechanism, provides mechanical locking against hydraulic shock, and maintains compatibility with standard JIC threading systems. This multi-functionality achieves enhanced reliability without requiring completely new specialized components.
Data Source
AI summary
A tubular hose stem with a flange, a first left hand threaded section on the outer surface of the stem generally adjacent the flange, a first JIC/swivel nut over the flange having an inner diameter smaller than the outer diameter of the flange, a second lock nut threadably engaged to the hose stem on a second left threaded section adjacent the JIC nut, a conical washer fixedly secured around the hose stem between the first and second threaded sections, an O-ring positioned adjacent the washer opposite the left side of the washer; and a ferrule having a first end fixedly threaded to the hose stem and having a second end larger in diameter than the stem. The lock nut may have knurled surfaces and the inner diameter of the ferrule and outer diameter of the stem may have circumferential raised ribs to engage hosing.