Rope Packing Seal for Blowout Preventer
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Solution Overview
Problem
Existing wellhead blowout preventer (BOP) devices fail to reliably seal at very high or very low temperatures due to the limitations of nitrile rubber and thermoplastic seal materials, which degrade under extreme conditions, and graphite or asbestos seals are also prone to failure at high temperatures.
Innovation Solution
A ram-type BOP design featuring a housing with a central bore and horizontal ram bores, equipped with primary and secondary rope packing seals held in continuous grooves on the ram surfaces, allowing for dynamic sealing and accommodating overlapping ends, which can withstand extreme temperatures by using reinforced rope packing materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitrile rubber or thermoplastic seal materials are used in BOP devices, then the device can operate at normal temperatures, but the seal fails at very high or very low temperatures due to material degradation
Solution Approach 1:
The patent uses composite sealing structures combining rope packing material with metal reinforcement elements. The rope packing provides sealing capability while the metal reinforcement maintains structural integrity at extreme temperatures, creating a composite seal system that overcomes the limitations of single-material seals.
Solution Approach 2:
The patent changes the material parameters by selecting rope packing materials specifically designed for high-temperature resistance, replacing conventional nitrile rubber or thermoplastic seals with materials that maintain their physical properties across extreme temperature ranges including above 650°F.
2Temperature
If graphite or asbestos seals are used to withstand high temperatures, then temperature resistance is improved, but the seals are still prone to failure at very high temperatures
Solution Approach 1:
The patent combines rope packing with metal reinforcement elements to create a composite seal that maintains both temperature resistance and structural integrity. The metal reinforcement prevents the graphite or asbestos material from deforming or failing under extreme thermal conditions.
Solution Approach 2:
The metal reinforcement acts as an intermediary structural element that supports the graphite or asbestos sealing material, preventing direct exposure to extreme stresses and temperatures that would cause failure, while still allowing the seal to function at high temperatures.
3Reliability
If continuous grooves are used to hold rope packing ends, then the device complexity increases, but the sealing reliability improves by accommodating overlapping ends
Solution Approach 1:
The patent divides the sealing structure into segmented grooves that are strategically positioned to hold and accommodate the ends of rope packing. This segmentation allows the packing ends to be contained in specific locations while maintaining overall seal continuity, rather than requiring a completely different sealing approach.
Solution Approach 2:
The grooves are pre-formed during manufacturing to receive and hold the rope packing ends in their proper positions. This preliminary preparation ensures that when the seal is assembled, the packing ends are already correctly positioned and secured, maintaining seal integrity without requiring complex assembly procedures.
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 BOP effectively seals against both the central bore and polish rods across a wide temperature range, including temperatures above 650°F, by utilizing dynamic rope packing seals that maintain integrity and sealing effectiveness even at extreme conditions.
Implementation Method 1
opposing ram ends encircle and press against the polish rod to form a seal of the central bore
Implementation Method 2
the rubber surfaces of their inner portions seal against the sealing surfaces
Data Source
AI summary
A blowout preventer (BOP) is provided in which each ram includes a primary rope packing seal formed from a first length of rope packing extending horizontally across the front face, rearwardly and then either or both of upwardly and downwardly over the top and/or bottom portion of the ram. The primary rope packing seal is held in, so as to protrude radially outwardly from, a continuous first groove formed in the ram. The continuous first groove is adapted to accommodate joined abutting ends or overlapping ends of the first length of rope packing. A secondary rope packing seal and a circumferential rope packing seal may be provided on the ram.