Blind Shear Ram Guide Arms for Pipe Centering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing shear ram assemblies in blowout preventers may fail to completely shear a pipe string if it is off-centered relative to the bore, leading to incomplete cutting due to the pipe remaining against the side wall during closure.
Innovation Solution
A shear ram assembly with guide arms that protrude from one ram block and have wedge surfaces to guide the pipe toward the axis of the bore, ensuring the pipe is centered and completely sheared, even if initially off-center, by sliding over the other ram block's blade when moved to a closed position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shear ram assembly uses conventional blades without guide arms, then the structure is simpler, but the pipe string may remain off-centered against the side wall during closure, leading to incomplete shearing
Solution Approach 1:
The shear ram assembly is divided into functional components: the ram body, the cutting blades, and the guide arms. The guide arms are separate elements that can be independently positioned and adjusted, allowing them to perform the specific function of centering the pipe without interfering with the cutting action of the blades.
Solution Approach 2:
The guide arms perform a preliminary action by centering the pipe string against the bore axis before the cutting blades engage. This preliminary centering action ensures that when the blades close, the pipe is properly positioned for complete shearing, preventing the problem of incomplete cuts that would occur if the pipe remained off-centered.
2Adaptability or versatility
If the pipe string is off-centered relative to the bore axis, then the initial positioning is more flexible, but the pipe may remain against the side wall during closure, causing incomplete shearing
Solution Approach 1:
The guide arms act as an intermediary mechanism between the off-centered pipe string and the cutting blades. They transfer and redirect the pipe string from its off-centered position to the centered position on the bore axis, mediating the transition smoothly and ensuring that the pipe is properly positioned for cutting regardless of its initial position.
Solution Approach 2:
Before the cutting action occurs, the guide arms perform a preliminary centering action on the pipe string. This preliminary action corrects any off-centered positioning, ensuring that when the blades engage, the pipe is aligned with the bore axis for reliable complete shearing.
3Reliability
If guide arms are added to center the pipe, then complete shearing is ensured, but the device complexity increases
Solution Approach 1:
The guide arms serve multiple functions: they center the pipe string against the bore axis, guide the pipe during the closing motion, and protect the cutting blades from lateral forces. By combining these functions into a single component, the design achieves reliable complete shearing without proportionally increasing complexity.
Solution Approach 2:
The shear ram assembly is segmented into distinct functional modules, with the guide arms as a separate, manageable component. This segmentation allows for easier manufacturing, assembly, and maintenance, reducing the practical impact of the added complexity while maintaining the reliability benefits.
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 guide arms effectively center the pipe string, ensuring complete shearing and preventing incomplete cuts by directing the pipe toward the axis, thus ensuring the pipe is fully severed regardless of its initial position within the bore.
Implementation Method 1
Each of the guide arms has a tip and a wedge surface on an inboard side extending rearward from the tip. The wedge surfaces are farther apart from each other than the blade and guide the pipe string toward an axis of the bore
Data Source
Figure 1
Figure 2~5
Figure 3~4
AI summary
A pipe shear ram assembly (11) has a housing (73) having a bore (75) extending vertically therethrough for the passage of a pipe string (77). Ram blocks (13, 51) have blades (17, 63) positioned such that one slides over the other when the first and second ram blocks (13, 51) are moved toward each other to shear a well pipe (77). A pair of guide arms (25) extend from one of the rams (13). The guide arms (25) have tips (29) protruding a greater distance than the blade (17). Each of the guide arms (25) has an inboard wedge surface (31) beginning at the tip (29) and extending along a line that intersects the longitudinal axis (28) for guiding the pipe string (77) toward a bore axis (79) of the bore (75) in the event the first and second ram blocks (13, 51) are moved to the closed position.