Liquan Wang

Error analysis and prototype testing of deepwater pipe flange connection tool

The key factor for underwater petroleum pipeline flange connection tool is its 20 bolts synchronous lead-in nuts. The alignment accuracy of bolts and nuts is critical for bolts lead-in nuts. In order to analyze the accuracy and design issues of the pipeline flange connection tool, the robot kinematics modeling method is adopted. Using the multi-body kinematics theory to homogeneous transformation matrix, the error model of deepwater pipe flange connection tool is established through total differential of the machinery pose transformation matrix. The error model of the tool is established by computer simulation, and the effect of the structure parameters on the bolt end pose error is analyzed. Based on the method of error matching design, the error in the deepwater pipe flange automatic connection tool is determined. Considering the specific structure of the connection tool, the adjusting mechanism for bolt angle error is also designed. Therefore, the hardware compensation of bolt angle error is achieved successfully, and it improves the positioning accuracy of the bolt end. Tests on bolt lead-in prototype are conducted. The experimental results show that the bolt could successfully lead into the nut and confirm the accuracies of the error model and design of the pipeline flange connection tool.

Aerostatic & Aerodynamic Performance of a Herringbone Thrust Bearing: Analysis and Comparisons to Static Load Experiments

The combined effects of external pressurization and herringbone grooves are studied according to the incompressible Whipple analysis; results are examined in terms of nondimensional parameters that bring out the interaction between the action of herringbone groove self-pressurization and external pressurization through orifices. It is found that interaction is beneficial in a wide range of rotational speeds. An optimized interacting design can improve the bearing stiffness and load-carrying capacity. The herringbone grooves add to bearing stiffness and load-carrying capacity even in stationary state (rotation speed is zero) and in steady state the action of herringbone groove self-pressurization further promotes bearing performance with negligible effect on orifice pressure ratio. The orifice flow tends to be saturated ahead because of the spiral grooves in the stationary state and their herringbone self-pressurization has negligible effects on flow rate in the steady state. Herringbone grooving is found to be the preferred configuration considering the bearing stiffness, air flow, and orifice pressure ratio. These predicted trends are qualitatively substantiated by tests.

Analytical and experimental study on sealing contact characteristics of subsea collet connectors

The mathematical model of the contact stress is established based on the theory of Hertz contact with the assumption that the contact of a seal gasket and hubs of collet connectors is cylindrical. The mechanical models of the seal are established separately by sealing theory in the preloading and operating modes, and the relationships between the preload, the contact stress, and the sealing width are obtained. The relationships of structural parameters and the preload are analyzed and verified with finite element simulation and experiments. An experimental system has been designed and experiments have been conducted to verify the analytical models. Finite element simulation results and experimental results agree with analytical ones very well and the differences of the preload and sealing width are acceptable.

Design of an Orbit-holding Traveling Mechanism of Girth Weld Ultrasonic Scanner

An orbit-holding traveling mechanism which is used in Automatic Ultrasonic Testing (AUT) equipment is designed in this paper. It is composed of an elastic orbit and an orbit traveler. The AUT equipment is used to inspect the defects of girth weld. The orbit is attached to a pipe near the girth weld. The traveler travels along the orbit with an angle adjusting mechanism used to make the scanner adapt to pipes of different diameters and a self-locking holding mechanism used for the constraint between the orbit and the traveler. The traveler is driven by a DC servo motor. The location of the traveler is measured using an encoder. The traveler is controlled by a PID speed feedback loop to make it travel along the orbit smoothly.

Design of a Novel Deep-Sea Flange Connection Tooling

Deep-sea Flange Connection Tooling (DFCT) is a special kind of tools to complete the flange connection of deepwater pipeline, which will greatly enhance the development of Chinas deepwater Tie-ins technology. In this paper, through analyzing the sealing theory of flange connection, paper has presented general structure scheme of tool, including mechanical structure and hydraulic control system, and the proposed scheme is feasible by theoretical analysis. Through checking the key parts’ strength of the DFCT by using the finite element method and doing research on the system multi-body dynamics simulation studies, the results show that the mechanical structure is reasonable. Thereby, paper provides a reference for the further development of the DFCT.