Session: NDE-03-01 NDE Reliability - Modeling and Experimental Analysis

Paper Number: 106521

106521 - Research on Sealing Reliability of High Pressure Flange Based on Magnetic Memory Bolt Looseness Detection 

In the large-scale, high-load, long-period operation of oil and gas exploitation, production site, high-pressure flange equipment will withstand up to tens or even hundreds of MPa pressure and a long time in corrosive media and complex vibration environment. In order to ensure the reliability of the seal, the high-pressure flange generally adopts the octagonal gasket sealing method. It achieves the ideal sealing effect by applying a proper bolt preload. Therefore, the change of bolt preload is the main reason affecting the sealing performance of the high-pressure flange. This study focuses on applying magnetic memory technology to detect high-pressure flange bolt stress. Based on experimental and simulation analysis, the correlation formula between magnetic signal and bolt axial force, contact stress on octagonal gasket sealing surface, and leakage prediction model are constructed to evaluate the sealing performance of high-pressure flange. The results show a stable linear relationship between the preload of high strength bolt and the magnetic memory signal. The simulation analysis results of the high-pressure flange-bolt-octahedron gasket reflect the relationship between bolt preload and gasket sealing contact stress. With the increase of bolt loosening, the non-uniformity of the stress distribution on the sealing surface increases, the average contact stress decreases, and the sealing performance deteriorates. Under vibration conditions, even if all bolts are reliably preloaded, it still causes fluctuations in the axial stress of the bolt and the contact stress of the sealing surface, which are more severe when the bolt is loose. In addition, the simulation results show that the bolt pre-tightening force of the high-pressure flange and the contact stress on the gasket sealing surface increase logarithmically under the pressure condition. Based on this calculation result, this study establishes a numerical relationship model between bolt pre-tightening force and gasket sealing stress. At the end of the study, combined with the simulation results of seal clearance height of the rough surface, the leakage prediction model of octagonal gasket sealing surface is proposed, which provides a new solution for evaluating the sealing reliability of high-pressure flange structure.

Presenting Author: Yanran Wang China University of Petroleum (Beijing)

Presenting Author Biography: Yanran Wang, a female Ph.D. candidate at China University of Petroleum (Beijing), is mainly engaged in the research of safety detection and intelligent diagnosis.

Authors:

Yanran Wang China University of Petroleum (Beijing)
Jianchun Fan China University of Petroleum (Beijing)