Caractérisation mécanique des tresses de valves à haute température

Abstract

Packed stuffing boxes are sealing devices used in valves, compressors and pumps. The packing ring is the most critical element of this assembly. The packing rings are compressed axially to produce lateral contact pressures large enough to confine the processed fluid within the pressure vessels and piping segments. Packed stuffing boxes house a gland seal to prevent leakage of fluid between sliding and/or rotating parts. Although popular, this old method of sealing has seen very limited analytical development. There is no standard design procedure for engineers to follow, and the standard qualification tests are limited to API622, 624, ISO-15848 1 and 2, which are quality control standards. Due to this lack of design procedure, structural integrity and leak tightness are rarely verified, and as a result 60 % of fugitive emissions from pressurized equipment are due to this type of sealing device. The mechanical properties of the compression packing material are the main factors affecting fluid-tightness at room and high temperature and yet there is little or no data available either in manufacturer’s catalogues or in the literature. Packed stuffing box research is scant and focuses mostly on the distribution of the contact pressure between the stem and packing at room temperature without considering the mechanical properties such as rigidity, thermal expansion and creep. It is proposed, in this project, to measure the mechanical properties such as pressure transmission ratio, short-term creep deformation and thermal expansion coefficient of two packing materials at high temperature. This project initiative will serve as a basis to launch a North American testing program to develop ASTM-like testing procedures for compression packing. The general objectives to achieve this research project about characterizing the mechanical properties of compression packing at high temperature are: • Make minor modification to the existing test rig and make necessary calibrations and thermal compensations to fine tune the measurement. • Develop a methodology and define test procedures to obtain the mechanical properties (lateral pressure coefficient, thermal expansion coefficient and creep strains). • Test two packing materials use in high temperature application and produce the above mentioned cited properties.

Date	24 Jan 2019
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Hakim A. Bouzid (Supervisor)