Analysis of Stresses and Strains in Packed Stuffing-Boxes

2014 ◽  
Author(s):  
Mehdi Kazeminia ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Design Procedure ◽  
Standard Test ◽  
Packing Material ◽  
Test Procedures ◽  
Analytical Methodology ◽  
Packing Materials ◽  
Standard Design ◽  
Packing Rings ◽  
Leak Tightness ◽  
Side Walls

Packed stuffing-boxes are mechanical sealing systems that are extensively used in pressurized valves and pumps. Yet there is no standard design procedure that could be used to verify their mechanical integrity and leak tightness. It is only recently that standard test procedures to qualify the packing material have been suggested for adoption in both North America and Europe. While the packing contact stress with the side walls is predictable using existing models there is no analytical methodology to verify the stresses and strains in the stuffing-box housing. This paper presents an analytical model that analyzes the stresses and strains of all the stuffing box components including the packing rings. The developed model will be validated both numerically using FEM and experimentally on an instrumented packed stuffing box rig that is specially designed to test the mechanical and leakage performance of different packing materials.

Stress Analysis of Packed Stuffing-Boxes

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Mehdi Kazeminia ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Structural Integrity ◽  
Design Procedure ◽  
Standard Test ◽  
Test Procedures ◽  
Analytical Methodology ◽  
Packing Materials ◽  
Standard Design ◽  
Packing Rings ◽  
Leak Tightness ◽  
Side Walls

Packed stuffing-boxes are mechanical sealing systems that are extensively used in pressurized equipment such as valves and pumps. Yet there is no standard design procedure in use to verify their mechanical integrity and leak tightness. It is only recently that standard test procedures to qualify packing materials have been suggested for adoption in both North America and Europe. Nonetheless the assessment of the structural integrity of the housing requires a well-documented design procedure to insure safe use of packed stuffing-boxes. While the packing contact stress with the side walls is predictable using existing models there is no analytical methodology to verify the stresses and strains in the stuffing-box housing. This paper presents an analytical model that analyzes the stresses and strains of the stuffing-box components including the packing rings. The developed model is validated both numerically using FEM (finite element method) and experimentally on an instrumented packed stuffing-box rig that is specially designed to measure the structural integrity and leakage tightness of different packing materials.

Mechanical Characterization of Valve Compression Packing at High Temperature

2019 ◽  
Author(s):  
Xavier Legault ◽  
Abdel-Hakim Bouzid ◽  
Ali Salah Omar Aweimer
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
High Temperature ◽  
Structural Integrity ◽  
Outer Boundary ◽  
Design Procedure ◽  
Critical Element ◽  
Packing Materials ◽  
Testing Procedures ◽  
Standard Design

Abstract Packed stuffing boxes are sealing devices used in valves, compressors and pumps. The compression packing is the most critical element of this assembly. Packing rings are compressed axially to produce lateral contact pressures large enough to confine the processed fluid within the pressurized valve and avoids leakage to the outer boundary. Although popular, this old method of sealing has seen very limited analytical and numerical development. There is no standard design procedure for engineers to follow, and the existing standard test procedures are limited to qualification and quality control tests such as API622, 624, ISO-15848 1 and 2. As a result, structural integrity and leak tightness are rarely verified, and consequently 60 % of pressurized equipment requiring fugitive emissions compliance are valves that use this type of sealing device. The mechanical properties of compression packing materials are the main factors affecting fluid tightness at room and high temperatures 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 packing mechanical properties such as rigidity, thermal expansion, creep and aging. 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 initiative will serve as a basis to launch a North American testing program to develop ASTM-like testing procedures for compression packing at high temperature.

Tightness Characteristics of Packings

2005 ◽  
Author(s):  
Manfred Schaaf ◽  
Thomas Klenk ◽  
Ralf Vogel ◽  
Jaroslav Bartonicek
Keyword(s):  
Chemical Industry ◽  
Packing Material ◽  
Leak Rate ◽  
Design Criteria ◽  
Fugitive Emissions ◽  
Test Procedures ◽  
Packing Materials ◽  
Material Characteristics ◽  
Characteristic Values ◽  
The Way

The demands on industry to reduce fugitive emissions are increasing, steadily /1/, /2/. On this background it is necessary to improve function and tightness of tightening joints like flanged joints and stuffing box packings. Function and tightness can only be guaranteed if the entire chain of parameters involved is taken in to account (design criteria, gasket factors, calculation, mounting procedure). On the field of flanged joints there are standardization projects on the way that address the topics of the new regulatory demands. Only few work is done regarding stuffing box packings, however. Similar to flanged joints a reliable function and tightness of stuffing box packings can only be achieved if the behaviour of the parts (bolts, gland, stuffing box) is known and their interaction is understood. Regarding the behaviour of stuffing box packing materials it is necessary to determine characteristics like deformation capability, relaxation, friction and leak rate. These characteristics have to be used to prove function and tightness. Some attempts to define these characteristic values have already been made; test procedures and test rigs to determine these values have been developed. Parallel to that, gasket manufacturers are developing new packing materials and entire packing sets in order to meet the more stringent requirements on tightness. One of these newly developed products are nonwoven packing sets which should be applicable up to temperatures of 280 °C in the processing and chemical industry. In the paper the most relevant packing material characteristics and the necessary tests to determine these characteristics are reviewed, first. Then the results of extensive tests with new nonwoven packing sets regarding tightness characteristics, friction, wear and gap extrusion are presented.

scholarly journals Evaluation of Tomato-Based Packing Material for Retention of Ammonia, Nitrous Oxide, Carbon Dioxide and Methane in Gas Phase Biofilters: A Laboratory Study

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 360
Author(s):  
José L. S. Pereira ◽  
Adelaide Perdigão ◽  
Francisco Marques ◽  
Catarina Coelho ◽  
Mariana Mota ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Laboratory Study ◽  
Packing Material ◽  
Control Treatment ◽  
Airflow Rate ◽  
Pig Slurry ◽  
Air Pollution Control ◽  
Gaseous Emissions ◽  
Packing Materials ◽  
Tomato Waste

Biofilters are an effective air pollution control technology to break down gaseous contaminants and produce innocuous end products. This laboratory study aimed to evaluate a biofilter media, mainly composed by tomato waste, as packing material to reduce NH3, N2O, CO2 and CH4 losses from stored pig slurry. Three mixtures of packing materials, with and without oxalic acid, were arranged in treatments, namely: mixture of tomato waste, pine bark and agricultural compost; mixture of tomato waste and rice husk; tomato waste only. A control treatment (no biofilter) was also included. The experiments were conducted using a system of laboratory scale biofilters connected to jars filled with pig slurry and under a constant airflow rate. The gas concentrations were measured for 14 days and the physicochemical of the packing materials were assessed. Results showed that biofilter media mixtures had a potential for NH3 retention ranging from 51 to 77% and the addition of oxalic acid to these biofilters increased NH3 retention to 72–79%. Additionally, the biofilter media mixtures with and without oxalic acid showed a potential retention for CH4 (29–69%) but not for N2O, yet with no impact on the global warming potential. It can be concluded that tomato based biofilters had the potential to reduce gaseous emissions from slurry.

Accelerated lifetime tests on e-textiles: Design and fabrication of multifunctional test bench

2017 ◽  
Vol 47 (8) ◽  
pp. 1925-1943 ◽  
Author(s):  
Giorgio De Pasquale ◽  
Andrea Mura
Keyword(s):  
Test Bench ◽  
Current Flow ◽  
Wearable Electronics ◽  
Mechanical Reliability ◽  
Test Procedures ◽  
Smart Fabrics ◽  
Standard Design ◽  
Fast Development ◽  
Accelerated Lifetime ◽  
Production Technologies

The development of e-textiles and conductive fabrics is strongly supported by the rapid growth of wearable electronics. Unfortunately, the fast development of production technologies for smart textiles has not been followed by standard design methods and validation procedures to certificate the electro-mechanical reliability of e-textiles. Then, the design of test procedures able to control the sources of failure in combination with cross-talk effects (e.g. between load and wear, cyclic loads and current flow, etc.) is crucial. Standard tests already used for traditional fabrics are not satisfactory in predicting the lifetime of e-textiles. This paper introduces the design of innovative machine to assess the performances and reliability of smart fabrics under fully controllable conditions.

Leak tightness of magnetic pulse crimped joints

2012 ◽  
Vol 3 (3) ◽  
pp. 243-250
Author(s):  
A. Loosveld ◽  
W. De Waele ◽  
K. Faes ◽  
O. Zaitov
Keyword(s):  
Stainless Steel ◽  
Steel Tube ◽  
Test Series ◽  
Stainless Steel Tube ◽  
Magnetic Pulse ◽  
Test Procedures ◽  
Burst Test ◽  
Master Thesis ◽  
Leak Tightness ◽  
Sealing Materials

The goal of this master thesis is to realize and investigate leak tightness of joints produced by theelectromagnetic pulse (EMP) crimping process. This way of joining metals has gained more attention lately.With EMP welding, leak tight joints can already be achieved. However, the crimping process has somemajor advantages over EMP welding like the fact that more material combinations are possible and itrequires less energy. To realize the leak tightness, two kinds of sealing materials are used: O-rings andadhesives. The workpieces consist of an aluminium or stainless steel tube which is crimped on a solidaluminium mandrel with circumferential grooves in it. First, some preliminary tests are performed todetermine how much the tubes deform in the grooves. This deformation mainly depends on the appliedcharging voltage and the geometry of the groove. With this information, it is possible to estimate the amountof compression an O-ring would undergo when placed inside this groove. On other workpieces, adhesiveswill be applied. Several test procedures can be conducted on the parts to investigate leak tightness. Theresults of a helium test and a pressure burst test on the first test series conducted at the Walloon researchcentre CEWAC already showed that the use of O-rings can be effective.

scholarly journals Towards Standardising SHPB Testing - A Round Robin Exercise

2018 ◽  
Vol 183 ◽  
pp. 02027
Author(s):  
Reuben Govender ◽  
Muhammad Kariem ◽  
Dong Ruan ◽  
Rafael Santiago ◽  
Dong Wei Shu ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Pure Copper ◽  
Round Robin ◽  
Standard Test ◽  
Test Method ◽  
Hopkinson Pressure Bar ◽  
Test Procedures ◽  
Draft Standard ◽  
Shpb Test ◽  
Pressure Bar

The Split Hopkinson Pressure Bar (SHPB) test, while widely utilised for high strain rate tests, has yet to be standardised. As an exploratory step towards developing a standard test method or protocol, a Round Robin test series has been conducted between four institutions: (i) Swinburne University of Technology, Australia (ii) University of São Paulo, Brazil, (iii) University of Cape Town, South African and (iv) Nanyang Technological University, Singapore. Each institution prepared specimens from a metallic material, and provided batches of specimens from their chosen material to the other institutions. The materials utilised in this round of testing were commercially pure copper and aluminium, magnesium alloy and stainless steel (316 grade). The intent of the first exercise is to establish the consistency of SHPB test results on nominally identical specimens at comparable elevated strain rates, conducted by different laboratories following notionally similar test procedures with some freedom in data processing. This paper presents and compares the results of the first batch of tests for copper, identifying variations between results from different laboratories. The variation between different laboratories’ results for copper is suffciently small that there is confidence in the potential to develop a draft standard in future.

scholarly journals Design and Optimization of Lug Bracket Assembly

2021 ◽  
Vol 13 (1) ◽  
pp. 55-67
Author(s):  
G. GOWTHAM ◽  
G. SHIVA SAM KUMAR SHIVA SAM KUMAR ◽  
AASA DARA
Keyword(s):  
Static Loading ◽  
Design Procedure ◽  
Initial Model ◽  
Stress Concentrations ◽  
Fighter Aircraft ◽  
Design And Optimization ◽  
High Speeds ◽  
Cantilever Structure ◽  
Standard Design ◽  
Optimized Model

An aircraft is an advanced mechanical structure made by man which has been dominating the skies from the early 19th centuries. It has been used for transportation of cargo/ passengers from one place to another in a shorter period of time. Advances in aeronautics lead to the development of fighter aircrafts with exciting and dominating characteristics. A fighter aircraft is to be designed in such a way that it can withstand heavy loadings on the wing due to its high manoeuvrability. A fighter aircraft is designed to be marginally unstable, which makes control easier and better during manoeuvrability at high speeds, but in this state there is a heavy fluctuating load acting on the wing. The wing is connected to the fuselage using wing fuselage lug attachment bracket. Since the wing is a cantilever structure, the load acting on the wing is concentrated on the hinge (lug bracket assembly). In this paper, a lug bracket is designed according to the standard design procedure and is validated using Finite Element Methods to ensure the static loading capability and stress concentrations in lug bracket. The validated model has been optimized using Altair Optistruct. The optimized model has been validated under static loading condition for the stress concentration and displacement and is compared with initial model in order to study and understand its behaviour under various conditions.

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