scholarly journals Long-Term Performance of Trestle Bridges: Case Study of an Indonesian Marine Port Structure

2020 ◽  
Vol 8 (5) ◽  
pp. 358 ◽  
Author(s):  
Yusak Oktavianus ◽  
Massoud Sofi ◽  
Elisa Lumantarna ◽  
Gideon Kusuma ◽  
Colin Duffield
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Field Measurement ◽  
Field Measurements ◽  
Element Analysis ◽  
Moment Capacity ◽  
Non Destructive

A precast reinforced concrete (RC) T-beam located in seaport Terminal Peti Kemas (TPS) Surabaya built in 1984 is used as a case study to test the accuracy of non-destructive test techniques against more traditional bridge evaluation tools. This bridge is mainly used to connect the berth in Lamong gulf and the port in Java Island for the logistic purposes. The bridge was retrofitted 26 years into its life by adding two strips of carbon fiber reinforced polymer (CFRP) due to excessive cracks observed in the beams. Non-destructive field measurements were compared against a detailed finite element analysis of the structure to predict the performance of the girder in terms of deflection and moment capacity before and after the retrofitting work. The analysis was also used to predict the long-term deflections of the structure due to creep, crack distribution, and the ultimate moment capacity of the individual girder. Moreover, the finite element analysis was used to predict the deflection behavior of the overall bridge due to vehicle loading. Good agreement was obtained between the field measurement and the analytical study. A new service life of the structure considering the corrosion and new vehicle demand is carried out based on field measurement using non-destructive testing. Not only are the specific results beneficial for the Indonesian port authority as the stakeholder to manage this structure, but the approach detailed also paves the way for more efficient evaluation of bridges more generally over their service life.

Avoid Exchanger Replacement Using Advanced Analysis and Fit for Service Approach

2021 ◽  
Author(s):  
Ibrahim M. Al Awadhi ◽  
Ashok M. Sharma ◽  
Sohail Akhter
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Heat Exchangers ◽  
Structural Integrity ◽  
Design Code ◽  
Element Analysis ◽  
Fit For Purpose ◽  
Design Pressure

Abstract Objective/Scope (25 - 75 word) Shell & Tube Heat exchangers are critical for incessant operation of processing plant. These exchangers may face integrity threats due to reduction in shell thicknesses at Nozzle to Shell Junction below design code requirements. This paper presents the Cost Effective fit for purpose approach utilizing advance Finite Element analysis to explore and recommend the solutions for existing numerous exchangers that are to be safely used even after reported low thickness on account of manufacturing imperfection. Methods, Procedures, Process (75 - 100 word) Reduction in Shell thickness below design value can affect its ability to sustain design pressure & vacuum including nozzle integrity for associated piping loads and service life reduction for exclusion of corrosion allowance. As short-term Mitigation methodology, weld overlay was adopted to restore the areas with lower thickness. For long term solution, fit for purpose review approach was adopted for continued usage of exchangers which involves nozzle load analysis using WRC & FEA based on PAUT thickness data and utilizing actual piping loads, derating of design pressure, comparison of thickness data to establish corrosion rate and service life of exchanger. Results, Observations & Conclusions (100 - 200 words) Thorough Integrity review based on design Code (ASME BPVC Section VIII) and WRC analysis have confirmed that majority of the exchangers have thickness higher than that required to sustain design pressure, vacuum conditions when considered with piping loads acting on nozzles. Thickness data comparison between three (03) year old manual UT and latest Phase array UT confirmed that majority of the exchangers are in clean non-corrosive service thus allowance for corrosion is not required. Where in the nature of exchanger service require corrosion allowance, it is considered in analysis and usage of stiffeners at nozzle to shell intersection and/or on full circumference of shell is recommended to prevent overstress due to piping loads / buckling distortion due to vacuum conditions respectively, based on detailed Finite element analysis (FEA). In order to establish more reliable long-term corrosion rate, next inspection after four (04) years is recommended and impact on integrity can be further evaluated based on the latest data. Change in exchanger nameplate is recommended to consider for design pressure as MAWP and accordingly adjust hydro test pressure followed by R-stamp requirements for rerating and repair. Shell side hydro test is restricted until recommendations are implemented Novel/Additive Information (25 - 75 words) Although conventional approach of replacing complete Shells to meet code requirement would have ensured process safety, performance and structural integrity. However, alternative fit for purpose approach utilizing advanced FEA has not only ensured all these but also led to potential cost saving of multimillion US$. Associated risks of thickness reduction due to corrosion may still be observed, however analysis confirmed structural integrity and safety of heat exchangers with low thicknesses. Accordingly, potential risk is mitigated.

Design and Analysis of Manufacturing Component Under Sustainability Considerations: A Case Study of Electronic and Mechanical Indexing Head for Milling Operation

2018 ◽  
Author(s):  
Nand K. Jha ◽  
Mahmoud M. Amin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cost Estimation ◽  
Minimum Energy ◽  
Solid Modeling ◽  
Milling Machine ◽  
Element Analysis ◽  
Milling Operation ◽  
The Cost

An attempt has been made to design and analyze Indexing Head a very important component in milling operation under sustainability considerations. The design of each component of indexing head is presented along with solid modeling and finite element analysis. The cost estimation for indexing head for milling operation is also presented. The design and finite element analysis of indexing head should be utilized by manufacturers of this very useful device in milling operation. It is used for cutting gears, spirals, splines, etc. The cost estimated of the manufactured indexing head shows it to be within reasonable limits of market. Finite element analysis of each component is safe. An electronic indexing is suggested as an improvement over the mechanical indexing head. A schematic of electronic indexing is presented. The electronic indexing head can be used with milling machine not provided with indexing head and will be portable. The minimum energy needed to manufacture the indexing head is also estimated.

A Review of Optimising the Design of a New Coke Drum Skirt

2019 ◽  
Author(s):  
Alex Berry ◽  
Warren Brown ◽  
Antonio Seijas ◽  
Sarah Cook
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Literature Review ◽  
Thermal Stresses ◽  
Fatigue Cracking ◽  
Element Analysis ◽  
Long Life ◽  
Welded Connection

Abstract Coke drums are subjected to severe thermal cycling with the skirt to shell connection weld being vulnerable to fatigue cracking. It is essential this connection is well designed to ensure a long life before repairs are inevitably required. Much has been written on coke drum skirt design with the aim of reducing the thermal stresses and strains encountered at the skirt connection weld, some designs have removed the weld completely allowing the drum to sit in an “egg-in-cup” arrangement. This paper includes a short literature review discussing Coke drum skirt designs and explains skirt behaviour during the drum cycle that results in eventual skirt cracking. A case study is reviewed in detail for a new pair of coke drums, where the predicted fatigue life of the chosen welded connection is assessed using axisymmetric, quarter symmetry and half symmetry finite element analysis supported by thermocouple data. The optimised design focuses on a conventional tangential design where the effects of the essential variables such as skirt thickness, skirt connection location, skirt-to head-gap and slot design (length, location & spacing) have been modelled and optimised to obtain a skirt design that produces the longest fatigue life for the intended duty cycle. Coke drum skirts must be installed onto the shell to exacting tolerances during manufacture to ensure concentricity and minimal gap between the skirt and shell. A brief overview of how this is achieved will be presented.

Sign in / Sign up

Export Citation Format

Share Document