Stress Analysis on Tubesheet Referring to TEMA Standard

A heat exchanger is a device used to transfer heat without mass transfer. The equipment must be designed according to established standards. The standard that is widely used is the standardissued by TEMA (Tubular Exchanger Manufacturer Association). The results of the design of theheat exchanger with these standards are considered less efficient in terms of the material. Theefficiency of the material used can be analyzed by stress analysis on the components that withstand the force, and one of these components is the tube sheet. Stress analysis on tube sheets can use finite element-based software. The results of the research show that the tube sheet design that refers to the TEMA standard is relatively safe because the maximum von Mises stress is below the yield strength of the material used, while the overdesign value is rather significant because the average von Mises stress is also far below the yield strength of the material used.

STRATEGIC MANAGEMENT PROCESS AND FIRM’S PRODUCTIVITY OF PLASTIC MANUFACTURING COMPANIES IN SOUTH-SOUTH, NIGERIA

The study examines how strategic management process affects firm productivity with specific reference to plastic manufacturing companies listed in the manufacturer association of Nigeria that has operational based in the South-South, Nigeria. The study employed cross-sectional survey design which is exploratory in nature because the data were collected at a particular point in time to examine how strategic management process affect productivity in the context of Nigeria plastic manufacturing sector.The population for the study was all the 34 plastic manufacturing companies listed in the 2018 edition of the directory of Nigerian manufacturer Association based in South-South Nigeria. The cluster sampling technique was adopted in this study. This was complemented with the simple random sampling technique. The analytical techniques employed were Correlation and Multiple Regression Statistics to determine the strength and direction of the relationship and test the hypotheses with the help of IBM data editor of Statistical Package for the Social Sciences. The findings of the study revealed thatthere is a significant relationship between strategy formulation, strategy implementation and productivity in the context of Nigeria plastic manufacturing sector. Furthermore, the findings showed that there is no significant relationship between strategy evaluation and productivity in the context of Nigeria plastic manufacturing sector. The study concludes that strategy formulation, strategy implementation, strategy evaluation makes a unique contribution to the variation of plastic manufacturing firms’ level of productivity to gain edge over rivals in the industry. Therefore, the study recommends that plastic manufacturing firms should implement formulated policies and strategies to match with the structure of the organization, increase value relevance and earnings quality for productivity.

Determinant Factors of Environmental Responsibility for the Passenger Car Users

The main aim of this study is to find out the demographic variables and their driving factors influencing the environmental responsibility of passenger car users. There are around 73.85 million passenger car was produced (OICA, 2018), and it is forecasted that 2 billion of car expected on the road before the end of 2040. Vehicles are the primary generator of emission per liter of fuel exhausts around 140-210 Co2 /km released in the air. The people who are using the vehicles are to be held responsible for the vulnerability which is resulted because of emission from the tailpipe. According to the Japan Automobile Manufacturer Association (JAMA), 80% of tailpipe emission was released by the vehicle users and the remaining 20% by the vehicle manufacturers. Therefore this paper understands the factors influencing the environmental responsibility of the passenger car users.

Analysis of Expansion Joints Movement Test in FCC Unit

The turboexpander is an equipment that works under very critical conditions requiring very low allowable nozzle forces and moments. A solution to minimize the piping loads transmitted to the equipment is the use of expansion joints (EJ). A usual piping stress analysis normally is not enough to guarantee the turboexpander reliability. This paper shows the results obtained in a movement test realized on metallic bellows EJ used in a turboexpander piping system. The EJ were designed according to the expansion joints manufacturer association code (EJMA), the diameters range from 0.457 to 2,898 m, the material of the bellows is Inconel 625 LCF and the shell materials are “killed” carbon steel, for refractory lined EJ or stainless steel 304H. A special test device was developed to apply the design movements on the EJ at the factory. A digital dynamometer was used for data acquisition and the tests were performed on 16 EJ of two distinct types: hinged and gimbal. The EJ were pressurized with water during the test. The reactions and corresponding displacements for each step of the test were recorded during loading and unloading.

Analysis of FCC Expansion Joints Movement Test

The Turboexpander is an equipment that works under very critical conditions requiring very low allowable nozzle forces and moments. A solution to minimize the piping loads transmitted to the equipment is the use of expansion joints. A usual piping stress analysis normally is not enough to guarantee the turboexpander reliability. This paper shows the results obtained in a movement test realized on metallic bellows expansion joints (EJ) used in a turboexpander piping system. The EJ were designed according to the expansion joints manufacturer association code (EJMA), the diameters range from 457 to 2,898 mm, the material of the bellows is Inconel 625 LCF and the shell materials are “killed” carbon steel, for refractory lined EJ or stainless steel 304H. A special test device was developed to apply the design movements on the EJ at the factory. A digital dynamometer was used for data acquisition and the tests were performed on 16 expansion joints of two distinct types: hinged and gimbal. The EJ were pressurized with water during the test. The reactions and corresponding displacements for each step of the test were recorded during loading and unloading.

Experimental Investigation of Heat Exchanger Tubesheet Hole Enlargement

An experimental study has been conducted to evaluate the effect of roller expansion of heat exchanger tubes in enlarged tubesheet holes on joint strength, tube wall reduction (i.e., thinning), and strain hardening of the tubes and surrounding tubesheet ligaments. Different levels of tube-to-tubesheet hole clearance, or overtolerance (OT), were investigated to simulate tubesheet in-service, and during-maintenance, hole enlargement process. The experimental results have shown that, in spite of increasing overtolerance level by up to seven times the maximum value allowed by the Tubular Exchanger Manufacturer Association (TEMA) standard, the average strength of the test joints has not declined below the strength of joints in the allowed TEMA OT range. Percent wall reduction (WR) of the expanded tube was found to increase linearly with increasing overtolerance value; although its maximum value remained well below the wall reduction limit for which a joint is rejected in industry. An observed increase in hardness of the expanded tube material is evidence of the high degree of strain hardening to which the expanded tubes are subjected compared with the surrounding ligaments. Pull-out forces, calculated using existing analytical methods, were found to compare well with the experimental results.