Becht Engineering Blog
In this section of the site contributing authors submit interesting articles relating to the various services, industries and research & development efforts of Becht Engineering.
Becht Engineering has significant consulting expertise with improving reliability for chemical plants and refineries as well as upstream projects for oil and gas production. This multi-disciplinary task involves the clients’ representatives (operations, maintenance, inspection and engineering) together with Becht Engineering corrosion, mechan
ical integrity and reliability experts.
Cooling Towers: Benefits of a Cold Eyes Review
Thursday, 18 April 2019
One key decision that often needs to be made is repair vs. replace. When has a cooling tower arrived at the point where a new tower should be considered? Maintenance costs, overall tower condition, environmental constraints, and performance optimization are all factors that need to be evaluated. If a new cooling tower is justified, how are the specifications for performance selected? What range, fan horsepower, approach to wet bulb, and water flow rate should be specified to best match plant requirements? The range is the difference between the hot water (return) temperature and the cold water (supply) temperature. The approach to wet bulb is due to the fact that, if the cooling tower were infinite in size, the cold water temperature would be at the wet bulb temperature. However, just like a shell and tube heat exchanger with a temperature difference between two streams, a finite cooling tower results in some...
Repair or Replace
Acceptable Practices for High Voltage Motor Lead Routing
Monday, 08 April 2019
Are Your Wires Crossed? By Rick Hoffman and Joe Rammage We recently evaluated a 15kV, 5000 hp, induction motor in a WPII enclosure manufactured by a foreign company. During an on-site inspection of the main terminal box it was discovered that the high voltage leads were touching. This raised significant concerns about the long-term reliability of the motor. Becht Engineering investigated the issue to determine the industry standards and best practices concerning routing of the motor high voltage leads. Shielded vs Non-Shielded Cables The National Electric Code requires all cables rated above 2.4kV to be shielded to prevent concentrated electromagnetic stresses from forming between the cable conductor and ground when the cable is in close proximity to a grounded surface. The addition of the metallic shield smooths out the electromagnetic field eliminating high stress points. Without it, the increased density of electromagnetic stresses where the cable is in close...
High Voltage Leads
Basics of Design By Analysis in ASME Section VIII, Division 2
Sunday, 25 November 2018
How hard can it be? I’ve heard from several (unnamed) analysts that because they have access to an FEA program and have successfully applied FEA in other fields, that FEA for pressure vessels should be a snap. What is it about FEA for pressure vessels that makes it unique? I was recently discussing with another blogger regarding some distinctive aspects of performing Design By Analysis for pressure vessels. We generated several questions, and so I decided to post this in a Question & Answer format. When do I have to use FEA in my pressure vessel design? The short answer here is that for most situations, you probably should not be using FEA to design your pressure vessel. The rules for designing pressure vessels in ASME Section VIII, Division 1 and ASME Section VIII, Division 2 have a long history of successful application. So, wherever possible, I would recommend that you...
Design by Analysis
ASME Section VIII Div 2
Cyclic Loading Fatigue
Elastic Stress Analysis
How To Quantify And Evaluate Oil Storage Tank Annular Plate Corrosion
Sunday, 18 November 2018
Nadarajah "Ranjan" Chithranjan
Materials Degradation and Corrosion
Failure of Oil Storage Tank Annular Plate
In the past ten years, there have been a few oil storage tank annular plate failures due to soil side corrosion and fatigue loading (filling and emptying) which has led to large spills. The corrosion tends to be localized in a groove fashion and the size of the flaw could vary from 3 feet to 12 feet in the circumferential direction. The location of the corrosion is also where the highest bending stress will occur during filling and emptying of tanks. See Figures 1 and 2 for the location of the failure on the annular plate. Since the location of failure is under the tank, the corrosion flaws cannot be detected easily from the outside of the tank. It can only be detected if an internal inspection is done which would require the tank to be emptied and cleaned and this is very expensive. However, with UT shear wave technology...