Becht Engineering Blog

Review of rigging attachments to the equipment being lifted have prevented lift failures.  When planning major crane lifts we are very careful about confirming the crane foundation, rigging stability/capacity, and crane capacity. Are we taking enough time to analyze the points of attachment for the rigging? Becht Engineering Heavy Lift Division says “NO”. Our experience is that reviews of rigging points of attachment have identified critical flaws that may have resulted in dropped loads. In industry today, the load/vessel designers typically design the lifting lugs and trunnions at the same time. It is our experience that the owners of the equipment and the crane contractors are assuming these devices are properly designed and rated. It is a common practice that the crane contractor assumes responsibility for rigging above the points of attachment. Generally, the consensus is that trunnions and lift lugs are designed by others and they should be right. That...

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...

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...

Risk based inspection (RBI) is a powerful tool to identify and manage mechanical integrity risks in fixed equipment and piping but is only one part of a robust reliability program.  RBI informs inspection decision making on where, when and how to inspect most of equipment but is frequently misinterpreted as a “Silver Bullet” that covers all necessary inspection activities in a refinery.  Most RBI programs have significant gaps that can result in costly reliability issues or unjustified maintenance costs.  RBI gaps can exist where risk assessments require input from outside of an inspection department or mechanical integrity group.  Examples of these gaps are when failures have process consequences but not mechanical integrity concerns, such as tube leaks in shell and tube heat exchangers and cyclones in an FCC Unit.  Another example is when mechanical integrity is dependent upon other systems functioning per design, such as fired heater tubes.  Quantitative RBI Programs...