If the behavior of discontinuity stresses due to pressure is not properly understood in elevated temperature design, unconservative designs can result. One particular issue with pressure stresses is the behavior of the discontinuity bending stresses. An example of discontinuity stresses would be with a pipe welded to a flange. When pressured, the pipe will radially […]
How long will the cyclone system in a Cat Cracker reactor or regenerator last? Cyclones systems in Fluidized Catalytic Cracker units (FCC) are typically designed to a creep allowable stress, where the stress field at various locations of the system has been determined by linear elastic analysis. The basic allowable stress for such internal structures […]
CFD was used to confirm that poor design of the steam inlet nozzle was the main contributor to deaerator head to shell weld cracking, and confirmed proposed design improvements. This recent Becht project illustrates one of the causes of deaerator cracking. A through-wall crack had been found at the head-to-shell junction at the steam inlet […]
Coke drums used in the delayed coking process have historically been subjected to severe operating conditions which result in numerous mechanical problems. The Coke Drum is far from your typical pressure vessel. However, the industry standard foundation, shimming, grouting and anchor bolt design continue to be identical to a typical pressure vessel. There is a […]
Coke drum lives can be extended by using an equipment health monitoring system, often without increasing the cycle time. Delayed coking is a form of thermal cracking used for processing “bottom of barrel” residuum. Thermal cracking produces a wide range of hydrocarbons along with coke, a solid structure of ~90 wt% carbon. In the delayed […]
It is often unsettling to have an inspection group discover a crack-like flaw in a piece of pressure containing equipment, particularly when the turn-around schedule is aggressive. Fortunately, there are well-established Fitness-for-service procedures in place to assess such flaws and help guide decision-making on whether to repair or to leave in place with a monitoring […]
So, you think you know what load case combinations to use for your ASME Section VIII, Division 2, Part 5 analysis to satisfy Protection Against? Common sense says to follow to Code rules in Table 5.3 – but do you fully understand what that means? And, what loads should you use to satisfy Protection […]
Process vessels such as towers, drums and heat exchangers may be exposed to low temperatures as a part of normal operation or as the result of an upset condition. Carbon and low alloy steels typically used in process vessels undergo a transition from ductile to brittle behavior as temperature is reduced and are at increased […]
While there are currently no explicit rules on how to perform a finite element analysis (FEA) if you are doing so in support of an ASME Section VIII, Division 1 vessel, there is good practice. Regarding rules, all you have is from Article U-2(g), which says: This Division of Section VIII does not contain […]
While fracture mechanics is used in fitness-for-service, FFS, for evaluation of crack like flaws that are detected and for evaluation of the potential for brittle fracture, it is also used in new design to evaluate fatigue life. The rules for high pressure vessels in Section VIII, Div 3 and ASME B31.3 Chapter X permit and […]
