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industrialgases

Becht Engineering counts most of the world's largest industrial gas providing companies as our clients.  Our services have included equipment consulting (including reformers and pressure swing absorbers), troubleshooting, failure analysis, development of equipment for new processes and reliability improvements.  We also have assisted companies in successfully converting from petroleum base oil fuel to natural gas.

Becht Industrial Gas Projects

  • Equipment Re-Rating
  • Specialized Design
  • Vessel Life Assessment
  • Technology Scale Up
  • Weld Misalignment

Equipment Re-Rating

reactor shell dataBecht has re-rated many pressure vessels and heat exchangers to higher design pressures and temperatures as well as de-rates to establish lower design pressures and temperatures as a consequence of corrosion or some other damage. As a part of any re-rate, an assessment of the vessels current condition is made looking for general corrosion and localized metal loss, environmental cracking, etc. Ultrasonic thickness (UT) measurement is used to check the vessel thickness vs. the minimum required by the code of construction. The figure shows a plot of typical thickness data obtained from a UT scan of a reactor vessel. Where thicknesses fall below the required (including the future corrosion allowance), a Fitness-for-Service assessment is conducted using the methods in API 579 – Fitness-for-Service.

Often a client may want to increase the design pressure of a vessel by using the higher allowable stresses permitted by the 1998 Edition of ASME Code Section VIII, Div.1. This is possible; however, the rules do not permit rerates for vessels built prior to the 1968 Code, and other rules contained in the 1998 Code must be followed, e.g., impact test requirements.

Becht has also conducted the analysis and the inspections necessary to bring a pressure vessel built to other Codes, non-ASME code stamped vessels and "used" vessel into a state. The requirements can vary by state. Becht has completed the application and technical requirements and submitted the application to the state for approval by the agency responsible for code and state regulations related to pressure vessels.

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Special Purpose Computer Program for Large Diameter (10-30ft)
Gas-Gas Heat Exchanger Design

gas heat exchangerSpecialized equipment oftentimes do not lend themselves to standard design tools or even Finite Element Analysis which can be expensive for complex equipment and require individuals with background in FEA. In this case the client's design methodology used a combination of experience, hand calculations, spreadsheets and subcontracted analysis using proprietary software. Their desire was to have all the design done in one comprehensive in-house software package with the capability of investigating multiple design options rapidly. Over an elapsed time of about one-year Becht developed Windows based application with a user friendly interface for the design of large diameter, fixed tubesheet, gas-to-gas heat exchangers. The program, uses the method of finite differences supplemented with built in subroutines, e.g., materials allowable stresses, perforated tubesheets, etc. based on ASME Code Section VIII, Div. 1 rules. The program was validated using more elaborate FEA methods.

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Vessel Remaining Life Assessment

pressure vesselAn incident in a process used to remove contaminants from a process waste gas required the shutdown of the unit. The process contains multiple similar vessels that follow the same pressure and temperature cycle daily. The vessels had been in service for more than 40 years. (A typical pressure cycle is shown in the sketch.) The client wanted to determine a safe remaining life for the vessels. As an initial step, Becht conducted a Finite Element Analysis (FEA) using the operating pressure and temperature cycles. The focus was on those areas of the vessel with high peak stresses where a crack may already exist or develop in future operation. The remaining fatigue life was based on the methods in ASME Code Section VIII, Div. 2. Working with our affiliated company (Sonomatic) an estimate was developed of the minimum detectable crack size in the vessel wall. Becht recommended a fracture mechanics crack growth analysis be conducted to determine the number of cycles for a crack of the minimum detectable size to grow/propagate through the vessel wall. This information is used to set the maximum interval between inspections and to set a safe margin below the number of cycles for a through-wall crack to occur. Based on the outcomes of the above a long-term inspection program for the vessels could be established,

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New Process Technology Scale-up

new process1Becht has worked closely with the a number of our clients' process research and engineering groups on the on the scale-up of new process technology. One example of such an activity is the development of a process and mechanical design specification for a pyrolysis-based fluid bed biomass pilot plant. Becht engineers in the areas of fluid-solids process design, process simulation, analytical methods and mechanical design worked with a joint venture company to develop a process design specification of sufficient detail to provide an EPC contractor information needed to develop the detailed design. The specification included the preliminary design of the three major vessels (see reactor sketch) and solids transfer lines. In addition, Becht worked on the development of the process model (PROII simulation), the characterization of liquid product from the reactor overhead system and recommended the analytical laboratory program and methods needed to characterize the reactor overhead products

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weld1A cryogenic piping system was found to have a numerous instances of weld misalignment of circumferential butt welds joining sections of the piping system. Becht was asked to evaluate the effect of such misalignment and if repairs were required. The photo shows a typical cross section through the pipe showing the misalignment. Becht evaluated the misalignment using the methods of API 579 Fitness for Service that address weld misalignment and recommended where repairs were required. In a similar case on a larger diameter chilled water system Becht used its affiliated company Sonomatic to conduct a UTweld2 inspection to define the misalignment. Since internal inspection was not feasible, a special UT setup was used to conduct a 360 degree scan from the outside diameter of the pipe. A similar API 579 evaluation based on the UT data was used to determine which welds required repair.

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