Combustible Dust Testing

Laboratory testing to quantify dust explosion & reactivity hazards

Flammable Gas & Vapor Testing

Laboratory testing to quantify explosion hazards for vapor and gas mixtures

Chemical Reactivity Testing

Laboratory testing to quantify reactive chemical hazards, including the possibility of material incompatibility, instability, and runaway chemical reactions

DIERS Methodology

Design emergency pressure relief systems to mitigate the consequences of unwanted chemical reactivity and account for two-phase flow using the right tools and methods

Deflagrations (Dust/Vapor/Gas)

Properly size pressure relief vents to protect your processes from dust, vapor, and gas explosions

Effluent Handling

Pressure relief sizing is just the first step and it is critical to safety handle the effluent discharge from an overpressure event

Thermal Stability

Safe storage or processing requires an understanding of the possible hazards associated with sensitivity to variations in temperature

UN-DOT

Classification of hazardous materials subject to shipping and storage regulations

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Biological

Model transport of airborne virus aerosols to guide safe operations and ventilation upgrades

Radioactive

Model transport of contamination for source term and leak path factor analysis

Fire Analysis

Model transport of heat and smoke for fire analysis

Flammable or Toxic Gas

transport of flammable or toxic gas during a process upset

OSS consulting, adiabatic & reaction calorimetry and consulting

Onsite safety studies can help identify explosibility and chemical reaction hazards so that appropriate testing, simulations, or calculations are identified to support safe scale up

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Engineering and testing to support safe plant operations and develop solutions to problems in heat transfer, fluid flow, electric power systems

Battery Safety

Testing to support safe design of batteries and electrical power backup facilities particularly to satisfy UL9540a ed.4

Hydrogen Safety

Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen

Spent Fuel

Safety analysis for packaging, transport, and storage of spent nuclear fuel

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Safety analysis to underpin decommissioning process at facilities which have produced or used radioactive nuclear materials

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Expert analysis of possible risk and consequences from nuclear plant accidents

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Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Environmental Qualification (EQ) and Equipment Survivability (ES)

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Laboratory Testing & Software Capabilities

Testing and modeling services to support resolution of emergent safety issues at a power plant

Adiabatic safety calorimeters (ARSST and VSP2)

Low thermal inertial adiabatic calorimeters specially designed to provide directly scalable data that are critical to safe process design

Other Lab Equipment (DSC/ARC supplies, CPA, C80, Super Stirrer)

Products and equipment for the process safety or process development laboratory

FERST

Software for emergency relief system design to ensure safe processing of reactive chemicals, including consideration of two-phase flow and runaway chemical reactions

FATE

Facility modeling software mechanistically tracks transport of heat, gasses, vapors, and aerosols for safety analysis of multi-room facilities

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Recent Posts

Using Finite Element Analysis to Evaluate High Wind Speed Buckling of Storage Tanks

Posted by The Fauske Team on 01.31.17

By: Karim Dhanji, Sr. Mechanical Engineer, Structural Services & Vibration

Large diameter thin-walled steel tanks are common for fuel and oil storage, particularly in the petroleum industry. The American Petroleum Institute (API) 650 standard is an industry standard on the design of such tanks. Until recently, code provisions were oriented towards the design of tanks operating at high levels of liquids. The emphasis was on preventing failure modes associated with yielding of the shell; thus, the majority of existing tanks were constructed with variable shell thicknesses with tanks getting thinner near the top. However, when these tanks are empty, they are very susceptible to bucking due to high wind loads, particularly on the thin upper shell courses. This was exemplified after Hurricane Katrina and Rita, during which many such storage tanks were damaged due to buckling. To account for the structural stability of the upper shell courses, stiffening rings (commonly called wind girders) are used to reduce the buckling length.

The API-650 standard deals with this problem using empirical design methods for stiffening the tank based on the tank’s thickness, height, and design wind speed. Other codes, such as the more recent EN1993-1-6 European standard, provide analytical relationships for evaluating buckling by verifying the design stresses. However, both standards have been criticized and can provide contradictory results.

In a recent project dealing with an oil storage tank at a nuclear plant, both the API-650 and the finite element software Abaqus was used by Fauske & Associates, LLC (FAI) to evaluate the tank. For the Abaqus analysis, a model of the tank was created using swept hex elements and material properties were defined. Next, a wind load distribution was applied to the exterior of the tank. Wind loads on a tank are asymmetrical as can be seen in Figure 1 below. One method to determine the loading distribution would be to use a scaled model and measure the pressure at various locations (using dimensional analysis techniques). Tanks with a similar height to diameter ratio will have a similar loading distribution. Thus, a literature search was conducted and an appropriate wind load profile was found and inputted into Abaqus. Once the loading was defined, appropriate boundary conditions were applied and a static analysis was performed.

The tank that was analyzed did not have a wind girder, so a static analysis was performed both on the as-designed tank along with a modified tank with a wind girder. Both stresses and displacements were solved for, as can be seen in Figure 2. Using the results of both the finite element analysis along with the empirical methods in the API650, FAI was able to make recommendations to the customer to safeguard their fuel storage tank from buckling when it operates at low liquid levels.

typical-cing-loading-distribution-for-a-cylindrical-structure

 

storage-tank

Topics: AHJ

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