Vessel Alterations
& Rerates

All Anvil alterations and rerates follow ASME Sec. 8 Division 1 and Division 2 regulations and NBIC Part 3 evaluation guidelines.

Rerate with Confidence

The stakes are high when transforming liquids, vapors, and gases in a molecular chain of events into final products like oil, gas, biofuels, and plastics. Whether a pressure vessel housing hydrogen, butane, or steam, processing these dangerous and potentially lethal chemicals requires specialized vessels and piping systems that can withstand extreme temperatures of up to 1,800° Fahrenheit and in highly pressurized environments.

Refineries or chemical processing plants may alter the temperature, design, or maximum allowable working pressure of these types of equipment for a variety of reasons, whether for more throughput, change in service, or safety relief system that may have a PSV set higher than the vessel. When they do, they turn to our mechanical engineering experts to help them provide alteration re-rates of their equipment to operate at different process conditions in accordance with NBIC Part 3 and within government and industry safety standards.

Our Process

Our mechanical engineers initially review the following documents to determine if it’s even feasible to re-rate a vessel before modeling, evaluating, and validating the altered design:

• Drawings
• Client specifications
• Manufacturing standard code U forms
• Inspection records
• NBIC compliance checklists and repair forms (R-1, 2)
• NB-370 jurisdictional laws and regulations

To determine an equipment’s optimal design to withstand new temperatures and pressures and to establish a new rate code, our team of mechanical engineering experts’ model, test, and validate the altered design.

Compress code evaluation software is used to model the entire vessel with new temperature or pressure settings and to calculate conditions like wall thickness, seismic, wind, static, fatigue damage, metal loss, pitting, weld distortion, and buckling among others. Adhering to either ASME Section VIII Division 1 or Division 2, Compress then validates the findings.

Equipment with non-standard geometric shapes and anomalies undergo ANSYS Finite Element Analysis simulation to accurately evaluate the new temperature or pressure conditions.

Finite Element Analysis

FEA software subdivides complex systems into smaller parts (i.e., finite elements), to calculate, model, and simulate static and dynamic aspects of a physical system. Using differential equations and a numerical mathematic technique called the Finite Element Method (FEM), engineers and designers can predict and understand how an object might behave under various physical conditions.

Thermal Analysis
-Steady State and Transient
-Coupled with structural analysis to calculate thermal stresses
-Refractory thermal performance and analysis for potential spalling

Structural Analysis
-Linear and Nonlinear, Large and Small Displacement
-Elastic, Limit Load, and Elastic-Plastic
-Plastic Collapse, Local Failure, Buckling, Ratcheting, Fatigue, Creep, and Vibration

All Anvil-completed re-rated alterations follow ASME Sec. 8 Division 1 and Division 2 regulations and NBIC Part 3 evaluation guidelines.

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