David R. Thornton, P.E.

Principal Engineer II

Years of Experience: 40+

Education and Licenses:

  • Master of Science, 1980, Theoretical and Applied Mechanics, Cornell University, Ithaca, NY
  • Bachelor of Science, 1975, Civil Engineering, Drexel University, Philadelphia, PA
  • Licensed Professional Engineer, Alaska, Florida, Iowa, Louisiana, Nebraska, New Jersey, New Mexico, and Texas

Areas of Specialization:

  • Fitness-For-Service Evaluations using API 579
  • Advanced Stress Analysis including Nonlinear Finite Element Methods
  • High Temperature Creep Analysis and Life Assessment
  • Fatigue, Structural Reliability, and Risk Assessment
  • Design of Pressure Vessels, Piping, and Tankage
  • Troubleshooting, Problem Solving, and Technical Support for Shutdowns
  • Project Consulting, including Development of Technical Specifications and Vendor Audits
  • Piping Flexibility and Vibration Analyses and Troubleshooting
  • Analysis of Pressure Transients in Liquid-Filled Piping & Heat Exchangers
  • Evaluation of Structures, including Tanks, for Structural and Foundation problems


Mr. Thornton has worked in a technical specialist role both as an owner-user and a consultant, providing engineering support to refineries and chemical plants worldwide.  He is a specialist in pressure vessel, piping, and tank design/analysis.  Mr. Thornton has skills in advanced finite element analysis with emphasis on non-linear behavior such as plasticity, buckling, contact, creep, and large deformation behavior.  He uses advanced analytical methods to provide practical and cost effective solutions to solve design and operational issues related to fixed equipment.


Mr. Thornton serves as a member of the joint API/ASME technical committee responsible for the development of Fitness-For-Service assessment techniques.  He has applied API 579 rules in evaluating localized corrosion, crack-like flaws, high temperature remaining life, and equipment distortion.  He has experience as the lead mechanical engineer at a major refinery, providing direction and guidance to others in evaluating and solving problems associated with fixed equipment.


Mr. Thornton has performed transient pressure analyses of liquid-filled refinery and transportation piping systems.  He has evaluated piping vibration problems and recommended methods to mitigate both vibration sources and effects.  He has performed analyses of shell and tube heat exchangers for rupture of high pressure tubeside fluid into the low pressure exchanger shells, and sized and located required shellside relief devices.


Mr. Thornton performs design and analysis of pressure vessels and their internals as part of refinery capital projects.  He has also provided non-process quality control auditing of contractors and vendors for major refinery projects.  He has extensive experience related to the design and analysis of equipment associated with high temperature FCC units, including pressure vessels, refractory-lined piping, and specialty valves.


In 2011, Mr. Thornton extended his technical coverage to the area of life-cycle management of upstream and transportation pipelines, including issues involving risk-based inspection, defect assessment, and repair techniques.