David RasmussenPrincipal Engineer Repairs Division
I started in the power plant business in 1959 when my engineer father took me to see the construction of Commonwealth Edison’s (Now Exelon®) Dresden Unit 1 Nuclear Reactor. I remember seeing the Blue Glow of the fuel bundles. I received a BSME at University of Wisconsin with a Minor in Energy Conversion. I went to work for AEP® 43 years ago as a steam turbine engineer and got an MBA 5 years later. I started Turbine Consultants in 1983 and merged it with MD&A in 2001.
What do you do here at MD&A?
I am a Principal Engineer in the Repairs Division. I focus on Steam Turbine Rotor straightening and turbine casing weld repairs for cracking and distortion. I also participate in Root Cause Analysis of steam turbine and mechanical failures. I also oversee Remaining Life Analysis. I provide weld repair procedures and metallurgical assistance to all the divisions of MD&A.
What is the most interesting job/ challenge you have come across in your career? And what is one piece of advice you would give?
I have performed or directed over 500 turbine casing weld repairs and over 1,000 failure analyses before I stopped counting 14 years ago so it is hard for anyone project to stand out. However, I remember performing major weld repair projects in the mid-1970s when the domestic OEM’s said my repairs would never work.
By using engineering, these methods offered clients an opportunity besides retiring the unit or spending millions on replacement parts.
I developed methods for straightening bowed rotors and out-of-round casings that were not runnable and OEM methods did not permanently address the problem.
My advice is “to FIRST determine the cause of failure and THEN evaluate alternatives before making a decision. Too many times I see someone making a decision on what to do before fully determining the cause of the failure.”
How do we quantify Out-of-Round or distorted Casings?
Distorted casings can be large 200,000# alloy castings that need to be concentric and maintain tight clearances (within the thickness of a few sheets of paper) to the spinning rotor. We use laser-scanning methods to supplement more traditional dimensional measuring tools needed to quantify absolute deviations from “round” concentric bores and “flat” sealing surfaces. Computer graphics allow plots of data to quickly assess excessive deviations and compare repair methods.
What are the Typical Inspections for a Distorted Casing / Blade Ring?
The casings and blade rings become distorted due to excessive thermal stresses that are in excess of the material’s yield strength. These high stresses can be from uneven heating and/or cooling and they can also lead to fatigue cracking.
Before the condition of a casing can be determined, various NDE (non-destructive examination) and dimensional measuring methods are used depending on what is found. We NDE to locate and size any cracking, metal sampling to quantify metallurgical property changes such as embrittlement, creep or past weld repairs.
We use the dimensional measuring methods to search for erosion, deflections, distorted sealing faces, thread damage, and out-of-roundness.
What is your favorite thing on your desk?
I have a brick that was from Thomas Edison’s office in Schenectady, NY. His vision made power generation affordable for the world.