With regular maintenance and upkeep, steam turbines last an average of 50 years. These turbines play a critical role in society, producing up to 90% of all electrical power in the United States. They’re incredibly efficient, rotating an average of 1,800 to 3,600 rotations per minute (RPM). That is much faster than wind turbines that average only 30 to 60 RPM with a low-speed shaft and 1,000 to 1,800 RPM with a high-speed shaft.
Steam power is accessible, efficient, and cost-effective.
To keep turbines running at their best, it is wise to schedule a steam turbine inspection an absolute minimum of once every two to three years. What takes place during these inspections? Learn more below.
What Tools Will Inspectors Use?
When inspecting steam turbines, many inspectors will use a borescope. A borescope is one of the best tools to complete routine inspections because they enable professionals to fully assess turbines without taking them apart or dismantling them. That means inspections are completed faster, getting results to you sooner and turbines back up and running as quickly as possible. Knowing a professional can be in and out also gives you the flexibility and freedom to request any additional inspections, should you suspect problems.
There are rigid, flexible, and video borescopes. Rigid and flexible borescopes both consist of a piece of tubing with a camera and/or eyepiece attached. Video borescopes may be rigid or flexible, but as the name suggests, they have the capability of taking video recordings for inspectors to refer back to.
What Exactly Are Inspectors Looking For?
When you are paying for regular inspections at least once every two to three years, it is only reasonable to want to know exactly what you are getting out of it. Here are a few of the things professionals search for during an inspection:
- First, the inspector will check for necessary documentation and certificates, such as the certificate number, cast or heat number, heat-treated condition, mechanical properties, chemical composition, and surface finish — just to name a few.
- Any unusual or concerning sounds. Before breaking out the borescope, the inspector will determine whether he or she can hear that anything is amiss. At this point of the inspection, they will listen for pitching, yawing, and blade noise.
- A cursory visual inspection, checking for damage, cleanliness, and fortitude of welded connections will occur.
- Hydrostatic testing may take place. Hydrostatic testing uses water pressure to test the integrity of various turbine parts, including the steam chest, casing, and emergency stop valves. If applicable, hydrostatic testing helps identify leaks and gauge the overall efficacy of equipment.
- Mechanical, borescope, and/or visual inspection may be used to assess turbines for the following: critical speed, bearing temperature, steam condition, lubrication oil condition, cooling water condition, vibration, valve operation, noise level, and more.
- Finally, the inspector will check all safety and alarm systems on the turbine and ascertain that they are in working order.
Steam turbines pack a lot of power and potential if you properly maintain them. In fact, the efficiency and potential of steam turbines continues to rise steadily over the years. “Since commercial introduction, efficiencies for large condensing steam turbines have increased from the midteens to up to 48%,” the Environmental Protection Agency (EPA) writes. Steam power and steam power are here to stay. Research to drive efficiency ever higher and increase the use of renewable resources in the industry is well underway.