Entries by Mike.Lake

Why Valve Freedom Testing is Critical

At STUG 2015, a survey revealed that 43% of D11 combined cycle users perform valve freedom testing on a daily basis, while 38% perform it on a weekly basis. The potential accumulation of deposits is a little more critical in these high temperature units, but exercising valves is important on any unit. For instance, on […]

Why is a Clean Generator a Happy Generator?

A generator is susceptible to four categories of aging factors which reduce the overall service life of the machine: 1) Mechanical aging; 2) Thermal aging; 3) Electrical aging; 4) Environmental aging. Simply stated, a dirty (contaminated) generator causes environmental aging. A few of the more common contamination elements include oil, water, dirt, dust, carbon, and […]

How 0.002” Can Ruin a Turbine

Steam turbines can reliably run for 30, 40 years or more. However everything wears and eventually fits, finishes and tolerances become unacceptable. For instance, the rabbet fit on the coupling faces of a three bearing machine will eventually become loose and in need of repair. This defect can cause misalignment, abnormal vibration levels and undue […]

Why Use Hydrogen to Cool a Generator?

A generator is a device that converts mechanical energy into electrical energy. According to the concept of energy conservation, all mechanical energy that is introduced into the generator is converted into useful energy (electricity) or useless energy (primarily heat). The efficiency of a generator is based upon the ratio of useful to useless energy. As […]

Safely Check for Gas Turbine Fuel/Air Leaks

Traditionally operations and maintenance personnel have used gas detectors to check the fuel pig tail flanges for leaks during the startup process. This is to ensure that no fuel is present that could cause a fire in the compartment. An less risky alternative to this process is to perform a soapy water check while the […]

Why is a Stator Core Made of Laminated Steel?

A turbogenerator stator is comprised of two major components: 1) the stator windings, and 2) the stator core. The stator core is made up of thousands, tens of thousands, or hundreds of thousands of individual steel laminations. Modern laminations are comprised of silica-steel, cold-rolled and grain-oriented as specific designs might require. The material is typically […]

Overlooked Gland Seal Can Be Big Trouble

The steam turbine gland steam seal system is designed to keep steam from leaking out of the turbine and to prevent air from leaking into the turbine. A gland seal system can be as simple as a spray chamber, loop seal and a steam ejector or as complex as surface condensers, air blowers or vacuum […]

Compressor Failures – Stator Vane Lock-up

Some compressor failures have been attributed to “lock-up” of the stator vanes. The vane roots are designed to rock slightly at their roots when moved with your hand. Rust and debris can inhibit this movement. An immobile vane changes the stress profile on the vane which can cause cracking and potential failure. Mechanics should check […]

Safety and Hand Grenades

Ever heard the adage “Close is only good in horseshoes and hand grenades”? We think that close calls are also important to maintaining a safe work environment. Exposing, analyzing, communicating and learning from these events is an important part of TGM®‘s safety program. We call these experiences “Near Miss” events. The resolution of one of […]

Protect your turbine with a good coat

Thermal Barrier Coatings (TBCs) protect the first several rows of hot gas path parts from the high combustion temperatures in many advanced large frame turbines. Not all coating applications are equal, and some can even reduce the efficiency of your unit. TBCs are designed to reduce the temperature of the buckets and stators while providing […]