• MD&A's Topless Alignment Services^® eliminates the time consuming and expensive process of reassembling the turbine for "Tops-On" measurements, saving hundreds man-hours labor per turbine section. Most centerline alignment activities are moved off the critical path, reducing outage duration by days.

A partial list of the benefits of Topless Alignment^® includes:

• No surprises , all alignment moves defined by 2nd week of outage.
  
  
• Reduced Outage Duration; 3 or more shifts – No "Tops-On" readings – There is no longer a need to rebuild turbine and measure steampath bore positions with upper half shells and casings installed.
  
  
• Saves about 300 man-hours per turbine section by not putting tops on.
  
  
• Increased Safety – Reduced need to perform heavy rigging of upper half shells and casings by 50% (No Tops-on measurements)
  
  
• Opening coupling checks are done with LP hoods off, allowing earlier LP disassembly.
  
  
• Upper and lower shells are only needed for 1 shift per section to measure distortion.
  
  
• Stationary component alignment is done off critical path – Most steampath alignment activities including Bearing shim changes and pad contact checks are moved off critical path
  
  
• Improved Turbine Efficiency - Elimination of startup rubbing maintains as-assembled internal clearances.
  
  A long line is taken through all turbine sections immediately after rotors are removed. This line is used along with opening coupling checks to calculate the ideal rotor alignment. Stationary component and bearing alignment can then be done off critical path while repairs are being made. Final coupling checks are done after final assembly, typically with only a few bearings requiring changes. If required, shim changes are typically less than .010" and bearing pads do not require re-bluing.

Why choose the MD&A Topless Alignment^® Method?

• Proven Alignment Process – Since 1991, MD&A has aligned over 800 steam turbine sections using it's Topless Alignment^® process, with a remarkable record for the lack of rubbing
  
  
• MD&A has the most Topless Alignment^® experience in the industry
  
  
• Alignments are performed by very experienced turbine engineers who perform many alignments each year
  
  
• Customer Focused

More on Steam Turbine Alignment …
Steam turbines operate with shaft seal clearances typically 0.020" to 0.040". With such small clearances between the rotor and the stationary seals, it is critical to properly align the stationary components during turbine maintenance. Aligning steam path components is best done by experienced alignment specialists who align multiple turbines each year.

During maintenance when upper half shells are unbolted and removed, the turbine lower half shells that hold the stationary components deflect, changing the position of those components with respect to the turbine rotor. Measuring the amount of Tops-On to Tops-Off movement is very time consuming and difficult. It requires the maintenance staff to remove the turbine rotor, and then rebuild the turbine with the rotor removed, so that "Tops-On" measurements can be taken.

Knowing how much each component moves between the Tops-Off position and the Tops-On position is important in doing a good turbine alignment. Knowing this amount allows the alignment engineer to offset the steam path components the appropriate amount so that when the turbine is assembled and the shell bolts are tightened, the centerline components move into their running position. When properly aligned, the tips of the packing seal teeth do not touch the rotor.

By design, the packing seal teeth are relatively sharp. When packing is not aligned properly, these sharp teeth are rubbed by the rotor, and the sharp edges are flattened or mushroomed over. Once flattened, the clearance between the tip of the tooth and the rotor is increased allowing more steam to leak past the seal. Also, given the same clearance between the packing teeth and a rotor, packing that has dull teeth does not seal as well as packing with sharp teeth. By performing a good alignment, packing rubs are minimized keeping the clearances tight and packing teeth sharp thus improving the long term efficiency of the turbine.

MD&A has developed a method for aligning steam turbines that does not require the extra re-assembly of the turbine required by the traditional Tops-On / Tops-Off method. MD&A uses a "Topless" Alignment sm Process that takes hours to perform rather than days, thus drastically reducing the amount of time and labor required for alignment. MD&A is the industry leader in this process and has successfully aligned over 800 turbine sections of varying makes and models since 1991.

Tops-On / Tops-Off Laser Alignment

Along with MD&A's proven steam turbine "Topless Laser Alignment®" method, MD&A offers Steam Turbine owners an option to align their turbine steampaths using the traditional Tops-On / Tops-Off method.  MD&A's laser alignment engineers have extensive experience aligning turbines of most makes and models and have the experience to align even the most difficult units.  All MD&A's alignment engineers have extensive OEM turbine maintenance experience.  These Engineers specialize in and are solely dedicated to performing turbine alignments for our customers.

Tops-On / Tops-Off alignment is the method recommended and employed by most steam turbine OEM's.  Until the 1990's, this method was primarily performed by running a piano wire through the center of a turbine and then taking relative readings to the wire.  Using a piano wire for these measurements greatly limited the amount of parallel centerline work that could be performed while taking steampath alignment measurements.   By using specialized laser equipment MD&A can quickly and accurately measure turbine centerline alignment, eliminating the need to work around a wire.

Advantages

• Provides turbine owners an effective method of aligning steam turbine centerline components.
• Allows for compensation of the "Tops-Off" component positions for shell distortion.
• Fully meets OEM alignment process specifications where Tops-On / Tops-Off alignment is specified.

If you have the need to perform Tops-On / Tops-Off alignment but need to shorten your outage by several days, please contact MD&A Laser Alignment Group to discuss the advantages of using MD&A's "Topless Laser Alignment® method.  MD&A has aligned over 800 turbine sections using the Topless Method, and may be able to make a significant impact on your outage schedule, by reducing the time needed to perform your alignment.