Safety Equipment & Systems – Dupont Sabine River Works Cogeneration Facility

Removable turbine-compartment outage roof for 7FA

Dupont Sabine River Works Cogeneration Facility
DuPont Company

Challenge. The location of our facility in a hot and humid, seaside climate presents many issues concerning heat stress, weather, and sun exposure. During planned and unplanned outages of our 7FAs, the turbine-compartment roof requires removal, which leaves the compressor and turbine sections of the units exposed to the elements.

   Once the piping, combustion parts, upper shells, and rotor are removed, maintenance personnel begin the tasks of compressor stator vane removal, turbine nozzle block and shroud block removal, stator slot cleaning, and various other half-shell tasks.

   This required maintenance crews to be on the unit’s half-shell exposed to all the elements without shade or cover. Unexpected thunderstorms and hot temperatures caused work delays and low productivity, which extended outages.

  Solution. Turbine compartment dimensions were obtained through drawings and field measurements, and a lightweight, fire-retardant, easy on/easy off outage roof was fabricated. Outage roof frame construction was lightweight aluminum square tubing that could be assembled or disassembled in two halves in case removal is required for crane access.

   The outage roof is delivered to unit area from laydown yard on a wagon in four pieces (Fig 8). Maintenance crews can easily lift sections of outage roof off of the wagon and handle them during assembly (Fig 9). Frame sections are bolted together on the ground (Fig 10).

   Because the roof is in sections, it makes it possible to remove a section without removing the entire roof, when lowering in compressor casing or turbine casing hardware. The cover is of a sunblocking material, and attached by snaps, enabling quick removal/installation. Once the roof is completely assembled, it can be set on and taken off the turbine compartment easily using shackles and chokers (Fig 11).

   The roof was attached to the turbine compartment walls by using the existing roof bolting holes and metal clips. The clips are slotted on the bottom side (side holding it to turbine compartment walls), to expedite removal/installation. The holddown bolts can be loosened enough to release the clamping side of the clip and removal/installation accomplished without removing all bolting.  

   The outage roof framing is conveniently stored in our plant laydown area in two halves without worries of rust and deterioration (another geographic problem). Sun cover can be folded compactly and stored with the clips in our parts warehouse, away from the elements, without taking up a lot of space.

Results

  • More productivity by OEM and site maintenance personnel resulting because of less exposure to the hot sun and unexpected thunderstorms. Crews can now work during any weather: hot, cold, sunny or rainy.
  • Better scheduling ability for incoming parts that had to be repaired in OEM shop since casing work could be accomplished without interruption.
  • OEM maintenance crews seemed to have a better attitude, and achieve better quality on tasks during hot summer days.
  • Decrease chances of heat exhaustion/heat stroke cases.