Page images
PDF
EPUB

and sloping down to about elevation 3178. A vertical reducing bend (fig. 127) at the lower end of each penstock, which has a point of intersection at elevation 3178, reduces each penstock inside diameter of 12 feet to 9 feet 3 inches before the penstock enters the powerplant.

Twelve-inch filling lines (fig. 128) are located in the filling line gallery above the penstocks. Water from any of three penstocks can be used to fill the fourth penstock by means of the interconnected filling lines. The filling line to each penstock contains a motoroperated gate valve and a guard valve. Manholes allow access from the filling line gallery into the penstocks.

Twenty-inch-diameter air vents (fig. 129) extend from the penstock inlets to the top upstream face of the dam. The air vents allow air to escape from the penstocks to the atmosphere when filling and allow air to enter when unwatering the penstocks. Eight-inch drains on the inlet transitions (fig. 130) extend to sumps below the penstock access chambers and provide drainage for leakage past the fixed-wheel gates.

The interior surfaces of the penstocks and makeup pieces were lined with coal-tar primer and coal-tar enamel. The exterior surfaces of the penstocks and makeup pieces exposed to the atmosphere and public view were painted with one coat of red lead priming paint and two coats of phenolic-resin aluminum paint. Unpainted exterior surfaces of the penstocks that were to be embedded in concrete were whitewashed to protect the lining during field storage.

(b) Design and Testing.-The penstocks were designed for a total head of 562 feet including water hammer, and to withstand external loads caused by concrete encasement. Measured from the centerline of the units, the maximum design static head is 479 feet. Each penstock has plate thicknesses which vary from 9/16 to 1 inch and is reinforced with stiffener rings. The makeup pieces were fabricated from 1-inch plate.

Penstock pipe sections, including stiffener rings, were fabricated from steel plate conforming to ASTM Designation A 201, grade B, firebox quality. The sleeve-type coupling center sleeves were fabricated from material conforming to ASTM Designation A 242.

All girth and longitudinal welds in the shells of the penstocks and makeup pieces were fully radiographed in accordance with the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1. A joint efficiency of 100 percent and a design working unit

[blocks in formation]

Inasmuch as the gates must be raised and lowered only under balanced head conditions, a filling valve is incorporated in the gate lifting stem o. each gate for balancing the head prior to raising the gates. In the event that high-pressure penstock water is unintentionally admitted to the turbine and draft tube while the gates are in place, a gate will blow off of its seat, shearing the bolts which fasten the lower guide lugs to each side of the gate. The top guide lugs are rigidly fixed to the gate, enabling the gate to swing out in the event that the lower guide lugs shear. The estimated weight of the 12 gates is 64,080 pounds.

(b) Design.-Maximum stresses were calculated on the basis of a dry draft tube and maximum tailwater surface, the maximum head being 39.5 feet. Under these conditions the combined stresses of the faceplate

and beams were permitted to reach 26,000 pounds per square inch. Other stresses conform to the American Institute of Steel Construction.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small]
[ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small]
[merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][subsumed][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
« PreviousContinue »