upper and lower seal seats, 2-inch-diameter bars were clamped on either side of the base, and wire was stretched over them. Measurements were then taken along the wire to insure equal distances from the wire to the seal seats. These readings were also plotted to measure the side seal clearances. Wires were strung between the opposite side tracks, and measurement was taken from the wire to the seal seat. In addition, both lower tracks were investigated for plane by crossing wires at the extreme end and then reversing the wires. Side guides were set, using templates extending from the concrete at a specified distance offset from the centerline. Wires were strung between the two ends of the side guides and the guides were brought to within the correct distance. A record was made before and after grouting the frames, and any error found after grouting was corrected by either grinding or shimming as required. The final installation was within the tolerances specified.

Minor changes in installation were performed under extra work order No. 28 and a purchase order.

262. Bulkhead Gates and Frames.

(a) General.--The twelve 9-foot 9-inch by 11-foot 11-3/8-inch turbine draft tube bulkhead gates, bulkhead gate seats, guides, latches, and bulkhead gate lifting frame were furnished by W. H. Reller Co. of Boise, Idaho, under invitation No. DS-3918.

The bulkhead gate bottom seat is at elevation 5350.00. The maximum tailwater level is at elevation 5386.00, and the minimum tailwater level with one unit operating is elevation 5375.00. Operation of the gates is accomplished by a bulkhead gate lifting frame connected to the hoist of the 5-ton gantry crane located at elevation 5397.50 on the transformer deck. Each unit has one gate equipped with a draft tube filling valve.

The bulkhead gates and embedded metalwork were installed by the Palisades Contractors under specifications No. DC-3675. Labor for installing the frames and guides was performed by ironworkers until September 22, 1954, and after this date all work was performed by millwrights. Work was started on April 26, 1954, and virtually completed on October 25, 1954. A view of the completed gates is shown in figure 185.

(b) Sequence of Erection Work.--The sequence of erection work and the dates for the principal operations are shown below:

(c) Installation of Gate Frames.-- The gate frames were set from plumb lines of 0.020-inch piano wire supporting 40-pound steel plumb bobs. The plumb lines were suspended from steel control templates set by a Bureau survey crew and were welded into place by the contractor. The templates were secured to angles which were welded to reinforcing steel at elevation 5377.17. After the frames and lower guides were set, the templates were removed. No blockouts were required for the templates since the frames were set before the walls above elevation 5377.17 were placed.

The seal seats were erected in sequence, bolted together and alined to complete the gate frame. The steel bottom seat (or sill) was installed, fitted to the concrete blockout within ±1/4 inch of elevation 5350, and accurately set with a machinist's level. The brass side seats were hung on anchor bolts on each side of the draft tube opening and were bolted to the sill. The bases of the brass side seats were fitted snugly on the sill to insure a tight fit. The brass upper seal seat was raised into position and bolted to the side seats.

Figure 185. --View of the powerplant draft tube gates taken from near the left training

wall looking south at the front of the powerhouse. This picture was taken prior to flooding of area and shows the draft tube gates in closed position. 456-108-2430, October 28, 1954.

The side seats were accurately alined along the outside edge at each anchor bolt location by means of the control plumb wire. A tolerance of 1/16 inch was maintained. The side seats were squared at each anchor bolt location by stretching a wire horizontally across the draft tube opening. The wire was supported away from the outside edge of the brass face on each side of the opening with a 1-inch round bar. The inside edge of the brass face was then squared to the 1-inch dimension. The upper seal seats were alined in a similar manner, with horizontal wires stretched across the top and bottom edges of the brass seats. The seals were squared, using the side seats as a reference plane. The upper and side seat brass pieces were fitted flush with tight joints to insure a metal to metal seal.

The lower guides were installed after completing the alinement of each seal seat frame. The guides were hung on anchor bolts on each side of the draft tube opening. Only the outside adjusting nut was used on each 1-inch anchor bolt for the guides. The 3-1/2-inch depth and 13-1/2-inch width of the guide blockout did not permit sufficient working space for adjusting the inside anchor nuts, so the inside nuts were omitted and steel wedges were used in conjunction with the outside anchor nuts for adjustments. The face of the guide angles was alined and squared within 1/16 inch of the theoretical clearance from the brass seats with gages made of steelplate. The inside edge of the guide angles was then set to a given dimension from the inside edge of the brass side seats. The dimension was obtained by measuring the spread between the inside edges of the brass side seats, and then adjusting any error equally between the left and right guides so as to insure a symmetrical setting of the guides with the correct horizontal spread between them. The correct spread was maintained within ±1/16 inch. All anchor nuts and alinement wedges were tack welded before grouting.

The bulkhead gate seats and guides had some irregularities when received from the fabricator. A representative from the fabricator corrected these errors at the project before installation of any parts. The installation contractor experienced difficulty in

setting the side and upper seal seats. The contractor contended that the design did not allow enough adjusting bolts for ease in squaring the brass seal seats; however, the installation contractor did not make claim for extra work.

(d) Installation of Intermediate and Upper Gate Guides.--The intermediate guides were installed after the lower guides were embedded. Several anchor bracket holes had to be slotted and a pair of anchor bolts above the splice shortened in order to allow entry of the splice plate behind the lower guide. Owing to insufficient blockout space, all inside anchor nuts were replaced with wedges for alinement. To aline the guides, a 40-pound steel plumb bob was suspended by a 0.020-inch piano wire anchored to a plate above the guide. The plumb wire was hung one-fourth inch upstream from the embedded angle and several inches from the edge. With the wire thus positioned on the lower guide, the intermediate guide was plumbed. The guides were squared at each anchor bolt location by stretching a wire horizontally between the right and left guides. The horizontal wire was supported away from the upstream face of the angles with a 1-inch round bar placed at a position of maximum spread. The inside surface edge of the guide face was then squared to the 1-inch dimension while maintaining the one-fourth-inch distance from the plumb wire. Check measurements were made on the guide spread to insure that the 10-foot, 7-1/2-inch dimension was maintained within the required tolerance of 1/16 inch. The splice between guides was welded and ground flush in several instances. All anchor nuts and alinement wedges were tack welded before grouting.

The upper guides and latches were placed after the intermediate guides were embedded. The latch plates were set on anchor bolts in the transformer deck, and then the upper guides were hung in place. The upper guides were installed in the identical manner used for placing and alining the intermediate guides. All guide splices were welded and ground flush, and all anchor nuts and alinement wedges were tack welded before grouting. The latch plates were leveled and grouted in a monolithic pour with the upper guides.

The splice plates presented difficulties in hanging the guides. These plates came welded to the lower ends of intermediate and upper guide angles. With an erection sequence of lower-, intermediate-, and upper-guide installation, the splice plates did not slip readily into place behind the lower embedded angles. Also, the ends of the guide angles were sheared off during fabrication, which distorted the angles and resulted in a poor fit. The contractor welded and ground the angles at the splices to improve this fit

up.

The field forces made certain suggestions for improving the fit-up in similar in-
These are included in the final construction report (see bibliography).

stallations.

(e) Gate Assembly.--The bulkhead gates arrived at the project completely assembled except for installing the rubber seals. The seals were placed in position on the gates and bolt holes were drilled through the rubber at locations determined by using the seal clamps as templates. The 3/16-inch projection of the rubber was obtained by gaging with a metal jig built to rest on the 1-3/4- by 1/2-inch by 12-foot 1-1/4-inch naval brass bar and project over the rubber with a built-in 3/16-inch offset. The top rubber was positioned from a piano wire, using the side naval brass bars as reference planes.

When the gates arrived at the project, checks were taken of all the critical dimensions. This inspection revealed a number of deviations from these structural tolerances; however, it was decided to postpone correction until it could be determined if operation of the gates indicated corrective work should be done. In addition to these dimensional variations, certain other discrepancies were observed which were corrected by the installation contractor.

(f) Operational Checks.--An operational check was made of the gates by raising and lowering each gate several times in its frame. All gates operated freely without binding. With the gates in a closed position, water was allowed to fill the tailwater basin area, and the leakage around each gate was observed. Leakage was nominal except at the top of each gate where the rubber had not been installed accurately to a 3/16-inch projection beyond the side brass gate seats. The contractor corrected the rubber projection when the gates were raised for painting during March, April, and May of 1956. Subsequent operation of the gates was good.

263. Butterfly Valves Installation. - (a) General.--The four 186-inch butterfly valves are located in the penstock laterals upstream of the powerplant f-line with their centerlines at elevation 5380.00. One valve is located between each turbine inlet pipe and the penstock. The valves are activated hydraulically with a piston stem connected through linkage to the butterfly leaf stem. The hydraulic control cabinets are located by the f-line on the generator floor at elevation 5397.50.

The valves were furnished by the Baldwin-Lima-Hamiltion Corp. Eddystone, Pa., under invitation No. DS-3911. The valves and controls were installed under item 153 of specifications No. DC-3675 by Palisades Contractors, who subcontracted the actual installation of the valves to American Pipe and Construction Co., Portland, Oreg. For general installation and assembly see figure 112. The total weight of the valves and controls was 1,267,369 pounds.

(b) Control.--The butterfly valve base plates were set to grade and leveled, using a precision level, micrometer target, and straightedge. The assembled valve was placed on station; and the upstream flange of the connector and the downstream flange of the valve were squared to the line of flow by means of a transit which was located on a known station with its line of sight normal to the line of flow. Offsets taken from the line of sight to the flange were used to square the valve and place it on correct station.

(c) Method of Assembly.-- Work began with the installation of the unit 4 soleplates on September 17, 1954. A millwright foreman and one man began cleaning parts for the unit 4 valve on September 22, 1954, and additional men were hired as required until the crew consisted of a foreman and four men.

The lower half of the unit 4 valve body was placed on the pedestals, cleaned, and the lower seals installed. The bearing carriers were cleaned and installed on the leaf stems. The upper body was cleaned, and the seals installed with the upper body in the vertical position. The assembled leaf and bearing carriers were placed on the lower body in the open position. The body flange studs were screwed into the lower body flange; then the upper body half was held over the lower body half by a crane, and the upper and lower flanges were squared to each other with jacks placed between the two flanges. After the studs were started in the upper flange holes, the jacks were removed and the upper body half was lowered the rest of the way by the crane. The remaining studs were then installed, and all studs were tightened until the flanges were in metal-to-metal contact. The connector was cleaned and installed. The assembled valve was then placed on station and squared to the line of flow.

Normally, the connector flange bolts would have been tightened as the next step in the assembly; however, the contractor was permitted to bolt the flanged section of the penstock to the connector. This procedure enabled the contractor to expedite welding on the penstock manifold. An installation view is shown in figure 186.

The packing glands were installed around the bearing carriers and the body flange studs prestressed. The inner half of the crosshead housing was cleaned and installed. The crank arm was then assembled with the drive stem. The actuating cylinder was dismantled, cleaned, reassembled, and lowered into position under the crosshead housing. The linkage was assembled between the crank arm and crosshead, and the outer half of the crosshead housing was installed. The actuating cylinder was then raised into position and bolted to the assembled crosshead housing. The position indicator was then connected to the drive stem and bolted to the crosshead housing. The cylinder was filled with oil to prevent rusting of the cylinder walls.

A temporary actuating pump was connected to the operating cylinder, and the leaf was moved as required as the seals were adjusted and fitted to the seal seat. After the best possible fit was obtained, the seal seat was scraped until line contact was obtained with the seal at all points.

The sequence of assembly on the other valves was essentially the same as on the unit 4 valve, with the following exceptions: (1) the seal was installed in the lower half while it was in the vertical position rather than waiting until it was on the pedestals in a horizontal position; (2) all of the body flange studs were installed before the two halves were assembled; and (3) the connector bolts were tightened at the time the connector was installed.