There are three A Plants: Brady, Picacho, and Red Rock.

Size: px

Start display at page:

Download "There are three A Plants: Brady, Picacho, and Red Rock."

Alexandra Evans
5 years ago
Views:

1 Agenda Number 11. 1

2 There are three A Plants: Brady, Picacho, and Red Rock. The Tucson Aqueduct was planned in two phases, designated as A and B, due to uncertainty at the time over the route that the southern portion of the aqueduct (Phase B) would follow. Phase A extended from the Gila River to the Marana area and included these three pumping plants. The photo is of Picacho Pumping Plant. 2

3 The number of units decreases as one moves downstream due to significant agricultural deliveries in Pinal County. The 54 discharge valves at all three plants are interchangeable. 3

4 Water flows from the forebay through the suction tube into the pump, then out through the discharge tube and up through the discharge line until it reaches the open canal once again. Maximum lift at each plant: Brady 148 feet Picacho 232 feet Red Rock 232 feet 4

5 The A Plants were originally fitted with 54 Streamseal Butterfly Valves made by Allis Chalmers. Rodney Hunt acquired Allis Chalmers in Rodney Hunt no longer manufactures this style of valve, but does provide maintenance and refurbishment services. 5

6 A key feature of the Allis Chalmers/Rodney Hunt valve design is the location of the seal on the outer edge of the valve disk. This means that the seal moves with the disk and is exposed edge on to flowing water. The retaining ring that holds the seal in place is a single piece of metal held in place by 36 bolts. 6

7 Pump unit at A Plant. 7

8 Discharge tube opened for inspection. 8

9 This is what we should see when inspecting a discharge valve. 9

10 Unfortunately, too often the valves leak. 10

11 11

12 Leaking leads to corrosion and erosion of the valve disk and body. 12

13 In 2010, CAP s Reliability Engineering team prepared an Equipment Assessment Report on the 54 discharge valves at the A Plants and concluded that: (1) the Mean Time Between Failure for these valves was far shorter than expected; and (2) it cost CAP twice as much to rebuild a valve as it cost to buy a replacement valve. Therefore, the report recommended developing a new valve specification and investigating valve replacement. 13

14 As part of the equipment assessment, a detailed history was developed for each valve, documenting when it was repaired/replaced and how long it remained serviceable. 14

15 A concept document was presented to CAP s Project Steering Committee for replacing all A Plant discharge valves. After PSC approval, a Project Planning Document was developed. The original plan called for installation and testing of a pilot valve with a new, tripleeccentric seat design, which was expected to lower fluid velocities within the valve and decrease corrosion damage. The triple eccentric valve is so named because the valve disk movement has three offsets against the symmetrical axes of the pipe. A triple eccentric pilot valve was installed in Operationally, the pilot valve has performed very well, with little leaking. But the design of the valve actuator has presented numerous challenges to our maintenance crews. In addition, the tripleeccentric valve costs roughly twice as much as the current valves. 15

16 Replacement of the A Plant discharge valves is a capital improvement project in the recently approved budget. This is the relevant page from the CAP Biennial Budget book. 16

17 The valve replacement project is among the 10 capital projects that account for about 2/3 of overall capital spending. All of the projects on this list, however, are being implemented in This slide is from Doug Dunlap s presentation at the October 15 Finance, Audit and Power Committee meeting and the November 5 Board meeting. 17

18 The chosen replacement valve is manufactured by Crispin. Unlike the Allis Chalmers/Rodney Hunt design, the seal for the Crispin valve is located in the body of the valve, not on the disk. The retaining ring for the seal is comprised of multiple segments, each of which is held in place by 2 bolts. The Crispin design has long been used at CAP s Twin Peaks, Sandario, Brawley and San Xavier pumping plants with good performance. Over the past 10 years, CAP spent 5 times as much maintaining discharge valves at the A Plants as compared to the 4 downstream plants that have the Crispin valves. 18

19 New Crispin valve ready for installation at Picacho Pumping Plant. 19

20 By the end of 2017 we will have installed 18 new Crispin valves at the three A Plants. CAP s Engineering Department plans to re engineer the actuator mechanism of the triple eccentric valve that was removed in 2015 so that it can be reinstalled as the 19 th valve. This will give allow us to continue to evaluate that design for possible future applications within CAP. 20

21 Given the maintenance costs and challenges CAP has had with the A Plant discharge valves, CAP s Reliability Engineering team selected that system for its first RCM analysis, which was completed in September RCM stands for Reliability Centered Maintenance. The goal of RCM analysis is to develop the ideal lifecycle maintenance plan for an asset one that will preserve required system reliability at optimum cost while achieving the organization s mission. An RCM based maintenance program uses inspections, condition assessment and monitoring systems to drive maintenance and modification decisions (as compared to a purely reactive program or one that is strictly time based). 21

22 The RCM analysis identified failure modes and effects for the discharge valves, which led to criteria to assess the condition of existing valves, including alignment, coating, seal damage, etc. 22

23 All A Plant discharge valves were inspected and evaluated based on 10 separate criteria. The 5 valves scoring the worst were slated for replacement during the 2015 fall outage, along with the triple eccentric pilot valve that had been installed in The worst scoring valve was one that was rebuilt by an outside vendor and installed just one year ago. 23

24 Before work can begin on the discharge valves, the plant must be dewatered. The first step is to set stoplogs at the outlet to the discharge line and in front of the pump suction tubes. 24

25 25

26 26

27 27

28 28

29 To insure worker safety, strict Lock Out/Tag Out procedures must be followed before the discharge tube can be opened and the valves accessed. 29

30 Access to the discharge valves (those not being replaced) is through the discharge tube coming off the pump. 30

31 The discharge tube is a confined space. As such, employees are not permitted to enter unless they have secured the required permit and have the appropriate personal protective equipment (PPE). 31

32 Mechanic Mike Mathews prepares to enter discharge tube at Picacho Pumping Plant. 32

33 The 13 valves not being replaced were serviced in place adjusting the positioning (fit) of each valve as necessary and installing new seals. Here, heavy overhaul mechanic Mitch Garvin works inside one of the 54 diameter discharge tubes. With the valve open, he can crawl into the pipe to remove the existing seal, take measurements, make adjustments, clean, and then install a new seal. 33

34 Many times, there are two men working on the same valve, one of the top of the disk and the other underneath. 34

35 Allis Chalmers/Rodney Hunt discharge valve prior to disassembly. Note Lock Out/Tag Out notice affixed to actuator. 35

36 The first step in disassembly is to remove the Dresser coupling. 36

37 Once the Dresser coupling has been removed, the upstream pipe spool can be removed, exposing the downstream side of the old Allis Chalmers/Rodney Hunt valve. 37

38 Old valve being lifted out after all bolts have been removed. 38

39 Mechanic Dave Lopez prepares a rebuilt Rodney Hunt valve for installation. 39

40 Flange surfaces on the pump case extension and upstream pipe spool are cleaned and prepared in preparation for new gasket and discharge valve installation. 40

41 Mechanics Tracy Jordan and Pat Ross applying silicone adhesive sealant on pump case extension flange. 41

42 New gasket being installed. 42

43 43

44 Pat Ross and Mark Hall lower a new Crispin valve into place from plant floor. 44

45 Mitch Garvin positioning new valve. 45

46 Once the valve is positioned, it is bolted onto the base plate and secured to the pump case extension flange. 46

47 Pat Ross and Tracy Jordan applying silicone adhesive sealant to valve flange. 47

48 Upstream pipe spool being lowered into place. 48

49 Tracy Jordan prepares the downstream pipe spool where the new Dresser coupling seal will sit. The exposed ends of both the upstream and downstream pipe spools must be cleaned, inspected and coated before the Dresser coupling is installed. 49

50 Upstream and downstream pipe spools in place. The remaining gap will be covered and sealed by the Dresser coupling. 50

51 Pat Ross positions Dresser coupling over gap between upstream and downstream pipe spools. 51

52 Retaining rings fitted to Dresser coupling. 52

53 Mechanic Mike Hawk assists as Dresser coupling bolts are tightened. 53

54 New Crispin valve fully installed, still in Lock Out/Tag Out status. 54

55 Mark Hall checking for leaks. As the plant is watered up, crews must continually check each valve for leaks, tightening bolts as needed to insure a good seal. 55

56 New Crispin valve in place, no leaks. 56

57 57

Generator Rebuild and Unit Refurbishment for the Wells Hydroelectric Project. NWHA Spokane October 30, 2014

Generator Rebuild and Unit Refurbishment for the Wells Hydroelectric Project NWHA Spokane October 30, 2014 0 The Wells Project WELLS Chief Joseph Rocky Reach East Wenatchee Wells Dam Location Columbia