Valve installation orientations

Size: px

Start display at page:

Download "Valve installation orientations"

Ann Clare Edwards
5 years ago
Views:

1 By: Greg Johnson, June,

2 Valve installation orientations

3 Valve installation orientations Flow horizontal stem vertical

4 Stem vertical - optimum Flow horizontal stem vertical An assist from gravity

5 Valve installation orientations Flow horizontal stem horizontal Beware of the dreaded cock & lock

6 Valve installation orientations Flow vertical stem horizontal

7 Body/disc guide Issues Misalignment between body guides and disc guides Discs hanging up when closing Discs cocking & locking Stems breaking Seating surfaces damaged Stems scratched when actuated

8 Misalignment Misalignment between components Body guide/bonnet guide misalignment Backseat bushing misalignment Yoke misalignment Yoke bushing misalignment Actuator pad misalignment Misalignment of actuator

9 Sloppy guides Sloppy guides due to as cast issues Poor machining Misalignment during manual fitting Limited or inept quality control Really bad guides

10 Some gate valves have excellent guiding for horizontal orientations Nuclear valves have precision-machined body guides Forged pressure-seal valves have welded-in, precision-machined body guides Many large AWWA water works valves have rollers and guides for smooth horizontal operation

11 History of the guide problem Was not an issue for decades Started to become an issue years ago Problems can be traced to change in manufacturing techniques & manufacturing locations

12 Changes in manufacturing Until most production moved abroad, body guides were cast oversize and then machined, or in some cases pre-machined and welded in to the valve body.

13 Machining body guides

14 Machined & welded guides

15 The dreaded Cock & Lock

16 The dreaded Cock & Lock

17 The dreaded Cock & Lock

18 The dreaded Cock & Lock

19 API 600 Requirements The body and gate shall have guide surfaces to minimize wear of the gate seats during operation of the valve, to accurately position the gate throughout the travel distance to its seat, and to ensure the alignment of the gate and stem in all orientations without gate binding or galling.

20 API 600 Requirements. For sizes DN 650 (NPS 26) and above, as a minimum, wedge guides and body guides shall be hardfaced and machined with appropriate tolerances and clearances to allow for proper valve operation in any orientation, including the effects of wear or galling.

21 Component misalignment Components must be machined correctly In horizontal orientation applications, alignment of components is critical Actuation can exacerbate the problem Actuators have no sense of feel Actuated stems will attempt to go over under or through obstacles The result can catastrophic and expensive

22 Component alignment Yoke bushing or actuator mount Yoke Stuffing box Backseat bushing Bonnet guides Body guides

23 Component alignment Yoke bushing or actuator mount Yoke Stuffing box Backseat bushing Bonnet guides Body guides

24 Component misalignment offset

25 Component misalignment offset

damages packing Stem-damaging misalignment may also occur

26 Large valves- (over about 24 ) are shipped horizontally Eccentric weight on packing combined with ship vibrations damages packing Stem-damaging misalignment may also occur Bare-stem shipments require precision expendable bushings New large valve issues

27 Large stem damage Large valves- (over about 24 ) are shipped horizontally Eccentric weight on packing combined with ship vibration damages packing Stem-damaging misalignment may also occur Gravity This side of packing can be over-compressed

28 Actuating valves used in horizontal orientation Position the valve safely in the stem vertical position Loosen packing slightly Using the handwheel, open & close the valve If possible check stem with dial indicator during cycling

29 Actuating valves used in horizontal orientation If no damage to stem is observed and stem is straight, install actuator After actuator is installed, repeat the above steps under manual control Operate the valve under power checking for damage

30 What about low emissions valves in horizontal orientations? Total misalignment of stem should be less than for most low E packings to work. Double check all dimensions and relational parts geometry Assemble the valve in the stem vertical position Confirm damage free movement of stem (cycle open and close) Optional: Perform an EPA method 21 type test- a low pressure gas test looking for bubbles at the packing area

31 What does it mean for the repair shop? Check the guides very carefully for proper engagement and minimum slop Newer (non-usa manufactured) valves need more scrutiny Try to determine from valve owner if horizontal orientation is a possibility If in doubt, hardface the disc guides Take extra care when actuating

32 Questions?

Fugitive Emissions Standards & Laboratory Test Methods for Valves

Fugitive Emissions Standards & Laboratory Test Methods for Valves By: Greg Johnson President, United Valve 50 Years in 50 Seconds 1964 Houston air pollution Measuring air pollution in 1974 1 50 Years in