Valves control the flow of fluids through piping systems and come in many types for different applications. Valves are either on-off valves that completely stop or start flow, or control valves that can partially restrict flow to regulate it. Common on-off valves include gate, ball, plug, and knife valves. Control valves include globe, butterfly, and diaphragm valves. Valve selection depends on factors like pressure, temperature, fluid chemistry and the valve's intended function in the system. Proper installation, handling, and maintenance of valves is important for safety and performance.

1. VALVES

2. 1.0.0 Introduction
• Valves are devices that control the flow of
fluids or gases through a piping system.
• Valves are made of a wide variety of materials
for compatibility to the fluid flowing through
it.

3. 2.0.0 Valves That Start and Stop Flow
• These valves are designed to be operated completely
open or completely closed.
• These valves cannot be used effectively to throttle, or
regulate, flow.
• Gate Valve
• Knife Valve
• Ball Valve
• Plug Valve
• Three-Way Valve

4. 2.1.0 Gate Valve
• Turning the hand-wheel lifts or lowers the disc
(gate).
• A partially opened gate causes turbulence.
• This turbulence not only causes piping
damage (water hammer), it also wears the
disc and seat surfaces.

5. 2.1.0 Gate Valve – Solid Wedge
Most common used:
a single, solid disc
that is rugged and
simple.

6. 2.1.0 Gate Valve – Flexible Wedge
A one-piece disc with
a cut or groove
around the edge to
compensate for
irregular sealing
edges.

7. 2.1.0 Gate Valve – Split Wedge
Self-
adjusting
and self-
aligning
discs.

8. 2.1.0 Gate Valve – Double (Parallel) Disc
Prevents valve
binding due to
thermal
transients.

9. 2.1.1 Valve Stem
• Connects the hand-wheel to the gate.
• Rising stem
– Hand-wheel and stem rising when opening
• Non-rising stem
– Hand-wheel and stem do not rise while opening
• Outside screw-&-yoke (OS&Y)
– Stem rises through the hand-wheel while opening
– Stem does not contact the fluid;
• therefore, the OS&Y is suitable for corrosive fluids

10. 2.1.1 Valve Stem
Rising Stem
Non-Rising Stem
OS&Y Stem

11. 2.2.0 Knife Gate Valve
• Gate is thin with tapered edge on the bottom
• Suited for slurry, pulp, waste, and low-
pressure applications

12. 2.3.0 Ball Valve
• Gate is a ball with a hole for flow through it
matching the pipe size

13. 2.4.0 Plug Valve
• Similar to the ball valve,
• It is a ¼-turn start-stop valve.
• Sealant is plug shaped.

14. 2.5.0 Three-Way Valve
• A multi-port plug valve installed at the
intersection of 3 lines.

15. 3.0.0 Valves That Regulate Flow
• These valves can not only start and stop flow,
they can regulate flow.
• The disc can be totally removed from the flow.
• The most common types are:
– Globe Valve
– Butterfly Valve
– Diaphragm Valve

16. 3.1.0 Globe Valve
• Valve movement is perpendicular to the
seat.
• Basic types:
– Angle
– Y-type
– Needle

17. 3.1.0 Angle Valve
• A globe valve that changes the
direction of flow.
• Usually, the ports are at 90-degrees to
each other.
• These are commonly used to replace
valve and elbow combinations.

18. 3.1.0 Y-Type Valve
• Has the straight-through flow of a gate valve.
• Has the throttling and flow control of a globe.

19. 3.1.0 Needle Valve
• Commonly used for precise flow control of
instrumentation applications.
• Not commonly available over 1” in size.

20. 3.2.0 Butterfly Valve
• Has a round disc that turns 90 degrees to
mate with the seat.
• Used in low-to-medium pressures and flows.

21. 3.2.1 Wafer Valve
• Butterfly valve that sandwiches between two
flanges.

22. 3.2.2 Wafer Lug Valve
• Butterfly valve that sandwiches between two
flanges and has lugs to match the bolt holes of
the flange.

23. 3.2.3 Two-Flange Valve
• The body has a flange cast on both sides.

24. 3.3.0 Diaphragm Valve
• Sealing disc is flexible and seals against the body.
• Suitable for slurries, highly corrosive materials,
and materials that cannot be contaminated.

25. 3.4.0 Needle Valve
• Has a tapered needle instead of a disc to allow
for fine adjustment to the flow.

26. 4.0.0 Valves That Relieve Pressure
• Used to control pressure, not flow.
• Two basic types are:
– Safety Valve
– Pressure Relief Valve

27. 4.1.0 Safety Valve
• Used in pipelines and tanks to prevent
ruptures due to excess pressure.
Water
Hydraulic (Sectional View)
Pneumatic

28. 4.2.0 Pressure Relief Valve
• In-line valve to control a specified pressure in the
liquid circuit.
• These usually have the pressure set at the factory.

29. 5.0.0 Valves That Regulate Direction of Flow
• These valves prevent backflow and are
referred to as “check valves”.
• Common types are:
– Swing
– Lift
– Ball
– Butterfly
– Foot

30. 5.1.0 Swing Check Valve
• Uses a hinged disc as the sealing member.

31. 5.2.0 Lift Check Valve
• A one-way-flow check valve that functions like
a globe valve.

32. 5.3.0 Ball Check Valve
• Much like a lift check except that it uses a ball
instead of a disc for sealing.

33. 5.4.0 Butterfly Check Valve
• Two disc hinged in the middle.

34. 5.5.0 Foot Valve
• Used at the bottom of a suction line to
maintain the prime of the pump.

35. 6.0.0 Valve Actuators
• Two primary purposes of valve actuators:
– Provide automatic operation of the valve,
– Reduce the effort required to manually operate the
valve.
• Four basic types of actuators:
– Gear
– Chain
– Pneumatic or Hydraulic
– Motor Driven, Electric or Pneumatic.

36. 6.1.0 Gear Actuators
• Reduces the effort required to manually operate the
valve.
• Three basic types:
• Spur Gear,
• Bevel Gear,
• Worm Gear.

37. 6.1.1 Spur Gear Actuator
• Valve stem and driver shaft are parallel.

38. 6.1.2 Bevel Gear Actuator
• Valve stem and driver shaft are 90 degrees to
each other and the gears are cone-shaped.

39. 6.1.3 Worm Gear Actuator
• Valve stem and driver shaft are 90 degrees to
each other. The driver gear (worm) looks like a
screw.
• Used primarily with butterfly valves.

40. 6.2.0 Chain Actuators
• Reduces the effort required to manually operate the
valve.
• Applicable where the valve is not easily accessible;
such as, too high to reach.

41. 6.3.0 Pneumatic and Hydraulic Actuators
• Uses fluid or air pressure to actuate the valve.
• Most of these are spring-loaded to ensure that
the valve fails in a fail-safe position.

42. 6.4.0 Electric- or Air-Motor Driven Actuators
• Uses motors to actuate the valve.
• Motor can be either electrical or pneumatic.

43. 6.5.0 Control Valves
• Variations of the angle, globe, or ball valves that
are controlled by pneumatic, electronic, or
hydraulic actuators.
• Most commonly used for pressure or
temperature control.

44. 7.0.0 Storing and Handling Valves
• Regardless of the size of the valve, the internal
seats, valves, and springs are precision
machined and must be handled carefully to
avoid damage.

45. 7.1.0 Safety Considerations
• When handling and/or working around valves:
– Be aware of all pinch points,
– Do not stand under a load,
– Be aware of surroundings,
– Never operate a valve in a live system without
authorization,
– Use a spud wrench, not your finger, to align flange
bolt holes.
– Never stand in front of a safety relief valve
discharge.

46. 7.2.0 Storing Valves
• Label all valves.
• Never store valves on the ground.
• Cover all open ends with ‘end protectors’.

47. 7.3.0 Rigging Valves
• Protect all threads and ends.
• Use the proper rigging equipment.
• Connect rigging to body only, not the stem,
handle, or through openings.
• Use a tag line, especially for larger valves.

48. 8.0.0 Installing Valves
• Best working height for manual actuator is
between 2’0” and 4’6” from floor.
• Follow schematics exactly.
– Direction of flow.
– Stem position.
• (vertical up works best, horizontal is acceptable, never
position stem vertical down.)

49. 9.0.0 Valve Selection, Types, and Applications
• Valves can be used in many different
applications.
• Valve selection is important; therefore, follow
design requirements exactly at installation.

50. 9.1.0 Valve Selection
• Important factors:
• Temperature.
• Pressure.
• Pipe size.
• Fluid chemistry.
• Valve function.

51. 10.0.0 Valve Markings and Nameplate Information
• Manufacturers Standardization Society (MSS):
– Developed standards for valve markings.
• American National Standards Institute (ANSI):
• American Society for Testing Materials International (ASTM):
– Both have adopted the MSS marking system.

52. 10.0.0 Valve Markings and Nameplate Information
• Bridgewall markings (globe valves):
– Indicates how the valve seat is angled in relation to the
inlet and outlet ports.
• Flow direction arrow:
– Proper direction of fluid flow.

53. 10.1.0 Rating Designation
• Pressure and temperature rating.
• Fluid types and other pertinent data.

54. 10.2.0 Trim Identification
• Identifies the material of the seat, disc, stem,
and other internal parts if they are different
from the body of the valve.

55. 10.3.0 Size Designation
• Indicates the numerical identification
associated with the pipe size of the
connecting ends.

56. 10.4.0 Thread Markings
• Identifies the size and type of threads for
valves that have threaded connections.

57. 10.5.0 Valve Schematic Symbols
• Valves are shown on schematics by symbols.