Course Content
Introduction to Valves
Overview of Valves 1. What is a Valve? A valve is a mechanical device that regulates, directs, or controls the flow of a fluid (gases, liquids, fluidized solids) by opening, closing, or partially obstructing various passageways. 2. Functions of a Valve Stopping and starting fluid flow Varying (throttling) the amount of fluid flow Controlling the direction of fluid flow Regulating downstream system or process pressure Relieving component or piping overpressure 3. Types of Valves (Detailed listing covered under classification section below) 4. Cost of Valves in Piping Systems Valves represent a significant portion of the total cost in piping systems, influenced by their size, type, materials, and complexity. 5. Importance of Valve Selection Proper valve selection is crucial for system safety, performance, maintenance, and cost-effectiveness. 6. Methods of Controlling Flow Through a Valve Moving a disc or plug into or against an orifice Sliding a flat, cylindrical, or spherical surface across an orifice Rotating a disc or ellipse about a shaft extending across the diameter of an orifice Moving a flexible material into the flow passage 7. Characteristics of Flow Control Methods Valve Body or Shell Main pressure retaining part Accommodates valve trim Provides passage for fluid flow Manufacturing: cast, forged, fabricated, or combination Materials: various metals and alloys Connection Ends: Butt welded Socket welded Threaded Flanged Wafer Lug Types of Body Passages: Reduced bore Full bore Crossflow or Split section Bonnet or Cover Encloses internal parts Designs: Simple cover (e.g., swing check valve) Supporting internals/accessories Valve stem opening Includes stuffing box Bonnet-less design available Connection to body: bolted, threaded, or welded Bonnet joint often a leakage point Same material as valve body 8. Valve Trim Definition: Internal parts in contact with fluid, removable & replaceable Components: Disc, seat, stem Additional Parts: Back seat, glands, spacers, guides, bushings, pins, springs Function: Controls flow by disc movement 9. Valve Disk Function: Allows, throttles, or stops flow Defines valve type (globe, gate, etc.) Manufacturing: cast, forged, fabricated Features: Hard-faced for wear Smooth finish for friction reduction Pressure retaining part (when closed) Movement: By stem By fluid (in check/safety-relief valves) 10. Valve Seat Provides sealing surface for disc Number varies by valve type Good seal critical to prevent leakage Types: integral or replaceable Attachments: screwed, welded, cast/forged Hardening: heat treatment, Stellite facing Surface finish crucial for sealing Seat Types: Metallic Non-metallic (for non-critical service) Combination seats (metal + elastomer) 11. Back Seat Parts: Stem shoulder + Bonnet surface Functions: Seals when valve is fully open Prevents leakage to packing Allows in-service gland packing replacement 12. Stem Connects actuator to disk Types of motion: Linear (gate, globe) Rotary (plug, ball, butterfly) Typical Material: Forged stainless steel Connection to disc: Threaded/Welded 13. Bonnet Bolt & Gland Eyebolt Bonnet Bolt: Seals bonnet and body Gland Eyebolt: Connects gland flange and bonnet Pushes gland bush to retain packing 14. Yoke, Yoke Bushing, Yoke Nut Yoke: Connects bonnet to actuator May be one-piece Must be strong Yoke Nut: Converts rotary motion to linear Yoke Bushing: Threaded, softer than stem May have anti-freeze sleeve bearings 15. Non-Pressure Retaining Parts Gland Flange Gland Sleeve/Bush Gland Packing: Graphite, PTFE Prevents leaks/fugitive emissions Needs proper compression & maintenance 16. Valve Trim Chart Trim Number: Standard material combination Standards: API 600, API 602 Common Grades: A410, A316, Alloy 20, Monel Usage: Simplifies ordering and specification 17. Classification of Valves By Function Isolation Control Pressure/Vacuum Relief Non-return Special Purpose By End Connection Threaded Flanged Butt Welded Socket Welded Wafer & Lug Ends By Motion Linear Rotary Quarter-turn By Actuator Type Manual Pneumatic Electric Hydraulic
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Topics covered
05:00
Introduction to Valves
25:00
Ball valves
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All About Ball Valves
18:00
Butterfly Valves
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All About Butterfly Valves
11:00
Globe Valves
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All About Globe Valves
14:00
Gate Valves
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All About Gate Valves
12:00
Needle Valves
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All about Needle Valves
08:00
Plug Valves
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All About Plug Valves
13:00
Piping Engineering Essentials: Types of Valves and Their Functions


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Overview of Valves

1. What is a Valve?

A valve is a mechanical device that regulates, directs, or controls the flow of a fluid (gases, liquids, fluidized solids) by opening, closing, or partially obstructing various passageways.

2. Functions of a Valve

  • Stopping and starting fluid flow

  • Varying (throttling) the amount of fluid flow

  • Controlling the direction of fluid flow

  • Regulating downstream system or process pressure

  • Relieving component or piping overpressure

3. Types of Valves

(Detailed listing covered under classification section below)

4. Cost of Valves in Piping Systems

Valves represent a significant portion of the total cost in piping systems, influenced by their size, type, materials, and complexity.

5. Importance of Valve Selection

Proper valve selection is crucial for system safety, performance, maintenance, and cost-effectiveness.

6. Methods of Controlling Flow Through a Valve

  • Moving a disc or plug into or against an orifice

  • Sliding a flat, cylindrical, or spherical surface across an orifice

  • Rotating a disc or ellipse about a shaft extending across the diameter of an orifice

  • Moving a flexible material into the flow passage

7. Characteristics of Flow Control Methods

Valve Body or Shell

  • Main pressure retaining part

  • Accommodates valve trim

  • Provides passage for fluid flow

  • Manufacturing: cast, forged, fabricated, or combination

  • Materials: various metals and alloys

  • Connection Ends:

    • Butt welded

    • Socket welded

    • Threaded

    • Flanged

    • Wafer

    • Lug

  • Types of Body Passages:

    • Reduced bore

    • Full bore

    • Crossflow or Split section

Bonnet or Cover

  • Encloses internal parts

  • Designs:

    • Simple cover (e.g., swing check valve)

    • Supporting internals/accessories

    • Valve stem opening

    • Includes stuffing box

  • Bonnet-less design available

  • Connection to body: bolted, threaded, or welded

  • Bonnet joint often a leakage point

  • Same material as valve body

8. Valve Trim

  • Definition: Internal parts in contact with fluid, removable & replaceable

  • Components: Disc, seat, stem

  • Additional Parts: Back seat, glands, spacers, guides, bushings, pins, springs

  • Function: Controls flow by disc movement

9. Valve Disk

  • Function: Allows, throttles, or stops flow

  • Defines valve type (globe, gate, etc.)

  • Manufacturing: cast, forged, fabricated

  • Features:

    • Hard-faced for wear

    • Smooth finish for friction reduction

    • Pressure retaining part (when closed)

  • Movement:

    • By stem

    • By fluid (in check/safety-relief valves)

10. Valve Seat

  • Provides sealing surface for disc

  • Number varies by valve type

  • Good seal critical to prevent leakage

  • Types: integral or replaceable

  • Attachments: screwed, welded, cast/forged

  • Hardening: heat treatment, Stellite facing

  • Surface finish crucial for sealing

  • Seat Types:

    • Metallic

    • Non-metallic (for non-critical service)

    • Combination seats (metal + elastomer)

11. Back Seat

  • Parts: Stem shoulder + Bonnet surface

  • Functions:

    • Seals when valve is fully open

    • Prevents leakage to packing

    • Allows in-service gland packing replacement

12. Stem

  • Connects actuator to disk

  • Types of motion:

    • Linear (gate, globe)

    • Rotary (plug, ball, butterfly)

  • Typical Material: Forged stainless steel

  • Connection to disc: Threaded/Welded

13. Bonnet Bolt & Gland Eyebolt

  • Bonnet Bolt: Seals bonnet and body

  • Gland Eyebolt:

    • Connects gland flange and bonnet

    • Pushes gland bush to retain packing

14. Yoke, Yoke Bushing, Yoke Nut

  • Yoke: Connects bonnet to actuator

    • May be one-piece

    • Must be strong

  • Yoke Nut: Converts rotary motion to linear

  • Yoke Bushing: Threaded, softer than stem

  • May have anti-freeze sleeve bearings

15. Non-Pressure Retaining Parts

  • Gland Flange

  • Gland Sleeve/Bush

  • Gland Packing:

    • Graphite, PTFE

    • Prevents leaks/fugitive emissions

    • Needs proper compression & maintenance

16. Valve Trim Chart

  • Trim Number: Standard material combination

  • Standards: API 600, API 602

  • Common Grades: A410, A316, Alloy 20, Monel

  • Usage: Simplifies ordering and specification

17. Classification of Valves

By Function

  • Isolation

  • Control

  • Pressure/Vacuum Relief

  • Non-return

  • Special Purpose

By End Connection

  • Threaded

  • Flanged

  • Butt Welded

  • Socket Welded

  • Wafer & Lug Ends

By Motion

  • Linear

  • Rotary

  • Quarter-turn

By Actuator Type

  • Manual

  • Pneumatic

  • Electric

  • Hydraulic

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