D-2 Install Valves Introduction
This section introduces the essential knowledge and skills required to install and work with valves in piping systems. You will learn key terminology, materials, and functions of valves, as well as how to select the appropriate valve for specific applications. The section also explores valve service ratings, actuators, and common valve types, along with their parts and functions. In addition, you will develop the ability to identify and understand critical components such as valve seats and stuffing boxes, including their materials, purposes, and installation considerations.
Learning Objectives
After completing this section, you will be able to:
- Define basic valve terminology.
- Identify the materials that valves are made of.
- Describe the purpose of valves.
- Select the correct valve for its intended use.
- Read and interpret valve service ratings and specifications.
- Name the types of valve actuators and visually identify a valve actuator.
- Visually identify, name, and state the purpose of common types of valves.
- Visually identify and name valve parts and describe their function.
- Identify, name, and locate valve seats; describe materials used to make them; and list the factors to consider when selecting a valve seat.
- Identify, name, and locate valve stuffing boxes, name their parts, and identify packing material and basic methods of installing valve packing.
- Read, interpret and apply manufacturer’s installation requirements for valves.
- Install valves correctly.
- State the correct stem positions and valve orientation.
- State specific valve installation dimensions from other valves, fittings, and equipment.
Topic areas covered in this publication are in alignment with SkilledTradesBC Harmonized 2018 Program Outlines.
Resources
You may be required to reference publications and videos available online at the WorkSafeBC website.
Terminology
The following terms may be used throughout this section. Note that some glossary terms may be in italics throughout the section content but are not included in this list. A complete list of terms can be found in the Glossary.
- backpressure: The pressure exerted on the downstream side of a valve seat. (Section D-2.1)
- ball valve: A quarter-turn valve with a ball-shaped closing element held between two seats. (Section D-2.1)
- bellows: A sealing device that prevents line media from leaking between the stem and the body. (Section D-2.1)
- butterfly valve: A quarter-turn valve that has a circular disk as its closing element. (Section D-2.1)
- cavitation: The noise caused when high-velocity turbulent flow and low pressure occur in a valve causing the water to form a gas bubble; the gas bubble rapidly turns back into water when the velocity drops and the pressure increases; cavitation results in deterioration of internal valve parts and premature failure. (Section D-2.1)
- check valve: A valve designed to allow the fluid to flow in one direction but to stop flow in the reverse direction; the valve closes to prevent backflow. (Section D-2.1)
- control valve: A valve that regulates the flow or pressure of a fluid; control valves normally respond to signals generated by independent devices such as flow meters, temperature gauges, etc.; control valves are normally fitted with actuators and positioners. (Section D-2.1)
- cryogenic valve: A valve suited for use at temperatures below –40°C (–40°F) (Section D-2.1)
- galling: A severe form of metal wear caused when sliding surfaces make contact, tearing areas of the metal surface. (Section D-2.1)
- lantern ring: A metal ring in a valve that provides for uniform distribution of stem packing pressure over the packing. (Section D-2.1)
- outside screw and yoke (OSY) valve: A valve with a stem that moves up and down outside the valve body, making it easy to see if the valve is open or closed. (Section D-2.1)
- quarter-turn valve: A valve in which the handle and stem move from fully closed to fully open in one-quarter of a 360° turn (90°). (Section D-2.1)
- stuffing box: An enclosure containing packing to prevent leakage around a moving machine part. (Section D-2.1)
- trunnion: A valve component such a pin or pivot on which something can be rotated, such in a trunnion ball valve, which has additional mechanical anchoring of the ball at the top and the bottom, suitable for larger and higher pressure valves. (Section D-2.1)
- valve actuator: A device used to open, close, or control a valve, such as manual handles and electrical, hydraulic, and pneumatic actuators. (Section D-2.1)
- wire drawing: The visual effect of erosion of a valve seat or disk. Wire drawing occurs when a valve is not closed perfectly tight. (Section D-2.1)
