You might also see valves classified by function instead of design.
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Common functional designations and their common design types include:
While valves might be a small part of your piping process or system in terms of space, they’re often a substantial portion of the design and build budget. They also have a significant impact on long-term costs and overall system performance.
Choosing a proper valve size is essential to both optimizing costs and ensuring safe, accurate, and reliable operation.
The first thing to consider is the overall size of the valve -- both in terms of physical dimensions and in terms of internal size and flow rates (CV).
Choosing a valve that does not fit properly in the space required could result in added costs. Choosing a valve which does not provide the ideal flow rate can lead to inaccurate flow control at the least and complete system failure at worst.
For example, if your valve is too small, it could cause reduced flow downstream while creating back-pressure upstream. If the valve is too large, you’ll find that flow control is drastically reduced the further you move from fully open or fully closed.
When choosing the proper size, be sure to consider both the connector diameter and the overall flow rate of the valve compared to your needs. Some valves offer excellent flow while others constrict flow and increase pressure.
This means sometimes you must install a larger valve to adjust for flow than the adapter diameter alone might imply.
With sizing and design out of the way, it’s also important to consider valve end connections.
Common Valve End Types. Source: Unified AlloysWhile the most obvious implication here is choosing an end connection compatible with your piping, there are also functional characteristics to common end types that might make one valve more suited to your needs than another.
Common valve connections and ends include:
Depending on your intended use, the materials with which your valves are made might be a critical aspect in ensuring safe operation and reducing maintenance and replacement costs over the life of your operation.
Stainless steel valves are excellent options in a range of processing environments, including those involving corrosive media (such as chemicals, saltwater, and acids), environments with strict sanitation standards (such as food and beverage manufacturing and pharmaceuticals), and processes involving high pressure or high temperatures.
However, if you are processing solvents, fuels, or volatile organic compounds (VOCs), choosing a valve material from a non-sparking material -- such as brass, bronze, copper, or even plastic -- is often a better option. In addition to selecting the correct body material, internal (wetted) trim parts should be evaluated for chemical compatibility as well. If your valve contains elastomers, they should also be evaluated for their chemical compatibility as well as pressure and temperature limitations.
Depending on your intended usage, you might find that valves must adhere to particular standards to meet regulatory requirements for safety, sanitation, or other concerns.
While there are too many standard organizations and potential regulations to cover in detail, common general standard organizations include:
There are also industry-specific standards to consider.
Major standards organizations by industry include:
Choosing the right valve for your project might seem complex. However, by starting with general characteristics -- such as valve design, valve size and actuation method -- you can quickly limit your options to determine the best valves for your needs.
Whether you’re designing a new processing system or looking to make upgrades to or maintain an existing system, Unified Alloys’ selection of valves and fittings can help you find the ideal solution for your application and usage environment. As a leading provider of stainless steel alloys, valves, flanges, and more, our experts have helped industries across Canada and North America for more than 4 decades. Need assistance or have a question? Contact us for personalized help.
Are you looking for more information about Marine Valve and its applications? Look no further than our Comprehensive FAQ Guide! Here, you’ll find all the answers to questions about valves used in all types of marine applications. Our main aim is to provide you with an authoritative and comprehensive overview of them, so whatever your experience or expertise level, you can explore the ins and outs of them.
Figure 1: Marine Valve
Marine valves are essential components of a vessel’s infrastructure, as they play a critical role in managing the pressure, rate of flow, and path of liquids circulating through the ship’s pipelines. If they are not appropriately managed, it can significantly affect the ship’s operation. For this reason, marine valves play a critical role in ensuring that vessels run efficiently and safely.
Valves are essential components in the shipbuilding industry as they help to regulate and control the flow of fluids, gasses, vapors, and slurries or semi-liquid mixtures throughout a vessel’s systems. Without this regulation, it would be impossible to ensure the proper performance of onboard operations.
Valves act as control points that enable users to efficiently stop, start, or redirect the flow of liquids and other substances. Not only do valves provide precise control over pressure and flow within the system, but they also allow for faster installation by eliminating extra pipes and connections, which saves time and money during construction.
Figure 2: Marine Valves Being Employed With Pipelines
A wide variety of valves are used in the marine industry, and they are all utilized for different purposes.
Although you may find many types of marine valves, here are the four primary tones:
Gate valves are among the most widely used valves on all types of vessels, controlling the flow of fluids through the pipes by raising or lowering like a gate. Like other valve types, it also has sub-categories: rising stem and non-rising stem.
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Figure 3: Gate Valve
The rising stem design, for example, involves threads that are specifically designed to fit within the internal threading of the bonnet. It ensures a secure and reliable connection between the two components. On the other hand, in the non-rising stem design, a valve disc is incorporated that has its own threading at one end which connects it to the stem. This design eliminates any risk of leakage due to relying on an external threading as there is no need for a separate bonnet component. Both designs have their distinct purpose and can be used for different applications.
They are lightweight and versatile valves used in different ships. Comparable to the throttle and choke valves found in cars, butterfly valves open and close by pivoting a central disk as the shaft turns. Constructed out of various materials such as metal, these valves have been designed to ensure simple maintenance, provide long-term durability, and reduce costs.
Figure 4: Butterfly Valve
It is one reason why they are prevalent among shipping companies. Butterfly valves also have the benefit of having higher flow rates as compared to other valves, thanks to their full-circle seat. While this design makes them relatively straightforward to operate, it also provides an extra layer of protection due to their ability to shut off the flow very quickly if necessary.
The globe valves are exceptionally important in regulating the liquid and gasses flow. These valves use a movable disk and stationary ring seat to do so. This type of valve is designed in a way that allows for both forward and reverses flow. It has several other types as well, such as screw-lift, screw down non return, and multi-turn ones.
Figure 5: Globe Valve
The main difference is the connection between the stem and the disc; in some models, the stem may be attached directly. In others, it may be connected through an actuator or a mechanism within the valve body. Screw-lift globe valves raise or lower the disk with a threaded stem that is rotated with an operating tool.
This type of valve has either one port open at once or two separate ports which can be shut off independently from each other; this allows for reversible flow control without any additional parts or mechanisms. Finally, multi-turn valves have more than one turn, which provides precise control over the valve stroke; they can also handle more significant flows compared to other types.
Relief valve assists in regulating and reducing pressure within marine pipes. Once the pressure reaches a particular level, the spring inside the valve will open, releasing the pressure. This spring can be adjusted to make the valve open more quickly or more slowly, depending on the needs of a particular situation.
Figure 6: Relief Valve
The relief valves are further categorized in two forms; self-regulating and automatic process control valves. Self-regulating valves are designed so that they can automatically adjust themselves as needed, depending on the amount of pressure being applied by adjusting the spring’s tension.
On the other hand, automatic process control valves require no manual adjustments and rely instead on a programmed system for regulating and controlling pressure levels. These valves are most often used for systems that operate without human input or assistance, such as machinery or equipment that run on their own.
Check the video to see how different types of valves work:
The check valve is a special type of marine valve, it’s automated and also referred to as the non-return check valve. It can rely on the medium flowing pressure in the pipeline to push the valve disc open and close. It makes it possible for it to effectively prevent any backflow of the medium when the flow ceases and the check valve disc is closed. The primary benefit of this function is that it significantly contributes to safety by protecting the integrity of the entire pipeline system.
Figure 7: Check Valve
Well, there are two methods to determine the installation position or location of check valves:
Installing the check valve is essential to guarantee that the flow of water inside a water pump is directed in the right direction, thereby ensuring its proper operating capacity. Consequently, the position of installation of the check valve can be divided into two scenarios: before or after the water pump.
The bottom valve, which is also known as the end valve, is a device that you can install at the vertical suction pipe’s end in front of the water pump. Its primary purpose is to provide a way for water to enter the pump without pumping. It ensures that when there is no water available in either the pump or suction pipe, then the pump will not be able to run and will only idle. Therefore, water must be filled into the pump initially for it to start up and begin its duty of pumping out water.
The other installation option is to place it behind the water pump. This placement method is ideal if the liquid level of the water source is higher than that of the pump itself. When starting and stopping the water pump, it is not necessary to close off the outlet valve from the pump. It can be especially beneficial when used in conjunction with a primary pipe water pump system, as it helps prevent backflow.
Selecting the suitable marine valve to ensure the efficient operations of a ship is no small feat. It can be intimidating if you’re unfamiliar with all that goes into it. To help, let’s start with the basics.
First, determine what type of valve you need and its size requirements. Known as ‘valve trim,’ this includes seat materials and body material – they should be selected based on the corrosive environment in which the valve will be housed, so get these details from your engineers and manufacturers.
Your selection should also consider parameters like pressure and temperature ratings for the specified conditions so you can find valves that will function properly within your system stress levels.
Finally, safety factors must always be considered when selecting a new valve; look for high-quality reliability ratings coupled with third-party certifications to make sure that your chosen parts will comply with strict regulations aboard ships.
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