Before discussing metal valve uses and the various jobs they do well, we should acknowledge the fact that many types of metals exist. Just like the category of "plastic" covers PVC, CPVC, ABS, polypropylene (PP), etc., "metal" includes cast & ductile iron, brass, bronze, carbon & stainless steel, and more! Knowing exactly when to use metal valves requires knowledge of the metal and the medium.
This blog post discusses different metal valve applications that, for one reason or another, plastic valves cannot handle. Countless specific jobs exist for metal valves, but we will focus on a broader view of applications. Diving into every single job would take far too long. But let's dig deeper into the different materials used and when to use metal valves!
Common Materials Found in Metal Valves
Many metal valves were around before the advent of thermoplastics like PVC and PP, so metal valves have a longer history than plastic valves. Materials such as cast iron and bronze have been around in a mostly unchanged form for centuries, so they are used for just about every type of equipment imaginable, including valves. However, superior materials have been developed in recent years that and are taking over!
Ductile iron is an upgraded form of cast iron with slightly different composition and process that goes into making it. Steel alloys are also very popular due to their toughness. Carbon steel and stainless steel are the most popular variants. Each metal has different properties and chemical compatibilities, so be sure to look those up before using a metal valve with an unusual liquid or gas.
When to Use Metal Valves
Plastic valves have limitations when it comes to temperature and pressure. Most plastics will start breaking down before temperatures reach 200F. Regardless of seal materials, plastic valves also don't handle high pressures well. Because of this, metal valves are necessary for more intense situations. The following are a few common metal valve applications.
High Temperature Applications
Metal alloys shine (sometimes literally!) in applications involving high temperatures! Popular plastics, such as PVC and CPVC have maximum temperatures of 140F and 200F, respectively. This makes them great for low temperature jobs, but completely unsuited for hotter environments. Luckily, metals such as bronze, iron, and steel are perfect for high temperature applications!
However, not all metals are created equal. For example, bronze has a temperature rating of 150F to 550F, depending on what grade it is. 316 stainless steel can be made to withstand temperatures up to 2000F. Cast iron doesn't start melting until it is heated to 2100F or higher! Do not install valves in areas where they will constantly be facing maximum temperatures! If exposed to dire circumstances occasionally, however, these valves will survive.
High Pressure Applications
Another area in which metal valves shine is applications that require high pressure. Pressure requirements can be due to necessity caused by the application, the media, or demand. Whatever those requirements are, plastic valves do not always meet them. The main problem with plastic valves is that they the material bends and leaks too easily. With metal valves, you don't have to worry about that.
We sell several lines of high quality metal valves that are made specifically for high pressure applications. Our GEM 316 stainless steel ball valves are tested up to 1000psi WOG (water, oil, or gas). Even this 1" Watts lead-free brass ball valve has a 600psi WOG rating, so you can carry out exceptionally demanding applications with inexpensive valves!
We carry metal ball valves, check valves, gate valves, and stop valves for all of your flow control needs. Check out our metal valves at wholesale prices by clicking the links below!