Common Plumbing Terminology Questions
What is a Supply Line?
The portion of the plumbing system connected to the supply of potable water (municipal system, well) that delivers that water to various fixtures in the building. In most structures, there are two supply lines – one routed through the hot water heater and the other routed directly from the source for cold water.
What is Dezincification?
Dezincification is the loss of zinc in brass components. This indicates a brass made of poor composition and can be reduced by selecting high quality brass suppliers. More Here
What is a Drain Waste Vent system (DVW)?
The portion of the plumbing system that removes waste water from the building or home.
What is a fitting?
A general term describing metal or plastic parts designed to connect tubes together or to valves or other fittings. A wide variety of ends are available.
What is a brass valve?
A general term describing a fitting that can be used to interrupt the flow of water to the rest of the plumbing system.
What is a PEX to Polybutylene tubing?
Polybutylene is made of plastic resin and was popular for installation between 1980-1995. It is often grey while PEX is generally white. These come in elbows, tees and inline adapters. Because of its large installation base, there is a need for PEX to Polybutylene connections.
What is an elbow?
A fitting with two ends that can change the direction of the water from one tube to another. The change in direction is most commonly 90° but can be 45° or 60° as well.
What is a tee?
A fitting with three ends where two of the ends are in-line and the third is at 90°. The sizes for a tee typically start with the two in-line ends and end with the end that is “on top”. Reducing tees are a useful transition piece when the system needs to transition from one size pipe to another. The measurement of a reducing tee is indicated as left, right and top. So ½ x ½ x ¾ would indicate that the run (or straight part) of the T is ½ and and the 90° top would be ¾.
What is a brass coupling?
A fitting with two, similar ends which are in-line with one another.
What is PEX A, PEX B, PEX C?
These are the three most common types of PEX tubing. Each is selected for use based on the system that is being installed. The primary difference is the flexibility of the piping.
What is PEX aluminum?
Commonly used in creating heated floors, this tubing has an aluminum layer to decrease the oxygen transfer between the contained water system and the atmosphere. This is used only in closed water systems.
What is GHT?
Garden Hose Thread. This brass component is likely the most familiar part because they are used at almost every home. The garden hose thread is unique because it has a female to male thread system. There is also a connection that has a swivel feature so that as you twist the component, you do not twist the attached hose.
What is an adapter?
A fitting with two ends where the two ends are of different mating types. There are straight adapters and elbow adapters. Male sweat, female sweat, male threaded, female sweat, swivel, AAAA.
What is a drop ear?
A fitting with two or three ends where one end is at a 90° angle to the other (two) and is a female threaded end. These are commonly used for shower heads but can be used for many purposes. Technically, they could be called an “adapter elbow” because they connect dissimilar ends which are 90° apart.
What is polybutylene?
Polybutylene is made of plastic resin. It is often grey while PEX is generally white. Because of its large installation base, there is a need for PEX to Polybutylene connections.
Dezincification Frequently Asked Questions
Defining dezincification and the resulting problems it can cause:
Dezincification is the selective loss of zinc from brass resulting in a weak spongy copper layer at the water contact surface. It’s an electrochemical reaction between zinc and certain chemicals found in water and can progress through the part causing leaks and blockage of the water path if it forms a “meringue” deposit. The loss of the wall’s cross section can cause mechanical failure by straight-forward fracture or increased vulnerability to stress corrosion cracking.
Why should we be concerned about dezincification?
Corrosion occurs in every material under the proper conditions, but understanding the fundamentals will allow you to make effective choices regarding correct alloy selection for new applications. Furthermore, this information will help in guiding corrective actions to address field failures and concerns about the changing corrosiveness of water. This is important when dealing with changing standards, legislation or codes which disqualify the use of traditional materials.
What water conditions contribute to the cause of dezincification?
There are two types of dezincification: layer and plug. With layer dezincification, the progression is slow along a broad front. This is primarily caused by water high in oxygen and carbon dioxide, slightly acidic water with a low salt content, soft water with a low pH and low mineral content, or waters high in chloride ions. Plug dezincification progresses faster and is localized. It’s caused by neutral or alkaline waters that are high in salt content with a temperature at or above room temperature.
Is there corrosion that is NOT associated with dezincification?
Absolutely. Stress corrosion cracking is rapid cracking in susceptible copper alloys caused by the combination of high stress and exposure to chemicals which attack the grain structure. In this case, problem chemicals such as ammonia, sulphates and mercury are to blame. Erosion corrosion is another type caused by fluid moving rapidly over a part’s surface resulting in loss of material and can include mechanical wear and abrasion as contributors.
How can we best prevent dezincification and in particular mitigate the effects of chlorine content when using brass?
Zinc has weaker atomic bonds than copper, which is more noble than zinc making it more resistant to corrosion. Also, zinc more readily forms compounds than copper. As a result 15% zinc has been the traditional maximum limit for avoiding dezincification, however, not all brasses are prone to dezincification. It turns out that brasses containing up to 35% zinc are dezincification resistant because of the use of certain alloying elements and/or thermal treatments.
What other factors contribute to dezincification?
Residual elements in the brass such as iron, manganese and cobalt, in addition to the previously mentioned water conditions, can be a factor at some concentration levels. Further, poor manufacturing controls that stabilize a zinc-rich phase and poor control of copper and zinc, resulting in higher than specification zinc contents can contribute to poor dezincification resistance.
What is the best testing method for dezincification resistance?
The universally recognized ISO 6509 test was standardized in 1981 because it was a short and simple test that produced results that correlated with long-term potable water corrosion problems in Sweden, Australia and South Africa. Often, it is the basis for other similar performance testing methods.
Are there any additional methods for improving dezincification resistance?
Thermal treatments are one technique, but have been shown to be not completely effective in arresting dezincification and prone to reduce strength and machinability. Another popular method is the addition of inhibitors, however too high a concentration can cause undesirable property changes, making the alloy brittle. Inhibitors can also cause other damaging forms of corrosion and might combine with certain residual elements like iron and manganese, rendering them ineffective.