[00:00:00] Speaker A: Hello and welcome to the Consulting Specifying Engineer podcast. I'm your host Anna Steingruber and today we're talking to Erin Kilberg, the Commercial Sales Manager at nipco, about material selection for plumbing and mechanical systems. In today's episode, we'll be talking mainly about ball valves and butterfly valves for plumbing systems and the differences between bronze and brass as the main materials here.
And now I'd like to introduce our guest. Erin Kilberg is a sales leader in the wholesale and retail sector which with over 23 years of experience, he's been with NIBCO for the last seven years where he is currently the Commercial Sales Manager. Thank you so much for joining us today.
[00:00:35] Speaker B: Aaron hello Anna. Thanks for having me.
[00:00:38] Speaker A: And so, to start off, can you give me a big picture overview of the importance of material selection in plumbing and mechanical systems?
[00:00:47] Speaker B: Sure. So codes and standards provide the foundation for material use in plumbing and mechanical applications and it is imperative to follow these guidelines. But general industry guidance does not always provide information that explains important differences between materials and a finished good and ultimately how a product is put to optimal use in a system.
NIPCO strongly recommends engineers look beyond the basic standard and code material guidance when making their selection of the appropriate alloy for specific plumbing mechanical applications, considering also the end use application to direct their product choice. This extra scrutiny is critical for specifying engineers who must match valve construction materials with the expected conditions of an intended service in order to achieve optimal valve performance and lifespan.
[00:01:40] Speaker A: Thank you. And today we'll be talking specifically about ball valves and butterfly valves. Can you give me a general review of each of these specific specifically?
[00:01:49] Speaker B: Sure. A ball valve is a quarter turn valve used to control fluid or gases in a piping system.
Quarter turn means you turn the valve handle 90 degrees to go from fully open to fully closed. It operates by using a handle to rotate a ball within the valve.
The ball has a port center. When the port is aligned with flow it opens and when turned perpendicular the valve is closed. Ball valves are popular because they can be used in a wide array of applications due to their ease of installation, ease of operation and ability to provide a bubble tight seal.
In most cases, a ball valve is bi directional for flow and omnidirectional for installation.
There is no up or down, right or left to a ball valve, so it is very conveniently installed and located in a system. Generally, the compact profile makes them much easier to fit into a system than a gate or a globe. For example, their quarter turn operation makes them faster to operate than a multi turn valve they are not as useful for throttling applications but are a mainstay for isolation service.
They are also easily automated compared to gate or globe valves.
A butterfly valve is another type of quarter turn valve used in a piping system.
The defining feature is a disc mounted on a rotating shaft which turns to open or close flow.
When the disc is parallel to flow the valve is open, when it is perpendicular it is closed.
Butterfly valves are popular for many reasons including a compact design graph, quick operation and affordability in most cases. Like a ball valve. A ball valve A butterfly valve is bi directional for flow and omnidirectional for installation. There is no up or down, right or left for a butterfly valve, so again it's conveniently installed or located in the system.
The disc profile is slim enough that using a butterfly valve for throtting applications makes them a suitable substitute for a glow valve while generating less of a pressure drop.
They are also easily automated compared to multi turn valves like gates or globes.
[00:04:12] Speaker A: So moving into ball valves in particular, there are two main materials which are brass and bronze. What are the major differences between the two of those?
[00:04:22] Speaker B: So Anna Traditionally our industry has accepted the norm for alloy identification that separates copper alloys into three distinct categories copper, bronze and brass.
The MSS ball valve standard SP110 covers many types of materials, but when it comes to copper alloy it is not specific.
Bronze, brass and lead Free brasses and bronzes are the primary alloys used in commercial plumbing and mechanical systems today. It is common to find a boundary set between bronze and brass at 15 to 20% zinc or even find the amount of zinc totally ignored, resulting in the terms bronze and brass being used interchangeably without meaning.
It should be noted that over time these groups have become less informational and instructive as to the appropriate use of such alloys.
Alloy performance is now recognized as the key factor in alloy selection, but I will provide some general definitions before I discuss the differences. I should define desincification, which is the selective corrosive loss of zinc from a copper alloy, a primary concern when a selection is made from copper zinc alloys.
De zincification can make valves brittle and porous, resulting in valves prone to fractures, leaks and failures.
For the guidance of this presentation or discussion, zinc content greater than 15% is highlighted as the point of increasing the risk of desincification.
One way to prevent desincification is to add inhibitors to the alloy that can make a ball valve desincification resistant.
It also needs to be stated that zinc content alone is not the determining factor for this type of selected corrosion, there are many factors that have to be in play in order for desyncification to occur.
So now when it comes to defining bronze and brass. For bronze, the traditional definition was a copper alloy with tin as a primary alloying element.
Today it's currently defined loosely as a copper alloy with less than 15% zinc or a high performance capability.
Bronze valves are predominantly used in or made from casting alloys, and the casting process produces a heavier product with thicker walls than a forged process.
Brass traditionally has been defined as a copper alloy with zinc as a primary alloying element.
Today it's currently defined as a copper alloy containing greater than 15 prune percent zinc and it's predominantly a forging alloy.
[00:07:18] Speaker A: Can you give me some pros and cons for both of these materials?
[00:07:24] Speaker B: Sure.
The pros of bronze are it has high corrosion resistance, durability, and it's often domestically made.
The cons for bronze are it's harder to machine and it's more expensive than brass.
For brass, the pros are good machinability.
Most people find it aesthetically pleasing in appearance and is generally a fraction of the cost of bronze.
The cons could be or would be corrosion resistance, it's often an imported product, and there are more limited product options when you're looking at brass options.
[00:08:06] Speaker A: So when engineers are considering which one to use, are there specific applications that they should look at or any additional considerations there?
[00:08:15] Speaker B: Yes, there are definitely considerations. So compatibility between a selected copper alloy component and system elements should include, but not be limited to the conveyed media, media treatment system, operating parameters, installation, practice and or other components within the system.
Every project and system should be evaluated in these terms and appropriate selections should be made after careful consideration.
However, for the purposes of this discussion, Anna, I would say high end service, mission critical applications and commercial projects generally would be well served by the use of cast bronze, buried surveys, media with a high level of total dissolved solids, water with low ph, high chloride, high chloride concentrations, or the presence of sulfates or heavily softened water are a few examples of environments prone to dezincification and could indicate a preference for bronze. When it comes to brass. Residential and light commercial projects are the areas where I would consider brass to be acceptable in speaking in very general terms.
[00:09:29] Speaker A: Great. And so now moving into butterfly valves. Can you give me an overview of the two main material and explain them each in a bit of detail, please?
[00:09:38] Speaker B: Sure. So in commercial plumbing, cast and ductile iron are the main materials. So it should be noted that there are two MSS standards that are used for commercial butterfly valves MSS SP 67 and 6868 refers to high pressure butterfly valves, but for the purpose of this discussion we'll discuss valves for the 67 standard and for MSS SP67, the most common materials are going to be cast iron and ductile iron.
Cast iron, also known as gray iron, has been around for millennia is an alloy made from 96 to 98% iron, 2 to 4% carbon and small amounts of silicone.
Ductile iron was developed in the 1940s and has a more modern alloy.
It is similar in composition to cast iron. The main difference is in the alloying process and with the addition of magnesium this causes the graphite to form modules which makes it more impact resistant and pliable.
[00:10:42] Speaker A: And so what are some specific pros and cons to each of these?
[00:10:47] Speaker B: So for cast iron the pros would be it's a very strong metal, it can withstand vibration well and is low cost relative to ductile and from a manufacturing standpoint, relatively easy to produce.
The cons would be it's extremely rigid and virtually any bending will cause it to crack or break.
For ductile iron, the pros would be good ductility, so it's more pliable and less likely to break or crack compared to cast iron. Ductile iron has superior corrosion resistance, tensile strength and yield strength. It also has a higher temperature limitation than cast iron, and ductile iron is capable of substituting for cast steel under certain parameters.
The main con would be it's more expensive than cast iron.
[00:11:39] Speaker A: And so what are some specific considerations for these materials? Are there any specific applications or reasons why an engineer might choose one over the other?
[00:11:48] Speaker B: If your application requires a tougher material is a mission critical application.
Ductile iron would be the superior material.
However, cast is more than adequate for many applications.
Consider that the valve is typically installed between two pipe flanges. If installed properly with the bolts tightened in their proper sequence and torqued, there is often little opportunity for the lug to crack or fail.
[00:12:17] Speaker A: Do you have any other final tips for choosing materials in plumbing or mechanical systems or something you haven't mentioned so far?
[00:12:24] Speaker B: Anna Again, thank you for this opportunity. I just want to repeat again that NIPCO strongly recommends engineers look beyond the basic standard ENCODE material guidance and also consider the end use applications to direct their product choice.
This extra scrutiny is critical for commercial plumbing and mechanical specifications and work.
And I would say if you have any questions to anyone listening to this podcast, I would ask them not to hesitate to reach out to me or their local NIP CO rep for answers or responses.
Can I do that one again?
[00:12:58] Speaker A: Thank you. Yeah, you can do that one again.
[00:13:00] Speaker B: Sorry.
Anna, thanks again for this. Okay, one, go ahead.
[00:13:06] Speaker A: Whenever you're ready, I'll wait.
[00:13:11] Speaker B: Anna, thanks again for this opportunity.
I just want to repeat again, NIPCO strongly recommends engineers look beyond the basic standard and code material guidance and consider end of use applications to direct their product choices. This extra scrutiny is critical for both plumbing and mechanical work, and I would like to add that if you have any questions to anyone who's listening to this podcast, I'd recommend they reach out to me or their local NIPCO rep for help.
[00:13:42] Speaker A: Great. Well, thank you again for joining us today, Erin. This has been a really wonderful overview and I really appreciate you taking the time to talk to us.
Thank you Anna, and to our audience. If you want more information on plumbing systems or choosing materials for these, please visit Consulting specifying
[email protected]. thank you again for joining us today and we'll talk to you next time.
