Plumbing Industry Terminology

When it comes to identifying stems, valves, and cartridges, it is helpful at times to know the Terminology of those parts. When you take a look at the historical usage of terminology in the plumbing industry, different words were calling the same parts different things - it can get confusing quickly. 

So, let's alleviate some of that confusion by illustrating common plumbing industry terminology:

You can see in this old American Standard parts breakdown where terms like “seat washer screw, seat washer, stuffing box, and stuffing nut” were used. 

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When you look at this Eljer parts breakdown, instead of using stuffing nut, they used the term “packing nut”. Instead of stuffing box, the manufacturer is using the term “bushing” - Not the more modern terms: bonnet or gland. Seat washer is still used and the screw is no longer called a "seat washer screw". Nowadays, we also hear the terms bibb washer and bibb screw. 

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Terminology at BWSC

So how do we use these terminologies at Barry E. Walter Senior Company? Let's start with where the handle attaches. We call the end of the stem (where the handle will go) the spline or broach.

Next, let's look at the part of the stem unit that seals against the valve body. We differentiate these by calling them glands or bonnets, rather than stuffing boxes or bushings.

So, what is the difference between a gland and bonnet for us? 

• When the stem is operating in the part that is sealing against the valve body, we will typically call it a gland. 
• When the stem is operating or moving in something besides the parts that seal inside the valve body (typically the valve body or a barrel or sleeve), we will call that part that screws in and seals against the valve body  the  bonnet.
• You can see an example of both a gland and bonnet in this picture. You can also see that both threads are 29˚ ACME Threads:

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Here are some other key identifiers that we like to use for identification purposes:

A single-lead thread will have one start or beginning. Since it's just one beginning, it will turn slower than a double-lead thread that has two beginnings.

Typically, when lever handles were used, the manufacturer wants the stems to turn faster, so double-lead or even triple-lead threads are incorporated.

Looking at the matching Crane stems below, Crane used the single-lead threads when they provided round, cross, or knob-handles, and they used the double-lead threads when they provided lever handles. 

​You can also see on these stems that the threads have a different angle or pitch - these are 60˚ Stub Threads.

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On these two stems, you can see one is a 60 Degree Stubbed Thread, and the bottom one, while similar to the 29° ACME Threads, is actually modified square and does not have much of an angle on the pitch. 

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Ceramics, Non-Rising Stems, Thermostatics, and Newer Cartridges

• When we get into some of the newer style cartridges such as ceramics, instead of the cartridge being a stem moving up and down compressing against the seat, you now have parts of ceramic cartridges that use a stem and a housing.   ​​

• In a typical housing like this, there will be internal stops that work with the stem to designate it as a quarter turn or half turn cartridge. 
• The tolerances in a ceramic disk cartridge are much tighter than a traditional compression stem - this is to provide the proper dimensions for the two disks to seal and not let water molecules through.​

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When discussing non-rising stems, we're talking about cartridges where the plunger moves up and down and the stem does not. 

These were typically used in decorative fixtures.





​As you can see in this picture, a typical non-rising stem will have plungers, stems, and a housing or bonnet. ​​​​

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​And in even more modern cartridges - thermostatics - there is an entirely separate set of components that are much more complicated than other cartridges.  These cartridges control temperature regardless of water pressure or volume.

Although thermostatic cartridges can occasionally include volume control, they typically only control temperature.   

Thermostatic cartridges most commonly use a wax element as the temperature control motor. The motor is attached to a shuttle that regulates the volume of hot and cold water.

Additionally, the use of springs and plungers allow the turning of the stem to control the temperature by adjusting the shuttle.

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​We hope this quick article will be a helpful resource for you and your team. Our goal here is to give you more information to help with the identifications of a cartridge.

If you still get stumped, you can always email or text a free parts identification request to:

• [email protected]
• 970-867-3858​

To learn more about our Parts ID process, check out our help desk video and download our free Stem Identification Guide by clicking the button below: 

Help Desk