Pressfittings: “M” or “V” profile? - EUROTUBI EUROPA SRL

When talking with plumbing installers, one of the most frequent topics is their preference for either the "M" or "V" pressfitting profile. The choice of one or the other is often a matter of "habit". Professionals who are used to a certain profile rarely choose to change to the other.

The reason behind this "habit" is quick to understand: "M" and "V" profiles are both valid, so it is rare that an installer chooses to change profile because they think that one or the other is more "technically" efficient.

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Both profiles must comply with the same regulations and have the same certifications There is no difference in functionality. Fluids pass through the fittings and pipes in the same manner. Even the maximum operating temperatures and pressures are the same.

The same pressing equipment can be used with both profiles (same force delivered in Newtons) but the jaws and chains are different.

On further evidence, during some of our experimental tests on competitors fittings, we found that the use of jaws declared valid for both the profiles, have led to cases of pressings with unwanted losses.



The presence of the "stalk" on the "V" profile, located after the pressing chamber, definitely makes inserting the pipe an apparently "cleaner" operation compared to inserting it in the "M" profile.
On the other hand, the stalk makes checking the proper positioning of the o-ring more difficult.

Installers' opinions

In large construction sites, various installers frequently work together, each with their own preferences in terms of which profile to use.
Often the choice between the "M" and "V" profiles is a matter of habit. In fact, it is very rare to find a professional who recommends one profile or the other for "presumed" technical factors.

Market presence

Often, it is the manufacturing companies who drive the presumed performance differences between the two profiles. In most cases, it is not the installer who prefers one profile or the other but the presence of one profile or the other on the local pressfitting market, leading the installer to choose the profile that is easier to find in a certain reason.

Let's summarize

Pressfittings: "M" or "V" profile? We have seen that the performance is identical, as are the certifications, so the choice is up to your installers.

Press Fittings were first developed in Europe during the s. From that point on, the use of Press Fittings has grown dramatically, and expanded beyond its original Copper/Plumbing applications. Today you can find Press Fittings in multiple industries/applications that require pipes, and tubes, to carry media.

With multiple Press Fitting and Press Tool Manufacturers producing quality products today, it can be a bit overwhelming when trying to understand what the differences are; and what all of this information means. Different materials, different Press Profiles, and different Press Tools can lead to a lot of confusion.

What are Pressing Tools?

The difference in material characteristics of the Copper, Stainless Steel, and Carbon Steel Press Fittings across all major manufacturers is negligible. Meaning the Carbon Steel material used by Manufacturer A for their Press Fitting is not very dissimilar to the Carbon Steel material used by Manufacturer B for their Press Fitting. Press Tooling Manufacturers know this and have designed their Tools with this knowledge. Press Tools are based on a certain “Pressing Force” to overcome the properties of the Press Fitting Materials, so their Tools can correctly Press the Fittings. This means that if a Press Tool can be used to install a Carbon Steel Press Fitting from Manufacturer A, that same Tool can be used to install the same Carbon Steel Fitting (Product Type and Size) from Manufacturer B.

Press Tools come in a variety of styles, as each one has a different Pressing Force it can apply. This Force, along with the Stroke Length of the internal Piston, directly determines what type of Press Fittings it can be used with. 

Tool Pressing Force

Copper Force Stroke Size Range 15kN 32mm 0.5" - 0.75" 24kN 32mm 0.5" -1.25" 32kN 40mm 0.5" - 4" Carbon Force Stroke Size Range 24kN 32mm 0.5" - 1" 32kN 40mm 0.5" - 2" 32kN 80mm 0.5" - 4" Stainless Steel Force Stroke Size Range 24kN 32mm 0.5" - 1.25" 32kN 40mm 0.5" - 1.25" 32kN 80mm 0.5" - 4" 120kN 60mm up to 6"

Note: The Tables above are a general representation of multiple Press Tool Manufacturers’ capabilities. With the addition of various Boosters, and other attachments, Size Ranges may differ from these figures.

Three Main Types of Press Profiles

While Press Tools may be interchangeable, Press Jaws are not. To start, Copper Tube Size (CTS) and Iron Pipe Size (IPS) have different diameters for the same Nominal Dimension. Looking at a piece of 1” CTS Copper Tube, it will have an outside diameter of 1.125”, while a 1” IPS Stainless Steel Pipe has an outside diameter of 1.315”. In addition to this, there are 3 main types of Press Profiles which can be used on either CTS or IPS Tube/Pipe:

V-Profile

• Utilizes Metal-to-Metal Contact to connect the Fitting to the Tube/Pipe
• Has a part of the Fitting beyond the Sealing Element

M-Profile

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• Utilizes Metal-to-Metal Contact to connect the Fitting to the Tube/Pipe
• The Fitting ends at the Sealing Element

Grab-Ring Profile

• A Grab-Ring inside the Fitting Housing bites into the Tube/Pipe and creates contact when the Fitting is “Pressed”
• Fitting has a more “flat” shape
• Fitting Deformation after being “Pressed” is not as dramatic as V or M Profiles

Determining factors as to why a certain Profile is used over another are generally based on the malleability of the Tube/Pipe material, and the Size of the Tube/Pipe. 

Copper

Smaller diameter Copper Press Fittings (0.5”-2”) utilize the Tube/Fitting deformation to create Metal-to-Metal contact, and do not need the added strength a Grab-Ring provides. However, larger diameter Copper Press Fittings (2.5”-4”) predominantly utilize a Grab-Ring to provide added strength.

Stainless

Schedule 5 & Schedule 10 Stainless Steel Pipe is malleable enough where the Stainless Press Fittings can be secured with either Metal-to-Metal contact, or through the use of a Grab-Ring; and as a result, utilizes all 3 of the Press Profiles.

• V-Profile is found on both CTS and IPS Stainless Steel Tube/Pipe sizes 0.5”-2”
• M-Profile is found on IPS Stainless Steel Pipe sizes 0.5”-2” in North America (up to 6” in Europe and other parts of the world)
• Grab-Ring Profile is found on CTS Stainless Steel Tube in sizes 2.5”-4”, and IPS Stainless Steel Pipe 0.5”-4”

Sch 40 Stainless Steel Pipe is not as malleable, and therefore requires the use of a Grab-Ring Profile.

Carbon

Carbon Steel Pipe does not deform as much as Copper Tube, or Stainless Steel Pipe. Therefore, Carbon Press Fittings are secured with a Grab-Ring on IPS Pipe sizes 0.5”-4” to ensure a secure connection.

Even though Press has been around for over 50 years, there still exists a lot of questions surrounding it. Thankfully, many Manufacturers have comprehensive information listed on their websites to help answer any questions that may come up; but remembering the basics covered in this overview will help answer many of those that you may have. 

Author:  Marcus Estrella, Director of Product Line Management, Merit Brass Company

3/28/ 11:54:41 AM

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