Steel Clamps with Rubber vs. Plastic Clamps – When to Use Which
Steel Clamps with Rubber vs. Plastic Clamps – When to Use Which
When dealing with pipe fastening – whether during boiler room reconstruction, water distribution in a family house, or heating installation – you face what seems to be a simple decision: a steel clamp with a rubber insert, or a plastic clamp? In practice, we see that this decision is often underestimated. People choose whatever is available or cheaper, and after a few years, they are troubled by noisy pipes, corroded clamps, or cracks in the pipe at the fastening point. This article will explain in detail what distinguishes both types, where each excels and where it fails – and how experienced plumbers make their decisions in practice.
Basic Construction and Material Properties
Steel Clamp with Rubber Insert
A steel clamp consists of a galvanized or stainless steel body and a rubber insert, which is either directly vulcanized inside the clamp or forms a separate insert. Steel ensures mechanical strength and resistance to deformation under long-term load, while the rubber serves multiple functions at once: it dampens vibrations, prevents direct metal contact between the clamp and the pipe, and to some extent compensates for thermal expansion of the pipe.
The rubber insert is a key element – why its correct selection is important is explained in detail in the article Why a Clamp Can Damage the Pipe – the Role of the Rubber Insert and Its Selection. Briefly: without rubber, a steel clamp would function like a choke or file on the pipe surface during temperature changes. Rubber elegantly solves this problem.
Typical steel clamps with rubber are available in inch sizes corresponding to the outer diameters of pipes – from small ½" up to large 3" and more. From our range, you can choose for example the steel clamp with one hole and rubber ½" for smaller distributions, or for larger diameters the steel clamp with one hole and rubber 2½" for main risers and larger distribution lines.
Plastic Clamp
Plastic clamps are mostly made of polypropylene (PP), polyamide (PA), or high-density polyethylene (HDPE). They are lightweight, inexpensive to produce, and reliably perform their function under normal operating conditions. Many types have an integrated softer inner part or rubber strips that serve a similar damping function as in steel clamps. Plastic clamps are commonly supplied in metric sizes (e.g., for DN15, DN20, DN25 pipes, etc.) or are shaped to suit specific types of piping – MLCP, PEX, Cu, PPR, etc.
Where the Steel Clamp with Rubber Clearly Wins
High-temperature applications and heating
This is probably the most important reason why plumbers almost exclusively choose steel clamps for heating systems. Heating systems operate at temperatures of 60–90 °C (sometimes up to 95 °C in older systems), and standard PP plastic clamps begin to lose rigidity and load-bearing capacity at temperatures above 60–70 °C. Galvanized steel retains its mechanical properties even at temperatures exceeding 200 °C, which you will never encounter in heating – but you have a huge safety margin.
The thermal expansion of steel pipe when heated from 15 °C to 80 °C is approximately 0.65 mm/m of length. The rubber insert in the steel clamp absorbs this movement – the pipe can shift slightly without causing stress in the clamps or in the pipe itself. A plastic clamp without rubber cannot handle this shift elegantly and may crack or deform after repeated thermal cycling.
Heavy diameters and large load-bearing capacity
With large pipe diameters – typically from 1½" upwards – the weight of the filled pipe increases rapidly. A steel pipe DN50 (approximately 2") filled with water and insulation can weigh 5–8 kg per meter. A plastic clamp under such a load gradually deforms – plastic under constant mechanical stress deforms irreversibly, the clamp loosens, and the pipe starts to "move". A steel clamp can withstand this without any problems.
Steel clamps are therefore standard for large diameters. For example, the steel clamp with one hole and rubber 3" is specifically designed for such demanding applications – boiler rooms, risers, technical rooms.
Humid environments and outdoor installations
Galvanized steel combined with rubber is significantly more resistant to mechanical damage, impacts, and vandalism than plastic. In technical rooms, basements, and boiler rooms, where people move with tools, where materials are stacked, and where mechanical stress is a risk, a steel clamp is much more durable. Plastic can break without warning upon impact.
Fire regulations and fire resistance
In some technical rooms and boiler rooms, fire regulations require non-flammable pipe fastening. Steel clamps meet this requirement automatically. Standard plastic clamps are flammable – and although fire resistance of clamps is rarely considered, it may be checked during inspections.
Where plastic clamps make more sense
Cold and potable water distribution
With cold water distribution (typically 5–25 °C), there is no reason to pay a premium for steel. Plastic clamps function reliably throughout the lifetime of the installation – 20 or more years. If you are working on a single-family home or apartment renovation and are running cold water pipes made of plastic (PEX, PPR, MLCP), plastic clamps are a natural and cost-effective choice.
Plastic pipe distribution in general
There is an important argument in favor of plastic clamps that a technically sound installer will never ignore: galvanic corrosion compatibility. When you use a steel clamp on a copper pipe without a proper rubber insert or with a damaged insulation, a galvanic cell is created that corrodes the pipe. With plastic pipes (PEX, PPR, PB), this problem does not arise, but a steel clamp can damage the surface of the plastic pipe with its sharp edges. A plastic clamp that matches the pipe diameter in shape eliminates this issue.
Dry construction, drywall, and concealed piping
If you are running pipes through dry walls, installation shafts, or behind plaster, plastic clamps are easier to install, do not require fastening into the substrate (many types have built-in clips), and their weight is irrelevant. Moreover, in areas without extreme humidity or high temperatures, there is no reason to prefer steel.
Economical projects and large areas
With underfloor heating PEX pipes embedded in a screed, the pipes are fixed using special plastic clips or tape to the mesh – here, only plastic clamps are used. Similarly, in horizontal hot water distribution in apartments, where dozens of meters of pipe need to be fastened, cost is the deciding factor – and plastic clamps are significantly cheaper.
Material combinations – beware of galvanic incompatibility
This is an area where many mistakes are made in practice. When combining different pipe and clamp materials, you must consider electrochemical compatibility. A steel clamp and a steel pipe – fine. A steel clamp and a copper pipe – here a problem arises if the rubber insert is not thick enough or intact. Copper and steel are far apart in the galvanic series, which, in the presence of moisture and an electrolytic environment (e.g., condensation in a basement), accelerates steel corrosion.
Therefore, steel clamps on copper pipes must always have an undamaged rubber insert that prevents direct metal contact. If the rubber is missing or cracked, it is better to use a plastic clamp or a stainless steel clamp. More on this issue can be found in the article Why clamps damage pipes – the role of the rubber insert and its selection.
Similarly: plastic clamps on copper pipes are galvanically corrosion-free, but may be unsuitable for hot water distribution (TÚV above 60 °C), where plastic softens. In such cases, the solution is either a steel clamp with rubber or a special clamp made from a heat-resistant plastic (PA6, PA66 or PVDF).
Size range and availability of dimensions
Steel clamps with rubber are standardized in inch sizes corresponding to the outer diameters of pipes. They cover a very wide range – from the smallest ½" clamp for the smallest distribution (e.g., DN15 steel or copper pipe) through medium sizes like 1" and 2" up to larger dimensions. Inch sizes and their conversion to millimeters can sometimes be confusing – this is covered in detail in the article How to convert clamp inch sizes to millimeters – a practical overview.
Plastic clamps, on the other hand, are manufactured in metric dimensions and are typically optimized for specific pipe types – for example, a clip for PEX 16×2 mm, for MLCP 26×3 mm, etc. This system is advantageous when you know exactly what type of pipe you are working with. The disadvantage arises when you need a clamp for an older pipe of unknown outer diameter – here, a steel clamp with rubber better tolerates slight dimensional deviations due to the elasticity of the insert.
| Property | Steel clamp with rubber | Plastic clamp |
|---|---|---|
| Max. operating temperature | 200 °C+ (steel), 80–100 °C (EPDM rubber) | ~60–70 °C (PP), 90–120 °C (PA) |
| Mechanical strength | High – does not lose rigidity under load | Medium – may "creep" under constant load |
| Vibration damping | Excellent – due to rubber insert | Good – if the plastic clamp has a soft inner layer |
| Corrosion resistance | Good (galvanized), excellent (stainless steel) | Excellent – plastic does not corrode |
| Galvanic neutrality | Depends on rubber insert and compatibility | Excellent – electrically neutral |
| Weight load capacity | Excellent – suitable for large diameters | Limited – suitable up to DN50 |
| Installation | Screw + plug, more secure | Simpler, sometimes without screw |
| Price | Higher | Lower |
| Fire resistance | Non-flammable (steel) | Flammable (PP, PA) |
| Dimensional system | Inch (DN pipe) | Metric or type-specific |
Practical scenarios from installation practice
Boiler room in a family house – complete installation
Imagine a standard boiler room in a family house: a boiler, a TÜV tank, a manifold for circuits and piping. The main pipe between the boiler and the manifold is steel DN32 (1¼"), with heating water temperature of 70–80 °C. Here, a steel clamp with rubber is an absolute necessity – any other choice simply makes no sense. Next to it runs cold water to the tank, which is copper DN20, temperature 10–15 °C – a plastic clamp would be sufficient there, but since both pipes are next to each other on the same base and the installer wants the boiler room to look consistent, most professionals install steel clamps everywhere in the boiler room.
More detailed requirements specifically for boiler rooms can be found in the article Clamps for piping in boiler rooms and technical rooms – specific requirements.
Bathroom renovation – PEX piping
During bathroom renovation, PEX or MLCP pipes with dimensions of 16×2 and 20×2 mm are used as standard today. The TÜV water temperature is 55–60 °C (set by the heating body). Here, plastic clamps are the optimal choice – they are cheaper, easier to install into hidden grooves, and fully sufficient for temperature ranges up to 60 °C and below. If the TÜV water will have a higher temperature (e.g. 65 °C for disinfection), we recommend PA clamps or steel clamps with rubber instead.
Family house, horizontal water distribution in the basement
Cold water, copper pipes 15 mm and 22 mm, a basement with humidity and occasional condensation on the pipes. Here, many installers reach for plastic clamps, but in terms of longevity, steel clamps with rubber are a better choice. Reason: plastic clamps in an environment with condensation and fluctuating temperatures gradually become brittle (UV radiation in the basement is not an issue, but temperature cycling and humidity still do not benefit old plastic). Steel clamps with rubber will last 30+ years without any maintenance.
Industrial hall – compressed air DN50
A compressed air distribution system from galvanized pipes DN50 (2") under the ceiling of the hall. The weight of the full pipe, vibrations from the compressor, and medium temperature of 20–40 °C. The clear choice: steel clamps with rubber. The rubber here dampens the vibrations from the compressor, which would otherwise resonate through the entire piping system and loosen threads and joints. A plastic clamp would not withstand the vibrations and, due to the weight of the pipe, would deform over time.
Vibrations and noise – an underestimated aspect of clamp selection
Noise from piping is a chronic problem in residential construction. Flowing water, hydraulic shocks, vibrations from the pump – all of this is transferred through rigid fastenings into the building structure and from there to neighboring apartments. A steel clamp with a quality rubber insert (EPDM thickness 3–5 mm) can reduce vibration damping by 15–25 dB compared to a rigid metal fastening without rubber.
A plastic clamp has ambivalent properties in this regard – soft plastic itself slightly dampens vibrations, but significantly less effectively than EPDM rubber. If you are dealing with noisy piping or installing in an apartment building where neighbors are sensitive to noise, steel clamps with rubber are clearly the better choice – even for cold water distribution.
Fundamental installation errors, including over-tightening clamps (which eliminates the damping effect of the rubber), are described in the article Common mistakes in clamp installation and how to avoid them.
Spacing of clamps and its influence on type selection
The spacing of clamps depends on the pipe diameter, pipe material, and temperature conditions. For plastic pipes such as PEX and PPR, recommended spacing is smaller than for steel piping – because plastic has higher thermal expansion and lower stiffness. Typically:
- PEX 16 mm: spacing 0.5–0.8 m (horizontal distribution)
- PPR DN25: spacing 0.8–1.0 m
- Steel pipe DN25: spacing 1.5–2.0 m
- Copper pipe 22 mm: spacing 1.5 m
With smaller spacing, the economic advantage of cheaper plastic clamps is greater, as you need more of them. Conversely, with larger diameters of steel pipes and larger spacing, the higher price of a steel clamp is less noticeable – and its mechanical advantages are most pronounced here. More details on correct spacing can be found in the article Installation of pipe clamps – correct spacing and fastening procedure.
Lifespan and maintenance – a long-term perspective
A galvanized steel clamp in a standard interior lasts 20–30 years without corrosion. If the environment is more aggressive (acidic vapors, salty humidity), we recommend stainless steel clamps (A2 or A4). The EPDM rubber insert also has a lifespan of 20–25 years at operating temperatures up to 80 °C; at higher temperatures or under the influence of ozone or UV radiation, it degrades faster. Replacing the worn rubber is possible on some clamp types without dismantling the entire clamp.
Plastic clamps are cheaper to replace, but in practice, they are replaced entirely. Their lifespan in normal conditions is also 15–25 years, but with repeated temperature stress at the edge of their tolerance (e.g., TÜV water at 60–65 °C), they can become brittle and crack sooner. More about maintenance and replacement is covered in the article Maintenance and replacement of pipe clamps – when and how.
Selecting the correct size – a brief summary
Without the correct size, even the highest quality clamp will not work. A steel clamp must fit precisely to the outer diameter of the pipe – not too tight (damaging the rubber and pipe), nor too loose (the pipe moves). Rule of thumb: the inner diameter of the clamp with the inserted rubber should be the same or 0–1 mm larger than the outer diameter of the pipe.
An overview of how to determine the correct size, including conversion from inches to millimeters, can be found in the article What pipe clamp diameter do I need – inch vs. metric pipe dimensions. A comprehensive view of selecting clamps according to material, type, and application is also provided in the introductory article How to choose the right pipe clamp – material, type, and application.
Most frequently asked questions (FAQ)
Can I use a plastic clamp on a heating pipe with a temperature of 70–75 °C?
Ordinary plastic clamps made of PP on heating pipes with a temperature of 70–75 °C are not recommended. PP starts to lose rigidity around 60–70 °C and under constant load it deforms – the clamp loosens and the pipe begins to sag. For heating pipe systems, the correct choice is a steel clamp with a rubber insert, which behaves stably and without deformation at these temperatures. If for some reason you insist on a plastic clamp, choose a type made of polyamide (PA6 or PA66), which tolerates temperatures up to 90–100 °C – but even so, a steel clamp with rubber is more reliable and more commonly available.
Why does a steel clamp with a rubber insert make noise on the pipe, even though it has a rubber insert?
The most common cause is over-tightening the clamp, which compresses the rubber to the minimum and causes it to lose its damping effect. Another possibility: the rubber is cracked, old or completely missing (sometimes clamps are sold without rubber). A third cause may be incorrect dimensions – the clamp is too large, the pipe moves and clatters inside it. Tighten the clamp correctly so that the rubber is slightly compressed (approximately 30 % compression), not fully compressed.
Is there a difference between a galvanized steel clamp and one made of stainless steel – where to use which?
A galvanized steel clamp is suitable for standard indoor use – boiler rooms, basements, installation shafts in dry or slightly humid environments. Stainless steel (INOX) is necessary in environments with aggressive vapors, chemicals, in industry with acidic or alkaline atmospheres, in food processing facilities or outdoors. For a standard family home, a galvanized clamp is fully sufficient.
Can I use a steel clamp with rubber on plastic pipes (PEX, PPR)?
Yes, a steel clamp with a rubber insert can be used on plastic pipes – the rubber protects the softer surface of the plastic pipe from direct contact with metal. It is, however, important to observe the correct dimensions (the outer diameter of the pipe must exactly match the inner diameter of the clamp with rubber) and not to over-tighten the clamp, as the rubber could cause shape deformation of the soft pipe. For PEX and PPR pipes, in many cases specially shaped plastic clamps are more convenient, but a steel clamp with rubber is also a technically correct solution.
How many kg can a steel clamp and a plastic clamp hold?
The load capacity of a clamp depends on the diameter, construction and especially on anchoring into the substrate (screw, anchor, base structure). A steel clamp anchored into concrete with an M8 screw can handle several dozen kilograms (20–50 kg with one anchoring point). A plastic clamp with the same anchoring can handle 5–15 kg, but at the upper limit of this range it will deform over time. For pipes DN50 and larger (where one section of pipe with water weighs 8–15 kg), steel clamps are therefore a safer choice.
Can a plastic clamp be repaired or adjusted to a slightly different diameter?
No, plastic clamps are fixed in shape and not designed for a range of diameters – each type is intended for a specific pipe outer diameter. A steel clamp with rubber has a slightly larger tolerance (+/- 1–2 mm) due to the elasticity of the rubber, but it also has a fixed opening. If you need to mount a pipe of a non-standard diameter, it is better to measure the outer diameter with a caliper and choose the corresponding clamp size – the procedure is described in the article Common questions about pipe clamps.
Conclusion: Simple rules for making the right decision
Choosing between a steel clamp with rubber and a plastic clamp is not complicated if you know a few basic rules. A medium temperature above 60 °C, large pipe diameter (from DN40 upwards), technical and boiler room environments, vibrations and noise – these are signs for a steel clamp with a rubber insert. Cold water, small-diameter plastic pipes, dry indoor installations at normal temperatures – these are ideal conditions for a plastic clamp.
In practice, many installers choose steel clamps with rubber in boiler rooms and for heating, and plastic clamps for cold and hot water distribution (up to 60 °C) in the living area or dry installation channels. This division is rational and functional. Where you are unsure, choose a steel clamp with rubber – it has a higher safety margin, longer service life and better acoustic properties. For a small price premium, it will reward you with many years of trouble-free operation.
The complete range of pipe clamps, including steel clamps with rubber in all standard sizes, can be found on the pipe clamp page.
Do you have a question about this topic?
Not sure how to decide or dealing with a specific situation in your home? Write to us – we are happy to help.