Common mistakes when securing piping and how to avoid them
Common mistakes in pipe fastening and how to avoid them
Proper pipe fastening is one of those things that seems like nothing can go wrong with – you buy a clip, screw it in, and that's it. Practice, however, tells a completely different story. After years of working with customers and plumbers, we know that mistakes in pipe fastening are not only common but also subtle: they do not appear immediately, but after months or years, when repairs become significantly more expensive. A pipe that is not firmly and properly secured will expand, vibrate, make noise, and in the worst case, bends the joints or cracks the fittings. This article is therefore a practical guide – from the most typical mistakes on construction sites to specific technical details that determine whether the installation will last for decades or the wall will have to be opened again in three years.
Why the method of fastening matters more than it seems
Heating system piping is not a static object. It operates in a cyclic temperature regime: in the morning it heats up to 60–80 °C, cools down to room temperature during the night. This cycle is repeated hundreds to thousands of times during the system's lifetime. Polymer piping (PB, PE-RT, PEX) has a thermal expansion coefficient several times higher than steel or copper – for PB piping, a value of around 0.13 mm/(m·K) is commonly given. In practice, this means that a 5-meter section of piping when heated from 20 °C to 70 °C will extend by more than 30 mm. If this extension has nowhere to go, or if the piping is fastened in such a way that it cannot slide, stresses arise in the system that are transferred to the joints, fittings, and anchors. Such systems are destined for problems.
At the same time, the opposite is also true: too loose fastening, when the pipe hangs and sways, causes vibrations and noise – that typical "knocking" in the wall that tenants of apartment buildings often complain about. Proper fastening must therefore address two conflicting requirements: firmly fixing the position of the pipe in space while also allowing for controlled expansion.
Most common mistake No. 1: Incorrect spacing of fastening points
This is statistically the most widespread mistake we see in customer projects – the pipe is fastened either too sparsely or, on the contrary, completely randomly, depending on where the hand happened to be. Manufacturers and standards (including EN 806 and recommendations from manufacturers such as Hepworth) define maximum spacing for each pipe diameter and material. These values are not approximate – they are derived from the mechanical behavior of the pipe under a given load, temperature, and pressure.
For orientation: for horizontal sections of PB or PE-RT pipe with a diameter of 15–16 mm, a maximum spacing of fastening points of 0.5 m is recommended at temperatures above 50 °C, while for cold water or low-temperature heating you can go to 0.7–0.8 m. For vertical sections, you can slightly increase the spacing. 15 mm copper pipe usually allows horizontal spacing up to 1.0–1.2 m, as it is stiffer and bends less. If you do not follow these values, the pipe will visibly sag over time, which not only affects aesthetics but also the hydraulic profile of the installation – places where air or sediment can accumulate arise.
Practical example from practice: In one customer project in a new family house, the plumber fastened the pipe "by eye," with a spacing of about 1.5 m. The system worked problem-free for the first year, during the winter season. When we came for the next service, the pipe in the technical room was hanging in parabolas, in two places it was touching adjacent runs, and a slow leak appeared at one joint. The entire technical room had to be partially renovated.
Most common mistake No. 2: Confusing sliding and fixed points
Every pipe run must have a combination of fixed points (fixed anchors, where pipe movement is completely stopped) and sliding points (where the pipe can freely slide along the axis, but is guided in the perpendicular direction). Confusing these two types of fastening is perhaps the most serious mistake, as it directly causes mechanical damage to the system.
A fixed point stops movement, a sliding point controls it. If you fasten the entire pipe as fixed points, expansion finds the weakest spot – which are usually fittings or direction changes. On the other hand, if there is no fixed point, the pipe moves chaotically, transferring the load to places where it is not desired (for example, to elbows connected to a manifold or boiler).
Specifically: pipe fastening strip for 16 mm pipe is typically designed as a sliding fastening – the pipe is held in it, but can slide along the axis. If you want to make a certain point a fixed point, you must supplement it with mechanical securing (for example, by inserting a rubber washer or a stopper that prevents sliding). This detail is often overlooked by plumbers.
Most Common Mistake No. 3: Using the Wrong Size Clamp or Bracket
Seemingly trivial detail that has, however, crucial consequences. Practice shows that installers sometimes take "what is at hand" – a 15 mm clamp is used on a 16 mm pipe, or vice versa, a 16–18 mm bracket is mounted on a 15 mm pipe, where the pipe moves freely to the sides. Both scenarios are bad.
An oversized clamp or bracket does not hold the pipe and allows lateral (side) movement. These are the vibrations and clatter we wrote about. Moreover, on vertical sections, the pipe can simply slip out of an overly large bracket and fall down – in the worst case, all the way to the nearest joint. On the other hand, a too tight clamp permanently deforms the pipe at the point of attachment, creates local stress, and in the case of polymer pipes, it can cause material brittleness at the cut site in the long term.
For Hepworth systems, there are clear product lines: 16 mm pipe bracket is intended exclusively for pipes with an outer diameter of 16 mm, while 16–18 mm pipe bracket is designed for a range of diameters from 16 to 18 mm and allows for a smaller dimensional tolerance. Always base your choice on the outer diameter of the pipe, not on the internal diameter (DN)! This is important especially for Hepworth pipe, where the outer diameter differs from the dimension marking.
You can find a helpful guide for selection in the article What size of clamp or bracket do I need for my pipe and for a broader context of comparing types of pipe support in the article Clamps vs. brackets for pipe support – when to use which.
Most Common Mistake No. 4: Missing or Incorrect Anti-Noise Protection
Heating and plumbing pipes transfer sound very efficiently. Metal supports without insulation directly attached to the pipe act as sound bridges – they transfer clatter and vibrations from the circulation pump, hydraulic shocks, and expansion movements directly into the building structure, where the noise is amplified even more. This problem is fully expressed in panel buildings or with frame construction.
The solution is simple and inexpensive: rubber or foam inserts between the support and the pipe, or between the support and the wall. Many modern brackets and clamps have them integrated; for older types, they need to be added. If the bracket does not have a rubber insert, it is sufficient to cover it with a soft foam tape, self-adhesive rubber strip, or special anti-vibration washers under the screws.
We dealt with a case in an apartment building, where the upper floor resident heard distinct knocking from the heating system at night. The entire piping was mounted with metal clamps without any sound insulation, directly into the concrete wall. After replacing the clamps with types featuring rubber inserts and placing rubber washers under the anchoring screws, the noise was almost completely eliminated – without any other changes to the system.
Most Common Mistake No. 5: Incorrect Anchoring Screws and Base Material
A support is only as strong as its anchoring into the wall or ceiling. A very common mistake is the use of too small or unsuitable anchors, insufficient anchoring depth, or drilling into hollow brick where it fits, rather than where the material is sufficiently solid. The result is a support that "pulls out" over time or moves together with the pipe – which defeats the whole purpose.
For standard home piping with clamps or brackets, it is standard to use an M6 or M8 screw with a suitable plastic anchor (diameter 8–10 mm, length 40–50 mm) into solid concrete or brick. Screws should be made of galvanized steel or stainless steel, especially in environments with higher humidity (boiler rooms, technical rooms). KOMBI M8 screw is specifically designed for the installation of Hepworth accessories – its combined thread allows use with various types of mounting elements and anchors without the need to buy multiple types of connecting materials.
Special attention should be paid to anchoring into drywall or light partitions. Here, a regular anchor is not sufficient – special anchoring (molly anchors, anchoring strips, or passage through drywall with anchoring into the profile) must be used. Otherwise, the support may be pulled out at the first major expansion force, and the pipe may fall.
Most Common Mistake No. 6: Missing Expansion Loop or Compensator
Even if the support itself is in order, the mistake can be in the overall design of the piping. On long straight sections (usually over 5 m), it is essential to include an expansion loop or "L", "Z", or "U" compensator that absorbs thermal expansion. If this is missing, even the best system of sliding and fixed points will not be enough – the stresses are too great and the system deforms.
We often encounter cases where the installer has laid the entire piping of a technical room in a straight line, properly mounted it with brackets, but forgot the expansion bends. After the first heating season, the entire bracket was pulled out of the wall due to the force exerted by the expanded pipe. The rule is simple: every section longer than 4–6 m (depending on the material and temperature) should have either a natural expansion loop (e.g., a corner joint) or an artificially created compensator. For more information on fixed loops, see the article How to correctly install a fixed loop for 15–18 mm pipe.
Most Common Mistake No. 7: Problems with Copper Pipe Mounting – Galvanic Corrosion
Copper pipe has specific requirements even in terms of mounting. Unlike polymer pipes, copper is stiffer and less prone to bending, but it is sensitive to direct contact with certain metals (galvanic corrosion) and must not be mechanically damaged during mounting. A sharp edge of a clamp on a soft copper pipe can, after years, create a cut from which a crack can initiate.
Special cases are compression fittings, which are used to connect copper pipes to fittings. The errors here are of two types: first, the use of an incorrect compression fitting for a given material and pipe size; second, incorrect tightening (too loose = leakage, too tight = deformation of the olive and pipe wall). Compression fitting 15×1 EK for copper pipe is designed precisely for 15 mm pipe with a wall thickness of 1 mm – and this specification is not accidental. Using a compression fitting for a different size or material (e.g., on PB pipe without an adapter) usually leads to a leak immediately or after a short time.
For combined installations where copper pipe meets polymer (e.g., when connecting a PB distribution line to a copper supply line from a boiler), specialized adapter solutions exist. Compression fitting 15×1 EK for copper or PB pipe is specifically designed for such transitional situations – it allows copper and PB to be joined in one fitting without the risk of leakage or degradation of the joint. More detailed information on the selection and installation of compression fittings can be found in the article Compression fittings for copper pipe – selection and installation.
Most common mistake No. 8: Ignoring adjacent pipes and crossings
Heating, cold water, drainage, and ventilation pipes must maintain mutual clearances when running parallel or crossing. If a heating pipe expands and hits an adjacent pipe, noise, mechanical damage to the surface layer, and in extreme cases, deformation can occur. The same problem arises when hot and cold pipes touch without thermal insulation – condensation, heat loss, and a drop in the temperature of hot water.
The minimum clearance between parallel pipes should be at least 20–30 mm for non-insulated runs; for insulated pipes, the issue is resolved directly by insulation. Crossings are solved by bending one of the pipes into an arc with sufficient clearance. Fixing at crossings must be handled carefully – there must be an independent clamp on each side of the crossing, not one shared between both pipes.
Most common mistake No. 9: Clamping directly after fittings or elbows
The place where a clamp should not be located is directly on a fitting, elbow, or T-joint. These components must remain free to avoid transferring bending forces from the pipe onto them. A clamp should always be placed on a straight section of pipe, at least 50–100 mm away from the fitting. If you place it directly after an elbow, the rigid anchoring of the fitting together with the expansion movement of the straight section creates a bending moment directly at the joint – which is the most critical point in the entire system.
This rule is especially overlooked in the "last" clamp before connecting to a fitting or manifold. The installer wants to bring the pipe as close as possible to the device and thus places the clamp just before the elbow. The result is that the fitting is subjected to a load it is not designed to carry. The correct approach is to leave the last 100–150 mm of pipe free (but properly guided in the correct direction) and to end the anchoring on a straight section before the bend.
Most common mistake No. 10: Not maintaining vertical and horizontal pipe alignment
This may seem like an aesthetic issue, but it actually has technical consequences. Horizontal pipes that are not truly horizontal accumulate air in local peaks. Especially in heating systems, this means air collects at the "humps" of the pipe and hinders circulation. Defoaming then becomes an annual ritual, even though the cause is an uneven pipe layout.
Vertical pipes that are not truly vertical must be clamped more frequently, as an angled layout creates a resultant force that pushes the pipe away from the wall. The clamp must not only support the weight of the pipe but also compensate for the lateral component. Therefore, professionals always recommend using a spirit level – not just "by eye."
Mistakes specific to Hepworth pipe – what to watch out for
The Hepworth system is designed as a closed system of compatible components. This means that each element – from the pipe, through the fittings, to the installation tools – is designed to work together. When someone deviates from this logic and combines Hepworth pipe with clamps from another manufacturer, the result is not always catastrophic, but it can be problematic.
Specifically: Hepworth pipe has precisely defined outer diameters that slightly differ from the nominal dimensions of other systems. A clamp for "15 mm" from another product line may have a slightly different inner profile, a different type of lock, or a different material composition. In extreme cases, a soft clamp from another manufacturer may permanently scratch the surface of the Hepworth pipe – which is a problem especially with pipes with an oxygen barrier (EVOH layer), where surface damage reduces system protection over time.
A good rule is to stick to the entire product range – installation tools from the same category on atria.sk are designed to match Hepworth pipes. More information on selecting the correct installation tools can be found in the article How to choose the correct installation tools for Hepworth pipe, and if you want to avoid diameter mix-ups, the article What size clamp or bracket do I need for my pipe will also help.
Difference between manual and machine installation – where mistakes differ
With manual installation (common in custom work), typical mistakes are different from those in machine installation (industrial halls, large apartment buildings). In manual installation, mistakes are mostly due to inattention, improvisation, and non-compliance with spacing rules. In machine installation, mistakes are more systematic – if the machine is set up incorrectly, the same mistake is repeated in a hundred places. Both approaches require a systematic approach to quality control. More on the differences can be found in the article Manual vs. machine clamping of pipes – differences and applications.
Checklist before concealing the installation
One of the most expensive mistakes is not the installation error itself, but concealing it before inspection. Once the pipe is poured into the floor or embedded in the wall, repairs will require demolition work. Always check the following before concealing:
- Are the spacing of the pipe clamps in accordance with the manufacturer's recommendations for the given diameter and material?
- Are the fixed and sliding points correctly placed and actually functioning as intended?
- Are all clamps of the correct size for the given pipe?
- Are the fixings into the wall/ceiling solid, without play, and made of suitable material?
- Is the minimum clearance from fittings and elbows maintained?
- Are long straight sections equipped with expansion compensators?
- Is the pipe truly horizontal/vertical (checked with a spirit level)?
- Are adjacent pipes at sufficient distance and without mechanical contact?
- Has a pressure test been carried out before concealing?
A pressure test (typically 1.5× operating pressure, for at least 30 minutes) not only verifies the tightness of the joints, but also confirms that the support system can withstand the load – because under pressure, the pipe deforms slightly and weak clamps will immediately reveal this.
Frequently asked questions (FAQ)
What is the maximum allowable spacing of clamps for 16 mm Hepworth pipe in underfloor heating?
Underfloor heating is a special case – the pipe is either firmly embedded in anhydrite or concrete, or supported in system underlays/profiled boards. In such a case, the spacing of clamps in the classical sense is not relevant – the pipe is supported along its entire length or at intervals defined by the system (typically every 100–200 mm). For distribution sections outside the floor area (supply and return branches to manifolds), standard recommendations apply: for PB 16 mm at a medium temperature of around 55–70 °C, a maximum of 0.5 m for horizontal runs.
Can I use clamps from another system on Hepworth pipe if they have the same diameter?
This is technically possible, but caution is advised. It is essential that the clamp does not have sharp edges that could damage the pipe surface (including the EVOH oxygen barrier), that the internal profile actually matches the external diameter of the Hepworth pipe, and that the clamp material (especially when in contact with copper) does not cause galvanic corrosion. The safest solution is to use original mounting accessories designed for the Hepworth system.
Why are my pipes knocking even though they are secured?
Knocking can have multiple causes even with proper securing: the clamps do not have rubber or foam anti-noise inserts and transfer vibrations to the wall; the clamp is of the correct size, but the pipe is too loose in it (the pipe moves within the clamp); hydraulic shocks in the system (fast closing of thermostatic valves) transfer shock waves along the pipe; or the pipe moves during expansion and hits another pipe or structural element. The solution depends on the cause – we address this topic in more detail in the article Loose or cracked clamps – causes and solutions.
Is it necessary to secure the pipe at places where it changes direction (elbow, T-joint)?
A clamp must not be placed directly on the fitting (elbow, T-joint) – the minimum distance is 80–100 mm from the fitting. However, a clamp should be placed on each straight section after the elbow or branch – ideally at this minimum distance. A change in direction creates bending moments that need to be absorbed as soon as possible on the straight section, not on the fitting itself. A more detailed procedure can be found in the article How to correctly install clamps and brackets on pipe.
How can I tell that a clamp has loosened or become damaged?
Visual signs: the pipe is visibly bent, the clamp is hanging down or rotated, the screw is loose or pulled out. Auditory signs: knocking, squeaking in the pipe, a change in the noise character after the heating is turned on. Functional signs: repeated need for bleeding (air accumulates at the bend), local temperature drop in the given circuit. If you suspect a problem, visually inspect the entire piping – loose clamps are usually visible. For hard-to-reach sections (running in grooves or shafts), a thermal camera may help.
Is one clamp sufficient for a very short pipe section (e.g. 0.5 m)?
For a section longer than 0.3 m, at least two clamps are recommended – one at each end of the section. A single clamp in the middle of a short section will hold the pipe's weight, but will not control the direction or lateral movement at the ends. Moreover, if there is a fitting at one or both ends, the rule of minimum distance of 80–100 mm from the fitting applies – which, for short sections, means placing clamps very close to both ends of the section.
Conclusion: System thinking as a way to prevent errors
Most errors in pipe securing do not stem from a lack of knowledge of specific details, but from the absence of a systemic view of the installation. Pipe securing is not an isolated step – it is part of a complex mechanical and hydraulic system that must function for decades under changing conditions. If securing is seen as a "quick final phase" before embedding in the wall, errors are almost inevitable.
A good installer thinks about each pipe section: where it will expand, where a fixed point is needed, what the load will be during a pressure test, and how the system will behave after ten years of operation. This foresight – supported by knowledge of recommended spacing, and the correct selection of components such as pipe bracket for 16–18 mm pipe or KOMBI M8 screw – is what distinguishes an installation that will function problem-free for twenty years from one that will need to be opened after the first heating season.
Further related topics can be found in our Knowledge Centre: Frequently asked questions about mounting accessories for Hepworth pipe collects the most common questions from practice, while the article Clamps vs. brackets for pipe securing – which to use when will help you choose the correct type of clamp for a specific situation. Proper securing is the foundation – all other layers of installation quality are built on top of it.
Do you have a question about this topic?
Not sure what to do or dealing with a specific situation in your home? Write to us – we are happy to help.