The Danger of

The Danger of "Thermal Expansion and Contraction" in Mechanical Installations

Imagine winter months at a construction site or industrial facility. While the outside is freezing cold, with temperatures dropping below zero, boiling water at 80-90°C flows through the mechanical installation pipes to heat the buildings or keep the process going.

These steel pipes, which appear silent and motionless from the outside, are actually engaged in a tremendous physical battle: Thermal Expansion and Contraction (Thermal Stress).

One of the most painful experiences we frequently encounter in the field at Öz Ayaz Boru is the bursting of substandard black pipes at the welds in the middle of winter, initially purchased under the assumption of being "budget-friendly." So, why does this physical reaction occur, and how can this disaster be prevented with the right pipe selection? Let's examine the hidden enemy of the installation in detail.

The Laws of Physics Don't Forgive: What is Thermal Shock?

Metals, by their very nature, are highly sensitive to temperature. A fluid at 80-90°C passing through a steel pipe stimulates the crystal structure of the metal, causing the pipe to expand (lengthen and widen). At the same time, if the outer surface of the pipe is exposed to freezing temperatures or an icy air current, the outer wall will contract (shrink).

The inside of the pipe tries to push outwards, while the outside tries to close inwards. This opposing stress experienced by the metal at the millimeter level is called thermal shock (thermal stress). If the system lacks proper expansion compensators (bellows) and the pipe quality is poor, the metal can no longer withstand this stress. There is only one place for the stress to be released: the weakest point of the pipe.

The Collapse of Substandard "Cheap" Pipes

The market is flooded with uncertified, second-grade steel pipes produced in substandard facilities to reduce costs. The fact that these pipes do not comply with the TS EN 10255 (formerly TS 325) standard is like a ticking time bomb for your installation. Why?

Unequal Wall Thickness: The wall thickness of a low-quality pipe is not the same at every point. While one side may be 3 mm, due to machine misalignment, the other side may be reduced to 2.2 mm. When thermal expansion begins, the stress is not evenly distributed in the pipe and accumulates at the thinner point.
Weak Weld Seam: Black seam pipes are produced by bending and longitudinally welding flat steel sheets (ERW). In cheap pipes, this welding process is not performed and tested according to high-frequency standards.
Cracking and Bursting: The thermal shock created by freezing cold and boiling water attacks the weak weld seam or thinned wall mentioned above. The result; pipes that crack lengthwise on the harshest winter days, flooded installations, and malfunctioning systems.
Why is the TS EN 10255 Standard of Vital Importance?

Thermal expansion is a law of nature; you cannot stop it. However, by choosing the right materials, you can safely control this force.

When you use certified pipes conforming to the TS EN 10255 standard in your installation, you purchase the following guarantees:

**Flawless Longitudinal Welding:** The seam of the pipe is as strong as the pipe's own body. There will be no cracking at the seam during thermal shocks.
**Homogeneous Thickness and Steel Quality:** Every millimeter of the pipe has the same wall thickness and the same carbon steel quality. Expansion stress is distributed evenly and harmlessly across the pipe surface.
**Pressure Test Guarantee:** Pipes meeting this standard undergo hydrostatic tests (100% leak test) before leaving the factory. Result: Don't Let Initial Savings Become Your Subsequent Disaster.

In mechanical installation projects, opting for substandard, "cheap" pipes to reduce initial purchase costs will end up costing you much more in the long run when considering repairs, labor, system downtime, and flooding.

At Öz Ayaz Boru, we don't leave your projects to chance. We ship certified and tested black welded piping, conforming to TS EN 10255 and TS EN 10217-1 standards, that fully resists freezing temperatures, thermal shocks, and high pressures, from our stock to all corners of Türkiye.

Contact our expert sales team today for steel pipe solutions that will reliably support your mechanical installations for years to come, and for competitive price quotes.