Materials, construction and standards that determine durability in district heating networks
At first glance, a ball valve is simply a piece of steel with a ball inside. In practice, it is a complex safety component designed to operate for 20–30 years under high temperature, pressure — and often without any maintenance whatsoever.

That is why in district heating, a “valve” is never a uniform product. The differences begin with construction, materials and workmanship — and end with the costs of failures, excavations and supply interruptions.

Below, we break down a good ball valve into its essential components.

Valve body – the foundation of the entire construction
The body is the element that:

• transfers pressure,
• operates at high temperature,
• is welded to the pipeline,
• once buried,
• often becomes inaccessible for decades.

In district heating networks, what matters is:

• the use of steel designed for elevated-temperature service,
• appropriate wall thickness,
• material homogeneity.

A cheap body made from random-grade steel may “hold up” on paper, but in the long run it is most often the component that causes the entire valve to fail.

Ball – the heart of the valve (and the most common source of problems)
The ball is responsible for tightly shutting off the medium. In a good ball valve:

• the ball surface is perfectly smooth,
• the ball material is resistant to corrosion and deposits,
• the ball does not “seize” even after years without movement.

In practice, the quality standard is a stainless steel ball. It ensures that after 10 years the valve:

• still rotates smoothly,
• does not “stick” to the seats,
• maintains Class A tightness.

Seals – invisible, but critical
Seals operate under the most demanding conditions:

• high temperature,
• pressure fluctuations,
• contact with district heating water chemistry.

In ball valves for district heating, what matters is:

• matching the seal material to the operating temperature,
• resistance to ageing,
• stability of parameters over time.

It is the seals — not the ball — that are often the first component to cause leakage failure in cheaper valves.

Stem – control safety
The stem transfers torque from the handle or gearbox to the ball. In district heating, its role is greater than it may seem:

• it operates underground,
• it is exposed to mechanical damage,
• it determines safety in the event of construction site collisions.

A well-designed stem:

• reduces the risk of leakage,
• enables safe operation for years,
• allows height adjustment to suit site conditions.

Welds – quality that cannot be corrected after installation
In welded valves, the weld is a structural element, not an afterthought. Its quality determines:

• the integrity of the connection,
• resistance to stress,
• the durability of the entire pipe–valve assembly.

This is why the following matter:

• welding technology,
• process repeatability,
• quality control.

A poorly made weld is a problem that cannot be fixed without excavating the network.

Ball valve materials – what steel for district heating networks?

Which steel for district heating?

In district heating networks, the standard materials are carbon steels rated for elevated-temperature service, such as:

• P235GH,
• other boiler and power engineering steels.

These provide:

• good weldability,
• stable parameters at high temperature,
• resistance to long-term loads.
  

Temperature resistance
A valve must perform not only at a given pressure, but also:

• at temperatures of 120–150°C,
• through heating–cooling cycles,
• without loss of tightness.

Corrosion resistance
Corrosion in district heating is not just rust — it also means:

• deposits,
• district water chemistry,
• electrochemical potential differences between materials.

That is why the right combination of the following is essential:

• body steel,
• ball material,
• seals.

Ball valve certifications and standards – what truly matters?

In serious projects, certifications are not a marketing add-on — they are a real requirement.

The most important standards and designations

• EN – European standards for construction and testing,
• ISO – quality and process standards,
• PED – Pressure Equipment Directive, mandatory for pressure-bearing equipment.
  

What is required in district heating?

• PED compliance,
• material traceability,
• quality documentation,
• production repeatability.

Without these, there is a risk of:

• problems during inspections and handovers,
• formal liability for the investor,
• failure to obtain operating approval.

Summary: why “a valve ≠ a valve”
A good ball valve means:

• the right body material,
• a stainless steel ball,
• durable seals,
• a safe stem design,
• controlled weld quality,
• full compliance with standards and directives.
  

These are the elements that determine whether, after 15 years, a valve:

closes with a single turn — or becomes the source of a costly failure.

GLOBTOS designs and manufactures ball valves for long-term service in district heating networks — where quality, safety and years of peace of mind are what count. If you need to select a valve for a specific network, temperature and operating conditions, contact the GLOBTOS team in Wrocław. It is better to do it right once than to return to the subject with an excavator.