Vacuum Test

A vacuum test is a test to evaluate the air or gas tightness of a system or component. Usually, tightness tests are performed under low pressure (vacuum), not under pressure. This test is used to determine whether there are leaks, especially in closed systems or equipment that must be leak-tight.

It is an effective method to check the tightness of the bottom welds of storage tanks. It can be applied to base lap and butt welds by our experienced personnel according to API 650 and API 653 standards. It can also be applied to reinforcement wall welds with our own corner welding apparatus.

How is Vacuum Testing of Welds Performed?
Vacuum testing of welded joints is a method used to check for leaks in welded areas. This test is particularly applicable to welded parts such as pressure vessels, pipelines, tanks and other welded parts requiring sealing.
Vacuum Test Methods
Vacuum testing of welded joints is usually performed by two different methods:

1. Vacuum Box Test
This method is used to test for leaks in welded areas of large surfaces or pipelines.

🔹 How is it done?
Preparation of the Test Area:
Clean the welded area and make sure that there is no dirt or oil residue on the surface.
Soapy water or a special foam solution is usually applied on the weld to make the leak evident.

Placement of the Vacuum Box:
The vacuum canister (test chamber with a transparent lid) is placed over the weld.
The edges of the can are pressed against the surface with a sealing gasket.

Vacuum Application:
With the help of a vacuum pump or ejector, a low pressure is created inside the canister (approx. -0.8 to -0.9 bar).
The vacuum level is maintained at a certain value.

Leak Detection:
If there is a crack or porosity in the weld, the foamy liquid will form bubbles due to the air drawn in.
Leakage points are determined by visually examining the bubble formation.

Results and Reporting:
Leaking areas are marked and necessary repairs are made.
Test results are recorded.

2. Pressure Drop Method
This method is often used for small parts or closed systems.

🔹 How is it done?
The welded part is sealed and connected to a vacuum pump.
Vacuum is applied and the pressure drop is monitored over a period of time.
If the vacuum level decreases over time, it is understood that there is a leak.
Things to Consider in Vacuum Testing
Cleanliness: The welding surface must be free of dirt, rust or oil.
Gasket Quality of the Vacuum Box: Tightness must be ensured.
✔ Vacuum Level Monitoring: A stable vacuum must be created and monitored for a drop.
✔ Use of Appropriate Test Solution: Foam or soapy water should make leaks obvious.

Advantages of Vacuum Testing
✅ Can detect even small leaks in welded areas.
✅ Safer than pressurized tests.
✅ It is fast and economical to implement.
This method is widely used, especially for quality control of pressure vessels, gas lines and liquid storage tanks.