Weld control

At Linde Metal Technology, we can perform a qualified nondestructive testing (NDT) of welded joints.
The test methods are based on different physical principles and therefore have distinct advantages and limitations. When choosing technology must consider several factors. This is the result we want to achieve with the test which determines the choice of method.
We have genuine, certified knowledge of the methods we offer.

We also perform destructive testing by macroscopic examination of welded joints, such as the development of new welding procedures or where you see the need for such a study. Welds are assessed based on specified acceptance limits, where both form deviations and discontinuities observed.

Visual test (VT)


Test principle:
Visual testing is perhaps the most important method of NDT (Non Destructive Testing). The method is used for screening for defects in both small and large structures
Detects:
Large and small surface breaking defects, defects and defects caused by degradation mechanisms, distortions, defects and deficiencies in the joints, leakage, general defects and deficiencies in production
Benefits:
Cost effective, immediate inspection results, portable equipment
Restrictions:
Accessibility to the inspection area, normally limited opportunities for detecting defects and flaws below the surface, requires training and experience to provide reliable results, the surface condition
Our expertise:
EN 473 level 2

Magnetic particle testing (MT)

Test principle:
The specimen is magnetized and then applied provningsmediumet, while the item is inspected to judge the results.
Application:
All materials may arrange to be magnetized.
Detects:
Defects in or just below the surface (pores, cracks, slag, etc.).
Benefits:
High sensitivity to small defects, immediate inspection results, portable equipment.
Restrictions:
Material (only ferromagnetic materials), limited inspection depth (mainly surface defects), requires training and experience to provide reliable results, the surface condition (max. Color thickness: 50 microns), references - standards necessary to evaluate the results.
Our expertise:
EN 473 level 2

Penetrant test (PT)


Test principle:
Penetrating fluid applied to the surface, visual evaluation with the possible optical instrument for assessing outcome
Application:
All material is not sucking or porous.
Detects:
Cracks that breaks the surface, the second error types that breaks the surface (pores, etc.) leakage.
Benefits:
Large sensitivity to small cracks, immediately inspection results, portable equipment
Restrictions:
Low and high temperatures, defects below the surface, requires training and experience to provide reliable results, surface treatment, surface conditions, the cleaning process, reference standards necessary to assess the outcome.
Our expertise:
Skilled senior testing personnel

Macroskopic examination

 

Test principle:
The weld is cut in the center and the cut surface is polished smooth, and then etched using a suitable reagent. Then, the visual examination is performed using a microscope 10-100-times magnification.
Application:
Visual examination of welded joints in most materials.
Detects:
- Welding overall structure
- The metallurgical structure of the base material and the melting zone
- The number of runs
- The extent of the heat affected zone of the base material closest to the fusion boundary at a welding (HAZ - heat affected zone)
- Groove depth and penetration
- Distribution of deposits on such as slag and porosity
Our expertise:
Skilled senior testing personnel