PSI - Issue 75

Kevin Mouradian et al. / Procedia Structural Integrity 75 (2025) 616–624 Kevin Mouradian et al. / Structural Integrity Procedia (2025)

620

5

a

b

Fig. 3. Undercut height along the weld length in (a) BW_TYPE specimens; (b) BW_UND specimens

3.3. Radiographic testing Digital radiography was used to inspect the specimens. Two types of internal imperfections were identified: lack of fusion (LOF) and porosity. The digital radiography facilitated the differentiation between various types of porosity defined in ISO 6520 ‑ 1 (CEN 2007). The results of the radiographic inspection, along with the corresponding quality levels according to ISO 5817 (CEN 2023a), are summarized in Table 3. The porosity and lack of fusion were detected in several specimens even though they were unintentionally produced. Regarding the additional requirements for welds subjected to fatigue loading provided in Annex B of ISO 5817, the limits for uniformly distributed porosity and linear porosity remain the same for quality level B and B90. Conversely, for clustered porosity, a more stringent requirement is applied for B90. Consequently, the clustered porosity observed in specimen UND_3 corresponds to quality level C63. Similarly, an additional requirement was introduced for quality level B90 in the case of elongated cavities. As a result, specimens TYPE_2 and TYPE_3 fall within the limits of quality level C63. Furthermore, the presence of lack of fusion was identified in some specimens, such as UND_4, where the imperfection measured 8.8 mm in length. According to ISO 5817, a short imperfection ( l =10 mm) of lack of fusion is permissible for quality level D. However, this imperfection is not permitted for quality levels C and B.

Table 3. Internal weld imperfections dimensions and quality levels Specimen Imperfection 1 2

3

4

5

6

2012 1.1mm d = 1 1.0% A =

2015 0.8mm h = 40mm l = 

2012 0.9mm d = 1 1.0% A 

2015 0.7mm h = 5mm l =  9.4mm l = 

2012 1.3mm d = 1 1.0% A 

2013 A 11mm d =

Porosity

BW_TYPE

5.8mm l = 

LOF

-

-

-

-

2015 2.3mm h = 60mm l = 

2012 1.2mm d = 1 1.5% A =

2014 1.3mm h = 26mm l =

2013

2013 A 15mm d =

Porosity

-

6.2mm

A d =

BW_UND

8.8mm l = 

LOF

-

-

-

-

-

Quality level B

Quality level C

Quality level D

Quality level < D

Uniformly distributed porosity – d : maximum pore diameter – A 1 : porosities area related to the projected area.

2012 2013 2014 2015

Clustered porosity – d A : diameter of area surrounding the gas pore.

Linear porosity – h : width of pores – l : length of porosity in longitudinal direction of the weld. Elongated cavity – h : width of pores – ∑ l : total length of porosity in longitudinal direction of the weld.