Definition - What does Tee Joint mean?
A tee joint refers to the welded point of two metallic materials that are joined in the same plane at a 180° combined angle with a 90° angle on either side, forming the letter "T".
Welded tee joints are often prone to excess porosity, increased moisture entrapment, cracking and crevice corrosion due to the containment geometry generated by the degree at which it is formed.
Corrosionpedia explains Tee Joint
Corrosion fatigue is common in welded tee joints, however tee joints have come into wider use in structural and machine applications.