Regarding Radiographic requirement for API 650 storage tank vertical joints

[GOSP75]

Dear Members,
As per API 650 section -8 subsection 8.1.2.2.
Regarding radiography of shell plate vertical weld joints API 650 stated as below.
8.1.2.2 The following requirements apply to vertical joints.
one spot radiograph shall be taken in the first 3 m (10 ft) of completed vertical joint of each type and thickness welded by each welder or welding operator. The spot radiographs taken in the vertical joints of the lowest course may be used to meet the requirements of Note 3 in Figure 8.1 for individual joints.
My query our project we are having shell plate thickness of 8mm,10mm, 12mm, 14mm,16mm,18mm and 20mm.
We are having 5 welders and We need take RT for each welder each thickness type for every first 3 meter weld Like first weld in 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm or only one joint in 8mm thickness is enough and balance joint in every 30 meter without considering no of welder.

Regards,
Shanmuga.

 

[JStephen]

I'm not sure I understand the question. But see Paragraph 8.1, which will allow you to lump some of those thicknesses together, assuming the weld types are the same. Also see Figure 8.1, which makes a couple of items clear that are not otherwise clear in the text.