API 650 Storage Tank - Horizontal Butt Joint RT Selection in the first 3 m

[Sajeev P]

As per API 650 Para 8.1.2.3 requires - One spot radiograph shall be taken in the first 3 m (10 ft) of completed horizontal butt joint of the same type and thickness (based on the thickness of the thinner plate at the joint) without regard to the number of welders or welding operators. If the contractor start welding on Horizontal butt Joint simultaneously at four locations, in that case how to select spot radiograph in the first 3 m (10 ft) of completed horizontal butt joint? Is it required to select 4 spots or one spot? Your expert interpretation /suggestions are highly appreciated.

 

[JStephen]

One shot, pick a spot.
If 4 welders started at exactly the same time and speed, then the first 2.5 feet welded by each of them would be the first 10' welded, so any one shot in those four 2.5' segments would work. In reality, it's not usually that precise.