Relevant requirements for non-destructive testing in GB150.4
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As shown in the figure below, what is everyone’s understanding of the terms marked in red?
Was it not clear enough? Literally, it means that A/B seams require 100% radiation or ultrasound treatment; this is what is done in most cases. However, some devices have lower requirements and do not necessitate 100% radiation or ultrasound treatment, but those that meet the requirements of 10.3.1 must have such treatment applied to 100%.
The inability to conduct internal inspections is mainly due to the fact that some chambers are sealed, preventing people from entering them, or they are chambers that cannot be visually inspected using conventional technical methods. However, I have never seen any design firm follow this principle in their designs; they all choose to ignore it.
The non-destructive testing agencies are rather arbitrary; the testing ratio of 200% – I have no idea where that figure comes from.
It can be understood in this way: for pressure vessels that cannot undergo internal inspections after use, the proportion of non-destructive testing is determined based on the risk level associated with their use, and it is decided by the designers. This clause overlaps a bit with the last one.
It’s a bit funny to write about this; the 2011 version makes much more sense. With a few extra words, it instantly becomes a joke.
I feel like a character ’ Not’ is missing; what was intended to be expressed is that the design documents do not specify pressure vessels that cannot be inspected after use due to the lack of 100% flaw detection. For example, in the case of water-sealed tanks, 20% flaw detection is specified, and the inlet pipe has longitudinal and circumferential welds inside the equipment. This internal pipe is not designed to withstand pressure, but it requires airtightness; it is not possible to test the airtightness of this internal pipe when the equipment is pressurized. At this point, the internal pipes should be 100% inspected for defects.