If bellow with 100% coldpul can really withstand high pressure integrity using control rods as is the priciple behind the 1997 pta blowegg rubber bellow design, we would not need any pressure balanced bellows or tied/hinged bellow arrangements in case of metallic bellows in the first place.
In fact, rubber bellows are in gasious/solid service, where small leakage may be permissible at times of high pressure.
It is not easy to determine exactly when rubber bellow cold pull compression is fully released under pressure and before it is tension, rubber bellow control rod nuts need to prevent further expansion; any small play in the control rod nuts can cause pressure integrity.
It might be popular in use, but not safe and sound enough in principle where leakage can cause loss of production!
Flex hoses at these locations could have been much better choice!
reg,
sam
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