I learned of an obscure tool recently- a roller tube expander. You use this to tight-fit a tube in a boiler's tube-sheet. So you can install or replace tubes in pressure vessels such as a boilers or heat exchangers. Check it out:
https://www.youtube.com/watch?v=u7UQKNapTBE
Failure:
https://youtu.be/HlXVP2HHTfo?t=696
Repair:
https://www.meggitt.com/products-services/heat-exchangers/
"Its innovative design means that single tubes can be easily replaced during overhaul periods, minimising costs to operators.
The operational lifetime of a tubular unit is 3 million flying hours and 50 million Serck Aviation bonded interfaces in the field have never failed."
Even the patent mentions:
"In addition to aerospace applications, the disclosed headers can be used generally in other transportation industries, as well as industrial applications."
But actually I think the spreader could be contained within some kind of bell-shaped header, and not actually attached to the heat exchanger tubes, just immersed in the same fluid. So replacement might be easy.
But any kind of spreader is adding weight compared with an empty header, so not sure if the easing of the fluid flow is worth the weight gain. No doubt this depends on the application.
2. Just because you could use the design in "other transportation industries" doesn't mean anyone is actually planning to do it. With the technology as expensive as it is right now, it would not make economic sense.
3. Having a spreader is not primarily about "easing the fluid flow," it's about ensuring that the entire heat exchanger gets fluid flowing through it. Typically this is worth it in applications where weight matters (because you can't afford the dead weight of part of the heat exchanger which is not actually getting much fluid flowing through it), but it is not worth it in industrial or HVAC applications (because it's cheaper to just build a bit larger of a heat exchanger). I do like the idea of a "floating spreader" - I will have to see if that has been done before.