How to calculate minimum bend radius?

[ChE51]

I have an issue with foam pigs being torn up in an 8" line. I have sourced a solid multiple cup poly pig to use as a temporary solution. It is an 8" pig, length = 16". It has a minimum bend radius of 12". I am concerned whether this pig will traverse a 45degree bend with internal diameter of 190.5mm. The manufacturer recommendation is a minimum ID of 194mm but I have told this is a very conservative number. The pig is fairly flexible but I just want to make sure it won't get stuck. Advice please?

 

[jte]

Are you really concerned about a 1.804% discrepancy? I'd say that you consider how many significant figures you're worried about and round the 194 number to two sig. fig's and round the 190.5 number to two sig. fig's as well. Let us know how that works out. Don't forget to figure in the typical 12.5% wall thickness tolerance and corrosion when you figure your internal diameter...

Put another way... Buy it and try it. If it gets stuck, increase the driving pressure by 2.075327% and see what happens. If the lost profit opportunity is so high that you are unwilling to take a chance on this, build a mock up and test the pig on that first.

jt