That’s an important step because it means new collars are simply not made with non-acceptable connections. So the whole world wound up using BSR to decide whether collar connections were good or bad API standards even got in on the act.
Ready? OK!įirst, Doyle’s idea was a good one in the 1960s our industry was using all sorts of stupid connections, and the BSR range (generally 2.25 to 2.75 was considered best) allowed us a good, solid, technically-based reason to throw those odd ducks in the trash. You may have noticed from the location of the scroll bar in your browser window that I might have a little more to say about it, if you’re willing to stick with me. Thus, make sure all your connections have a BSR of 2.5 to maximize their fatigue life. He finds the magical point was (… drum roll please …) 2.5! Then he looks for the crossover point, where the pin and the box are equally likely to fail. That works as confirmation that he’s on the right track BSR, at least in the extremes, tells us something about the “balance” of the connection.
He found, first, that collars with a high BSR were more likely to crack in the pin than the box, and collars with a low BSR were more likely to crack in the box than the pin. Specifically, he looked through inspection reports for drill collars that had cracks in them. Good ol’ Doyle knew better than to assume that, what with all the changing geometries and loadings going on. If it were actually balanced, that BSR should be 1.0.
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