Claxton Engineering enjoys a fine reputation for coming up with highly effective engineering solutions, often within very tight deadlines.
The company is strongly inclined towards practical and reliable designs, but at the same time is not afraid to challenge conventional thinking.
You look at some solutions and they are so elegant, so simple, that you wonder why nobody has thought of them before. Claxton’s retractable riser guide arms are a perfect example of this. The retractable arms enable drilling or workover risers to be run and landed safely and reliably on subsea wells; they also save rig time and render the whole process reasonably independent of the weather.
But any normal guide arms would do this – what is the advantage of the arms being retractable? The problem is that to fit over the standard guide posts fitted to subsea wells, the fixed arms need to extend about 6 ft from the riser, and so they are incapable of passing through the rotary table of even the biggest jackup drilling rigs. It is therefore normal practice to fit the arms to the riser below the rig floor – maybe on the Texas deck, if the rig has one. But this is not always easy owing to limited access or restrictions on the span of the structure to be fitted. Indeed, on modern jackups the presence of pollution containment units below the rig floor makes the task almost impossible. Then it is sometimes necessary to feed the riser into the rig from a boat stationed below it – with obvious economic and operational implications.