In 2010, I was working on preliminary for 4 new refineries. The national content requirements were strong then, but I remember it as 15% import tax, and that was on anything, including intellectual property like process and design drawings. We had to work-share with Brazil engineering/design firms or could not get the work.
The 50% may not all be “tax” per se, but it comes close to approximating the bottom line you actually pay. When you import, there are always custom duties and other associated fees. And people you pay to expedite working through the customs/import process.