Perspective is determined by camera position, not focal length. The reason many people think focal length is the determining factor is because one must get much closer to a subject with a short focal length lens than one must get with a long focal length lens if one wants to fill the frame with the subject. But it is the subject distance that is actually the determining factor in perspective.

If your compressor is 10 meters tall and your camera is 10 meters above the top of the compressor, the bottom of the compressor will be twice as far from the camera as the top of the compressor is. Items at the bottom of the compressor will look half as wide as the same size item at the top of the compressor.

To get what we consider the 'normal' perspective of an object, we tend to use a focal length that either matches or is a bit longer than the diagonal of the sensor. That is, if we use a 36x24mm full frame camera with a diagonal of 43.3 mm, then we use a roughly 45-50mm lens. This gives us an angle of view that requires us to be slightly more than twice as far from an object we are imaging as the maximum width/height of the object. If we are imaging an object that is four feet wide and four feet high, we need to back up a little more than eight feet to capture it with a normal lens.

The type of projection a lens uses to represent a three-dimensional world on a two dimensional image plane can also result in what we call geometric distortion. But this is different from the perspective distortion that results from a very close or very far camera position.

To get a view where objects on the far end of a three dimensional subject appear the same size as objects on the near side of the subject, we must use a telecentric type lens that will give us an orthographic view of our subject. One of the basic requirements of a telecentric lens is that the lens must be at least as large in diameter as the subject. That tends to make them very expensive. Unless you have a budget that matches or even exceeds the military budget of a small country, or unless your gas compressor is very small, it's doubtful you could consider a telecentric lens for your project.

Another solution to get an approximate orthographic view is to use a linear motion scan camera¹ (a/k/a parallel motion scan camera) or use a more typical camera to produce a panorama where each shot is taken from a different position opposite the subject's width.

¹ Typically, the object being photographed is moved past the sanning camera at a constant speed, but the obverse can also be the case, such as with aerial or satellite camera platforms that image the surface of the earth as they pass over it.