So if there is an update after the first drawing, we call it a revision (or even shop drawings, due the term might not apply correctly) but not the as-built. We use the term as-build for the final drawings that are prepared based on the constructed item. I am from the water sector and perhaps a bit off from petroleum. I've seen it on the internet." BigInch's favorite client. If your scope of work is only for the equipment, or one piece of equipment, then you must verify only the equipment drawings and their information, otherwise you should be prepared to do all the above. In other words, correct all the drawings and information so that all dimensions and actually all information is shown EXACTLY WHAT was built and WHERE. All information joint features, tees, valves, diameters, wall thicknesses, class factors, materials should be tied back to their exact locations as they have been shown on the drawings, dimensions and any other differences corrected.
Piping Plans will most probably need as-built info markups and correction. All piping features and equipment should be verified as-built, in place by someone that understands piping. If the surveyors have done any as-built work, then I would guess that they have located the pipeline's features according to MP or KP (mile post, kilometer post) stations and elevations, and/or perhaps GPS coordinates.
General Arrangements will most likely not need any, or maybe a little work. In this forum, rightly or wrongly, we usually assume PID mean Piping and Instrumentation Diagrams, so we (I) don't get what surveyors (land surveyors?) are doing with those, because PIDs do not (usually) have any linear dimensions at all on them.