Assuming you know the original starting position, you can use trigonometry to work out the profile of the pipeline.
If you take coordinates $(x_n,y_n)$, and with a measured 'inside pipe travel distance' of $d_n$ meters inside the pipe, down a slope of $\theta_n°$, then that coordinate can be caluclated:
It is important to note, that while the negative incline of the pipe is increasing, this approach will slightly over-estimate the altitude of each point, and slightly under-estimate as it is levelling out. Over a long run of pipe, this should even out, and the total change in altitude from end to end will be fairly accurate.
Here is an image of the graph that I was able to generate using the data that you supplied above: