There is an interesting little tool in the Plant 3D piping environment, Line to Pipe.
This tool is normally used to route pipe lines with the aid of Polylines,
some think this is extra work, which it is,
though this allows you to route lines under the normal one-degree limit or at even odd angles,
when combined with the Elevation and Routing options this can make routing pipes over a thing like existing pipe racks or alongside steel work.
if you look at the image below,
there is a polyline showing a pipe line with a route showing rise and run,
here being a 1:100 so the pipe is at less than a degree, in this case around 0,6°
Selects Line to Pipe
Select the polyline to convert to a pipe run and accept.
The pipe should then be routed no matter the angle (NB100 in this case)
this is as long as your elbows bends allow it but you can enable cutback elbows or pipe bends
There is another similar trick between tanks (or other equipment) with nozzles
there are two tanks with line construction lines between them,
this could be lines that will determine the orientation of the nozzles when manufacturing,
Add a nozzle like normal but on the Nozzle Location drop down, select Line.
Click the underline text Select Line.
Select the line to align the nozzle to.
The nozzle should align to the line, fill in the rest of the details and accept.
Then do the same for the other tank and you can route line between then.