Abstract: A coil of continuous steel tubing string is stretched along the ground. An elongate bundle of instrument lines, including thermocouples and pressure sensor wiring, is threaded into the bore of the tubing string. The instrument lines are landed at multiple spaced apart measurement points along the string. The string and the contained bundle are cut at pressure measuring points. A tubular sub having a side port is supplied for each point. One set of cut line ends is threaded through the sub and reconnected with the other set. A pressure sensor is inserted in the string at the cut point and connected with pressure sensor wiring and the port. This process is repeated along the tubing string. The product is a continuous tubing string housing a plurality of pressure sensor assemblies connected to ports along the string and a plurality of thermocouples operative to measure temperature at points along the string.