Pipe vs tube
Pipes and tubes have distinctly different characteristics. Pipes are identified as nominal bore (NB) which is a measure used for the designation of the diameter of the pipe. Usually the size of NB / nominal diameter (ND) / nominal pipe size (NPS) is not necessarily the same as the outside diameter (OD) of the actual pipe size. While the tube, identified with the OD are all the same size.
Each pipe has the same OD size, usually known as NPS, while the thickness (schedule) is different. For pipes under 12″, the NPS size is greater than the OD, while for pipes 14″ and above the NPS size is exactly the same as the OD. Usually just multiplied the NPS by 25.4 mm as the conversion. Meanwhile, each pipe has a different schedule, according to needs.
Tube is a cylindrical object that has a hole in the middle to drain the fluid. Unlike the pipe, the tube is relatively small in size and is not limited by the spool (a certain size on the pipe, usually 6 meters). Tubes are also more flexible and easier to shape than pipes.
Tube is used for instrument equipment. Or rather, it is used to drain the fluid in the Heat Exchanger. In the HE, the fluid flowing in the tube will be heated up and down with other fluids.
In terms of size, the tube is measured through the Outside Diameter. Unlike the pipe which has an OD that is not the same as its NPS, the tube is measured in units of thickness called bwg. Pipes are made in large sizes, tubes are made small but many. This aims to expand the contact surface with other fluids, so that heat exchange will be more effective. You should also know that the thickness of the tube is Bwg, which is a measure of the thickness of the tube used by TEMA (tubular exchanger manufacturers association), bwg stands for birmingharm wire gauge. .