MS pipe (Mild Steel pipe) is used widely in the HVAC industry. Piping work is normally carried out to connect a chiller plant with Air Handling Units (AHUs) and Fan Coil Units (FCUs). The chiller system, water cooled or air cooled, produces chilled water and then this chilled water is pushed around via the MS pipe lines to various AHUs and FCUs located inside the building. Therefore, MS pipework is an integral part of any centralized air conditioning system primarily in commercial buildings such as an office building, a mall, a hotel, a hospital, an airport, a warehouse, etc. There are two lines of MS pipe in any given HVAC system. First line is the supply line that carries the chilled water to various AHUs and FCUs. The second line is a return line that brings back the unwanted heat from the building to the evaporator and subsequently this heat is transferred over to the chiller condenser. This is how a closed loop chiller plant operates and just like arteries, MS pipes play an important role in this closed loop operation.
Different sizes of MS pipes are used in an HVAC system. Depending on the chiller capacity in TR (Tonnage of Refrigeration), the main MS pipe line from the chiller system ranges from 300 NB (Nominal Bore) to 500 NB. Nominal Bore is basically the inner diameter in mm. From this main line, branch lines ranging from 150 to 250 NB are carved out. And thereafter, 50 NB to 150 NB of MS pipe lines are used to connect to the AHUs. Whereas, 25 NB to 32 NB of MS pipe lines are used to connect the various FCUs spread across the building.
Classes of MS pipe
A design engineer pays close attention not only to different sizes of MS pipe lines but also to different classes of MS pipe. Operative pressure, cooling flow, proximity to sea, proximity to sewage, corrosiveness are some of the factors that determine the class of MS pipe to be used in any centralized air conditioning system. ‘A’ class is a light class of MS pipe, ‘B’ class is a medium class, and ‘C’ class is a heavy class. Generally, ‘B’ class of MS pipe is sufficient for most HVAC projects across India. However, in certain instances depending on the environmental and load conditions, the C class of MS pipe is chosen.
Valves and Guages in the MS pipe loop
Once the sizes and classes of MS pipe have been identified by the HVAC design engineer, the next task is to form the loop between the chiller and various AHUs / FCUs. And it is not a straightforward process to form the loop. Firstly, the design should be made in such a way that it reduces the overall length of MS pipework. Secondly, to control the pressure, flow, and temperature, various valves and gauges are used. These valves and gauges are installed on the MS pipeline at the inlet and outlet of the AHU or FCU. Some of these valves and gauges are air vent valve, butterfly valve, balancing valve, Y strainer, pressure gauge, and temperature gauge. Besides the valves and gauges, pumps also play an integral role in this loop. Pumps are used to circulate the chilled water in this loop. The pumps are deployed in the return line. Of course, it goes without saying that pumps should be chosen based on the correct flow and pressure calculations.
In addition to laying the MS pipe, it is equally important to insulate these MS pipe loops with the proper insulating material. Generally, 19 mm thick nitrile is used to insulate the MS pipe. Insulation is extremely crucial in order to completely eliminate the heat transfer between the MS pipe and the surroundings. Without proper insulation, the chilled water in the supply line will gain heat from the surroundings, thereby defeating the purpose of cooling a building satisfactorily.
The next stage is that of the installation. Forming these MS pipe loops is a man-hour intensive process. Accurate drawings should be provided to the installation team. And based on the 2D drawings, the installation team lays the MS pipe line in addition to installing the valves and gauges. Welding tools, cutting tools, fastening tools are needed to complete the MS pipework in a typical HVAC project. Besides the tools, sealants and adhesives are also used.
TheSmartHVAC sources MS pipes from leading manufacturers in India.
Because of the economies of scale, TheSmartHVAC is able to offer its customers high-quality piping work at the lowest price point. The design team as well as the installation team is adept at managing MS pipework with a considerable ease. The manufacturers of MS Pipe can reach out at [email protected]