HVAC stands for Heating, Ventilation, and Air-Conditioning-three closely related fundamental functions with both commercial and residential applications. The concept was coined by Volkart Brothers, being the pioneers in this segment, and was introduced way back in 1950.

The steady growth of the real estate market in India has created opportunities for major developers to promote large format office spaces and associated structures like malls, resorts, hi-tech hospitals, etc. This growth has necessitated in realizing the importance of the HVAC and Fire-fighting systems in both residential and commercial structures as a prime essential for safety and health.

HVAC can further be distinguished as two separate segments

  • Commercial Cooling - large spaces of hotels, IT parks, malls, airports etc.
  • Process Cooling -for sterilized rooms of pharmaceutical and manufacturing industries.

The primary use of HVAC is to regulate room temperature, humidity, and air flow, ensuring that such elements remain within their acceptable ranges. Effective control of such factors minimizes health-related risks.


For application of MS Pipes in this segment, details regarding the common practices followed, sizes of steel pipes used, and specifications required are as given below.

Class of MS Pipes to be used in Air Conditioning and Chiller Systems depends on environmental conditions like proximity to sea, corrosiveness, cooling flow, cooling zone and operating pressure.

  • Pipes used in Fan Coil Unit - 25 NB to 32 NB.
  • Pipes used from chiller header to AHU (Air Handling Unit) - 50 NB to 150 NB.
  • Pipes used in chiller branch lines -150 NB to 250 NB.
  • Pipes used in chiller main lines - 300 NB to 500 NB.

Pipe Size Material Specification
Up to 40 NB MS "C" Class IS 1239 : 1973
Part I & II
50 NB - 150 NB MS "C" Class IS 1239 : 1973
Part I & II
200 NB &
250 NB
Welded pipe with minimum 5 mm thickness IS 3589 : 1966
300 NB Welded pipe with minimum 6 mm thickness IS 3589 : 1966
300 NB & over Welded pipe with minimum 8 mm thickness IS 3589 : 1966