Working hours labour laws - planning to change from 8 hrs to 12 hrs

I am Kumar. Working in a company as HR. presently total plant working in 8 hrs shifts. manpower shortage is happen in some of areas. we are planning to change from 8 hrs to 12 hrs. Is any special facility available in labour laws for change it ? please suggest....

HOURS OF WORK
4.1 Section 51 of the Factories Act, 1948 prescribes that no adult worker shall be required or
allowed to work in a factory for more than forty-eight hours in any week. Further, Section 54
stipulates that subject to the provision of Section 51 no adult worker shall be required or
allowed to work in a factory for more than nine hours in any day. However, there is a provision
to this section which states that subject to the prior approval of the Chief Inspector, the daily
maximum hours specified in Section 54 may be exceeded in order to facilitate the change of Shift.
Hope this clarifies.

You cannot engage workers for 12 hours a day on a regular basis. Labour Law does not permit such engagement even if you pay extra wages (at double the rate) for the additional 4 hours that the workers work because the maximum hours including overtime should has been defined under various Acts, viz, Factories Act, Plantation Labour Act, Mines Act or Shops and Commercial Establishments Act. Under no Act it is more than 60 hours a week.

clarification on Working on Sundays or National Holidays
Hello I a working in a Manufacturing in need on clarification on Working on Sundays or National Holidays want to file any Letter to inspector of Factories in this regard