Application of the Industrial Employment (Standing Orders) Act 1946
As correctly stated, as per Section 1(3) of the Industrial Employment (Standing Orders) Act 1946, it applies to every industrial establishment with 100 or more workmen. However, the proviso extends it further, as seen below:
(3) It applies to every industrial establishment wherein one hundred or more workmen are employed, or were employed on any day of the preceding twelve months. Provided that the appropriate Government may, after giving not less than two months' notice of its intention to do so, by notification in the Official Gazette, apply the provisions of this Act to any industrial establishment employing such a number of persons less than one hundred as may be specified in the notification.
So, you can approach the State Government for certification of your Standing Orders by relaxing the employee limit criteria. Incidentally, if the unit is in Madhya Pradesh, then the MP Industrial Employment (Standing Orders) Act 1961 applies, and you are eligible to get it certified. The applicable provision reads as follows:
Section 02: Application of the Act
(1) This Act shall apply to:
(a) every undertaking wherein the number of employees on any day during the twelve months preceding or on the day this Act comes into force or on any day thereafter was or is more than twenty.