According to Fiqah Jafriya, what is the minimum age for a woman to perform Hajj without a Mehram?

According to Fiqah Jafriya, what is the minimum age for a woman to perform Hajj without a Mehram?

فقہ جعفریہ کے مطابق عورت کی محرم کے بغیر حج کرنے کی کم از کم عمر کتنی ہے؟
Explanation

Saudi policy allows women of a certain age (usually 45 and above) to perform Hajj without a Mehram, which may be considered by some within the Jafri school of thought.