The size specifications of Stainless Steel Flanges vary depending on the standard, pressure level and nominal diameter. Here are some key information from the stainless steel flange size specification table compiled based on the search results:

‌Nominal diameter range‌:

The nominal diameter ranges from DN10 to DN5000 (i.e. 1/2″～80″).

‌Common standards‌:

National standard: such as GB9112-88 series.
American standard: such as ANSI B16.5, ANSI 16.47 Class150～1500.
Japanese standard: such as JIS 5K～20K.
German standard: such as DIN2527, 2543, 2545, etc.
Other standards include Italian standards, British standards, Ministry of Chemical Industry standards, Ministry of Machinery standards, pressure vessel standards, etc.

‌Pressure level‌:

The pressure level ranges from 0.25Mpa to 250Mpa (i.e. 150Lb ～2500Lb).

Please note that since the size specification table of stainless steel flanges involves a lot of specific data and may vary due to standard updates or different manufacturers, it is recommended to refer to the latest relevant standards or consult professional manufacturers to obtain accurate information in actual applications.

In addition, when purchasing flanges, try to choose products that meet national standards to ensure their quality and safety.