The heat number and produce number are marked in every flange, so we can trace the quality in each piece of flange. It means every flanges have record in our factory. 2010-03-20
The marks form of flanges: (SAMPLES)
1. (Logo) ANSI B16.5 150LBS 1"
A105 Heat No.
2. (Logo) DIN25xx PNxx DNxx RST37.2 Heat No.
2. (Logo) JIS 5K 15A SS400 Heat No.
Or we can mark as per of buyers' request.