Blind flanges is to seal off the end of a pipe, providing a removable seal
Blind flange , officially known as a flange cover, is also called a blind flange or pipe plug. It is a type of flange without a hole in the middle. Its main purpose is to seal off the end of a pipe, providing a removable seal.
Standard:
GB/T9119-2010 HG/T20592-2009 HG/T20615-2009 DIN ASME BS JIS
Material:
304:F304 S30408 S30408II S30408III S30400
304L:S30403 S30403II 30403 30403II
316L:31603 31603II 31603III
2507(F53) 2205(F51) TP310S(06Cr5Ni20) TP321(06Cr18Ni11) S22053III=2205III T321-32168=321
Contrary to all the flange types seen above, blind flanges do not have a center hole, and are used to blind or seal a pipeline, a valve/pressure vessel and block the flow of the fluid.Blind flanges have to withstand remarkable mechanical stress due to the system pressure and the required bolting forces.
Blind flanges allow easy access to the pipeline, as they can be easily unbolted to let the operator execute activities inside the terminal end of the pipe (this is also the reason why the blind flange type is used as manhole for pressure vessels, at times).
It is maybe interesting to observe that, while this flanges type is easier to manufacture, they are sold at a premium average cost per kilogram compared to the other flange types.