8-character blind flange

Go and check the standards for 8-character blind plates, compare the dimensions, and you’ll know. Which side should it be installed on? It should be carried out according to your schematic diagram.

Valves and eight-character blind flanges should also be of the same grade; otherwise, differences in the dimensions of the sealing surfaces may lead to sealing problems. Normally, the blind plate is installed on the side where the medium flows into the valve.

In principle, that is the case, but for certain special situations, such as 600# and 900# as specified in ASME B16.5, some of the information is identical.

The 8-character blind flange at 4.0 MPa is thicker than one at 2.5 MPa, with all other parameters remaining the same. Can it replace it?

It is to be reconfirmed that if it is merely a thickness issue, the dimensions of that part must be taken into account in the drawings. However, it is not recommended to dry it in this way, as it gives an impression of a makeshift workshop.

If the grades are different but the size of the sealing surface is the same, with only a difference in the thickness of the blind plate, in many cases on site such details aren’t taken into account; installing it doesn’t necessarily lead to any problems. But when I talk about the impact on sealing performance, one must also take into account the entire flange joint. In such cases, the performance of gaskets and the preload of fasteners has little consideration in terms of installation (it becomes even more difficult to take these factors into account when there are different pressure levels). Strictly speaking, the flange (in this context, a blind plate is treated as equivalent to a flange, and its strength certainly varies depending on the pressure level), the gasket (the required sealing pressure differs at different pressures), and the fasteners (either too high or too low a tightening force can have a negative effect on the seal) – only when these three elements are well matched can good sealing performance be achieved. Therefore, in certain operating conditions where the hazards such as medium toxicity and flammability are low and the pressure is not high, strict adherence to regulations is often not necessary. For example, if it really is 600 lb and 900 lb, even if the dimensions of the sealing surfaces are exactly the same, from my design perspective, I absolutely cannot approve such a substitution.