What are flange assembly, gasket materials and fasteners?

What are flange assembly?

1. Before assembling the flange, the flange surface must be cleaned, especially the sealing surface.

2.When assembling the slip on flange, insert the pipe end into two thirds of the inside diameter of the flange, and then the flange and the pipe are spot welded in one place.For horizontal piping, spot weld from above, then check and calibrate the flange position from different directions with a square so that the sealing surface is perpendicular to the center line of the piping.If there are no errors, weld the second point.

3.Correct the position of the flange from the left and right directions with an angle square.After correction, welding the third and fourth spot welding, spot welding process is completed.

4.When matching the flange, the bolt hole of the flange to be installed should be aligned parallel with the corresponding bolt hole of the fixed flange.The deviation shall not be greater than 1.5‰ of the flange outer diameter and shall not be more than 2mm.

5.When selecting flanges for equipment or valve parts, note that the flange size of the original equipment or valve part is the same as that of the pipe.

ANSI ASME B16.5 class 1500 A350 LF2 weld neck flanges

Common rubber gasket materials

Rubber sheets and rubber asbestos sheets are the most commonly used flanged gasket materials.

1. Industrial rubber sheet – It is also called an industrial vulcanized rubber sheet or a rubber sheet.

2. Rubber asbestos sheet – It is generally used as a gasket for equipment and pipe flange connection sealing surface. The medium can be water, steam, air, various gas, ammonia, lye, and oil.

What are flange fasteners?

Flange fasteners are bolts, nuts and washers used to connect flanges.Hex head bolts are usually used in low pressure pipelines and stud bolts in medium and high pressure pipelines.Nuts that go with bolts come in two types – the first type is round on one side of a hexagon and flat on the other.The second is that both sides are round.The hardness of the nut should be less than that of the bolt or stud, so as not to damage the thread on the bolt and reduce the fastness after long use.

For better disassembly and repair, the protruding length of the nut should be within 5 mm after the flange is tightened, and not more than twice the pitch. Washers do not have to be added if there are flange connecting bolts. When the thread on the screw is slightly shorter, a washer can be added as the length compensation to leave room for the subsequent secondary tightening. But it is strictly forbidden to use the superimposed washer to compensate for the shortage of the thread length. The number and diameter of bolt holes on the flange and the specifications of the connecting bolts are specified in the relevant flange standards. The flange bolt holes are generally 2 to 3 mm larger than the bolt or stud diameter.

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