Flange connection tightly depends on flanges, bolts and gaskets

Update:09-03-2021
Summary:

China Flange Clamps Indispensable in chemical companies […]

China Flange Clamps

Indispensable in chemical companies are all kinds of pipe fittings and parts, especially flanges, gaskets, and bolts are more important, because in chemical production usually pipeline connections, and the most commonly used connection method in pipeline connections is flanges. Connection, that is, first fix two pipes, pipe fittings or equipment on a flange, then add a flange gasket between the two flanges, and finally tighten the two flanges with bolts to make them tightly connected stand up. However, if the flange connection is to be tight, it is necessary to ensure that the flanges, gaskets and bolts are closely connected.

1. Check before installation

(1) Before installation, check the flange surface for damage such as scratches, nicks, corrosion, etc. If the dents and scratches on the flange sealing surface exceed 0.2mm, and the coverage exceeds half the width of the gasket sealing surface, the flange It must be replaced or the sealing surface reworked and repaired. In addition, before installing the flange, check the position of the nut supporting surface on the back of the flange. It should be parallel and smooth. Check whether the flange is aligned, and there must be no misalignment or hole.

(2) Before installation, confirm that the size and grade of the gasket used are consistent with the flange markings, and ensure that the gasket is new, clean and dry, otherwise the sealing may not be tight and the medium may leak.

(3) According to the equipment and pipeline design requirements, check whether the bolts and nuts are used correctly. The threads and contact surfaces must be free of dirt, rust, heavy skin, nicks, burrs, chips and other foreign substances that affect the torque during the tightening process. Welding or machining methods to repair bolts are not allowed.

It is worth noting that the bolts and nuts must be lubricated before use, so that the bolts have a low coefficient of friction when they are tightened, and the anti-slippage and corrosion resistance of the bolts and nuts are improved, and the studs must be lubricated before use. Degrease and dry the threads, nut threads and contact surfaces, and then apply uniform lubricating oil to avoid affecting the tightness of the flange connection; if necessary, you can also use a high temperature anti-seize agent to ensure the tightness of the flange connection. So as to achieve the sealing effect.

2. Flange bolt fastening

According to the bolt size and flange pressure level, choose non-torque wrenches or hammer wrenches, torque wrenches, bolt tensioners and other fastening tools. Their respective scope of application is that torque wrenches and bolt tensioners are suitable for high temperature, high pressure, and flammability. Explosive and other important equipment and pipe flanges; non-torque torx wrench or hammer wrench is suitable for general equipment and pipe flange fastening.

Pay attention to the tightening of flange bolts: According to the field equipment and flange, one tightening circle is calculated as one time, and the number of tightening (at least 3 times) and the hammering load (strength) of each tightening are reasonably set. The load is too fast and too large to prevent the gasket seal from failing.

Well, the above is an introduction to the main points to ensure a tight flange connection. I hope everyone can understand.

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