How to tighten the larger head flange?

Available: front, back, left, right ； Then front, back, left, right ； Tighten gradually several times. Here it means first tightening the front, rear, left and right four ； Then there are four close to these four with the same rotation direction. ； After tightening the first pass, perform the second and third passes until tightened.

for* * flange, the flange surface must be cleaned and the gasket must be cleaned before solidification, otherwise leakage may occur easily.

Before tightening, the flange surface must be cleaned and the gasket must be cleaned, otherwise leakage will easily occur. Then we first align the flange surface, tighten the upper, lower, left and right sides of the flange surface with a little force, and then use a pneumatic wrench to tighten symmetrically. In this way, the force used is uniform and the effect is guaranteed.

In addition to the above, there is another point worth noting; leave the flange for more than four hours after tightening, so that the bolt stress is released and then tightened again. Just tighten it three times like this. high pressure * * The bolts of the flange are best designed to be hydraulically tightened.

To fasten larger-sized head flanges, the diagonal fastening method is generally used, that is, two bolts on the upper, lower, left, and right are tightened in advance, and then the remaining bolts are tightened after positioning them, so that they will not be misaligned. Generally, a pneumatic wrench is used to fasten flanges, and large-size flanges can be tightened well in three passes (never use a sledgehammer to hit the flange). For high-pressure flanges, after tightening them, use high-torque tools or heated bolts to apply force to all bolts until the torque value is reached.

Tightening the screws evenly spaced will do the trick.

Taking the cylindrical syngas compressor designed by New Billon as an example, we usually tighten the head in this way. After aligning the flange with the cylinder, first put 4 nuts diagonally, bring the head basically to the position, and then install other nuts. , use a hammer wrench to tighten, check the gap between the head and the cylinder, adjust it evenly, and then use a hydraulic wrench to tighten diagonally. When tightening with a hydraulic wrench, tighten with a small torque first, and finally tighten diagonally with a hydraulic wrench to the required torque.

fasten* * Lan, there are two key points.: 1. Necessary pre-tightening force, 2. The pre-tightening force of each bolt is the same. The size of the pretightening force is related to the operating temperature, bolt specification and material grade. You can check the relevant information. Ensure that the pre-tightening force of each bolt is the same, and the flange tightening effect can be guaranteed even without hitting with a sledgehammer. more important * * Lan recommends using a multi-head bolt tensioner. Four heads are better. Before stretching the bolts, check the threads of the bolts and nuts and apply anti-seize agent. The stretching should not be completed at one time. Depending on the size of the pre-tightening force, it should be pre-tightened at least 3 times. Stretching not only ensures the same pre-tightening force for each bolt, but also extends the service life of the bolts. Tensioner installation is highly recommended. Large high-pressure flanges designed and manufactured abroad all use the tensile preloading method, which I think is very reasonable!

The first thing is to wipe it clean, tighten it symmetrically, and pre-tighten all the bolts 2 to 3 times. If the use temperature exceeds 350 degrees Celsius, it needs to be kept at this temperature for a certain period of time for heat tightening.

If the operating temperature is high, remember to heat it tightly.

Generally, it is the diagonal principle, clockwise or counterclockwise, until it is tight to the right position. The specific time when it is suitable depends on the situation on site!