Generally, DN700 flange is selected based on the material, diameter, temperature and pressure of the pipe. When the pressure or temperature changes, the outer dimensions of the flange will change accordingly. For example, for a DN700 pipe, you need to know the material, operating pressure and temperature of the pipe, and you can choose a DN700 flange based on these three parameters. The bolts and gaskets that match the flange are also related to these parameters.
DN700 Flange Connection Methods
Before tightening the bolts, the gap of the DN700 flange sealing surface should not be greater than 2 times the thickness of the gasket. It shall not be put in place with the help of additional auxiliary tools, nor shall the method of tightening the bolts be used to adjust the spacing of the flanges or eliminate the deflection of the flange joints. The allowable gap between the flange joints or the matching of the final closed end of the pipeline shall comply with the regulations.
When the pipeline is connected to the moving equipment (such as the inlet and outlet of the rotating equipment such as the pump), the installation allowable deviation of the flange joint shall comply with the corresponding regulations, and no additional installation load shall be added.
The bolts shall pass freely through the bolt holes perpendicular to the flange, and the nuts shall be flat against the back of the flange. Pipes or other connectors that may affect the centering of the flange have been properly supported.
DN700 Flange Installation Methods
The excessive installation deviation of the DN700 flange joint shall be corrected before the gasket is installed.
When assembling the DN700 flange joint, the size of the gasket shall be consistent with the size of the flange. Only one gasket is allowed between the sealing surfaces of a pair of flanges. The gasket installation should be kept coaxial with the flange to prevent the gasket from blocking the medium flow channel.
Appropriate methods should be used for positioning during the installation of the gasket. Do not use tape to fix gaskets, and do not use grease (unless the gasket manufacturer has special requirements).
Close the flange to ensure that the gasket is not crushed.
Unless otherwise specified in the installation procedure document, when tightening the bolts with a torque wrench, use an approved lubricant evenly applied to the working surface of the bolts and the bearing surface of the nuts or washers to prevent the lubricant from being contaminated on the gasket and flange sealing surface.
Anti-seizure lubricant is not required for new coated bolts. However, anti-seizure lubricant should be applied when used for the second time.
Assemble the bolts and nuts on each bolt hole of the flange, tighten or rotate the nuts manually to the marked position appropriately, and the number of threads extending from the nut at the end of each bolt is equal.
The same specification bolts should be used for flange joint assembly, and the installation direction should be consistent. The bolts should be tightened symmetrically. After tightening, the bolts should be close to the flange without wedge gaps. When washers are required, no more than 1 should be added to each bolt. All nuts should be fully screwed into the bolts. In any case, the threads on the nut that are not fully engaged should not be greater than 1 pitch. When using a bolt tensioning device, the bolt length should be checked.
When assembling a DN700 flange joint, if the pressure rating or mechanical properties of the two flanges are significantly different, the bearing capacity of the flange with a lower pressure rating or lower tensile strength should be considered. The bolts should be tightened to the predetermined torque.
Our DN700 Flange
If you want to buy some DN700 flange, you need to distinguish between different types of DN700 flange according to your own needs to ensure that flange you purchase can meet your production needs. If you have any questions, please don’t hesitate to contact Elite Piping Manufacture Co.
