How to Verify Flange Tightness - Proper Installation Steps for Flanges

Before installation, it's essential to inspect the inner cleanliness of the pipe, the condition of the flange surface and gasket for any damage, and ensure the bolts and gaskets match the design specifications. If the flange sealing surface is rusted, use a manual wire brush or other suitable tools to remove the rust and a cleaning agent to eliminate stains. Assess the condition of the sealing surface and avoid using severely damaged flange sealing surfaces. During maintenance, examine the flange sealing surface after disassembly and replace it if damaged.

50. Before installing the flange, inspect and verify the flange sealing surface and gasket to ensure there are no defects that could affect the sealing performance. Additionally, remove any protective grease present on the flange sealing surface.
50. The bolts used to connect the flanges should be able to penetrate smoothly.

50. The installation direction and the exposed length of the flange bolts should be uniform.
50. Hand-tighten the nut to ensure smooth rotation on the stud.
50. The flange installation should be aligned properly, and the parallelism of the flange sealing surfaces should meet the specifications' requirements.

Bolt Tightening Procedure 

The flange connection bolts should be tightened in a symmetrical sequence, gradually increasing the tightening torque until the final required torque is reached. The specific steps are as follows:

Step 1: Hand-tighten the nut and use a manual wrench to preliminarily tighten it, ensuring the parallelism of the flange is maintained.

Step 2: Tighten the bolts to 30% of the final torque value, ensuring symmetrical tightening, and verify the consistency of the flange spacing.

Step 3: Tighten the bolts to 60% of the final torque value, ensuring symmetrical tightening, and verify the consistency of the flange spacing.

Step 4: Tighten the bolts to the target torque value, ensuring symmetrical tightening, and verify the consistency of the flange spacing.

Step 5: Sequentially tighten the bolts to the target torque value to ensure consistency and verify the flange spacing.

After tightening the flange bolts following the above steps, use a marker to draw a cross line along the end face of the stud/nut. Include details such as the flange number, target torque value, operator, and operation time.

How to Verify Flange Tightness

The pipeline pressure test is a vital method for assessing the sealing performance of flanges. Throughout the pressure testing process, it's essential to check the sealing performance of each pair of flanges to ensure there is no leakage. The flange sealing performance test during the pressure testing process should include the following steps:

50. If a leak is detected in the flange, it is strictly prohibited to tighten it under pressure. Instead, identify the leak point, make a mark, and address it after releasing the pressure.
50. Inspect the flange's parallelism and the bolts' tightening torque after pressure release. If the parallelism is not aligned, loosen the bolts opposite the opening end, readjust the flanges' parallelism, and retighten following the bolt tightening procedure. If only the bolt torque fails to meet the requirements, it can be adjusted directly to the target torque.
50. After adjusting the flange, conduct another pressure test. The test is deemed successful if there is no leakage and the flange bolts are remarked. If leakage persists, the flange must be opened after pressure relief, and the flange sealing surface and gaskets must be inspected. Replace any damaged gaskets with new ones. If the flange sealing surface is damaged, replace or repair it onsite. Once the issue is resolved, conduct another pressure test until it passes and remark the flange bolts.

Conclusion

We're pleased to address any inquiries regarding manufacturers of 3-inch pipe flanges, 4-inch pipe flanges, Chinese 3-inch pipe flanges, or Chinese 4-inch pipe flanges.