14’’ Flange Clamp Installation

The injecting online leak sealing technology is a common emergency repair method in the process industry that can safely, economically, and efficiently eliminate leaks from devices, flanges, pipes, and valves. The work to repair flange leaks makes up about 90% of the total workload in several online leak sealing operations. This is due to the installation and machining flaws, such as uneven clearance, eccentricity, reducing, etc. that are present in most flanges currently in production. The online leak sealing clamp is intended for defective flanges and must be precisely machined and installed to ensure a successful seal.

Project Background

A leak sealing company situated in the Southeast Asia region had approached IMSA Projects for a flange leak solution. Common causes of flange leakage are as follows:

·      Uneven Bolt Stress. An incorrect bolt-up procedure or cramped working conditions near the flange can leave some bolts loose while others are overtightened and crush the gasket. This can cause in-service leaks, especially in high-temperature services when the heavily loaded bolts relax.

·       Improper Flange Alignment. Improper flange alignment, especially flange face parallelism, causes uneven gasket compression, and local crushing, and can cause subsequent leakage. Improper flange centreline alignment can also cause uneven gasket compression and flange leaks.

·       Improper Gasket Alignment. If a gasket is installed off-center compared to the flange faces, the gasket will be unevenly compressed and make the joint prone to leakage.

·       Thermal Shock. Rapid temperature fluctuations can cause flanges to deform temporarily. This is typically a greater potential problem in high-temperature applications.

·       High Vibration Levels. Excessive vibration can loosen flange bolts and ultimately cause flange leakage.

Table 1: Design details

Figure 3: Full Assembly

Figure 2: Clamp Design

With the above being said there are main integrity concerns regarding this job. They are as follows:

·       A rapid change in temperature and pressure within the valve could potentially cause the leak to worsen over time which would pose a safety risk.

·       The continuous leakage would cause corrosion over time which may spread and compromise the bolting system of the flange.

·       Corrosion of the flanges and bolting system would result in the weakening of the valve’s structural integrity

Figure 1: 14’’ HP BFW Valve Flanges

Our Solution

After carefully assessing the inquiry, IMSA Projects recommended a flange insert clamp design to the client. The clamp was designed in accordance with ASME VIII Div 1, and the information received from the client. A common flange clamp design would consist of a groove machined into the clamp, which would sit over the top of the flange gap, so that sealant could be injected through.

In this case, because the flange gap is greater than 10mm, the typical flange clamp design would not be a viable option, and thus a lip-type clamp would be a suitable choice. The lip on the flange clamp would fit into the gap between the flanges, which would allow for sealant injection to completely fill up the enclosed space and arrest the leak (refer to figure 2 below). Strong backs are used to add structural integrity to the equipment being sealed. It’s a safety measure that cannot be avoided should the pressure be astronomically high or the equipment itself looks heavily corroded. For this job, a lug-type strongback system was recommended as the pressure was moderately high. Figure 3 refers to the overview of the clamp assembly including the strong backs.

Conclusion

The client was pleased with the service provided and advised that the clamp was successfully installed and had sealed the leak. The valve can now operate at optimal efficiency with no product loss. The clamp installation prevented an unplanned turnaround from taking place, hence a maximum of 5 years can be added to the lifespan of the equipment.

IMSA Projects prides itself in its excellent customer support and commitment to customer satisfaction in terms of service delivery. Contact us for your leak-sealing solutions.