Flange integrity and protection is critical to containment of fluids in a piping system. Loss of containment, whether in chemical, hydrocarbon, gas or water distribution pipelines, has a significant environmental and operational impact. This could pose a serious security risk.
Flange corrosion problems
Crack corrosion is a common damage mechanism where there is a concentration of corrosive substances in a localized area. In fact, the rate of corrosion is accelerated by the concentration of corrosive materials within an enclosed space. The crack between the faces of two flanges is the ideal environment for corrosion development. The flange face is especially prone to crevice corrosion when flanges are used in extremely corrosive environments.
Over time, corrosion that begins in the inside diameter clearance of a flange can spread to the gasket area. The concentration of corrosive materials between the sealing surface and the gasket material can influence the corrosion rate.
The gasket functions as a seal that covers the face surface from the edge to the end of the machined surface. Corrosion in the sealing zone can result in loss of containment and product leakage with potentially catastrophic consequences for the environment.
Insufficient external flange protection can lead to damage to flanges and fasteners, accelerating deterioration of system integrity. The consequences of this situation are not easy to predict, as they depend on the prevailing conditions. The degradation of the substrate can be slow and continuous, depending on the severity of the environmental conditions; however, under extreme conditions, the external corrosion process can quickly reach a point where the structural integrity of the system is impaired and could result in a catastrophic loss of containment.
Flange face repair
The corrosive action of chemicals, crevice corrosion, galvanic corrosion, and high pressure steam damage can lead to deterioration and consequent leakage of the flanges.
Belzona’s flange face molding technology eliminates the need for traditional welding methods that involve hot work. It allows a simple application in emergency situations, especially in places with limited access, such as offshore platforms.
Belzona’s exclusive repair kit is designed to help combat common flange joint mating surface problems.
Flange protection with Belzona encapsulating membrane
Para responder a los problemas de corrosión externa en bridas, Belzona ha formulado dos recubrimientos; uno que se puede cortar y remover y otro aplicable con pulverizador. Estos han sido diseñados específicamente para la protección de las bridas, sujeciones y tuberías asociadas para impedir el ingreso de humedad y prevenir la corrosión atmosférica, galvánica y por grietas. Ambos sistemas comienzan con una capa del inhibidor de corrosión, Belzona 8411. Luego, se puede usar Belzona 3411 o Belzona 3412 para formar una capa de encapsulado flexible y fuerte.
These durable systems are used to protect flanges of most shapes, sizes, and configurations from corrosion, and encapsulate the flange to keep moisture out. Belzona 8411 inhibitor also has mold release properties, allowing layers of Belzona 3411 or Belzona 3412 coating to be removed from the joint to allow inspection.
If maintenance is required, the coating is simply cut with a sharp knife at the level of the separation plane on both flange faces.
Las dos mitades de la membrana se repliegan hacia atrás para dejar a la vista los pernos y las bridas. Una vez finalizado el trabajo de mantenimiento, las membranas se despliegan nuevamente a su posición original y se sellan aplicando Belzona 3411 o Belzona 3412.
These systems are easy to apply, do not require heat, and form a tough, elastic protective barrier once set. Additionally, Belzona 3412 has been designed to be applied quickly and effectively with the Belzona spray gun.
Erosion resistance test
As flanged connections are a critical component within the piping system, effective monitoring and inspection techniques are required to minimize unscheduled outages due to leaks to meet increasingly demanding production requirements.
Since the sealing faces of the flanges can only be inspected during a system outage, it is vital that this process be done as simply as possible and therefore removing external corrosion should be a priority.
If it is not possible to interrupt service, the inspection can be performed using ultrasonic techniques but, again, this process can be much more complex and imprecise if external corrosion is not controlled. Therefore, protection against external corrosion of flanges and fasteners is critical in order to monitor the system and allow more realistic and effective quality control and inspection procedures.
The Belzona 3411 encapsulation system can be used not only to provide complete corrosion protection for flanges, fasteners and their associated piping, but also as a preventative system that helps facilitate monitoring and inspection of flange faces.
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