Maximum Variable Pressure of Gaskets in Sealing High Pressure Vessels

16 October 2017

What factors affect gasket performance when that product is utilized in a high-pressure vessel? Think about it for a moment. Imagine a horizontally oriented storage unit and the seals that secure a discharge port or an access hatch. What’s the first thing we notice when these rounded ports come into view? It’s the encircling ring of bolted fasteners, a feature that somehow influences the maximum variable pressure threshold of the gaskets.

Explaining Pressure Variability

Constants are welcome elements in any engineering discipline. They’re nice and easy to predict. Unfortunately, there are typically score of variables in motion at any given moment when a real-world engineering event is underway. Furthermore, if the engineered systems are responsible for a fluid, then the variable number swells as strange dynamic forces have their way. In high-pressure vessel design, rolled sheet metal panels and welded seams contain those dynamic forces, with a series of auxiliary fittings and pipes also channeling the fluid load when the liquid is moved elsewhere. Gaskets are the glue that hold the access plates and flange connectors securely in place on and around the storage vessel. How, then, do these seals react to the pressure variables we’ve briefly summarized so far?

Maximum Variable Pressure Ratings and Gasket Behaviour

As described earlier, one of the more immediate performance factors is identified on sight. It’s the mechanically applied torque, the pressure applied on the gasket material by the ring of fasteners. That steely band of bolts is perceived as a bolt load versus gasket load issue, a relationship that alters the elastic properties of the seal. Dependent on bolt torque, the stress placed on the port seal material will also plastically deform the gasket and produce a subsequent shift in the gasket’s spring index. Do these hampered performance features mean danger is in the air? Yes, to be absolutely blunt, the material changes will create an opportunity for a sealing defect. Picture a pressure increase. The gasket compresses, which it should, but if its maximum variable pressure rating isn’t satisfactory, then its compromised plasticity attribute will stop the seal from ‘springing’ back after the loading event has passed.

Leakage occurs if the gasket can’t vary its shape to accommodate this maximum variable pressure feature, so the selected material must be elastically and plastically designed to ensure full dimensional expansion after the fluid loading event has elapsed. By design, there are engineering equations that establish a required mutability feature within the sealing material. They add fastener load, material type, fluid pressure characteristics, and other pressure vessel-related criteria to complex formulas so that the seal always performs at its adaptable best.

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