Allied Seals supplies O-rings, square rings, and custom sealing solutions for industrial applications. Here’s a quick overview of what we do and how we help customers choose the right seal.


Allied Seals supplies O-rings, square rings, and custom sealing solutions for industrial applications. Here’s a quick overview of what we do and how we help customers choose the right seal.


An O-ring is one of the most widely used sealing components in the world — a simple loop of elastomer that sits in a machined groove and prevents fluid or gas from passing between two mating surfaces. Despite their modest size, the decisions behind O-ring selection — material, sizing, gland design — determine whether a system runs reliably for years or becomes a recurring maintenance problem.
Square rings share the same familiar torus shape as O-rings but with one key difference: a flat, square cross-section instead of a round one. That geometry change gives them more sealing surface area, better resistance to rolling and twisting, and strong performance under high-pressure static loads — often making them a direct, drop-in upgrade over a standard O-ring with no groove redesign required. This article covers how square rings are constructed, when they outperform O-rings, material options, and what to watch out for in installation and service.