John Crane Type 58B Replacement Mechanical Seal

The High-Pressure Step-Up Within the Same Seal Family

Sharing its core architecture with the 58U, the 58B adds hydraulic face balancing to handle pressures several times higher than its unbalanced sibling, without changing the seal's overall footprint or working length. Because it uses components common to the rest of the 57B/58B/58U range, plants can standardize on this platform and shift between balanced, unbalanced, or wedge variants as service conditions demand, without stocking entirely separate seal families. That pressure headroom is exactly why it's specified across refinery, petrochemical, and general high-pressure chemical processing duty where the 58U's lower ceiling isn't enough. Fitment steps for this O-ring pusher family are covered in our blog.