John Crane Type 59U Replacement Mechanical Seal

An Economical Wedge Seal for Moderate-Pressure Corrosive Duty

Dropping the hydraulic balancing found in the 59B keeps this seal simpler and more affordable, while holding onto the PTFE wedge construction that carries it through the same cryogenic-to-high-temperature range and corrosive chemical exposure. Its short overall unit length suits straight-through shaft configurations where a longer balanced assembly wouldn't fit, making it a practical choice for general low- to medium-pressure duty across chemical, refinery, and petrochemical lines. Where the 59B earns its place on higher-pressure, higher-stakes service, the 59U covers the same temperature and chemical extremes at a lower cost when pressures stay moderate. Wedge-seal fitment steps are covered in our blog.