PumpWorks ANSI Pump Cases
PumpWorks ANSI pump cases (casings) are the heavy-duty pressure vessels of the PWA and PWA-IL series. They are designed not only to house the impeller but to withstand the rigorous stresses of chemical process industries (CPI).
While most manufacturers treat the casing as a basic cast component, PumpWorks treats it as a high-precision engineered part with several standard upgrades.
Material Superiority: The Carbon Steel Standard
The most significant differentiator is the use of ASTM A216 Grade WCB Carbon Steel as the standard material.
Impact Resistance: Unlike Ductile Iron, which can be brittle and prone to cracking under thermal shock or physical impact, Carbon Steel is much more resilient.
Weld-Repairable: If a Carbon Steel case suffers internal wear or minor pitting, it can be welded and re-machined. Ductile Iron is generally considered non-repairable; once it's worn, it's scrap.
Freezing Protection: Carbon Steel is significantly more resistant to rupture if priming fluid is accidentally left in the pump during freezing temperatures.
Specialized Case Designs
PumpWorks offers different casing geometries depending on the specific application needs:
Standard Volute (PWA): A standard high-efficiency spiral casing designed for general process applications.
Circular Volute (PWA-LF): Used in the Low Flow series.The circular design, combined with a precisely machined discharge channel, provides stable hydraulics and minimizes vibration when running at low flow rates.
In-Line Case (PWA-IL): Designed to be installed directly into a pipeline like a valve. This case features a centerline discharge for simplified piping and a smaller footprint.
Self-Priming Case (PWA-SP): Includes a large priming chamber that allows the pump to clear air from the suction line without external valves or air separators.
Key Engineering Features
Class 150# & 300# Options: Standard cases come with ANSI Class 150# flange ratings. However, PumpWorks offers Class 300# (375 PSI MAWP) options in both Flat Face (FF) and Raised Face (RF) designs—often at no additional cost.
Back Pull-Out Design: The case is designed so that the entire "power end" (shaft, bearings, and impeller) can be removed for maintenance without disconnecting the casing from the piping.
Centerline Discharge: This design makes the pump "self-venting," preventing air binding and simplifying the piping layout.
Precision Machining: Every case is machined to strict ANSI B73.1 or B73.2 standards, ensuring 100% interchangeability with existing Goulds or Durco installations.
When to Replace the Casing
The casing is the most expensive "wet end" part, so it is usually the last thing to be replaced. You should consider a new casing if:
Wall Thinning: The interior wall has worn down by more than 25% of its original thickness due to erosion or corrosion.
Unrepairable Pitting: Pitting is so deep that a weld repair would compromise the pressure rating.
Flange Damage: The flange faces are warped or scarred deeply enough that they can no longer maintain a seal.
Cracks: Any visible crack in a pressure-retaining vessel is an immediate "fail" and requires replacement.
Would you like me to find the specific dimensional drawings for a certain case size, or help you compare the Class 150 vs Class 300 pressure ratings?
