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Stainless steel centrifugal pump volute casings staged on a pallet after casting and machining
Solution

Pump Material Selection

Cast iron through to UHMW-PE. How the Flowsteer range maps onto water that ranges from clean to chemically hostile.

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The Situation

Why This Matters

Most pump failures that arrive as warranty questions are material failures, not hydraulic ones. The duty point was right; the casing was wrong for the water.

The Flowsteer range covers a deliberately wide material span — grey iron, ductile iron, carbon steel, bronze, SS304, SS316, PP, PE and UHMW-PE — because water duties range from potable supply to dosed effluent, and no single material covers both.

The decision is made from the water analysis at its worst, not its average. A stream that is benign for eleven months and dosed for one is a dosed-water duty.

Stainless steel centrifugal pump volute casings staged on a pallet after casting and machining

Stainless steel centrifugal pump volute casings staged on a pallet after casting and machining

Step by Step

How It Works in Practice

  1. Start with the analysis, not the budgetChloride content, pH, dissolved solids and temperature decide the material. Price decides which acceptable material you buy, not whether an unsuitable one will do.
  2. Separate casing from impellerThey see different conditions. The FA series ships a bronze impeller in a cast iron casing precisely because the impeller sees velocity and the casing does not.
  3. Check the temperature against the materialPolymers lose strength long before they visibly deform. The KCP is published to 80 °C and the VNP to 80 °C operating; beyond that, metal is the only option.
  4. Decide on abrasion separately from corrosionUHMW-PE is chosen over PP when the stream is abrasive as well as aggressive. They are two different attacks on the same part.
  5. Specify the shaft material tooThe FA publishes four shaft options — ASTM 420, 304, 316 and 1045 — because the shaft can see the pumped liquid at the seal.
  6. Write the specification into the orderA material decided by phone and not recorded on the order is a material that will be assumed at the next reorder.
What You Gain

What Changes When You Do This Properly

  • Metal and polymer from one catalogueThe choice does not force a change of supplier or a second dimensional standard.
  • Published material listsThe FA and KCP series both publish their full material options rather than quoting on request.
  • Options at every levelCasing, impeller, shaft and seal are specified separately rather than as a single grade.
  • Unconfirmed values marked TBCWhere the source catalogue does not publish a material list, as on the DE series, we mark it rather than guess.
Applies To

Pumps This Solution Covers

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Guides on This Subject

Stainless steel centrifugal pump volute casings staged on a pallet after casting and machining
Material Guide

Pump Materials Guide

Grey iron through to UHMW-PE. What each wetted material is for, and the failure it is chosen to prevent.

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Machined closed impellers and flanged casings laid out for assembly
Design Guide

Open vs Closed Impellers

Efficiency on one side, solids passage and adjustability on the other. The choice is decided by the water, not the pump.

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Questions

Pump Material Selection FAQ

SS304 or SS316?

SS316 contains molybdenum and resists chloride pitting far better. If the water is brackish, heavily chlorinated or chemically dosed, specify 316. For softened and treated water at low chloride, 304 is usually sufficient.

When should I move from metal to polymer?

When the analysis shows the chemistry will attack both iron and stainless. At that point the KCP series in PP, PE or UHMW-PE changes the failure mode from material loss to ordinary bearing and seal wear.

Why is the FA impeller bronze but the casing cast iron?

The impeller sees high velocity water and erodes; the casing does not. Matching the material to the duty of each part rather than to the pump as a whole is cheaper and lasts longer.

What if I do not have a water analysis?

Tell us what the water is and where it comes from, and what has failed before. A pump that corroded through in one season tells us more than an average analysis does.

Put Pump Material Selection to Work on Your Plant

Tell us the pumps you have and the duties they run, and we will say where this applies and what it would change.

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