Short answer: titanium and C-type nickel alloys can each be appropriate in different chemical pump services. The selection should follow the actual chemistry, concentration, temperature, contaminants, oxidizing or reducing condition, velocity, solids, component form and hydraulic duty—not a fixed material ranking.
What this comparison is actually screening
This article is for maintenance engineers, distributors and procurement teams evaluating an impeller, casing, cover, shaft sleeve, wet-end package or complete ANSI process pump replacement. It is not a corrosion-rate table and it does not approve an alloy for every acid or chloride service.
For a useful first screen, keep five questions together:
- What is the complete liquid composition, including impurities and cleaning or upset conditions?
- Is the environment predominantly oxidizing, reducing, mixed, aerated or intermittently exposed?
- What are the normal, minimum and maximum temperature, concentration and velocity conditions?
- Which exact component is being specified, and is it cast, wrought, welded or repaired?
- Will the proposed component meet the installed pump’s dimensional, mechanical and hydraulic requirements?
Condition-based screening: titanium or a C-type nickel alloy?
The table below is a decision aid, not a guarantee. A row identifies the type of engineering review to perform; it does not replace project data, a manufacturer’s applicable material specification or competent corrosion review.
| Service condition or question | Titanium route | C-type nickel-alloy route | Evidence still required |
|---|---|---|---|
| Nitric-acid or another strongly oxidizing duty | Screen titanium when the exact chemistry and temperature support a stable passive condition. | Screen a C-type alloy when the mixture, contaminants or component requirements make a nickel-alloy review appropriate. | Full composition, concentration range, temperature, aeration, contaminants and selected component form. |
| Mixed or reducing acids | Do not infer suitability from nitric-acid experience. Recheck the reducing species and transient conditions. | Often merits a C-type nickel-alloy review, subject to exact chemistry and manufacturing form. | Process chemistry, upset cases, velocity, crevices, heat treatment and approved material specification. |
| Chloride-bearing or wet-chlorine service | Screen titanium for the actual wet, oxidizing and temperature conditions; do not generalize to dry chlorine or every chloride mixture. | Review C-type alloys when mixed chemistry, reducing conditions or localized corrosion mechanisms are credible. | Chloride source and level, moisture, oxidizers, pH, temperature, solids, velocity and exposure cycle. |
| Unclear service data | Neither material should be selected from the chemical name alone. | Neither material should be selected from the alloy name alone. | Pause quotation approval and collect the RFQ inputs listed below. |
The terms “titanium” and “C-type nickel alloy” describe a screening family, not a complete purchase specification. Confirm the exact grade, product form, heat treatment, weld-repair controls and documentation for each wetted part.
How to evaluate the titanium route
Titanium can be a credible candidate in selected oxidizing and chloride-bearing services, but the passivity assumption must be tied to the real environment. Moisture, oxidizing state, concentration, temperature, contaminants, crevices and flow conditions can change the assessment.
Do not write that titanium is corrosion-proof or that it works across an unqualified concentration range. Instead, record the exact service window and ask the supplier to identify the material form being offered. If an impeller or casing is specified as a titanium casting, the RFQ should name the required casting specification, such as ASTM B367 Grade C-3 / UNS R52551 where that grade is the approved requirement. That designation must not be presented as an equivalency for wrought Titanium Grade 2, which is a separate wrought-material reference.
Also check the non-metallic parts around the impeller: gaskets, elastomers, mechanical-seal faces, flush arrangements and fasteners can control the practical service limit even when the primary wet-end metal is acceptable.
How to evaluate the C-type nickel-alloy route
Hastelloy is used as a family or trade name across several nickel-alloy products, so the approved grade and product form must be named. C-type nickel alloys are often considered when a service includes mixed or reducing chemistry, aggressive contaminants or a corrosion mechanism that needs a broader alloy review. That does not make every C-type alloy suitable for every process, and the product form matters.
Specify whether the requirement concerns a wrought alloy, a casting grade, weld metal, fasteners or another component. Do not use C-276 / UNS N10276 as a blanket substitute for a casting designation. The drawing, material specification, heat-number traceability, treatment condition and inspection plan should identify what is actually being supplied.
For background on this distinction, see the C-276 pump-parts material and fitment guide and the Alloy 20 vs C-276 material selection guide.
Where sulfuric acid changes the question
A sulfuric-acid service should not be treated as a simple extension of a nitric-acid or chloride screen. Concentration, temperature, water content, impurities, aeration, velocity and operating transients can materially change the selection.
Use the sulfuric-acid impeller material selection article and the Chemical Resistance Guide as starting points. If the exact condition is not listed, do not interpolate from a nearby row or convert a screening label into a corrosion-rate promise.
The same discipline applies to impellers and casings: the geometry, clearances, balance and hydraulic curve still have to be checked after the material route is selected.
Aftermarket replacement: material is only one fitment gate
An aftermarket titanium or nickel-alloy component should be released only after the installed pump and proposed component are identified. A familiar brand, nominal size or flange pattern does not prove that the part will fit or perform as intended.
For Goulds 3196, Durco Mark III or another ANSI reference, send the exact pump/model/component information. A proposed part may be a complete wet end, a single impeller or a broader assembly; the correct scope depends on the mating parts and the evidence available.
New RFQ input checklist
Include as much of the following as possible so the material and fitment review can be performed together:
- Installed pump manufacturer, model, size, frame or group, serial/asset number and nameplate photo.
- Exact component required: impeller, casing, cover, shaft sleeve, seal chamber, wet-end kit, power end or complete pump.
- OEM part number, position code, current drawing, section view, BOM or dimensional photos.
- Liquid name and complete composition, including concentration range, impurities, solids, pH where relevant, chloride source and oxidizing/reducing conditions.
- Normal, minimum and maximum temperature; flow, head, speed, specific gravity, viscosity, vapor pressure and suction conditions.
- Required material wording and product form. If a casting is required, state the applicable ASTM and UNS designation; do not substitute a wrought alloy name.
- Seal faces, elastomers, flush or barrier arrangement, gaskets, fasteners and any retained components.
- Required records: drawing approval, MTR, heat-number traceability, PMI, dimensional report, balance, hydrostatic test, NDE or repair-weld disclosure.
- Installation location, delivery country, quantity, required date and whether the request is a replacement, spare or new application.
Need a technical material and fitment review?
Send the pump nameplate, component reference, duty point and liquid conditions. ANSI Pumps Pro can screen the material route and identify the dimensions, documentation and interfaces that must be confirmed before quotation.
Related engineering resources
- Chemical Resistance Guide — screen listed chemistry, concentration and temperature conditions.
- Material Selection Guide: Alloy 20 vs C-276 — separate alloy families from casting designations and fitment evidence.
- C-276 Guide — review chemistry, product form, traceability and component fitment.
- Sulfuric-Acid Impeller Article — keep concentration and temperature attached to the screening decision.
- Exotic Alloy ANSI Pump Products — review available high-alloy pump and replacement routes subject to engineering confirmation.
Frequently asked questions
Is titanium automatically the right choice for nitric acid?
No. Nitric-acid service still requires the actual concentration, temperature, contaminants, operating cycle and component form to be reviewed. The result should be documented for the specific pump component.
Does ASTM B367 Grade C-3 mean wrought Titanium Grade 2?
No. Do not publish or purchase those as equivalent labels. If ASTM B367 Grade C-3 / UNS R52551 is required for a casting, state that casting designation separately from the wrought Titanium Grade 2 reference.
Is C-276 suitable for every sulfuric-acid or chloride service?
No. C-276 requires a project-specific review. Check the exact chemistry, concentration, temperature, impurities, velocity, oxidizing or reducing condition, product form and pump component.
Can an aftermarket impeller be quoted from the brand and size alone?
No. Confirm the exact pump/model/component, dimensional interfaces, hydraulic duty, material grade, seal arrangement and required inspection records before quotation approval.
