1. When a replacement is worth evaluating — and what to compare between suppliers
Replacing a centrifugal pump that still runs is usually driven by operations, not by a defect in the original design: spare parts with uncertain delivery, a discontinued model, technical support far from the plant, repeated failures of the same component, or a process change that moved the pump away from the point it was selected for. Each reason calls for a different check.
Repeated seal or bearing failure, for example, may come from operation far from the best efficiency point, insufficient NPSH or misalignment — and may recur if the cause is not identified in the survey.
Delivery times vary with model, material, production backlog and logistics; this page does not publish generic lead times for imported pumps or for FBCN. What can be compared objectively is what each supplier states in writing in the proposal: delivery time of the complete pump; delivery time and availability of each recommended spare part; documents supplied (data sheet, curve, dimensional drawing, parts list, installation and operation manual); tests included and whether they will be witnessed; warranty; and technical support channel.
The criterion applies to FB and to any other supplier.
For FBCN, the technical manual (MTEC-03/00) documents: back-pull-out construction, which lets the bearing assembly be removed without disconnecting the piping from the volute; a parts list numbered to DIN EN 24250 — casing (102), shaft (210), impeller (230), bearings (321), mechanical seal (433) or packing (461), casing wear ring (502) and impeller wear ring (503), shaft sleeve (524); bearings specified per bearing-frame size in Table 1 (for example, 6306 C3 or 6310 C3, with different arrangements in the largest sizes); and oil lubrication, with a level dipstick or an optional constant-level oiler.
With this list, spare parts can be specified when the pump is bought, with delivery time requested item by item.
Note
Support in Portuguese and in the same time zone helps diagnosis at plants in Brazil, but what shortens a shutdown is having the right documents before the failure: model curve with the duty point, dimensional drawing, coded parts list, installation and operation manual, and the start-up records (pressures, current, vibration, bearing temperature). Ask for these documents at purchase — from any supplier.
2. Compatibility: compare drawings and installation
A normalized centrifugal pump follows standardized construction or dimensional requirements. Check the declared standard and scope for each unit. The FBCN manual describes mechanical construction to ASME B73.1; compatibility with an existing installation must be confirmed using both equipment drawings.
In ASME B73.1, dimensional interchangeability applies to pumps of the same standard dimension designation defined by the standard itself and covers mounting dimensions, size and location of suction and discharge nozzles, input shaft, baseplate and foundation bolt holes. The FBCN designation follows a different logic — FBCN 150-400 means a DN 150 discharge flange and a 400 mm nominal impeller — and the manual does not map it to ASME B73.1 dimension designations.
The reference to the standard therefore does not replace a dimension-by-dimension comparison. And even when the dimensions match, Q×H point, speed, power, NPSHr, flange class and facing, materials and sealing are still checked separately.
What to compare on the drawing: DN and position of suction and discharge nozzles, distance from shaft to suction flange, shaft-to-base height, overall length, foot or baseplate dimensions and bolt holes, and the shaft end (diameter, length and key).
For the 43 standard sizes these dimensions are in the manual dimension table and on each model page; for FBCN 50-200, for example, DN 80 suction, DN 50 discharge, 160 mm shaft-to-base height and a Ø 24 mm (m6) by 50 mm shaft end. For the 100-500 and the ten large sizes (150-500 to 300-340), the dimensional drawing is supplied by engineering on request.
Reuse of foundation and connections depends on this comparison; it must not be assumed from the reference to the standard.
The comparison leads to one of three outcomes, which the proposal makes explicit before the order: the dimensions match and FBCN sits on the existing baseplate, with the coupling realigned; there are position or flange differences solved with a spool piece, reducer or baseplate adaptation; or the dimensions do not close and the pump set comes on a new baseplate, with the piping and, if needed, the foundation reviewed.
In every case, the piping must arrive aligned with the nozzles, without being forced to make up for a dimensional difference.
3. The survey sheet: what engineering needs from the installed pump
Assessment starts with installation data: fluid, flow in m³/h, head in m, temperature, viscosity at that temperature, and available drive speed and power. If a value is not yet available, identify the gap in your enquiry. The nameplate, dimensional drawing, suction conditions and operating history complete the survey used to compare the proposed and installed pumps and identify modifications before installation.
Nameplate. A photo of the nameplate is the most useful item in the survey: manufacturer, model and size, serial number, speed and usually the design point. With the serial number, the data sheet and certified drawing can be requested from the original manufacturer or found in the plant file.
Mind the designations: for FBCN, the numbers give the discharge flange DN and the nominal impeller diameter in mm, and the suction DN is different — FBCN 150-400 has a DN 200 suction. Similar designations from other lines do not mean the same dimensions or the same curve.
Mechanical interfaces. Flange class and facing; direction of rotation; coupling type and size; motor power, speed, frame and mounting. On FBCN, cast iron flanges are ANSI B16.1 125 lb FF or 250 lb FF, depending on size, and steel or ductile iron flanges are ANSI B16.5/B16.42 150 lb RF; rotation is clockwise viewed from the drive end (manual, Table 1). If the installed pump has a different class or facing, gasket and connection are defined in the replacement design.
The manual also covers electric motor or diesel drive, flexible coupling with or without spacer, coupling guard in carbon steel or non-sparking material, and a welded structural steel baseplate.
Suction and process conditions. Available NPSH (or the data to compute it: liquid level elevation, vessel pressure, suction line losses and vapour pressure at pumping temperature), suspended solids, duty cycle and the real operating range — not just the design point.
The FBCN manual gives a minimum flow of 0.1 or 0.15 Qopt and a maximum of 1.1 Qopt, depending on the size group, where Qopt is the flow at the optimum point, and a maximum suction pressure of 10 bar (Table 1). If the installed pump spends part of its time outside that range, the replacement must address it — with another size, another impeller diameter, speed variation or recirculation — rather than simply replace the equipment.
Materials and sealing. Casing and impeller material of the installed pump, sealing in use and failure history. FBCN has a cast iron, ASTM A216 WCB carbon steel or ASTM A743 CF8M stainless casing, each with its own pressure × temperature limits in the manual; the choice follows from the fluid and temperature, not from what was installed.
Sealing may be packing — standard ST arrangement, lubricated by the pumped fluid, for clean and non-aggressive fluids; S1, sealed with clean external liquid, for toxic, aggressive or malodorous fluids and suction under vacuum; S2, for fluids with particles or fibres; S3, with external flushing, for abrasives or crystallisation risk — or a mechanical seal selected for the application.
The temperature limits of each arrangement are in the manual and are confirmed during selection; for fluids with suspended solids, the manual asks for FB to be consulted. If the installed pump circulates thermal oil, include the FBOT series, dedicated to that service, in the comparison.
Documents to check in the proposal. Confirm the FBCN model, speed and impeller diameter, the curve with the duty point marked, NPSHr at that point, the dimensional drawing for checking against the existing installation, materials and sealing, the list of adaptations and the recommended spare parts. Performance testing, witnessing and material certificates are included when specified in the order.
As a range reference, the manual gives for the series DN 25 to 300, flow up to 2,200 m³/h, head up to 135 m, temperature up to 260 °C and speed up to 3,500 rpm. These are series limits, not limits of a single model, and they are not simultaneous: some sizes are limited to 1,750 rpm, and the ten large sizes are on request.
u = π × D × n / 60 → D = 0,250 m; n = 3.500 rpm → u ≈ 45,8 m/s (> 40 m/s)Impeller tip speed (u in m/s, D in m, n in rpm). The FBCN manual limits u by impeller material: cast iron up to 40 m/s; ductile iron and carbon steel up to 60 m/s; stainless steels up to 80 m/s. Check it whenever the replacement changes the speed.
| Installed pump data | What it is for | Where to get it |
|---|---|---|
| Nameplate (photo) | Manufacturer, model, size, serial number, speed and usually the design point | On the pump; with the serial number, data sheet and drawing can be requested from the original manufacturer |
| Dimensional drawing or field measurements | Compare nozzles, shaft-to-base height, feet or baseplate, bolt holes and shaft end | Plant technical file; otherwise, a sketch with the measured dimensions |
| Actual duty point and operating range | Place the point on the FBCN curve and check the manual flow range | Flow meter and suction and discharge gauges; without a meter, an estimate from the curve with its uncertainty stated |
| Fluid, temperature, viscosity and solids | Materials, sealing arrangement and performance correction for viscosity | Safety data sheet (SDS) and process data |
| Available NPSH or data to compute it | Compare with the model NPSHr at the duty point and at the highest expected flow | Liquid level elevation, vessel pressure, suction losses and vapour pressure at temperature |
| Installed motor and coupling | Assess reuse: power with margin, speed, frame and shaft end | Motor and coupling nameplates |
| Failure history | Avoid repeating the cause: seal, bearing, wear, cavitation | Plant maintenance records |
Engineering note
How to validate the replacement on paper: request the curve of the proposed FBCN model with the duty point marked and overlay the installed pump curve and the system curve. Check four items: the point within the manual flow range (0.1 or 0.15 to 1.1 Qopt); NPSHr at the duty point and at the highest expected flow against NPSHa, with the margin adopted in the design; absorbed power at the highest expected flow against the motor, with the reserve from Table 2 of the manual (the reserve depends on the power band; confirm the selected motor in the proposal); and impeller tip speed against the material limit. If any item fails, the proposal changes model, impeller, speed or motor before the order.
4. Technical migration process checklist: from survey to commissioning
The process has five steps, with FB Bombas application engineering and the client maintenance team. The time each step takes depends on size, adaptations and contracted scope and is stated in the proposal — there is no standard duration.
Step 1 — Survey. The client sends the survey sheet from section 3: nameplate, dimensional drawing or field measurements, original data sheet and curve where they exist, measured duty point (flow from a meter; without one, an estimate from pressures and the curve, with its uncertainty stated), fluid and temperature, available NPSH, motor and coupling data, and failure history.
Step 2 — Technical proposal. Check the model, speed, impeller diameter, curve with the duty point, dimensions, materials, sealing and required modifications. Request comparison with the installed pump curve and drawing when available, and confirm which documents, spare parts and services the proposal includes. Delivery time and commercial terms must reflect that scope. Before ordering, validate the interfaces with the team responsible for installation.
Step 3 — Manufacturing and tests. Delivery time as per the proposal. The FBCN manual gives the hydrostatic test pressure as per ANSI B73.1 (Table 1). Performance testing, points and tolerances, witnessing and material certificates are defined in the order; FB Bombas reports an in-house test bench. The test curve, when contracted, is the reference for comparing the performance measured in the field after start-up.
Step 4 — Field replacement. With the plant shut down, the installation team removes the old pump and installs FBCN on the existing baseplate or on the new one, as per the proposal. The piping is connected aligned with the nozzles, with no load on the pump; motor direction of rotation is checked with the pump uncoupled; coupling alignment follows the coupling manufacturer tolerance and is checked again after the piping is connected; bearing oil level is checked before start-up.
Duration depends on size, access and the planned adaptations.
Step 5 — Start-up and verification. Follow the installation and operation manual of the supplied pump, with the pump and suction line full of liquid and the suction valve fully open, without running for long periods below the manual minimum flow. Record suction and discharge pressures, flow (if there is a meter), motor current, bearing temperature and vibration, and compare pressure × flow with the model curve.
Vibration and temperature limits follow the project specification and the standards adopted by the client. Start-up support by FB is a start-up and commissioning service, with the form of support, checks and records defined in the contracted scope.
5. Petrobras CRC and design requirements: what the registration covers
FB Bombas reports registration in the Petrobras supplier registry (CRC, formerly CRCC). According to Petrobras, the CRC is issued to suppliers that meet criteria of the family of interest, is valid for tender eligibility for up to one year and is not required to take part in procurement; it is not a product certification. Request the documentation during your enquiry to check the registration families and validity.
When replacing a pump at a Petrobras facility or for another buyer with its own specification, the buyer data sheet decides: required standards, materials, sealing, tests, inspection and documentation. FBCN is offered on the basis of what its manual documents — among other points, mechanical construction to ASME B73.1.
If the specification asks for more, such as API 610 for the pump or API 682 for the sealing, ask for the proposal to answer item by item: compliant, not compliant or with exception.
The CRC does not replace the technical check of the replacement either: drawing, curve, NPSH, materials and sealing are still checked unit by unit, as in sections 2 and 3. For hydrocarbons in classified areas, H2S service or specific refining requirements, the petrochemical and oil and gas application guides detail what to verify.