Flowserve WXB/WXBB API 610 BB5 Barrel Pump

WXB and WXBB API 610 BB5 double-case barrel pumps

The Flowserve WXB is a horizontal, multistage, double-case barrel pump in the BB5 category of API 610, and the WXBB is its low-flow, high-head companion. Both use a diffuser inner element housed in a barrel casing, with a balance drum to carry axial thrust. They are aimed at users who want the hydraulic range of a ring-section pump but also want the safety and serviceability of a barrel casing. Seven Star LLC supplies Flowserve WXB and WXBB pumps and spares in Oman and the GCC as an independent supplier in Muscat.

WXB is a series name rather than one catalogue number, so every pump is configured to the duty. The series is described by four frame sizes, thirteen hydraulics and up to sixteen stages for the WXB, and one size with eight hydraulic designs and up to eight stages for the WXBB. Pumps are built to individual customer specifications on the basis of API 610 (BB5).

WXB and WXBB technical specifications

How the WXB double-case design works

The outer barrel is a pressure vessel designed to ASME pressure vessel practice and to withstand twice the rated nozzle loads required by API. Inside it sits a compact, radially split cartridge that holds the rotor, diffusers, suction and discharge heads, seals and bearing assemblies. Because the whole element is a cartridge, it can be pulled and replaced as one unit, and the major assembly, mechanical seal fitting and rotor setting can be done in the workshop rather than in the field. Centerline mounting lets the barrel expand symmetrically about its supports.

The impellers are precision-cast and dynamically balanced, with a large-eye first stage to improve NPSH behaviour. Multi-vane diffusers balance radial loads throughout the flow range including part-load operation. A thrust balancing device keeps axial thrust nearly constant, so balance line flow stays small and efficiency holds at all loads. Renewable wear rings are standard on casings and impellers so running clearances can be restored economically.

WXBB low-flow variant and back-to-back option

The WXBB extends the WXB into applications where flow is small but head is very high. It uses Barske-style impellers, which give a constantly rising head curve and stable operation at low flow, and it runs direct drive at two-pole speed so no belts or gearbox are needed. A back-to-back (opposed) impeller arrangement is available for higher discharge pressure; the central bushing and sleeve improve rotor dynamics and rotor stability in pumps with higher stage counts. The back-to-back configuration is the route to the 200 bar figure on the WXB.

Where the WXB fits and which parts relate to it

Flowserve lists the typical applications as pipeline transfer, crude oil, lean amine, refinery charge, reactor product transfer, column bottoms recycle, boiler feed and refinery boiler feed, ethylene feed, solvents, naphtha, wash oil, hydrocarbon charge, condensate, produced water re-injection, and booster and recycle duties. The pump is seen as a medium-duty barrel pump, so for the most severe high-pressure services a larger BB5 design may be more suitable. Related Flowserve equipment on the same train includes the API 682 mechanical seals, Limitorque or other actuators on isolation valves, and the HPX or other API 610 pumps used as booster or charge pumps.

WXB selection and ordering checklist

• Flow, differential head and NPSH available, with the minimum and maximum operating points; the WXB covers up to 300 m³/h and the WXBB 4.5 to 35 m³/h.
• Pumped liquid, density, viscosity, vapour pressure, temperature range and any H₂S, chloride or CO₂ content that sets the material class.
• Suction pressure and maximum discharge pressure, which decide between the standard and back-to-back configuration.
• Barrel material: carbon steel, stainless, duplex, super duplex or low-temperature carbon steel.
• Nozzle orientation (top-top or side-side) and flange standard (ASME or DIN).
• Seal type, API 682 category and flush plan; bearing lubrication method.
• Driver power, speed and whether the WXBB direct drive at two-pole speed is intended.
• Testing scope: ISO, API and Hydraulic Institute performance tests at full flow, pressure and speed.

Installation, commissioning and maintenance of the WXB

Barrel pumps are sensitive to piping strain and to thermal start-up. Align the pump to the driver with a thermal growth allowance, and warm the casing gradually on hot services to avoid thermal shock. Make sure suction piping is free from air pockets and the minimum flow line is functional, since multistage diffusers do not tolerate extended operation at low flow unless they were selected for it. Set the balance line, seal flush and bearing lubrication as per the data sheet before the first start.

Routine maintenance concentrates on bearing oil condition, vibration, seal leakage and wear ring clearances. The cartridge design shortens turnaround: a spare cartridge or a pre-assembled spare rotor lets the plant swap the element and send the removed one to the workshop. Record the pump serial number when ordering any wear part so the correct hydraulic and stage count is matched.

Typical WXB applications in Oman and the GCC

In Oman and the GCC the WXB and WXBB series are relevant to refinery charge and transfer duties, hydrocarbon pipelines, produced water re-injection, amine units in gas plants, condensate service and boiler feed in power and desalination plants. Hot ambient temperatures, sand and dust make bearing housing protection and clean lubrication important, and humid coastal sites call for correct external coatings and material choices.

Information to send with an RFQ for a WXB pump

Please include the process data sheet or duty points, fluid properties, pressure and temperature, number of pumps, API 610 edition and material class, seal specification, driver details, testing requirements and delivery destination. If you are replacing an existing pump, add the nameplate, the pump size and stage count, and the serial number so that we can confirm the correct match.

Documents and quotation

A Flowserve WXB and WXBB brochure is attached on this page, covering the operating parameters and design features of both pumps.

Send your duty point and project specification, and Seven Star LLC will prepare a quotation for your WXB or WXBB pump or spares for delivery in Oman and the GCC.