The normal life cycle for a hardworking and crucial asset such as a boiler feed pump is 20 years. However, a Sulzer BB3 pump removed from a refinery in Argentina has been given a new lease of life at 40. Rejuvenating legacy equipment is a specialist field that needs considerable expertise for a successful outcome.

BB3 pumps operate throughout the oil & gas industry as well as the hydrocarbon sector. In this case, one example was running as one of a pair of boiler feed pumps in a refinery in Argentina. The pump had to be taken out of service at short notice and refurbished quickly to ensure adequate capacity for the boiler.

Minimized downtime
The spare pump continued to operate but the failed pump was sent as a critical repair to enable it to return to active duty at the earliest opportunity. This would minimize any downtime and secure the reliable service of the pump for years to come.

Sulzer regularly provides maintenance services to the refinery and was one of the first to be invited to submit a quote for the inspection and subsequent repair of the pump. Sulzer’s bid was accepted in the main because of the price and the quality that the company offers, but also because of the speed with which such repairs can be completed.

The pump, which had been in service for more than forty years, was removed and shipped to the service center in Buenos Aires. The initial inspection revealed damage to the pump body as well as corrosion of the pump case. The shaft was damaged and all the wear rings would also need to be replaced.

The pump shaft was removed and inspected in-house using non-destructive testing (NDT) procedures and found to be damaged beyond repair, so it was also replaced. These tests are crucial in detecting structural flaws and in this case, tests were conducted on all of the pump components.

Once the full extent of the required repair had been established, the casing walls were rebuilt using a welding process that adds a layer of material that can be machined back to specifications. With the welding complete, this section was again inspected using NDT before the casing was transferred to the machine shop where it could be re-bored.

Comprehensive testing
In the meantime, the new pump rotor was reassembled and balanced, while the wear rings were replaced when the casing repairs had been finished. The pump was put back together before being hydro tested at 1.5 times working pressure. The test procedure was designed and performed by Sulzer’s engineers to ensure that pump was ready to be reinstalled.

Throughout the repair project, constant contact with the customer was maintained explaining the findings and the proposed resolutions. The customer was happy with the quality of the work completed and the attention to detail that ensured a robust repair.

Esteban Obiglio, sales manager, at Sulzer explains: “It is essential in any overhaul project to deliver the best possible solution and ensure the customer is kept up-to-date. It is also important to understand the expectations of your customer and make every effort to deliver a cost-effective and reliable repair.”

Future plans
Throughout the project, the customer frequently visited the service center to review progress and discuss options for the pump that remained in service, which was a similar age and therefore facing comparable issues with erosion and wear. One potential solution, suggested by the customer, was to replace the casing, a project that could be completed in approximately two weeks.

Esteban concludes: “The customer was looking to the future and by discussing possible solutions, was able to assess all the options and make an informed decision. The refurbished asset will provide cost-effective and reliable service for many years to come.”

Opened in the summer of 2017, the North Depot at the Abu Dhabi International Airport was intended to meet the additional demand from Etihad Airways and would become the airport’s exclusive provider of J1 fuel. Its opening was a major stepping-stone on the road to the Midfield Terminal Project, which in turn is a key part of the country’s 2030 vision, the government’s plans to transform the Emirate’s economic base.

The ADNOC group fuels as many as 34 aircraft per hour via 26 fuel depots across the UAE. When it came to upgrading the fuel circulation pumps for the North Depot aviation facility, ADNOC turned to pumps’ supplier, Flowserve UAE. In addition to supplying the pumps, Flowserve will have overall responsibility for the upgrade project and coordinate the package for the end-user.

Upgrading VSDs
The existing set up was not very energy efficient and so the entire system was being replaced. Flowserve looked to WEG’s expertise and experience to upgrade the variable speed drives (VSDs). A global supplier of motors and drives, WEG can supply VSDs as stand-alone devices or alternatively they can be custom built within electrical panels as was the case with this project. Here, they supplied four LV VSD panels, two 132 kW and two 185 kW, along with filters.

VSDs provide enhanced control of the entire operation, controlling the speed and direction of the motors, while also offering protection. They ensure the energy consumption is proportional to the load requirements, providing substantial energy savings for the user. They also offer flexibility, as they can be programmed to come on and off for certain periods of time, with the option to modify the drive for specific applications, as was the case with this project.

Bespoke solution
“Every project will have its own unique requirements. This was a customised solution, built for the specific project,” explained Darshan Balkrishna Shejekar, development sales manager, LV Automation at WEG. “As usual this was not a straightforward project as oil and gas projects demand a high level of engineering.”

In this case, a key requirement was the need for a low harmonic solution. This specific requirement is often requested in oil and gas applications, an area where WEG has a growing reputation for its expertise. WEG’s solution was to provide input harmonic filters for the VSDs to give a lower harmonic performance.

Additionally, the distance from the VSD to the motor was close to half a kilometre, which is not a usual scenario. Longer cable lengths lead to higher IR losses and other issues such as capacitance build up, presenting a threat to the motor winding and lifespan. To address this issue, it was important the VSD was sized correctly and equipped with suitable output filters to mitigate voltage spikes and provide the required protection for the motor.

This was therefore a complex solution, tailored to the specific requirements of the customer, and purpose built at WEG’s manufacturing facility in Brazil. The panels had to be manufactured at one of WEG’s facilities that had been approved by ADNOC.

When the panels arrived in Abu Dhabi, WEG’s engineering and application local support team provided assistance with installation, set-up and commissioning as required by the customer. The team was also available for any support required throughout the life of the installation.

“In recent years we have added significantly to our after-sales support team in the region and this was certainly a factor that has allowed us to deliver both the products and the service that these type of projects require,” added Shejekar.

Extensive testing
The panels will also have to be extensively tested, in line with ADNOC requirements. This will include a factory acceptance test (FAT) as well as a witness test from the customer. For a project such as this, the customer will specify an extensive range of test requirements. Performing these tests is even more difficult given the current restrictions imposed by the global pandemic, but WEG has been able to innovate by providing remote online witnessing of tests for its customers.

A major breakthrough
Being involved on a project for ADNOC is a great opportunity for any company operating in the region, but it is not one that is easily gained. To be trusted by one of the biggest oil and gas companies in the world and earn a place on its approved vendor list (AVL) requires considerable effort, investment and commitment alongside expertise and experience.

In addition to the increasing personnel in Dubai, WEG has partnered with an agent in Abu Dhabi, which has helped to increase the in-country-value score that is essential to getting approval in this case. Positive references from within the oil and gas industry have also contributed. WEG has been a trusted supplier to Saudi Aramco and PDO Oman and has established its reputation in the region through projects such as the Duqm refinery project.

“This project enhances further the reputation of WEG in the region and justifies the investments made over many years. The opportunities we are receiving due to our expertise and reliability of products and services reinforces our position as a major player in the oil and gas sector,” concluded Shejekar.

A new salt extraction plant off the north coast of Holland has been brought online ahead of schedule, preventing a potential halt in production when the existing onshore well developed issues. Frisia Zout BV, part of K+S Minerals and Agriculture GmbH, was able to overcome the time and technical challenges of accelerating the project by working in partnership with Celeros Flow Technology (Celeros FT).

The bulk of the salt produced by Frisia Zout BV goes loose to a 40,000-tonne storage facility for delivery in bulk to industry. The remainder is packed in smaller quantities for use in food production or made into cubes for water purification.

The salt is extracted under licence from the Dutch government. The existing borehole licence
allowed K+S to extract salt from underground on the mainland. Due to regulatory changes, the new licence would only permit extraction from subsea sources off the coast. Consequently, a new borehole and associated plant was required at the Frisia Zout BV site.

New challenges
K+S began planning for a new pump building in 2017, and construction began in April 2020 with the aim of bringing it onstream before the existing extraction licence expired at the end of 2021. However, unforeseen difficulties arose with the existing onshore well, which meant that production would cease sooner than anticipated. To bridge the gap, Frisia Zout BV began bringing in salt water by tanker, but this was an expensive alternative. As a result, it became imperative to bring the new offshore well onstream as soon as possible.

Time pressures were not the only challenges the company faced. Due to the natural geology, the extraction route to the new offshore resource was not a straight bore: it changed direction twice before reaching the salt deposits. In fact, the new plant is fed by one of the deepest wells in the world and has 5 km of pipework beyond the water injection pumps. As a result, the process water has to be pumped in at high pressure (250 barg) and at a high flow rate (450 m³/h) to extract the amount of salt required, making the choice of pumps critical to success.

Total solution
Frisia Zout BV has a long and established relationship with Celeros FT through the ClydeUnion Pumps brand, based not only on the high quality of ITS OEM pumps but also on its ability to respond quickly to any operational issues. The company turned to its trusted flow control partner once again for help in meeting the unique circumstances encountered at the new salt well.

Celeros FT brand ClydeUnion Pumps assessed the flow requirements for the water injection process at the new plant and verified that CUP-BB3 pumps could be made to meet requirements. The pumps were specified with Duplex stainless-steel casings because they would be operating in a salt-laden environment. Celeros FT manufactured, supplied, installed and commissioned the mission-critical pumps for injecting water into the new offshore salt cavern, meeting unusual requirements for high pressure and high flow rates. In addition, they supported Frisia Zout BV in bringing an older pump back into service as a spare: assessing it and upgrading the casing to ensure it met the new duty requirements.

Jouk Riemer, project manager for Frisia Zout BV, explained: “We have used CUP-BB3 pumps in the past and found that their multistage centrifugal design gives better performance, compared to plunger pumps, for this application. We wanted to use them again for the new project. The Celeros FT team responded to the challenges magnificently, using their engineering expertise to identify the best solution to meet the pressure and flow rates we required, delivering the pump skids to meet the new construction schedule and helping us keep the project on track.”

Future assured
The new salt extraction plant came online in December 2020. Its CUP-BB3 pumps meet the high pressure and flow rates required for the application and can run in parallel, which has improved productivity. The availability of a spare pump gives extra confidence that production downtime will be minimal. The company’s ability to meet the accelerated project deadline is particularly impressive when you consider that the Covid-19 pandemic was already affecting supplies of materials and components. The Celeros FT team worked hard to ensure that this did not have any impact on their customer.

Celeros FT also provided specialist engineering expertise throughout the installation and commissioning phase and will continue to ensure the pumps operate satisfactorily throughout the plant’s 15-year lifespan, though the pump building may be required to serve more than one well in future as demand for K+S high purity salt continues to grow. Easy replacement of wear parts and ongoing service support from Celeros FT will ensure that the BB3 pumps continue to meet operational parameters throughout the extraction plant’s lifetime.

Riemer said: “The combination of high quality OEM equipment and practical engineering skills offered by Celeros Flow Technology was instrumental in delivering this project ahead of time. I’m convinced it would have taken a lot longer to get what we required from another pump manufacturer. The company’s responsiveness was crucial in meeting our revised deadline, reducing costs and keeping extraction at this site viable.” Riemer concluded: “This is the first offshore extraction well we have developed but it has been a largely positive experience thanks to Celeros Flow Technology. They brought invaluable engineering expertise and specialist pump knowledge to this project and are a fundamental part of its success.”

As important assets, pumps are designed to provide reliability while maintaining their designed efficiency for many years. Whilst pump designers have somewhat of a free hand when designing pumps, some design features for the petrochemical market must meet the requirements of API 610. In the last 30 years API 610 has evolved from 5th edition to 12th Edition. Sulzer has both the expertise and engineering facilities to take those vintage pumps in to their service centre designed many years ago to API 610 5TH Edition and return them back to the customer as API 610 12TH Edition. Manuel Monroy, Field Engineer at Sulzer, explains a range of improvements that can be implemented, taking the Pacific JTC® multi-stage centrifugal pump as an example.

Innovative solutions
Pumps designed for a specific service many years ago may not be operating now at the conditions for which they were designed. At Sulzer, the mindset is to offer repair solutions to customers’ equipment with the latest upgrades available in the industry which improve reliability and efficiency. From 1958 to 1989 the Pacific JTC multistage diffuser pump was introduced to the petroleum industry, as well as the power industry, both fossil and nuclear.

The JTC is a horizontal split case diffuser style pump with a back to back impeller configuration. Most split case pumps are of the volute style with hydraulic passageways cast throughout the casing halves. The casing of the JTC is a much simpler design, shown on Figure 2. The casing has one major diameter that radially locates all the inter-covers. The intercovers, which are sealed on their outside diameter with the casing, to prevent inter-stage leakage, contain the diffuser and return guide vanes and transfers the fluid from the discharge of one impeller to the inlet of the next impeller. The bolt pattern used to bolt the two halves together does not have to weave around volute passageways, making it easier to achieve uniform loading on the split line required for sealing purposes.

Opposed impellers
Other pumps with similar designs are the IR CNTA, IR HMTA and the Worthington WT. The JTC and CNTA pumps are designed with opposed impeller configuration compared to the IR HMTA and Worthington WT, which are designed with impellers in tandem. The opposed impeller configuration on the JTC and CNTA balances the axial thrust created by the impellers. Tandem impeller configurations create a very high inboard thrust, balancing this thrust requires a more in-depth design compared to the opposed impeller design.

Most of the pumps shipped many years ago were shipped with packing seals. The JTC has a small shaft diameter and the gland packing is crucial. Not just for sealing the product from leaking to the atmosphere, but it also acts as a bearing, consequently aiding both centre and throttle bushings in maintaining rotor stability during operation. The use of gland packing to seal the pump’s stuffing box often requires adjustment in the field which is a continuing maintenance headache for many operators. The introduction of the mechanical seal and its superior sealing technology increased the demand for aftermarket upgrades that paved the way for retrofitted pumps and new industry standards.

Retrofitted JTC pumps are now commonly equipped with mechanical seals eliminating fugitive emissions, a major driving force behind this was the release of API-610 7th edition which standardised on mechanical seals and the stuffing box requirements. However, the modification of existing pumps with packed stuffing boxes to mechanical seals did not come without problems. With the addition of mechanical seals, mounted on a slender shaft, the pumps rotor dynamic behaviour changed.

This change led to the accelerated wear of the close running clearances, an increase in vibration, further opening up of the clearances and the vicious cycle continued until the pump could no longer perform its function both mechanically due to high vibration and hydraulically due to internal leakage. The change in rotor dynamic behaviour resulted in the creation of innovative solutions to maintain and increase the mean time between repairs (MTBR) of the JTC pump.

JTC pump overhaul
Recently, during a routine turnaround, a chemical plant located in Pasadena, TX., took the opportunity to overhaul their JTC pumps with a view to improving both bearing and seal life. Sulzer’s Houston Service Centre provided engineering support and repair solutions to increase the MTBR. The pump was a typical JTC small shaft design with mechanical seals, originally designed for packing.

The customer’s supplied JTC pumps arrived at the service centre with significant damage. The customer noted that the pumps were experiencing constant seal and bearing failures. Excessive wash-out was found on the casing inner diameter where an O-ring provided interstage sealing between the inter-covers and casing diameter. Sulzer’s quality (QA) team also found the case split line flatness out of tolerance. Typical wear was found throughout the rotor wear components from years of service.

To meet the customer’s expectations, Sulzer’s Houston service centre engineering team took on the task of providing a solution to increase the MTBR of their existing pump. Equipped with state-of-the-art 3-dimensional laser scanners and API experienced engineers, the service centre began by completely reverse engineering the original JTC pump. After a design review, a proposal to repair and retrofit the pump was created and presented to the customer.

Sulzer had two main objectives, repair the casing damage to original design standards and provide a solution to eliminate the accelerated wear of the close running internal clearances.

Casing repair
To restore a pump case inner fits and bring them back to original equipment manufacturer (OEM) tolerances, boring of such fits is practiced in the industry. When boring a pump case, alignment of the pump case to its centre line is the most important step in the machining process and of the entire repair. It was important to strategise and properly engineer and execute the appropriate repair process that would allow the restoration of the pump’s critical case fits. The stacked diffuser design on the JTC required multi-point inspection on all internal mating faces to ensure parallelism and concentricity met Sulzer’s standards. To correct out of tolerance runout, Sulzer engineered and manufactured special tooling to properly correct excessive runout on critical mating surfaces.

To remove the wash-out and runout found on the pump case, it was put through multiple machining phases. The case split line was planed on one of Sulzer’s planer mill. The case bore fits were also machined to the required dimensions maintaining tight tolerances and concentricity to the case split line. Finally, the case inner walls were machined, with the case halves torqued, to ensure parallelism between both inner walls that axially locate the inner element located 40 in apart.

Rotor upgrade
When addressing accelerated wear in the close running clearances of the JTC pump there are two typical improvement options: provide non-metallic composite materials for the wearing parts and reduce the running clearances or upgrade the rotor from a spacer sleeve designed rotor to a split ring designed rotor.

On this occasion Sulzer implemented non-metallic materials for all stationary wear components, such as eye and hub rings, throttle bushing and centre bushing. Distinct pressure distribution seen on the throttle bushings and centre bushing required additional design calculations and ultimately resulted in the implementation of the perforated insert (Perf-Seal) design shown on Figure 3.

A Perf-Seal insert has radially drilled holes throughout the non-metallic insert and these prevent differential pressure from extruding the insert from the metal holder.

Non-metallic composite materials are capable of withstanding temperatures of up to 500°F (260°C). They are widely used in the pump industry for wear ring components, bushings and inserts. The major benefit of these composites is the ability to withstand occasional dry running. If there is a pump failure then the non-metallic rings become the sacrificial pieces, all other components can be repaired and re-used. The composites also allow for reduced running clearances, which provide improved stiffness and damping along the length of the rotor improving rotor stability and an increase in pump efficiency. It should be noted that reliability is the main reason for converting to the non-metallic rings, efficiency is secondary.

With the case fully restored and with new wear parts machined at the service centre, the pump was ready for assembly. The impellers were individually balanced and the assembled rotor check balanced. The loose design fit between the impellers and shaft required critical runout inspection during assembly. Finally, during the rotor stack up, all impellers and diffusers were set to their corresponding running position to ensure the impellers’ and diffusers’ hydraulic passageways were properly aligned.

Further upgrades
Due to time constraints, the upgrade of the rotor from sleeve to split ring design could not be accommodated. The existing spacer sleeve design with two locknuts at each end designed to lock the rotor together is known to create run-out problems both at assembly and during operation. The rotor can be further upgraded to a split ring designed rotor. This eliminates the spacer sleeves between the impellers and allows the impeller thrust at each individual stage to be transferred to the pump shaft via the split ring.

With the elimination of the spacer sleeves, the shaft diameter can be increased in some cases by 0.5–0.75 in (12–9 mm) through the impeller section of the pump shaft. This also allows an interference fit between the shaft and impeller, reducing runout on the impeller wear surfaces and providing the ability to balance to a much tighter balance criteria. The upgraded pump can now meet the vibration requirement of the latest API 610 standards. If the impellers are weldable then back hubs can be welded to the existing impellers, allowing the existing impellers to be re-used. If the original impellers are cast iron they must be replaced.

For components with complex geometry, such as impellers and case diffusers, Sulzer used Crea Form® scanners to allow rapid 3D modelling of customer supplied equipment. The 3D scanner is a powerful tool widely used in the industry to properly enable the manufacturing of cast components. This allows Sulzer to provide replacement impellers meeting the existing hydraulic and envelope requirements. For changes in pump performance, Sulzer engineering can analyse existing performance data and can adjust the hydraulic components accordingly to meet new process conditions. During time restricted turnarounds where a new rotor requisition is not feasible, Sulzer engineering can perform a mechanical review of the existing rotor and advise on necessary rotor changes needed to improve bearing life and improve rotor stability.

Centring shim
The original rotor design on the JTC includes a centering shim, which ensures the rotor fits tightly into the pump casing by shimming the centre stage casings accordingly. The disadvantage of having a centering shim in the middle of the rotor is having to disassemble half of the rotor to properly adjust the shim should the rotor not fit into the casing with the proper axial clearance, see an example of in case rotor assembly detailed on Figure

4. An upgrade is available that removes the centre shims and moves it to the front of the 1st stage diffuser.

By providing a laminated shim, quick adjustments can be made to the rotor axial length for final assembly. This upgrade is ideal for quick bundle swaps and has the potential to reduce lead-time on repairs.

To increase bearing life, bearing housing upgrades can also be achieved by retrofitting the existing cast iron housings with Sulzer’s carbon steel ball-ball or ballsleeve arrangement bearing housings. These are designed with integral fins that dissipate heat and can be equipped with a wide variety of instrumentation connections such as resistance temperature detectors (RTDs), bearing coolers and vibration probes. In some cases, new air-cooled bearing housings may allow for the removal of existing water-cooled housings and the associated piping.

Sulzer’s bearing housing assemblies can increase the bearing sizes for ball-ball arrangements or implement shorter length/diameter ratio (L/D) journal bearings for sleeve-ball arrangements. The housings are also equipped with Inpro® isolators to protect the housing internals from contaminants. Engineers can custom design the bearing housing mating flanges to adapt to the current pump case bolt pattern and minimise any case re-work.

The petrochemical industry has a wide range of split case diffuser pumps similar to the JTC, like the IR CNTA, IR HMTA and Worthington WT. Although, rotor configurations between them vary, many of the reliability challenges remain the same among these product lines. Instead of scrapping an outdated split case diffuser pump, some of the JTC upgrades detailed above may be the practical solution to restore and improve pump performance while upgrading to API’s 610 12th edition and ultimately increase MTBR.