Pump alternatives for severe duty applications in hazardous environments
Robbie Graham, Business Development Manager for the Process & Chemical Solutions group at SPP-Rodelta – a strategic partnership between SPP Pumps and Rodelta – looks at the advantages of OH5 pumps, which include smaller physical footprints and lower weight, less downtime at installation, and reduced costs and carbon footprints.
The API 610 standard for centrifugal pumps is a watchword for safe pumping operations in the petroleum, petrochemical and natural gas industries. This stringent standard applies to pumps operating in environments where a spark would be catastrophic and is strictly enforced.
API 610 ‘overhung’ (OH) pumps are used in a wide range of offshore and onshore applications. These include common applications such as crude oil export, process transfer, cooling water, and booster pumps, as well as more specific onshore applications like flare knockout Drum (KOD) pumps, reflux, and oil recovery pumps.
These pumps are a common feature of the oil and gas fluid handling world, but that is not to say that they cannot be improved on to deliver more than just extremely safe, mission-critical performance. When designing pumps, hydraulic performance and safety are of paramount importance, but manufacturers are increasingly taking into account things like cost and environmental impact. While the OH2 pump is widely specified and used across many scenarios that call for API 610, it is by no means the only choice.
In specifying and selecting pumps according to API 610 standards, all parties must be able to grasp the intricacies of the various pump designs outlined within the standard. This understanding is crucial for OEMs, EPCs, consultants, and end-users alike. While there may be overlap between designs, certain applications – particularly those where OH2 pumps are commonly specified – can significantly benefit from considering an OH5 design, especially when dealing with low NPSHa applications, lower temperature fluids (below 250°C) and lower head applications (less than 300m). There are several advantages of opting for an OH5 design in such scenarios: reduced footprint and weight, longer mean time between failures, and ultimately, diminished cost and carbon footprint. Moreover, the vertical, in-line configuration of the OH5 design offers additional benefits, such as simplified maintenance access and enhanced fluid flow efficiency, making it a compelling choice for a diverse range of operational requirements.
This has significant benefits, especially for offshore and pre-packaged skid applications, where space is at a premium, and where they could be used to pump anything from boiler feed to oily surface water, crude oil and sour water to hydrocyclone feed and condensate recovery.
Lighter weight, smaller footprint
The highly versatile OH5 pumps typically weigh around 25% less than a comparable horizontally mounted pump because they lack a large baseplate.
The standardised dimensional features of OH5 designs, compliant with BS4082, facilitate the straightforward design and provision of installation templates, which can be supplied prior to pump delivery. This enables the installation process to proceed concurrently rather than sequentially, with tasks such as grouting of the baseplate and welding of pipework completed ahead of the pump’s arrival.
Such an approach offers several advantages to the customer: it allows the absorption of project overruns, streamlines the installation timeline, and provides a reusable method for preventing contaminants from entering the process system. Additionally, the installation dummy serves the dual purpose of keeping the line open for the process if needed, further enhancing operational flexibility and efficiency.
Meeting Sustainable Development Goals
Of increasing importance to manufacturers is adherence to the United Nation’s Sustainable Development Goals. This is another area where the OH5 pump has a significant impact. Because it involves less steel in its configuration, there is already a reduction in carbon in its manufacture. Because of its compact nature, its installation requires less supporting concrete and steel and lightens the overall weight, important for LNG ships and offshore rigs. What’s more, it costs less to ship and accounts for fewer emissions than larger, heavier OH2 equivalents.
OH2 or OH5?
Of course, not every API 610 pumping application can be switched to an OH5. There are many scenarios where OH2 or other OH solutions will be optimal, such as higher-energy applications or applications with higher temperatures. But just because an application has traditionally used OH2, it doesn’t mean that it always has to. From a safety, cost, size, weight, and environmental perspective, the OH5 alternative offers some compelling benefits.
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