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Pump alternatives for severe duty applications in hazardous environments

Published by , Editorial Assistant
Hydrocarbon Engineering,

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 applications both offshore and onshore. These include common applications such as crude oil export, process transfer, cooling water and booster pump applications as well as more specific onshore applications like flare 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 of the scenarios that call for API 610, it is by no means the only choice.

In the realm of specifying and selecting pumps according to API610 standards, it is imperative that all parties involved 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 greatly 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 300 m). There are several advantages of opting for an OH5 design in such scenarios: reduced footprint and weight, longer meantime between failures and ultimately, diminished cost and carbon footprint. Moreover, the OH5 design's vertical, in-line configuration 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 design

The highly versatile OH5 pumps typically weigh around 25% less than a comparable horizontally mounted pump because of their lack of a large baseplate. This also means that pump installation work can be started at an early stage. The overall lead time can be reduced by pouring the sole plate and welding pipework in situ before the actual pump is on-site. This presents opportunities to absorb any project overruns by completing installation activities in parallel rather than in sequence.

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 absorption of any 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.

Contribution towards sustainable development goals

Of increasing importance to manufacturers is their adherence to the United Nation’s Sustainable Development Goals. This is another area where the OH5 pump has a big impact. As 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 off-shore rigs. What is 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. For example, where higher energy applications, or applications with higher temperatures. However, just because an application has traditionally used the OH2, it does not mean that it always has to. From a safety, cost, size, weight and environmental perspective, the OH5 alternative offers some compelling benefits.

Written by Robbie Graham, Business Development Manager, Process & Chemical Solutions, SPP-Rodelta.

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