Step into any petrochemical plant, power station, or metallurgical workshop, and you’ll find that among numerous pump models, the OH5 centrifugal pump is a reliable product that stands firm even under harsh operating conditions such as high temperature and high pressure.
The OH5 centrifugal pump is an "overhung, horizontal, centerline-mounted, single-stage, radially split" pump type. Its most prominent feature is the integral design: the pump body is directly fixed to the base via feet, and the pump shaft shares a common shaft with the drive motor (i.e., a direct-coupled structure). This seamless connection design minimizes misalignment errors and improves operational stability, making it particularly suitable for transporting high-temperature, high-pressure, or corrosive media — in these scenarios, reliability must not be compromised.
API 610 is a globally recognized standard for the design and manufacture of centrifugal pumps in the oil and gas industry. Under this standard, overhung horizontal pumps are classified into the OH (Overhung Horizontal) series, which includes six types (OH1 to OH6). The OH5 is clearly defined as a "direct-coupled, centerline-mounted" pump type, requiring precise alignment between the pump casing centerline and the base mounting surface. It can effectively offset stress caused by thermal expansion, avoiding pump body deformation and seal failure — this is crucial for long-term stable operation in high-temperature environments.
The working principle of the OH5 pump is very simple: the impeller rotates at high speed to generate centrifugal force, drawing fluid from the suction port, flinging it radially outward, and then discharging it into the pipeline after being pressurized by the volute. Thanks to the direct-coupled design, the motor rotor and pump impeller rotate coaxially, resulting in higher transmission efficiency, less vibration, and simpler maintenance (unlike pumps with couplings that require frequent alignment adjustments). For high-risk media such as flammable and toxic substances, the OH5 is usually equipped with mechanical seals or dry gas seals — these mature solutions ensure leak-free operation in high-risk application scenarios.
With its compact structure and stable performance, the OH5 pump has a wide range of applications: industries such as oil refineries, chemical plants, LNG terminals, offshore platforms, and power stations use it for tasks such as boiler feed water, hot oil circulation, acid-base transportation, and solvent reflux. A few years ago, when I participated in the renovation of a hot oil circulation system at an oil refinery, I personally witnessed its capabilities. The original pump had been plagued by frequent leaks and excessive vibration caused by thermal deformation, requiring shutdowns for maintenance every few months. After replacing it with the OH5, the centerline-mounted design offset thermal expansion stress, and the direct-coupled structure eliminated transmission losses. The entire system operated continuously for more than two years without a single failure — considering the limited on-site installation space and the need for 24/7 uninterrupted operation, this performance was truly impressive.
Most pumps from OH1 to OH4 adopt independent motor drives with couplings (requiring on-site alignment during installation) and have different mounting methods (e.g., OH1 is foot-mounted, OH3 is a vertical pipeline pump), while the OH5’s direct-coupled, centerline-mounted design is unique. By removing the coupling, it not only saves valuable installation space but also offers superior thermal alignment performance — these two advantages are particularly prominent in confined spaces or high-temperature environments. Of course, it has minor limitations: the direct-coupled design imposes certain restrictions on motor size and power, so it is not suitable for extra-large or ultra-high pressure conditions. However, for most conventional harsh operating conditions, its advantages are almost irreplaceable.
With its rigorous design complying with the API 610 standard, efficient and stable operational performance, and wide applicability, the OH5 centrifugal pump has become an indispensable core equipment in modern process industry. Today, as industries have increasingly high requirements for safety, energy conservation, and intelligence, selecting the appropriate OH5 model is by no means a simple equipment purchase — it is a strategic decision that can ensure the smooth operation of the entire process system. Whether you are facing high-temperature environments, corrosive media, or limited installation space, the OH5 can provide the reliability and performance required for industrial production.
If you want to learn more about industry-related knowledge, click here to find out more!
-
