Pumps are an essential component, and one of the most used pieces of equipment, in the oil, gas and petrochemical industries. They can be found at all stages of these applications – upstream, midstream and downstream – from delivering oil from the ground to a ship, oil refinery, or storage to speeding up the fluid flow from one point to another. Due to the varied tasks pumps are required to perform, the types of pumps used are also extremely diverse, varying in type, size and materials. Here, we take a look at some of the key considerations during pump selection in these industries.

Type of pump

Ensuring you select the right pump for the application is important to ensure maximum efficiency, and minimal operating and maintenance costs. Poor pump selection is also likely to result in downtime and heavy costs to repair or replace a damaged pump.

Pumps in the oil, gas and petrochemical industries are usually divided into two categories: centrifugal and positive displacement pumps.

Centrifugal pumps are the most commonly used type as they can be utilised in a wide range of applications. They are usually found in applications such as handling low viscosity fluids that don’t contain air, fumes or large amounts of particles like lighter hydrocarbons and water, as well as filthy fluids and where there are higher flow rates.

For example, single stage centrifugal pumps are primarily used for transferring low viscosity fluids that require high flow rates. They are usually used as part of a larger pump network comprising other centrifugal pumps such as horizontal multistage pump units for crude oil shipping or water injection pumps for secondary oil and gas recovery.

Positive displacement pumps are used in services with viscous and gas entrained liquids at a lower flow rate but at higher pressures and often under difficult suction conditions. There are special types of positive displacement pumps available such as high pressure piston pumps for drilling and hydraulic fraccing operations.

Progressive cavity pumps have also become a popular option due to their highly versatile design enabling them to handle sand particles, gas and oily water for a range of applications including transportation and injection.

Meeting relevant standards

There have been many pump codes and standards that apply to different pumping applications. Due to the critical nature of the oil, gas and petroleum industries, it is important to ensure the selected pump meets the relevant standards.

The main relevant standards for these industries are American National Standards Institute (ANSI), American Petroleum Institute (API), International Standards Organization (ISO), and American Society of Mechanical Engineers (ASME).

In the past, some standards have had more impact in certain regions of the world than others, however, there has been a degree of convergence as they have borrowed from each other and the rise of globalisation.

API standards

API sets the standard for pumps in the oil, gas and petroleum industries. They are used to define systems, tests, equipment design and ability to handle high temperature and pressures. Pumps that meet these standards are some of the highest quality available.

There are various applicable API standards depending on the type of pumps, but some of the most important are API 610 for mechanically sealed pumps, API 685 for sealless pumps, API 676 for positive displacement pumps – rotary, and API 764 for positive displacement pumps – reciprocating.

API pumps have some advanced features over ANSI pumps, manufacturer’s standard pumps and other types in these harsh applications, such as having the capability to withstand relatively high allowable nozzle loads, provisions for larger and better mechanical seals, better bearings and components. These result in higher performance and reliability. It is also generally easier to align, commission, operate and maintain API pumps as well.

ANSI standards

ANSI pumps are horizontal, end suction, single stage centrifugal pumps with an overhung impeller and back pull out. Their defining feature is that they are interchangeable across manufacturers and brands as they must meet dimensional standards set by ANSI, making them identical in interface and envelope dimensions regardless of the manufacturer.

ANSI B73.1 is the main standard of interest for the oil, gas and petrochemical industries as it sets the key dimensions for 27 pump sizes – including overall height and length of the bare pump, nozzle and shaft diameters, the size, location and spacing of mounting bolts, etc. – giving end users a range of options.

It also specifies some performance characteristics and a number of design features intended to ensure reliable service and simplified maintenance. It is comparable with ASME B73.1 standard.

ISO standards

The ISO is an independent organisation that oversees, creates, and promotes internationally accepted standards for numerous industries, and ISO safety symbols are recognised across language barriers to increase hazard awareness and safety compliance.

These standards have historically had more impact in Europe and Asia, and are comparable to ANSI standards. ISO 5199 and ISO 2858 cover the same type of industrial pumps as ANSI B73.1.

The main difference between these two ISO standards is that the older ISO 2858 is focused on external dimensions and mounting details, while ISO 5199 also specifies a variety of performance requirements (e.g. minimum bearing life) and construction features (e.g. general layout, seal configurations).

In general, ISO 5199 compliant pumps will meet or exceed ANSI B73.1 requirements in terms of performance, reliability, serviceability and longevity. However, they can’t be used as direct substitutes for ANSI B73.1 pumps without some adaptations to the mounting plates and motor couplings.

ISO 15783 specifies the requirements for sealless rotodynamic pumps that are mainly used in chemical processes water treatment and petrochemical industries. It includes design features focused on the selection, installation, maintenance and operational safety of the pumps.

However, it doesn’t cover dimensional and hydraulic performance requirements and further technical requirements which are detailed in ISO 5199. ISO 2858 relates to end suction centrifugal pumps and specifies the main parameters and designation. It specifies the principle dimensions, mounting details and nominal duty point of a maximum operating rating of 16 bar.

ASME standards

There are a couple of relevant ASME standards for pumps in the oil, gas and petroleum industries. ASME B73.1 and ASME B73.3 are relevant for horizontal end suction centrifugal pumps used in chemical processes.

The difference is ASME B73.1 is applied to sealed horizontal, end suction, overhung, radially split, singlestage, mechanically sealed pumps, and ASME B73.3 is applied to sealless versions of these. They are comparable to ANSI standards.

These standards specify a number of key dimensions for pumps including overall height and length of the bare pump, nozzle and shaft diameters, and the size, location and spacing of mounting bolts. They also specify some performance characteristics and a number of design features that are intended to ensure reliable service and simplified maintenance.

ASME B16.5 relates to pipe flanges and flanged fittings, including defining and standardising pressure and temperature ranges for: flange ratings within various material groups, flange dimensions for various ratings and fitting designs and flange bolts.

Material selection

Pumps in the oil, gas and petroleum industries are frequently required to operate under extreme environmental conditions, such as extremely high temperatures and pressures, or extremely low pressures and cryogenic temperatures, depending on the specific application.

Pumps must be manufactured from materials capable of withstanding their operating conditions and be nonreactive with any chemicals they will be exposed to. Material choice is often governed by the prevention of corrosion, erosion, wear resistance, oxidisation and buildup on pump components. Some pumps must also be able to handle abrasive or volatile materials.

Selecting metallic and non-metallic pump components that are compatible with the liquid can help decrease the onset of premature and costly downtime or failure. The most common materials in the oil, gas and petroleum industries are carbon steel and stainless steel due to their strength, corrosion resistance and ability to handle high heat.

Sizing the pump and seal selection

Pumps are often oversized for an application and therefore operate in an unstable region of the performance curve. There are a number of reasons a pump could be oversized.

A certain degree of error can occur at the specification stage due to the need to estimate the equipment requirements, as well as the possibility of the published literature having different reference values for flow resistance coefficient or fittings losses.

Another reason a pump may be oversized is to account for the system design to be expanded in a few years if needed, as a correctly sized pump for the current conditions would be unable to meet possible future additional demand. Sometimes a safety margin will be added and a larger pump procured and installed to cater for future expansion of the system.

Other reasons oversizing may occur include a pump was oversized to account for expected build up of corrosion products on the pipe interior, which would increase the pump total head requirement, or a safety factor was added to increase pump capacity and head to counter the effects of wear.

Oversizing can also be the result of factors such as a pump was urgently needed and the right size was out of stock, a pump was selected from the spares inventory due to budget constraints, or a new pump was bought to replace an existing pump that was already oversized.

However, oversizing – along with misalignment – is one of the biggest problems contributing to excessive pump maintenance. This can cause  a number of problems, including shortening the mean time between repair on seals and bearings, as well as turned and cast components.

It also has the knock on effect of resulting in higher energy costs due to a higher performance in terms of flow and pressure requiring more power from the motor, which can lead to unnecessary energy consumption.

Undersizing is also an issue. If a pump is undersized in regards to power it will lead to a lower flow rate than required in the system and the need to either install additional pumps or make adjustments to the system like adding recirculation lines or opening discharge valves.

Some pumps such as progressive cavity pumps can have additional problems if undersized. As the flow of a progressive cavity pump is a function of cavity size, if the pump is undersized and the cavity size is too small for the application, it will need to pump faster. This can result in reduced suction, increased wear, and pump failure.

These problems can be avoided by properly sizing the pump and configuring the system with a variable frequency drive (VFD). Selecting the right seal is also important. If an improper mechanical seal is selected it can result in premature seal failure.

Misapplication of a seal design is one of the most common reasons for centrifugal pump failure, and once the seal fails it can have costly consequences like loss of product, environmental contamination and other maintenance issues.

These are just some of the considerations to take into account when selecting a new pump for operation in the oil, gas and petroleum industries. Ensuring the right pump is selected is key to optimum performance and minimal maintenance costs.

Find Related Companies In The Pump Industry Capability Guide

Related articles

©2024 Pump Industry. All rights reserved


We're not around right now. But you can send us an email and we'll get back to you, asap.


Log in with your credentials


Forgot your details?

Create Account