What Is API 675, and What Does It Mean for Chemical Injection Pumps?
API 675 is an American Petroleum Institute standard for reciprocating controlled-volume pumps used in petroleum, chemical, and gas industry services. For chemical injection pumps, API 675 establishes requirements related to design, performance, testing, materials, controls, and documentation. Specifying an API 675 pump can help ensure predictable, repeatable chemical dosing in demanding process applications.
At MJ Systems, chemical injection and metering are core areas of expertise. The company provides chemical injection pumps, metering equipment, flow measurement, pulsation control, instrumentation, and packaged systems for oil and gas, petrochemical, water treatment, and other industrial applications. MJ Systems works with pump technologies designed for demanding controlled-volume applications, including Hydra-Cell API 675 metering pumps. By evaluating pressure, flow, chemical compatibility, accuracy, controls, and supporting equipment together, MJ Systems helps customers select chemical injection solutions based on actual process requirements rather than a pump specification alone.
Understanding API 675 Requirements for Chemical Injection Pumps
API 675 establishes requirements for reciprocating controlled-volume pumps and pump units. These pumps are often called metering pumps because they are designed to deliver controlled quantities of fluid.
In chemical injection, that controlled delivery is particularly important. Operators may need to inject relatively small quantities of corrosion inhibitors, scale inhibitors, biocides, scavengers, or other chemicals into processes operating at substantial pressure.
API 675 addresses areas including:
- Pump design
- Performance
- Materials
- Testing and inspection
- Controls and instrumentation
- Accessories
- Documentation
- Pump and system requirements
The standard provides a common framework that pump manufacturers, engineering firms, system integrators, and end users can reference when specifying controlled-volume equipment.
What Types of Pumps Does API 675 Cover?
API 675 applies to positive displacement, reciprocating controlled-volume pumps used in petroleum, chemical, and gas industry services.
These pumps use reciprocating motion to displace a controlled volume of fluid. Depending on the design, the pumping element may incorporate a diaphragm, plunger, or other configuration appropriate for controlled-volume service.
The important distinction is the pump’s ability to provide controlled, adjustable delivery rather than simply move as much fluid as possible.
Chemical injection is a natural application for this type of equipment because treatment effectiveness often depends on maintaining a specific injection rate.
Typical applications can include:
- Corrosion inhibitor injection
- Scale inhibitor injection
- Hydrate inhibitor injection
- Biocide dosing
- H2S scavenger injection
- Process additive dosing
- Water treatment chemicals
- Other controlled chemical feeds
Not every chemical injection pump automatically meets API 675 requirements. When API 675 is specified for a project, the selected pump and its configuration should be evaluated against the applicable requirements of the standard.
Why Does API 675 Matter for Chemical Injection Accuracy?
API 675 matters because chemical injection applications often depend on predictable, repeatable pump performance.
Simply knowing that a pump can reach the required flow and pressure does not necessarily tell an operator how consistently it will deliver chemical across its operating range.
Controlled-volume pumps are intended to provide adjustable flow with predictable performance. API 675 establishes requirements and testing practices intended to demonstrate that performance.
This is particularly important because inaccurate dosing can create two different problems.
Underdosing may leave the process insufficiently treated, potentially reducing protection against corrosion, scale, hydrates, biological activity, or other conditions.
Overdosing can waste expensive treatment chemicals and increase operating costs without necessarily providing additional process benefits.
For operators, repeatable chemical delivery can therefore contribute to better chemical management, more predictable treatment, and improved process control.
Flow meters may also be incorporated into a chemical injection system when operators need independent verification of actual chemical delivery. Technologies such as Coriolis flow meters can complement an API 675 chemical injection pump by measuring what is actually flowing through the system.
What Performance Requirements Are Important Under API 675?
API 675 focuses on controlled and repeatable pump performance, including the relationship between the pump’s set point and its actual delivered capacity.
Three concepts are especially useful when evaluating metering performance:
- Accuracy: How closely actual pump delivery corresponds to the expected or specified output.
- Repeatability: How consistently the pump returns to the same output under the same operating conditions.
- Linearity: How closely changes in pump output correspond to changes in the pump’s capacity setting.
These characteristics matter because a chemical injection pump often needs to operate across a range of dosing rates rather than at one fixed condition.
An operator may need to increase or decrease chemical delivery as process conditions change. Predictable performance across the operating range makes those adjustments more useful and easier to control.
Performance should still be considered in the context of the complete system. Suction conditions, fluid properties, pressure, piping, valves, pulsation, and other factors can influence actual chemical injection performance.
Does an API 675 Pump Guarantee a Good Chemical Injection System?
No. An API 675 pump can provide an important foundation for a chemical injection system, but the standard does not eliminate the need for proper system design.
A reliable chemical injection package requires the pump and supporting equipment to work together under actual operating conditions.
Important system considerations include:
- Minimum, normal, and maximum injection rates
- Suction and discharge pressure
- Chemical viscosity and temperature
- Wetted-material compatibility
- Available NPSH
- Process connections
- Flow measurement
- Pulsation control
- Valves and backpressure requirements
- Instrumentation
- Control strategy
- Maintenance accessibility
Pulsation is one example of why the surrounding system matters. Reciprocating positive displacement pumps inherently produce pulsating flow. Depending on the installation, properly selected pulsation dampeners can help control pressure fluctuations and protect downstream piping and instrumentation.
Flow measurement can provide another layer of process visibility. Rather than relying exclusively on theoretical pump output, a properly selected flow meter can verify the actual chemical injection rate.
API 675 should therefore be considered within the context of the complete chemical injection system, not as a substitute for sound application engineering.
How Do You Choose an API 675 Chemical Injection Pump?
Choosing an API 675 pump begins with defining the actual operating conditions and project requirements.
Before selecting a pump, identify:
- Required flow: Establish minimum, normal, and maximum injection rates.
- Discharge pressure: Determine the normal and maximum pressure the pump must overcome.
- Chemical properties: Identify chemical composition, concentration, viscosity, temperature, and other relevant properties.
- Material requirements: Confirm compatibility between the chemical and all wetted components.
- Turndown: Determine how much the required injection rate may vary.
- Control method: Define how pump output will be adjusted and controlled.
- Measurement requirements: Determine whether independent flow verification is necessary.
- Project specifications: Identify the required API 675 edition, purchaser requirements, testing, documentation, and other project-specific provisions.
MJ Systems offers Hydra-Cell P Series metering pumps designed to meet or exceed API 675 performance requirements. Hydra-Cell’s hydraulically balanced diaphragm technology uses a seal-less pumping chamber without dynamic seals, packing, or cups.
Available configurations cover a range of flow and pressure requirements, providing options for chemical processing, oil and gas, water treatment, and other metering applications.
The appropriate model should always be selected according to the application’s actual operating envelope rather than the API designation alone.
Frequently Asked Questions About API 675
What does API 675 stand for?
API refers to the American Petroleum Institute. API Standard 675 covers reciprocating controlled-volume pumps and pump units used in petroleum, chemical, and gas industry services.
Is API 675 required for every chemical injection pump?
No. API 675 is not automatically required for every chemical injection application. It may be specified by an end user, engineering company, project specification, or operating standard when controlled-volume pump performance and other API 675 requirements are needed.
What is the difference between API 675 and API 674?
API 675 addresses reciprocating controlled-volume pumps, which are commonly used for metering and chemical injection. API 674 covers reciprocating positive displacement pumps used for other types of process service. The appropriate standard depends on the pump’s intended function and project requirements.
Does API 675 cover the entire chemical injection skid?
API 675 primarily addresses the controlled-volume pump and pump unit requirements within its scope. A complete chemical injection package may include additional equipment such as tanks, flow meters, valves, pulsation dampeners, instrumentation, piping, and controls that require separate engineering and project specifications.
Specify the Right Chemical Injection System With MJ Systems
API 675 provides an important framework for specifying reciprocating controlled-volume pumps used in demanding petroleum, chemical, and gas applications. For chemical injection, the standard can help establish expectations for pump design, performance, testing, and documentation.
Meeting the needs of an actual application, however, requires looking beyond the standard alone. Flow rate, pressure, chemical properties, materials, measurement, pulsation, controls, and supporting equipment all affect how well the complete chemical injection system performs.
MJ Systems provides API 675 metering solutions along with chemical injection pumps, Coriolis and other flow meters, pulsation dampeners, valves, instrumentation, and packaged systems. Its application-focused approach helps customers match equipment to the technical and operational requirements of each process.
Need help specifying an API 675 chemical injection pump or complete metering system? Contact MJ Systems to discuss your application.