API 670 is one of the most important and globally recognized standards for rotating machinery protection systems. Developed by the American Petroleum Institute ( API), it provides a precise, safe, and reliable framework for monitoring, protecting, and controlling vibrations in rotating machinery in critical industries such as oil and gas, petrochemicals, power generation, and heavy industry.
In large industrial plants, rotating machinery such as pumps, compressors, gas and steam turbines, generators, industrial fans, gearboxes, and large electric motors play a crucial role. Malfunctions or failures of these machines can lead to millions of dollars in damages, production losses, and even safety incidents. API 670 establishes criteria for the condition monitoring of these machines, their early warning systems, automatic protection mechanisms, and safety precautions.
In this article, we will attempt to provide a complete definition, application description, standard structure, required equipment, installation requirements, advantages, differences to other standards, and the significance of the API 670 standard in simple yet professional language.
What is the API 670 standard?
API 670 – Machinery Protection Systems – provides guidance for the design, selection, installation, operation, and testing of protection and monitoring systems for rotating machinery . This standard defines the following:
-
Which sensors and monitoring devices should be used?
-
How should the system be installed, configured, and tested?
-
How sensitive and accurate are these sensors?
-
Under what conditions do the warning zone and the reaction zone apply?
-
How to store and analyze data
-
What requirements apply to system protection and vibration protection?
In other words, API 670 creates a common language for equipment manufacturers, design engineers, project contractors, and operations and maintenance teams.
Why is API 670 important?
API 670 occupies a special position in the industry for several important reasons:
1. Prevention of significant economic losses
Failures of rotating machinery can lead to production downtime and losses amounting to millions. Protection systems that comply with API 670 standards can reduce this risk.
2. Increased security
Improper operation of construction machinery can lead to explosions, fires and serious injuries.
3. Extending the service life of the devices
Monitoring vibrations and preventing permissible limits from being exceeded can extend the service life of bearings, shafts, rotors and components.
4. International Standardization
Since API 670 is a standard, it is used by oil companies in various countries.
5. Extremely high reliability
This standard establishes a minimum quality level for vibration protection devices, thereby significantly increasing operational safety.
What components does the protection system according to API 670 include?
A complete system according to the API 670 standard consists of the following components:
1. Vibration sensor
Contains:
-
Short-range probe
-
Vibration speed sensor
-
Vibration accelerometer (accelerometer)
These sensors measure the dynamic properties of the rotor.
2. Axial position sensor (axial position)
To avoid collisions between the turbine blades, the axial displacement of the shaft is measured.
3. Speed/overspeed sensor
Protection of turbines and compressors from the effects of increased rotational speed.
4. Monitoring and protection system
Contains:
-
anxiety phase
-
Emergency shutdown relay (isolating relay)
-
Vibration therapy card
-
Observation room
The most commonly used systems are from brands such as the Bentley Nevada 3500.
5. Data acquisition system
Performing vibration analyses, FFT analyses, trend analyses and troubleshooting.
6. Cables, accessories, structures and connections
It meets intellectual property protection standards, is explosion-proof and offers cable protection.
Devices that need to be protected according to API 670.
API 670 is recommended for use in all sensitive rotating machinery , including:
-
Gas turbine
-
Steam turbine
-
centrifugal compressor
-
piston compressor
-
centrifugal pump
-
industrial fans
-
dynamo
-
transmission
-
crankshaft
-
Large engines and drive systems
This applies particularly to facilities located on important production lines.
Different versions of the API 670 standard
The API 670 standard has been updated several times since its initial release.
The goal of these updates is to improve security and accuracy, as well as to adapt to new technologies.
The most important components of the update include the following points:
-
More precise vibration sensors
-
The demands placed on systems that operate at extremely high speeds are constantly increasing.
-
Requirements for digital systems
-
Stricter rules for explosion-proof zones
What are the most important provisions of the API 670 standard?
This standard contains several important and practical sections:
1. Proximity sensor
These sensors are used to measure the distance between the rotor shaft and the bearing.
The API-670 standard defines the following:
-
How accurate are these sensors?
-
How do I install this?
-
What is the permissible distance from the axis?
-
How to protect cables
2. Speed and vibration acceleration sensors
Measure the vibration of the machine housing.
The rule states the following:
-
Where should the sensor be installed?
-
Which sensitivity level should I use?
-
How do you establish a connection and create an interface?
3. Position of the shaft axis of rotation (position in the pressed state)
This component is designed to prevent excessive back-and-forth movement of the shaft within the thrust bearing.
4. Speed limiter
To protect the turbine:
-
There must be two or three independent channels.
-
Do not trust the core control system.
-
High-precision speed measurement
5. Monitoring and protection system
The rule clearly states the following:
-
The system must have two warning levels (alarm) and an emergency shutdown (operational capability).
-
Capable of performing tests
-
The relay output signals must comply with safety principles.
-
Each channel functions independently.
6. Requirements for cables and installations as well as for explosion-prone areas.
This standard covers the following aspects:
-
Applicable cable types
-
Cable protection
-
Delivery box
-
EX standard for work in hazardous areas
7. Testing and calibration requirements
The API-670 standard emphasizes the following points:
-
The system must be thoroughly tested before being put into operation.
-
The sensor is calibrated.
-
The data obtained should be compared with the manufacturer’s specifications.
Differences between API 670 and other standards
1. API 670 and API 671
-
API 670: Protection of measuring instruments against vibrations.
-
API 671: High-strength connectors
2. API 670 and API 610
-
API 670: Monitoring and Protection
-
API Standard 610: Standard for centrifugal pumps
3. API 670 and ISO 10816
-
ISO 10816 Vibration assessment standard
-
API 670 standard for vibration protection systems
4. API 670 and ISO 7919
-
Rotor vibration measurement according to ISO 7919
-
API 670 is more comprehensive and places greater emphasis on security.
Advantages of implementing API 670
1. Improvement of equipment reliability.
The main equipment is subject to very strict controls.
2. Prevention of sudden failures
Unusual vibrations can be detected quickly .
3. Extending the service life of bearings and rotors.
The system issues a warning before actual damage occurs.
4. Reduced maintenance costs.
Defects are detected before major failures occur.
5. Personal protection
In the event of a sudden increase in vibrations or speed, the system immediately switches off the device.
6. Standardization of industrial projects
The company can use similar devices in different projects.
Disadvantages and problems with the implementation of the API 670 standard
Despite its many advantages, the API-670 standard also presents some challenges:
-
Purchasing standard equipment is expensive.
-
Installation requires experienced professionals.
-
The sensor is extremely sensitive to faulty installation .
-
Regular calibration is required.
-
The complexity of systems that operate at high speeds.
Typical systems are based on the API 670 standard.
World-renowned brands produce protective systems according to this standard:
1. Bentley Nevada (General Electric)
The 3500 and 3701 series are among the most popular systems in the world.
2. SKF
CM and IMx systems.
3. Emerson
CSI and AMS systems.
4. Brewer and Kyrgyzstan
High-precision sensors and devices for vibration measurement.
This type of equipment is widely used in the oil industry and in power plants.
The significance of the API 670 standard for Iranian industry
In Iran, the API 670 standard is of particular importance due to
the rapid development of the oil, petrochemical, metallurgical, and energy industries. Most of the turbines and compressors installed in Iran are from world-leading manufacturers, and all of this equipment requires protective systems.
The application of the API 670 standard in Iranian industry has led to the following results:
-
Improving safety in the production line
-
Reduce the number of emergency braking maneuvers.
-
Extending the lifespan of important equipment.
-
Reduction of basic maintenance costs.
In conclusion
API 670 is one of the most important industry standards for the protection of rotating machinery. It provides a detailed framework for the selection of sensors, the design of monitoring systems, the proper installation of equipment, and the implementation of protection systems.
Operating a critical rotating equipment without adhering to this standard significantly increases the risk of unexpected failures, production interruptions, billions in losses, and safety incidents.
In fact, the API 670 standard guarantees the application of the best vibration protection methods to prevent mechanical damage.