What You Need to Know About Api 671 Latest Edition of Time
Api 671 is a standard that specifies the requirements for special-purpose couplings for the transmission of power between the rotating shafts of two machines in the petroleum, petrochemical, and natural gas industries. Such applications are typically in large and/or high-speed machines, in services that can be required to operate continuously for extended periods, are often unspared, and are critical to the continued operation of the installation. By agreement, it can be used for other applications or services.
The latest edition of Api 671 was published in August 2020 and is the fifth edition of the standard. It covers the design, materials of construction, manufacturing quality, inspection, and testing of special-purpose couplings. It is applicable to gear, metallic flexible element, quill shaft, and torsionally resilient type couplings. Torsional damping and resilient type couplings are detailed in Annex A; gear-type couplings are detailed in Annex B; and quill shaft style couplings are detailed in Annex C.
The latest edition of Api 671 introduces some changes and updates from the previous edition, such as:
Revised definitions and terminology to align with ISO standards
Added requirements for torsional analysis and dynamic testing
Added requirements for lubrication systems and monitoring devices
Added requirements for documentation and data reporting
Added informative annexes on coupling selection, alignment, installation, operation, and maintenance
If you are involved in the design, selection, installation, operation, or maintenance of special-purpose couplings for the petroleum, petrochemical, and natural gas industries, you should be aware of Api 671 latest edition of time and its implications for your work. You can purchase a copy of the standard from IHS Markit, Techstreet, or GlobalSpec.
Benefits of Special-Purpose Couplings
Special-purpose couplings are designed to accommodate parallel (or lateral) offset, angular misalignment, and axial displacement of the shafts without imposing unacceptable mechanical loading on the coupled machines. This reduces the stress and wear on the shafts, bearings, seals, and other components of the machines, extending their service life and reliability. Special-purpose couplings also help to isolate vibration, dampen shock loads, and compensate for thermal expansion of the shafts.
Special-purpose couplings can be classified into different types based on their design and functionality. Some of the common types are:
Torsional damping and resilient type couplings: These couplings use elastomeric or metallic elements to provide flexibility and torsional damping. They can absorb shock loads, reduce noise and vibration, and accommodate moderate misalignment. They are suitable for low to medium speed and torque applications.
Gear-type couplings: These couplings use toothed hubs and sleeves to transmit torque and accommodate angular and axial misalignment. They require lubrication and periodic maintenance. They are suitable for medium to high speed and torque applications.
Quill shaft style couplings: These couplings use a hollow shaft with splines or keys to transmit torque and allow axial movement of the shafts. They are often used in tandem with gear-type couplings to provide additional flexibility. They are suitable for high speed and torque applications.
How to Select and Use Special-Purpose Couplings
When selecting a special-purpose coupling for a specific application, several factors should be considered, such as:
The type, size, speed, power, and torque of the machines to be coupled
The amount and type of misalignment (parallel, angular, or axial) expected between the shafts
The operating conditions (temperature, pressure, humidity, corrosion, etc.) of the environment
The availability of lubrication and maintenance facilities
The cost and performance trade-offs of different coupling options
Once a suitable coupling is selected, it should be installed, aligned, lubricated, and maintained according to the manufacturer's instructions and best practices. Proper installation and alignment are essential for ensuring optimal performance and longevity of the coupling and the machines. Improper installation or alignment can cause excessive vibration, noise, heat generation, wear, and failure of the coupling or the machines. Lubrication is also important for reducing friction and wear of the coupling components. Periodic inspection and maintenance are necessary for detecting and correcting any issues that may arise during operation. ec8f644aee