As already mentioned above, couplings in compliance with the API Standard 671 are used for critical applications in the petroleum, gas and chemical industries. Generally, these couplings are required to operate continuously for longer time periods. The Standard 671 also specifies that couplings must be designed to accommodate angular misalignments and axial displacements of the shafts.
Some projects rely on earlier editions of the API 610 standard, particularly the 8th edition. That edition includes a requirement for balancing all components to ISO 1940-1 Grade G 1.0, which, in practice, means balancing the transmission unit and both hubs. This requires that OEMs balance the hubs before machining the keyway, wasting time and resources. Furthermore, the ANSI/AGMA 9000 Class 9 coupling standard is the only mandatory requirement in the latest API standard.
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In addition, slip fits can disrupt the balance of a piece of machinery. Taking the example above, a typical H7/g6 slip fit could result in a total clearance of 0.069 millimeter or an axis displacement of 0.034 millimeter when the set screws are tightened. This introduces an imbalance of 500 gram-millimeter in a 14.8-kilogram hub. While this is a worst case scenario, customers could certainly expect an average imbalance of 250 to 300 gram-millimeters, more than 10 times the ISO 1940-1 Grade G 1.0 limit.
In addition to the vibration issues that balancing can cause, balancing coupling components is an involved and time-consuming process. As a result, the balancing process delays the final assembly of equipment while providing no added value to the customer, who is paying for the balancing service.
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This bicentennial edition, includes more than 12,500 time series, mostly annual, providing a statistical history of U.S. social, economic, political, and geographic development during periods from 1610 to 1970.
Elastomeric (or thermoplastic) seals can be preferable in applications when bolted joint members have high misalignment or require frequent (daily) assembly & disassembly. One of the disadvantages of this type of seal is the elastomers inability to function properly when exposed to extreme temperatures and its tendency to wear/degrade over time. This type of seal may need to be periodically replaced to maintain the highest sealing integrity at the pressures used in hydraulic nut applications.
To further enhance our standard metal seal performance, technical research was performed evaluating a variety of surface coatings ranging from chemical conversion coatings, electrodeposited coatings, PVD coatings, and diffusion coatings. Many factors were considered when narrowing down the potential candidates, such as: wear resistance, corrosion resistance, coatings ability to be applied to different base metals, manufacturing processing impacts, environmental waste impacts, lead time and costs. The top candidates were selected to run through standardized accelerated wear testing to compare the relative performance of each coating versus the baseline uncoated sample. A couple of images are shown below highlighting two standout coatings showing their effectiveness in improving base metals wear properties.
Determining the appropriate method to safely disassemble the coupling hub will reduce the risk of damaging the hub and its mating equipment, as well as reducing the amount of time spent servicing the machinery.
There is a higher purchase cost associated with a hydraulic removal tool as a hydraulic pump and hose kit is required for operation, however this is offset by the decrease in time spent on the job and the repeatability of using said equipment.
The area of focus for this article is going to be around the installation and removal of the crosshead to piston rod connection. One of the most common crosshead to piston rod configurations is the direct connection of the piston rod to the crosshead, see figure 1 above. In this type of crosshead arrangement, the piston rod is threaded into the crosshead and secured using a single jam nut. The resulting bolted joint geometry has a very short effective bolt length with little bolt stretch and is not well suited for the dynamic loads generated in the piston rod during compressor operation. The short joint geometry results in a connection that is sensitive to having the proper preload to function reliably over the service life of the compressor. Additionally, if this joint fails during compressor operation, the damage to the compressor can be extensive and resulting in very costly repairs, extended machine downtime, and lost production.
Compressors can run many years between service intervals. The durability of the seals used is very important to ensure that the disassembly process is as easy as the assembly process. Elastomeric seals have a tendency to degrade over time resulting in inability to hold pressure on removal. Riverhawk uses special metal to metal seals with wear & galling protection to enhance seal life and durability.
In the end, the goal is to achieve accurate preload levels in the crosshead connection and maintain those loads over between machine service intervals. Hydraulic crosshead nuts will significantly improve the likelihood of achieving a repeatable target preload, in addition to improving safety and decreasing installation and removal times when compared to torqued hardware.
When a scheduled shutdown takes place, Field Technicians and Engineers use this downtime to perform preventative maintenance or upgrades within a specific window of time. It is worth noting, that during this downtime, the output of the powertrain being worked on comes to a stop, which makes quite an impact on the overall operation or efficiency of the plant. It also goes without saying, the potential cost of any additional downtime not planned for can be detrimental.
Due to these issues, a better method of achieving a more accurate bolt loading is to use a Hydraulic Tensioner. Tensioning reduces or eliminates many variables in the bolting process which are present when torque is involved. The results from tensioning will provide improved accuracy and repeatability in addition to reduced installation and removal time.
When improvements of load distribution over multiple threaded fasteners are required, such as split line flanges, gasketed joints or any joint that needs precision sealing, tensioning is the method of choice. This is true because multiple fasteners can be loaded at the same time using multiple tensioners and one common hydraulic power unit, that will evenly load the joint. When using torque, achieving uniformity is an exceedingly difficult task to do.
When selecting a pump kit for your next application, the three questions outlined below can serve as a guide for your selection. Choosing the right pump for the right job can actually cut down time spent on a job, which can ultimately translate to a savings on cost.
There will be times where you will find yourself in need of a varying supply of hydraulic pressure to your equipment or tooling in order to finish a job. Determining the type of supply that is needed will help you select the appropriate pump for the job.
Not all jobs that require the use of a hydraulic pump will be performed in a repair shop or factory floor. You may be required to service equipment outdoors or in an environment with limited space. Having a pump kit that is compact and easily transportable will cut down on the time required to complete a job off-site.
Even if the nut does not gall and stick, friction remains a problem. The amount of friction can vary from bolt to bolt which leads to preload variation. Friction also tends to cause the bolt to wind up, which relaxes over time and loses its initial clamping force. Hydraulic bolt tensioning eliminates this issue.
The RX671 group microcontrollers deliver superior real-time performance with the RXv3 core running at 120MHz. The HMI functions enable contactless operation by proximity switches and voice recognition, making it possible to realize hygienic HMI suitable for the new normal. A wide variety of packages, including the 4.5mm x 4.5mm 64-pin TFBGA, is all equipped with 2MB flash memory and 384KB SRAM to meet a wide range of needs with a single chip.
The initials of the encyclopaedia's contributors appear at the end of selected articles or at the end of a section in the case of longer articles, such as that on China, and a key is given in each volume to these initials. Some articles were written by the best-known scholars of the time, such as Edmund Gosse, J. B. Bury, Algernon Charles Swinburne, John Muir, Peter Kropotkin, T. H. Huxley, James Hopwood Jeans and William Michael Rossetti. Among the then lesser-known contributors were some who would later become distinguished, such as Ernest Rutherford and Bertrand Russell. Many articles were carried over from the 9th edition, some with minimal updating. Some of the book-length articles were divided into smaller parts for easier reference, yet others much abridged. The best-known authors generally contributed only a single article or part of an article. Most of the work was done by journalists, British Museum scholars and other scholars. The 1911 edition was the first edition of the encyclopaedia to include more than just a handful of female contributors, with 34 women contributing articles to the edition.[5]
Robert Collison, in Encyclopaedias: Their History Throughout The Ages (1966), wrote of the eleventh edition that it "was probably the finest edition of the Britannica ever issued, and it ranks with the Enciclopedia Italiana and the Espasa as one of the three greatest encyclopaedias. It was the last edition to be produced almost in its entirety in Britain, and its position in time as a summary of the world's knowledge just before the outbreak of World War I is particularly valuable". 2ff7e9595c
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