Seven Keys To Effective Oil Analysis
Follow these seven simple steps to help maximize the benefits of oil analysis:
Identify the equipment critical to your operational productivity. At the bare minimum, the lubricants in those components should be analyzed regularly. (Ideally, all lubricants in use at your facility should be tested regularly.)
Register the equipment with the lab. This will help the lab identify appropriate tests for your specific application. Registration also facilitates trending.
Use proper sampling procedures. Improper sampling may produce erroneous test results. Problems could be missed and go untreated, leading to costly problems later. Or conditions may be misdiagnosed, resulting in incorrect, unnecessary and money-wasting actions being taken to correct a nonexistent issue.
Provide complete and accurate information with each sample you submit to the lab. Missing or inaccurate information may lead to a misdiagnosis. Complete all fields on the submission form, including the specific lubricant in use, the component it services, the hours the oil has been in use, and more. Also ensure that the information is legible to help avoid misinterpretation.
Submit samples promptly to the laboratory for analysis. Although a delay inherently has virtually no effect on the sample itself, it does increase the potential for contamination. Also, the condition of the oil in use in the equipment will continue to change over time. The more time that passes between when the sample is taken and when it is analyzed, the less alike the sample will be to the fluid still flowing in the machine. Therefore, the results of the analysis will have less relevance.
Review and respond to test results appropriately. Promptly review the analysis documentation to determine what, if any, action is necessary.
Use oil analysis regularly, not just when you suspect a problem. As part of a preventive maintenance program, regular oil analysis establishes a baseline for monitoring the condition of your lubricants and the components in which they are used. Much like routine, periodic medical screenings, the regular collection of analysis data over time may help identify trends and spot potential complications in early stages, so that they can be corrected and not become big problems.
How do we measure static gel strength development?
Historically, the SGS of a cement slurry was determined by a method using a couette-type rotational viscometer. Today, more specialized instruments have been developed that allow the measurements to be done under conditions of high temperature and pressure.
API-10B6 was developed to establish the testing protocols to determine SGS by different mechanisms, including a rotating-type apparatus, an intermittent rotation-type apparatus and an ultrasonic-type apparatus (removed in the latest API adoption due to patents exclusivity).
Test method using rotating-type static gel strength apparatus
The apparatus contains a pressure chamber that can be heated and pressurized according to a simulated cement job schedule. The SGS is calculated from the torque required to rotate a paddle of known geometry at very low speed. The rotation speed of the paddle during the SGS measurement portion of the test is usually a continuous 0,2 r/min. The initial stirring to simulate placement in the well is typically conducted at 150 r/min.
Test method using intermittent rotation-type static gel strength apparatus
This apparatus works on the same principles/methods as the previous one with the sole difference that this it operates intermittently during the SGS testing phase at 0,01 r/min for 6s after a time interval adjustable between 1 min and 10 min. In general, an intermittent rotation every 3 min is used.
Test method using ultrasonic-type static gel strength apparatus
The instrument measures the static gel strength of API cement under high temperature and high-pressure conditions. The instrument is equipped with an internal processor board that sends and receives an ultrasonic pulse through the slurry, then performs post processing of the data to determine the static gel strength (SGS) versus time plot. Additionally, as an option, the instrument may be used to determine the compressive strength of the cement using the same algorithms and method found in a conventional Ultrasonic Cement Analyzer (UCA). This testing methodology was included in API10B6 original version but was later removed as it’s patent protected and exclusive to Chandler Ametek. The machine is known as Static Gel Strength Analyzer (SGSA).
