World-class condition monitoring of hydraulic systems involves the successful integration of a number of strategic elements. While in the past, walk-around inspections and gage data were the primary means of monitoring system health, today’s modem oil analysis programs apply a host of sophisticated new tools and instruments. Reliability teams at the plant site frequently commission small laboratories. In many cases the instrumentation suite includes portable and unattended sensors. The situational context is changing too as today’s hydraulic systems are increasingly designed for higher pressures, speeds, and temperatures. This paper presents a review of strategic elements that, when well conceived and implemented, can deliver vital aiding information for achieving even the toughest condition-based maintenance goals. These include the selection of test slate, deployment of incipient failure advisories, setting of targets and limits that define nonconforming conditions, exception testing, and proactive maintenance.

The post Advancements in Fluid Analysis Technologies and Strategies for Hydraulic SystemCondition-Based Maintenance appeared first on Tesibis.

A wide range of fluid degradation and contamination-related issues can affect turbine lube oil systems. One serious and growing concern is the presence of sludge and varnish. This condition can occur in even the most well-maintained machines. Surprisingly, it can also happen when oils are not particularly old or contaminated. And it can occur with even the most thermally robust synthetic lubricants and hydraulic fluids.

In turbine systems, there are few failure conditions that can disrupt operation as quickly and completely as a varnished and seized-up control valve operation. This can be the cause of a tripped turbine forced outage or other production losses. So too, sludge in many circulating lube oil systems can gum up flow controls, strainers and critical oil ways. In recent years, there has been a large number of reported cases associated with varnish and sludge formation in turbine-generator applications. Explanations for these problems have varied but typically include Group II mineral oil solubility issues, additive instability, bulk oil oxidation, adiabatic compressive heating and electrostatic discharge, among others. This paper will review precursor conditions that lead to sludge formation, some of the common lubricant degradation methods and the role of oil analysis in recognizing the potential risk well ahead of failure.

The post Review of Degradation Mechanisms Leading to Sludge and Varnish in Modem Turbine Oil Formulations appeared first on Tesibis.

There has been much said in recent years about the increased propensity of some modern oil formulations to produce sludge and varnish. Ironically, many of the oils accused of contributing to varnish are the same oils endowed with exceptionally high oxidation stability due to advanced refining technology and formulation science. To better understand this paradox, let’s begin by defining a new term.Lubricants have an intrinsic Impurity- holding Capacity (IHC) relating to their ability to retain very small (submicron) impurities in solution. These impurities are largely oil-degradation products, but include other oil suspensions as well.

This holding capacity is like an imaginary silo or cup within the oil. If the cup is half empty, it has unutilized or reserve capacity. However, conditions can occur that can cause an overfill, leading to insoluble suspensions in the oil and varnish (sometimes called the “dumping point”).

The post What is Your Oil’s Impurity-holding Capacity (IHC)? appeared first on Tesibis.

The products of lubricant degradation are called sludge and varnish. These products start in the dissolved form and accumulate until the lubricant reaches its capacity, referred to as the saturating point, forcing any excess to convert into insoluble degradation products. In certain instances, deposits form on machine surfaces at the exact location where the oil has degraded. In other cases, the oil degrades in one location but, the insoluble degradation products are carried elsewhere by the moving fluid forming deposits on surfaces.

The post Sludge and Varnish in Turbine Systems appeared first on Tesibis.

Do you know about silt lock? This common condition causes motion impediment failure in certain machines. While this type of failure usually doesn’t involve wear or permanent internal damage to the machine, it is sudden and abrupt. Silt lock is the result of solid contamination and is amplified by other conditions that must be controlled where possible. It is most often associated with hydraulic systems and produces seizure or jamming of components.

Because of its lack of warning or predictability, silt lock is responsible for some of the most devastating and destructive catastrophes in mechanical machinery. These include mechanical casualties, prolonged production losses and even loss of human life.

Silt lock has been found to be the root cause of countless failures related to aircraft, spacecraft, passenger cars, elevators, turbine generators, tower cranes, etc.

The post Recognizing the Causes and Hazards of Silt Lock appeared first on Tesibis.