RAM analysis: maintainability, availability and reliability

The acronym RAM stands for Reliability, Avaliability and Maintenability, the pillars for the industry to function as expected. And to measure these indicators, there are a series of tools and methods that help make these concepts tangible: RAM analysis.

RAM analysis aims to ensure that operating, maintenance and disposal costs remain below an acceptable level. To do this, it establishes the relevant performance parameters as soon as they are acquired and monitors them during all phases of the asset’s life cycle.

This data, taking into account the effect of degradation caused by the age of the equipment and the effects of maintenance, contributes to efficient plant management.

But before going into the analysis, it is important to go back over the basic concepts, starting with the ABNT NBR 5462 definition:

• Reliability is the ability of an item to perform a required function under specific conditions, during a given time interval.

• Avaliability is the ability of an item to perform a certain function at a given time or during a given time interval.

• Maintenability is the state in which an item is maintained or put back into condition to perform its required functions, under specific conditions of use, when maintenance is carried out under determined conditions and by means of prescribed procedures.

What is RAM? 

This is an analysis in which the parameters lead us to a strategic vision based on these three fundamental pillars, which can be measured using a few calculations. The three are interrelated and serve as a parameter for observing the overall state of the plant.

It is important to consider the context and variables of each industry when determining the RAM analysis. In other words, the proposal is flexible and comprehensive, encompassing the essential factors within these three fundamental concepts, but which make sense for the reality and condition of the industry in question.

Here are some basic calculations that can be used for each of the core concepts.

Availability and reliability: the role of maintenance management   

The concepts of reliability and availability are strongly linked. After all, variations in one indicator have an impact on the other.

The following formula is commonly used to calculate availability: Availability rate = (Operating time / Total time) * 100%.

The unavailability rate: Indicates the time the equipment was unavailable for operation. It is calculated using the formula: Unavailability rate = (Downtime / Total time) * 100%.

The Mean Time Between Failures (MTBF) is the average period between failures and is useful for describing reliability. The following formula is used to calculate it:

It is worth noting that reliability is calculated as a probability. It is also possible to calculate the failure rate: 1/MTBF, or the probability of failure: (P): P = 1 – R.

This information makes it possible to measure the number of failures and thus carry out strategic asset management.

Maintainability and its importance for maintenance

In general, the concepts of reliability and availability are more present in day-to-day industrial life. Maintainability, on the other hand, often appears indirectly in the expectation that maintenance will restore the machine’s full operating capacity in the shortest possible time. It is therefore highly desirable that the asset remains functional until the end of its expected useful life, and this is the concept of maintainability in practice.

But that’s not all. As well as recovering operating capacity, we want the amount and duration of maintenance to be as short as possible. In other words, in the ideal scenario, the machine operates at full capacity, remaining idle for as little time as possible.

However, for this to be possible, there are a number of factors that can impact on the percentage of return to full operating capacity after maintenance and, of course, the recurrence rate. In other words, the greater the damage and the longer the machine has operated faulty, the tendency is for the maintainability index to be lower and the cost associated with the asset to be higher.

MTTR – Maintainability calculation 

To measure maintainability, it is quite common to calculate the Mean Time to Repair (MTTR). This represents the average time required to carry out corrective maintenance on all removable items in the asset. This type of maintenance forecast analyzes how long repairs and maintenance tasks will take in the event of a system failure.

The result of the calculation influences reliability and availability forecasts and analysis. In other words, it can be used in reliability forecasting to calculate asset availability. The three concepts are therefore practically inseparable for efficient industrial plant and maintenance management.

Another factor associated with maintainability is the total cost of the equipment. In other words, an increase in maintenance capacity can lead to a reduction in operating and support costs. Thus, a more sustainable asset reduces maintenance time and operating costs. Obviously, maintenance is expected to be efficient and thus enable the asset to return to operation more quickly.

Maintenance, an ally of efficient asset management

When well defined, maintenance management is a process that guarantees the efficiency of machinery, anticipating possible unforeseen events by identifying a potential failure. This makes it possible to take preventive action before a failure occurs, which will certainly compromise the production flow.

Want to know more about management? Check this out: Asset management vs. maintenance management: what’s the difference? (dynamox.net)

And to ensure that reliability, availability and maintainability rates are close to desirable, it is essential to acquire asset data. Get to know all the features and applications of the Dynamox technology! Talk to our specialists.