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Availability, Reliability and Maintainability

EPCONSULT has extensive expertise in reliability, availability and maintainability (RAM) analysis – including projects that involved RAM analysis for onshore processing plants, offshore topsides and onshore and offshore export systems.

RAM analysis is typically used to predict the performance of process and transportation systems and to provide a basis for the optimization of such systems. The primary performance indicator is availability, which is the fraction of time that the system is fully functional. In the concept phase, it can aid concept selection, and subsequently, RAM analysis can inform front end engineering and detailed design decisions. Generally, a complex process facility is divided into a number of subsystems. Those facilities identified as having the greatest influence on availability can be investigated in more detail and design changes made to optimize performance.

RAM analysis: Availability, Reliability and Maintainability

We use commercial software for performing RAM analysis, using either Monte Carlo simulations or analytical methods. Analytical methods for RAM analysis make the simplifying assumption that failure and repair times are exponentially distributed. Monte Carlo methods allow any probability distributions to be used to describe failure and repair times. Monte Carlo approaches also allow more complex interactions between the components of the system to be considered. The Monte Carlo approach involves repeatedly sampling times to failure and repair from the selected failure and repair probability distributions. The performance of the system over many lifetime cycles is simulated to obtain a statistical estimate of system parameters such as availability.

We are able to link RAM analysis with process simulation. In this way we deal with situations where part of a system might go down and a reduced throughput can be calculated and taken into account in the availability computation. The varying production profile over the field life can also be considered.

We can model all components from the reservoir through to the delivery point.

Fault Tree Analysis

Fault tree analysis (FTA) is a method of calculating the probability of an event from the probabilities or frequencies of its causal events. It can be applied in a wide variety of ways, some of which include:

  • To calculate the reliability of a system that has to operate on demand, e.g. quick release mechanisms, emergency shutdown systems, firewater systems and high integrity pressure protection systems (HIPPS)
  • To calculate reliability of components such as valves and connectors from reliability data relating to their component parts
  • To calculate the likelihood of a particular hazardous scenario in terms of the likelihoods of equipment failures and human errors leading up to it

FMEA/FMECA

EPCONSULT has in-depth experience in conducting Failure Modes and Effects Analysis (FMEA) and FMECA (Failure Modes, Effects and Criticality Analysis). We have applied FMEA/FMECA techniques to the evaluation of a diverse range of hardware such as valves, collet connectors, FlexJoints®, diverless repair systems and tanker loading buoys.

An FMEA identifies failure modes, their causes and effects, the safeguards already incorporated and the potential additional measures that could be considered. In addition, an FMEA includes a qualitative assessment of the severity and probability of occurrence of each failure mode.

An FMECA is similar to an FMEA, except that the severity and probability of occurrence of each failure mode are assessed quantitatively rather than qualitatively. These analyses are presented in a spreadsheet format. Traditionally, the spreadsheet was filled out directly, and it was always difficult to be sure whether the study was truly systematic. However, EPCONSULT has developed a highly structured approach to the performance of FMEA/FMECA that increases confidence that important issues have been captured. This is achieved by carrying out a number of preliminary steps, including the preparation of a component relationship diagram, a function net for each system function and a failure net for each system failure mode. All data are input into the relevant diagrams and finally the FMEA/FMECA spreadsheet is generated automatically by software from the various diagrams.

FMEA/FMECA can be applied as a precursor to a RAM/FTA Analysis or a Quantitative Risk Assessment (QRA), or as a complete or standalone study.

Safety Integrity Level (SIL) Verification

EPCONSULT has extensive experience in the assessment of safety instrumented systems in accordance with international standards IEC 61508 / 61511 and US standard ANSI/ISA S84.01. Safety Integrity Levels (SIL) levels are identified in a SIL assessment, performed in a team based study with a multi-disciplinary team led by a SIL Facilitator . The SIL levels that have been identified define the required probability of failure of the safety instrumented functions in the system. A SIL verification assessment makes use of different qualitative and quantitative reliability techniques (including FMEA / FMECA, FTA, RAM) to verify that the reliability requirements for a safety instrumented system, defined by the SIL levels for the different safety instrumented functions of the system, are met.

Reliability Data Processing

EPCONSULT has expertise in reliability data processing (RDP) studies. Typically this involves developing reliable new devices for use in the oil and gas industry including developing confidence in the reliability of the calculated availability.

The purpose is to systematically study the recurring failures data of a product to determine the pattern of the failures, the causes of failures, the underlying time-to-failure distribution and the associated stress levels. The failure data could be gathered from field service failures or failures in a testing laboratory.

The main results from RDP include the failure rate, the mean life, the reliability (or failure probability) of components, equipment and systems and their associated confidence limits at desired confidence levels. The RDP study can also assess the effectiveness of a client's data collecting system.

Understanding the reliability performance of the product is critical for decision making, for example, choosing the right vendor, optimizing the life cycle cost, applying the correct burning-in strategy, etc.

Please contact us to request further details of our RAM and reliability analysis services


 
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