10.3 Problem analysis

The problem was initially thought to be due to a failure of the HPU control module. However, the problem was traced, eventually, to a failing DC power supply unit (PSU) which powers the control module. Once the problem was identified, replacement of the power supply unit resolved the issue. What should be noted from this seemingly straightforward problem is that both reactor and regenerator HPU units had suffered from the same problem. On closer inspection, both power supply units were of the same make and had been first installed (as part of the HPU units) at around the same time. At the time of the incident, the power supply units

Figure 11. A typical FCCU slide valve actuator (left) and HPU & control module (right) [12].

The other key performance indicator for tubular joints is fatigue life prediction. In recent years through the use of proper joint configuration in design, use of joint flexibility approaches in analysis, the issue of fatigue life estimation has been argued away. In principle the acceptance criteria for ALE for a fixed offshore structure is the exceedance of the minimum RSR values. In recent years, integrity management codes of practice including API RP2SIM (2014) [10], ISO 19902:2007 [11] provide

guidance on the ALE for fixed operating steel structures.

Minimum RSR values for the Gulf of Mexico (API RP 2A, 2014) [9].

Typical schematic for load displacement curve—ultimate strength [8].

Figure 10.

Maintenance Management

Table 1.

72

## Maintenance Management

were estimated to be 10 years old. Aging was attributed as the cause of the problem, as within 6 months, another slide valve HPU had also suffered from an almost similar problem.

Equipment Obsolescence Masterplan was also updated. This is typically reviewed on a yearly basis to manage overall life cycle of aging EC&I assets. Figure 12 is an example of an equipment obsolescence dashboard which lists EC&I equipment

This case study highlights several important aspects of managing aging assets:

analysis. Equipment failure rate, for example, will show whether an equipment is approaching end-of-life. However, quality data is essential and data clean-up

• Information is in the data. Useful insights can be obtained through data

• Obsolescence management is essential for EC&I equipment. All equipment should be captured in an asset list and the aging strategy should be clearly defined. This could be through various way which include replacement, upgrade, life extension (through supplier extended support), life extension

• EC&I equipment typically will have shorter life-cycle than an asset overall design life. Therefore, EC&I aging strategy has to be put in place much earlier than other assets such as structures and mechanical equipment. With E&CI equipment, analysis down to the major component level (e.g. PSU) should be done. This may need to also include supporting equipment such as interface modules, equipment communicators and workstations as well as software.

• Remediation of aging asset can be based equipment criticality and/or actual equipment condition. There are various methodologies that can be employed to determine equipment criticality such as failure mode, effects and criticality

asset, obsolescence status and remedial plan.

DOI: http://dx.doi.org/10.5772/intechopen.82841

Maintenance Management of Aging Oil and Gas Facilities

often is required before analysis can be done.

(with available spares) or run-to-fail.

Figure 12.

75

Example of an equipment obsolescence dashboard (HSE UK KP4 report) [7].

There are several failure mechanisms that are typically found due to aging. Unfortunately, a detail inspection of the power supply unit was not carried out to identify the aging mechanism. Table 2 shows common aging mechanism for primary containment (piping, vessels, heat exchangers), structures, safeguarding systems and electrical, control and instrumentation (EC&I) [HSE UK RR823 Plant Aging Study] [8].
