Page 283 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

13/260 Stations and Surface Facilities
product flow through the mainline include compressors, sections as part of a corrosion prevention program, and not
meters, piping, manifolds, instrumentation, regulators, and include all factors that could be considered to support a relative
pressure relief devices and other safety systems, and block costbenefit analysis for a comprehensive risk-based mainte-
valves. nance budget.
Smaller station facilities, such as block valves, manifolds, Evaluators can and should use the results from other risk
meters, andregulators, are often located within small, protected analysis methods, such as matrix or process hazard analysis
aboveground areas, or inside buried vaults, often made of con- (PHA) techniques, to provide information supporting an index-
crete. Larger pipeline stations, such as pump/compressor sta- based analysis (see Chapter 2). PHAs (e.g., HAZOP, “what-if”
tions or tank fms, can cover many acres and be heavily scenarios, FMEA) are sometimes completed every several
secured. Most station facilities could be more accessible than a years to meet PSM requirements, but they do not routinely
buriedpipeline, so they typically have unauthorized access pre- gather and integrate large volumes of facility data as would a
vention measures such as fencing, locked gates, barbed wire, comprehensive risk model. Existing PHA action items can be
concrete barriers, berms, lighting, and security systems. evaluated for risk reduction effectiveness by developing a rela-
Dependmg on the station’s size and use, they may be manned tive risk mitigation scenario (defined in risk model terms) and
continuously or visited by operations or maintenance personnel calculating a costhenefit ratio (action costiscore reduction).
periodically. This is dmussed in Chapter 15.
Station piping and equipment are sometimes built from dif-
ferent materials and operate at different pressures than the Scope
pipeline. Ancillary hazardous materials and processes can also
be present at liquid stations, which adds to the level of risk and As discussed in Chapter 2, the scope of a risk assessment
complexity. should be established as part of the model design. This chapter
assumes a risk assessment effort that focuses on risks to public
Tanks safety, including environmental issues, and covers all failure
modes except for sabotage.
Product storage tanks might warrant their own rating system Sabotage can be thought of as intentional third-party dam-
since they are often critical components with many specific risk age. The risk of sabotage commands a special consideration for
considerations unique to each individual tank. A risk model can surface facilities, which are more often targeted compared to
use industry standard inspection protocols such as API 653, buried pipelines. Sabotage often has complex sociopolitical
which specify many variables that contribute to tank failure underpinnings. As such, the likelihood of incidents is usually
potential. Common variables seen in tank inspection criteria difficult to judge. Even under higher likelihood situations, mit-
are igative actions, both direct and indirect, are possible. The
potential for attack and an assessment of the preventive meas-
Year tank was built ures used are fully described in Chapter 9.
Previous inspection type, date, and results As noted in Chapter 1, reliability issues overlap risk issues
Product in many regards. This is especially true in stations where spe-
Changes in product service cialized and mission-critical equipment is often a part of the
Types of repairs and repair history transportation, storage, and transfer operations. Those involved
Internal corrosion potential and corrosion mitigation with station maintenance will often have long lists of vari-
Construction type ables that impact equipment reliability. Predictive-Preventive
Shell design, materials, seam type Maintenance (PPM) programs can be very data intensive-
Roofdesign considering temperatures, vibrations, fuel consumption, filter-
Leak detection ing activity, etc. in very sophisticated statistical algorithms.
Anodes under tank When a risk assessment focuses solely on public safety, the
If bottom was replaced, year bottom replaced, minimum bot- emphasis is on failures that lead to loss of pipeline product.
tom before repair, and minimum bottom after repair Since PPM variables measure all aspects of equipment avail-
Corrosion rate ability, many are not pertinent to a risk assessment unless serv-
Cycling frequency ice interruption consequences are included in the assessment
Cathodic protection. (see Chapter IO). Some PPM variables will of course apply to
both types of consequence and are appropriately included in
any form of risk assessment. See page 19 for discussions on
reliability concepts.
111. Station risk assessment
Sectioning
A station risk assessment model is just one of several important
tools normally used within a pipeline operator’s overall risk For purposes of risk assessment, it may not be practical to
management program. Ideally, the station risk model would assess a station facility’s relative risks by examining each in-
have a flexible user-defined structure and be modular, allowing station section ofpiping, each valve, each tank, or each transfer
the evaluator to scale the risk assessment to the needs of the pump for instance. It is often useful to examine the general
analysis. For example, the user may decide to simply employ an areas within a station that are ofrelatively higher risk than other
index-based approach to prioritize higher risk pipeline facility areas. For example, due to the perceived increased hazard asso-