Page 148 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

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B4. Backfill (0-2 pts) Findings such as damaged coatings, debris (temporary wood
supports, weld rods, tools, rocks, etc.) buried with the pipeline.
The type of backfill used and backfilling procedures are often low-quality coating applications over weld joints, etc., will
critical to a pipeline’s long-term structural strength and ability still be present years later to indicate that perhaps insufficient
to resist corrosion. It is important that no damage to the coating attention was paid during the construction process.
occurred during pipeline installation. Uniform and (some-
times) compacted bedding material is usually necessary to
properly support the pipe. Stress concentration points may C. Operation (suggested weighting: 35%)
result from improper backfill or bedding material.
Knowledge and practice of good backfillisupport techniques Having considered design and construction, the third phase,
during construction warrants 2 points. operations, is perhaps the most critical from a human error
standpoint. This is the phase in which an error can produce an
B5. Handling (0-2 pts) immediate failure since personnel may be routinely operating
valves, pumps, compressors, and other equipment. Emphasis
For this variable. the evaluator should check that components, therefore is on error prevention rather than error detection.
especially longer sections of pipe, were handled in ways that Most hazardous substance pipelines have redundant safety
minimize stresses and that cold-working of steel components systems and are designed with generous safety factors.
for purposes of fit or line-up were minimized. Cold-working Therefore, it often takes a rather unlikely chain of events to
can cause high levels ofresidual stresses, which in turn can be a cause a pipeline to fail by the improper use of components.
contributing factor to stress corrosion phenomena. Handling However, history has demonstrated that the unlikely event
includes storage of materials prior to installation. Protecting sequences occur more often than would be intuitively pre-
materials from harmful elements should be a part ofthe evalua- dicted. Unlike the other phases. intervention opportunities here
tion for proper handling during construction. may be less common. But a system can also be made to be more
The evaluator should award 2 points when he sees evidence insensitive to human error through physical means.
of good materials handling practices and storage techniques As a starting point, the evaluator can look for a sense of
during and prior to construction. professionalism in the way operations are conducted. A
strong safety program is also evidence of attention being paid
B6. Coating (0-2 pts) to error prevention. Both of these, professionalism and safety
programs, are among the items believed to reduce errors.
This variable examines field-applied coatings (normally The variables considered in this section are somewhat redun-
required for joining) and provides an additional evaluation dant with each other, but are still thought to stand on their own
opportunity for precoated components. Field-applied coatings merit. For example, better procedures enhance training;
are problematic because effects of ambient conditions are diffi- mechanical devices complement training; better training and
cult to control. Depending on the coating system, careful con- professionalism usually mean less supervision is required.
trol of temperature and moisture might be required. All coating Operations is the stage where observability and controllabil-
systems will be sensitive to surface preparation. ity should be maximized. Wherever possible, intervention
Ideally, the coating application was carefully controlled and points should be established. These are steps in any process
supervised by trained individuals and preapplied coating was where actions contemplated or just completed can be reviewed
carefully inspected and repaired prior to final installation of for correctness. At an intervention point, it is still possible to
pipe. Coating assessment in terms of its appropriateness for the reverse the steps and place the system back in its prior (safe)
application and other factors is done in the corrosion index condition. For instance, a simple lock on a valve causes the
also, but at the construction stage, the human error potential is operator to take an extra step before the valve can be operated
relatively high. Proper handling and backfilling directly impact perhaps leading to more consideration of the action about to be
the final condition of the coating. The best coating system can taken.
be defeated by simple errors in the final steps of installing the This is also the place in the assessment where special product
pipeline. reaction issues can be considered. For example, hydrate forma-
The maximum points can be awarded when the evaluator is tion (production of ice as water vapor precipitates from a hydro-
satisfied that the constructors exercised exceptional care in carbon flow stream, under special conditions) has been
applying field coatings and caring for the preapplied coating. identified as a service interruption threat and also. under special
conditions, an integrity threat. The latter occurs if formed ice
The evaluator must be careful in judging all ofthe variables travels down the pipeline with high velocity, possibly causing
just discussed, especially for systems constructed many damages. Because such special occurrences are often controlled
years ago. System owners may have strong beliefs about how through operational procedures, they warrant attention here.
well these error-prevention activities were carried out, but A suggested point schedule to evaluate the operations phase
may have little evidence to verify those beliefs. Evaluations is as follows:
of pipeline sections must reflect a consistency in awarding
points and not be unduly influenced by unsubstantiated C 1. Procedures 7 pts
beliefs. A “documentation-required” rule would help to ensure C2. SCADNcommunications 3 pts
consistency. C3. Drug testing 2 pts
Excavations, even years after initial installation, provide C4. Safety programs 2 pts
evidence of how well construction techniques were camed out. C5. Surveys/maps/records 5 pts