API RP 1133 pdf free download
API RP 1133 pdf free download.Managing Hydrotechnical Hazards for Pipelines Located Onshore or Within Coastal Zone Areas.
4 Overview of Hydrology and Hydrotechnical Hazards at Onshore and Coastal Zone Pipelines Pipelines are static features within a dynamic environment with rivers, floodplains and coastal zones representing some of the most active areas within a landscape. Rivers can change course, migrate, deepen, and widen slowly over time or suddenly during large flood events. Coastlines and shorelines can retreat during hurricanes and, coastal land loss, particularly throughout coastal Louisiana, can cause pipeline exposure and suspension of previously buried pipeline segments. These hydrologic and geomorphic effects can put pipelines at risk for damage or failure. Understanding how rivers and coastal zones change and alter the landscape provides a framework for realizing the potential toll that hydrotechnical hazards can have on pipeline infrastructure and can increase the effectiveness in protecting the environment during the design, construction, operation, and integrity management of pipelines at river crossings, and throughout coastal zones. A brief description of riverine and coastal hydrology and hydrotechnical hazards is presented below.4.1 Riverine Hydrology and Fluvial Geomorphology The magnitude of hydrotechnical hazards and potential for damage to pipeline integrity is greatest at pipeline water crossings during flood events. Water depth is deepest and water velocity is typically fastest during floods. As a result, floods have the potential to carry large debris, impart significant bending stresses and vortex-induced vibrations on unsupported pipeline spans, and potentially remove sediment from river bottoms and soils from banks, thereby exposing previously buried pipelines to lateral water forces and impact from waterborne debris. Understanding a river’s hydrology and geomorphology can help assist pipeline operating companies to better assess a river’s potential for scour, channel migration, avulsion, etc. at pipeline water crossings. By evaluating the magnitude and frequency of flood events at water crossings, operators can efficiently direct resources to mitigate the potential hazards of floods and river erosion. Data describing the quantity, timing, and duration of both current and historic information regarding water levels and streamflow conditions for many streams and rivers is collected and published by various governmental agencies. The primary agencies responsible for collecting these data in North America include the U.S. Geological Survey (USGS) and Environment Canada (EC). Further details regarding publicly available data sources is provided in Annex A.4.1.1 Overview—Flood Timing, Duration, Magnitude, and Frequency The hydrology of a particular river or stream is defined by the timing, duration, and quantity of flowing water. The observed rise and fall of the water levels or discharge at a given point can be graphed over time; such a graph is called a hydrograph. The portion of a hydrograph where the water levels increase from base flow to the flood event’s peak is termed the “rising limb”. The portion of the hydrograph once the peak has passed and water levels return to base flow is defined as the “falling limb”. The timing of flooding describes when flood events typically occur throughout the year. For example, rivers draining the Rocky Mountains tend to have predictable springtime flooding in response to snowmelt. Conversely, rivers within the arid American southwest and mid-west tend to flood in response to large rainfall events which can potentially occur throughout the year. Timing of flood events is more predictable within areas dominated by snowmelt, and consequently, flood preparation and response planning is easier than in areas where flooding is dominated by extreme rainfall events. API RP 1133 pdf download.
