API RP 1133:2010 pdf download

API RP 1133:2010 pdf download.Guidelines for Onshore Hydrocarbon Pipelines Affecting High Consequence Floodplains.
4.3 MATERIAL SPECIFICATIONS FOR TRENCHED AND DRILLED CROSSINGS
Materials specified for a pipeline crossing should comply with previously established practices and standards for pipeline construction. Allowances should be made for any additional stresses that may be induced during the installation of the pipeline, particularly in the case of a directionally-drilled crossing. More information on pipeline design can he found in ASME B31.4 and ASME B31.8. Analysis of stresses induced during the installation of a pipeline crossing should be performed by a qualified professional engineer.
Pipe specifications should include limitations on maximum, as well as minimum, yield strength. The selected grade of pipe should provide sufficient ductility to minimize the likelihood of damage during installation. Additional wall thickness or pipe yield strength should be considered as a corrosion allowance in areas where mitigation or repair would be difficult or impossible (i.e., a drilled crossing).
Buoyancy calculations must be made for trenched crossings to ensure that the pipeline will not float after installation. The pipeline crossing should be designed with an adequate safety factor to provide negative buoyancy during all anticipated conditions. The pipeline will float if the weight of the pipe and coating is less than the fluid displaced by the pipeline. The greater density of salt water must be accounted ft)r when crossing salt-water courses. Buoyancy can be controlled by the use of continuous concrete coating, concrete weights or screw anchors. Typical buoyancy calculations may he fiund in Pipeline Rules of Thumb Handbook or AGA Submarine Pipeline On—Bottom Stai,ilitv A,za1wis and Design Guidelines.
In addition to providing protection against corrosion, pipe and weld joint-coating systems for trenched and directionally-drilled crossings should be sufficiently durable to prevent damage during installation. If gravel or rock is expected to be encountered, the coating system should include a highly abrasion-resistant, smooth-surfaced outer layer with a high hardness factor. The outer coating should he well bonded to the first layer coating. For example. the first layer of coating could be a Ilision-bonded epoxy (FBE) of 22 mils — 24 mils and the outer coating could be an epoxy-based polymer concrete of4O mils —60 mils.
4.4 VALVES
4.4.1 General
Block or check valves should be considered on pipelines crossing floodplains adjacent to large watercourses to limit the volume of a potential release. The check valve acts as a one-way flow device and automatically prevents the backrard flow from the downstream pipeline section into lower elevations within the floodplain. The block valve can be operated either locally, automatically or remotely to isolate the pipeline in the floodplain from upstream and downstream pipeline sections.
A variety of valve types can be used and their effectiveness depends on proper design, location, and prompt action by the pipeline operator or control system to minimize a pipeline release.
4.4.2 Determination of Valve Type and Location
The type, location and necessity of block and/or check valves should he based on an engineering/risk analysis of the floodplain and should take into account the following variables:
a. Uses of the watercourse (barge traffic, potable water supply, farm irngation, etc.).
h. Environmental concerns.
c. Topographic conditions (potential spill volume).
d. Materials being transported.
e. Access.
f. Availability of power and communication (if valves are or will he automatically or remotely operated in the future).
g. Security.
h. Regulatory requirements.
The pipeline’s elevation profile is one important factor to he considered when choosing valve locations.
It is important that valves he installed at locations accessible during flood conditions. If vaLves must be installed within a floodplain, barricades, valve guards. or other means of protecting the valve from floating debris during flood conditions should be considered.