This article is about SAES-L-120 which is about Piping Flexibility Analysis and download SAES-L-109 PDF for piping and mechanical engineers, supervisors and project managers. This is saudi aramco standard based on international codes and standards and useful for piping and mechanical engineering knowledge to get job as engineers, QC Supervisors and QC managers, Engineering managers and technicians.
SAES-L-120 PDF Download
SAES-L-120SAES-L-120 Piping Flexibility Analysis
This SAES-L-120 standard provides the design requirements for conducting flexibility analysis of piping systems. It serves as a supplement to the ASME B31.1, B31.3, B31.4, and B31.8 codes, depending on their applicability.
The standard applies to both onshore and offshore piping systems that are not restrained, including the transitional sections between underground and aboveground piping.
However, it does not apply to fully restrained aboveground or underground piping systems or offshore sub-sea pipelines. These systems may have different design considerations and requirements.
Additionally, the standard does not cover nonmetallic process piping systems, whether they are aboveground or underground. The flexibility analysis for nonmetallic piping in all areas should follow the guidelines provided in ASME B31.3, which specifically addresses the design of nonmetallic piping systems.
General Requirement for SAES-L-120 PDF Download
The responsibility for ensuring the flexibility and compliance of piping systems lies with the design agency. They are required to check and evaluate each piping system according to the applicable code. The design and analysis of the piping system should be conducted by a qualified stress engineer.
The stress engineer must possess the necessary qualifications and experience in designing and analyzing piping systems. Their qualifications should be verified by the Consulting Services Department (CSD) and approved by the Project Management Team (PMT) or the project proponent. The minimum criteria for the stress engineer’s qualifications include an engineering degree or equivalent from an accredited organization and a minimum of 5 years of experience in designing and analyzing pressure piping systems. Deviations from these requirements may be considered acceptable but must be reviewed and approved by the Chairman of the Piping Standards Committee in the Consulting Services Department.
The flexibility analysis reports, which assess the flexibility and behavior of the piping system, should be documented as part of the design package and submitted for review as outlined in Appendix A of the standard.
The flexibility analysis for the piping system should be performed in accordance with the allowable limits specified in the applicable code. It should consider the highest differential temperature imposed by design, operation, startup, shutdown, transient, steam out, and design contingency conditions. All credible thermal load combinations must be taken into account.
The piping system should have sufficient flexibility to prevent failures due to overstress or fatigue, leakage at joints, and detrimental stress or distortion in the piping or connected mechanical equipment caused by excessive thrusts and moments. The computed pipe movement should be within the prescribed limits and should be properly accounted for in the flexibility analysis. Moreover, the behavior of the piping system should be studied to ensure that it does not have any physical effects on adjacent systems or equipment.
Piping Flexibility Analysis Requirements
The piping flexibility analysis requirements are as follows:
The following piping systems are exempt from both detailed and formal flexibility analysis requirements:
a) Fully restrained underground lines.
b) Fully restrained aboveground lines, as defined in section.
Stress analysis considering straight pipe will not calculate the forces on the pipe supports.
c) Duplicate piping systems do not require individual formal piping flexibility analysis. One calculation is sufficient.
Detailed piping flexibility analysis should be performed, at a minimum, for each of the following piping systems:
Lines falling under the following categories:
a) Lines in sour gas service with a nominal pipe size (NPS) of 10 inches or larger.
b) Lines in sour crude service with an NPS of 12 inches or larger.
c) Aboveground flow-lines, test-lines, and trunk-lines between two axial restrains, such as camel crossings or anchors.
d) Gas manifold headers in the Gas Manifold Unit, including future planned connections as defined in the Design Basis and Specifications Package (DBSP).
Lines that contain expansion joints.
Lines supported by other lines, if preapproved by the Chairman of the Piping Standards Committee. (Note: Pipe sizes 2″ and smaller supported by not less than 4 times its diameter pipe do not require approval if the stresses on both pipes are within the allowable limits of the codes.)
Lines with internal refractory lining. The increased stiffness of piping systems caused by the refractory lining should be included in the piping flexibility analysis.
Relief systems relieving to the atmosphere. The discharge piping should be restrained to contain the thrust loads.
Jacketed lines with a nominal pipe size of 6″ NPS and larger. Lines connected to any of the following:
a) Fired heaters and steam generators.
b) Rotating equipment suction and discharge nozzles with an NPS of 2″ and larger.
c) Air-cooled heat exchanger lines with an NPS of 4″ and larger.
d) Reactors for all lines.
e) Pressure vessels and tanks lines with an NPS of 8″ and larger.
These requirements ensure that the specified piping systems undergo the necessary flexibility analysis to account for factors such as sour service, expansion joints, refractory lining, relief systems, and connections to specific equipment or vessels.
Design Considerations of SAES-L-120 PDF Download
The design conditions for piping flexibility analysis are as follows:
Temperature Range: The analysis should be based on the temperature range specified by the design code. The thermal expansion range should be considered between the minimum and maximum temperatures.
Minimum Considerations for Detailed Piping Flexibility Analysis:
a) Steam Out Condition: For lines connected to vessels that cannot be disconnected during steam out or similar operations, the analysis should consider the thermal expansion and stresses resulting from this condition.
b) Solar Radiation: The effect of solar radiation at a temperature of 160°F should be considered for empty piping systems.
These requirements ensure that the piping flexibility analysis takes into account specific design conditions, such as steam out operations and the impact of solar radiation, to accurately assess the behavior and stresses of the piping system.
Load Conditions
The load conditions to be considered in the piping flexibility analysis are as follows:
Sustained Load: This load case includes the effects of pressure, pipe weight, contents, weight of piping components, insulation, and other sustained loads.
Thermal Load: This load case considers the thermal expansion and displacement of the piping system resulting from the temperature range it will experience.
Operational Case: This load case accounts for the displacement of the piping system during normal operations and the loads exerted on attached equipment.
Hydrotest Load: This load case considers the weight of the test medium (water) during hydrostatic testing.
Occasional Load: This load case considers the sustained load along with additional loads due to short-duration upset conditions such as wind or earthquake. Wind and earthquake loads should not be considered simultaneously in the stress analysis.
Wind Loads: Wind loads exerted on piping systems with a diameter of 10″ NPS and larger at elevations of 10 meters and higher should be considered in the stress analysis. Refer to SAES-A-112 for environmental loads that may affect piping design.
Earthquake Loads: Earthquake loads should be calculated following the guidelines of UBC Section 2336 and SAES-A-112.
These load conditions cover various scenarios that the piping system may experience during its service life, ensuring that the stress analysis considers the effects of different types of loads and displacements.
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