SAES-L-460 PDF – Pipeline Crossings under Roads

This article is about SAES-L-460 which is about Pipeline Crossings under Roads and Railroads and download SAES-L-460 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-460 PDF Download

SAES-L-460

SAES-L-460 Pipeline Crossings under Roads and Railroads

This standard is crucial as it sets forth the fundamental guidelines and criteria for the design and installation of pipeline crossings beneath various infrastructure elements such as roads, parking lots, railroads, and airport runways. Its purpose is to ensure the safe and efficient passage of pipelines through these crossings.

It is important to note that this standard is applicable to pipelines in all types of services, encompassing a wide range of industries and sectors. Whether it’s pipelines carrying oil, gas, water, or any other substance, this standard provides essential requirements that must be adhered to during the design and installation processes.

Moreover, it is worth mentioning that this standard works in conjunction with the latest edition of API RP 1102, specifically focused on the crossing of steel pipelines under railroads and highways. By referencing API RP 1102, this standard ensures consistency and compatibility with established practices and guidelines in the industry.

Furthermore, it is important to highlight that when pipeline crossings involve government roads and railroads in Saudi Arabia, additional requirements imposed by the Saudi Arabian Government must be followed. These specific requirements serve to align the pipeline crossing activities with local regulations and ensure compliance with the governmental framework in place.

Pipeline Crossing Design Criteria:

According to this standard, the design criteria for pipeline crossings are outlined as follows:

1. Minimum Cover Requirements: Unless the crossing involves concrete slabs, concrete encasement, bridges, or culverts, there are specific minimum cover requirements for carrier steel pipes or steel casings. These requirements can be found in Table 1 of the standard. It is important to maintain adequate cover to ensure the protection and integrity of the pipeline.
2. Use of Carrier Pipes without Casings: For road crossings involving new pipelines or existing pipelines undergoing rehabilitation, carrier pipes without casings should be used as the normal installation method. However, this is subject to the stresses being within acceptable limits as specified in paragraph 7 of the standard. This installation method is applicable when the stresses on the pipeline are within acceptable levels.
3. Casings for Railroad Crossings: In the case of pipelines under construction, casings are required for all railroad crossings. This additional protective measure is necessary to ensure the integrity of the pipeline when crossing railroads.
4. Design Approval for Railroad Crossings: For existing pipelines, the design of railroad crossings must be approved by the Consulting Services Department and the operating organization. This ensures that proper engineering practices and safety considerations are taken into account to protect both the pipeline and the railroad infrastructure.

Commentary Note: The standard provides some additional commentary to explain the intent and purpose behind certain requirements. In this case, it emphasizes that the purpose of protecting pipelines with casings at railroad crossings is not only to safeguard the pipelines from railroad loads but also to prevent any damage to the railroad infrastructure in case of gas leaks or oil spillage. Railroads are considered potential ignition sources, and therefore, all necessary safety measures must be considered during the design process.

Design Calculations for Steel Pipe

The standard specifies the design calculations for steel pipes, taking into account the applicable design requirements and methodologies. The key points regarding design calculations for steel pipes are as follows:

1. Compliance with Design Requirements: The pipeline must meet the design requirements outlined in SAES-L-410, which covers various aspects of pipeline design. The stresses affecting the uncased pipeline must be comprehensively considered, including both circumferential and longitudinal stresses.
2. Design Procedure Selection: The design procedure for steel pipes can be based on either the latest edition of API RP 1102 or SAER-6078 (Analysis and Design of Buried Pipeline) developed by Saudi Aramco. These methodologies provide guidelines for analyzing and designing buried pipelines. It is important to adhere to the chosen methodology for consistent and accurate design calculations.
3. Use of Crossi Software: Saudi Aramco has developed Crossi software, which utilizes a conservative approach in its calculations. The use of Crossi software is permissible, subject to the approval of the Chairman of the Piping Standard Committee. If the stresses calculated by Crossi are within acceptable limits, further analysis using other methodologies may not be necessary.
4. Designing Pipelines According to API RP 1102: When using API RP 1102, the soil density is typically assumed to be 120 lb/ft³ for earth load calculations. However, a higher value can be used based on field data. The design wheel load should be determined as either the maximum wheel load from a truck’s single axle or the maximum wheel load from a truck’s tandem axle set. The effective stresses must not exceed 90% of the specified minimum yield strength (SMYS) for both steel casings and uncased steel carrier pipes. The design factor “F” for determining pipe wall thickness due to internal pressure is based on the appropriate location class.
5. Designing Pipelines According to ADBP (SAER-6078): ADBP is specifically applicable for highway crossings. Traffic load classifications, such as AR-2, AR-10, AR-20, and AR-40, based on tire load, should be used in stress calculations as required. Unlisted traffic load classifications can be evaluated based on tire loads, with additional guidance provided in Appendix B of the standard. The effective stresses must not exceed 90% of the pipe’s SMYS. The modulus of soil reaction is typically taken as 150 psi, but a higher value can be used based on field data. The Winkler spring coefficient (ko) depends on the pipe diameter and can be calculated using the provided expression for sandy soil, considering the range of modulus of subgrade reaction (ks) suggested by Terzaghi for loose sand.

These design calculations ensure that the steel pipes are appropriately sized and can withstand the expected loads and stresses while maintaining the required safety factors. Adhering to these guidelines helps ensure the integrity and longevity of the pipelines under different crossing conditions. Following articles are related to SAES-L-460 PDF Download.

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SAES-L-450 PDF Download – On-Land and Near-Shore Pipelines

SAES-L-440 PDF Download – Anchors for Buried Pipelines

SAES-L-410 PDF Download – Design of Pipelines

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