This article is about SAES-L-440 which is about Anchors for Buried Pipelines and download SAES-L-440 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-440 PDF Download
SAES-L-440SAES-L-440 Anchors for Buried Pipelines
This standard specifically addresses the design requirements for reinforced concrete or structural steel anchors used on buried pipelines. It provides guidelines and specifications for the design of anchor blocks to ensure their structural integrity and suitability for supporting pipelines.
When designing reinforced concrete anchor blocks, the requirements of SAES-Q-005 and SAES-Q-001, which are Saudi Aramco Engineering Standards for reinforced concrete structures, shall also be followed. These standards provide additional guidelines and criteria for the design, construction, and quality control of reinforced concrete structures.
Sizing of Anchor Blocks
The sizing of anchor blocks for pipelines in sandy soil and soil with friction and cohesion follows specific guidelines outlined in this standard. The company-owned program SOPTAB (Size Optimization of Thrust Anchor Blocks) or other equally qualified programs/analyses are used to determine the dimensions of the anchor blocks, taking into account various factors:
- The Log-Spiral theory is employed to calculate the passive earth force exerted by the backfill soil mass against the anchor block.
- The preliminary dimensions of the anchor block are established based on the bearing pressure exerted by the anchor flange on the concrete mass and the punching shear of the anchor flange through the concrete block.
- Optional consideration is given to the 3-D effects in the failure zone of the backfill soil mass, which can enhance the passive earth force by multiplying the computed 2-D passive earth resistance by a factor (F3D) obtained using the Brinch Hansen theory.
- Friction on the bottom and sides of the anchor block is accounted for using appropriate soil models and parameters.
- The hyperbolic load-deformation model is used to compute passive resistance based on the deformation of the backfill soil under the applied service thrust force on the anchor block.
- The “transition length,” “active length,” or “length to point of virtual anchor” of the pipeline is computed based on pipe friction to incorporate the effect of pipe-soil interaction in the sizing of the thrust anchor block.
- An iterative approach is adopted, adjusting the dimensions of the concrete anchor block until all safety and stability conditions are satisfied. This includes checks for ultimate load carrying capacity, factor of safety against overturning and sliding, and bearing pressure at the base of the anchor block due to vertical and lateral loads.
Additionally, the design of the load transfer system for transferring load from the pipeline to the anchor block, as well as the reinforcing steel, shear capacity, flexural reinforcement, and other design aspects, should be based on the full thrust force exerted on the anchor block.
More Information Related to Sizing of Anchor Blocks for SAES-L-440 PDF Download
The appendix of the standard may provide a typical example of designing a full thrust anchor block using the SOPTAB program. Designers should also follow applicable codes and standards for the specific design requirements related to steel components, reinforcing steel, and other relevant considerations.
In addition to the software mentioned earlier, the software ADTAB (Analysis and Design of Thrust Anchor Blocks) is available for use by CSD (Civil Structural Division) engineers only. For further details about its usage, the Civil Engineering Unit of CSD should be contacted.
When sizing concrete anchors, specific considerations should be taken into account based on the site conditions:
- Rock Areas: a) If the anchor block is embedded in very hard cemented soil (highly weathered rock), the SOPTAB program should be used for sizing. b) If the anchor block is entirely above ground, standard engineering procedures should be used for design.
- Well Compacted or Very Dense Natural Soil: a) If the anchor block is above the water table, the SOPTAB program or equivalent methods should be used. b) If the anchor block is partially or entirely below the water table, the SOPTAB program or equivalent methods should be used, but with adjustments: i. Friction should be reduced by 30%. ii. Uplift pressure should be accounted for.
- Sabkha Soil: a) The designer may strengthen the soil and reduce settlement by using a soil pad, geogrids/geotextiles, or other ground improvement techniques.
- If the anchor block is above ground, the SOPTAB program is not applicable. Standard engineering procedures should be followed with the approval of CSD. b) The designer may consider using a piled anchor. In this case, the anchor block will be above ground, and standard engineering procedures should be followed with the approval of CSD.
It’s important to obtain allowable bearing pressures from the geotechnical report, ensuring that settlement is limited to 25 mm or less. Additional specific details for sizing concrete anchors can be found in Appendix-B of the standard.
Stability of Anchors
The stability of anchor blocks for buried pipelines is determined by ensuring that the resultant of all anchor forces has a line of action parallel and close to the centerline of the pipeline. The approach for checking the stability of concrete thrust anchor blocks is different from checking the stability of foundations, as outlined in SAES-Q-005. Factors of safety used in SAES-Q-005 for foundations are not applicable to buried pipeline anchor blocks.
The stability of an anchor block against overturning is assured by aligning the pipe thrust force and the resisting forces. A separate sliding stability check, as per SAES-Q-005, is not required for pipeline anchor blocks since they are sized based on allowable movement criteria.
anchor attachments:
- For fabricated anchors, the attachment to the pipeline should be done using a full encirclement sleeve welded at each end with continuous full-size fillet welds. The size of the welds should not exceed 1.4 times the pipe wall thickness. The sleeve should have strength at least equivalent to the pipe.
- Welded anchor flanges embedded in concrete should have sufficient stiffness to ensure proper distribution of the load within the allowable concrete bearing stress.
- The finished steel fabrication, including the pipe, sleeve, and anchor flange or anchor plate inside the anchor block, should be coated according to SAES-H-002.
- A minimum distance of no less than 10 cm should be maintained between the rebar and the sleeve or anchor flange to ensure adequate cathodic protection of the pipeline. Additionally, four 60-pound magnesium anodes should be installed for the pipeline, with one at each quadrant of the anchor. Following have more articles related to SAES-L-440 PDF Download – Anchors for Buried Pipelines.
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