SAES-L-420 PDF – Scraper Trap Station and Appurtenances

This article is about SAES-L-420 which is about Scraper Trap Station and Appurtenances and download SAES-L-420 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.

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SAES-L-420

SAES-L-420 Scraper Trap Station and Appurtenances

This standard specifically addresses the design requirements for permanent pipeline scraper launching and receiving stations. It serves as a supplement to the ASME B.31.3, ASME B31.4, and ASME B31.8 codes, which are relevant to pressure piping, as well as other Saudi Aramco Piping Standards that contain design requirements.

It’s important to note that this standard does not apply to valves of special design, such as ITAG (Inline Trap and Gate) valves, which are used for launching or receiving small size scrapers. The use of these valves does not violate the requirements of this standard.

Overall, this standard provides the minimum mandatory requirements for designing piping and appurtenances related to permanent pipeline scraper launching and receiving stations.

General Requirements for Scraper Trap Station and Appurtenances

This standard focuses specifically on the design requirements for permanent pipeline scraper launching and receiving stations. While it supplements the ASME B.31.3, ASME B31.4, and ASME B31.8 codes, which are applicable to pressure piping, it also incorporates design requirements from other Saudi Aramco Piping Standards.

The purpose of this standard is to establish the minimum mandatory requirements for the design of piping and associated components in scraper trap stations. These stations are crucial for the periodic scraping of pipelines, as specified in SAES-L-410. The standard outlines the necessary design considerations and specifications to ensure the effective and efficient operation of scraper traps.

It’s important to highlight that this standard does not cover valves of special design, such as ITAG valves, which are used specifically for launching or receiving small size scrapers. The exclusion of these valves from this standard does not indicate a violation, but rather acknowledges their specialized nature and alternative design requirements.

Overall, this standard provides comprehensive guidelines and requirements for the design of permanent pipeline scraper launching and receiving stations, supplementing the existing codes and standards applicable to pressure piping. By adhering to these requirements, the design and implementation of scraper trap stations can be carried out effectively and in compliance with industry best practices.

System Design for Scraper Trap Station

In the design of scraper trap station piping for onstream scraping operations, the following components and features are required:

1. Scraper trap closure: A standardized design should be used if it meets all operating requirements without a significant increase in cost.
2. Full bore trap isolation valve: This valve should have the same nominal size as the pipeline to allow for effective isolation of the trap.
3. Barred tee: Installed in the mainline, the distance between the centerline of the branch and the near end of the trap isolation valve should be minimized. If it exceeds three pipe diameters, it should be sloped back to the branch.
4. Tieline valve: Positioned at the branch of the tee, it should be located at the minimum practical distance from the mainline.
5. Bypass line: A bypass line should be included between the tieline valve and the trap. It should have a kicker valve and a second block valve to ensure tight shut-off in the bypass line.
6. Pressure equalizing valves: Small size pressure equalizing valves should be installed around the trap isolation valve and kicker valve. A small diameter equalizing line with a locked-open block valve should connect the narrow end of the trap with the other end to prevent

Station Layout

When designing the layout of scraper trap stations, the following considerations should be taken into account:

1. Location within the plant area: Scraper trap stations near a plant area onshore should be positioned within the plant’s Secondary Safe Design (SSD) fence. The lateral piping between the trap and the plant should generally be constructed above grade, unless otherwise permitted as per SAES-L-310.
2. Orientation of scraper traps: The orientation of the scraper trap should be away from critical equipment as much as possible to prevent any collisions. The following minimum orientation requirements apply:a) For on-land and near shore pipelines, the distance from the closure door to critical plant equipment (as per SAES-L-100) should not be less than 45 meters.b) Onshore and offshore scraper traps should be oriented in a way that no equipment or above-grade piping is within a sectorial area of a 45-meter radius by 20 degrees (10 degrees to each side of the centerline of the trap) from the closure door.
3. Vertical orientation for offshore platforms: Launchers used on offshore platforms may have a vertical orientation. Platforms should be provided to allow easy access to valve actuators and closure operating mechanisms. All valves should be accessible from one side of the trap.
4. Work floor and clearance in onshore plants: For onshore scraper trap stations, a suitable work floor should be provided with sufficient space around the traps for loading and unloading scrapers and for access by equipment such as forklift trucks. The clearance between the bottom of the trap and the finished grade in onshore plants should be approximately 1 meter. A surface drainage system should also be in place to collect any spills and wash water from the trap.
5. Above-grade construction for cross-connecting piping: The piping that cross-connects the upstream and downstream pipelines, as well as associated kicker and equalizer lines, should be constructed above grade at all scraper trap stations.