SAES-L-131 PDF – Fracture Control of Line Pipe

This article is about SAES-L-131 which is about Fracture Control of Line Pipe and download SAES-L-131 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-131 PDF Download

SAES-L-131

Fracture Control of Line Pipe

According to the standard SAES-L-131, the purpose is to establish requirements for line pipe supplementary fracture toughness to control crack propagation in carbon steel pipe used for off-plot transportation piping. The scope of the requirements includes the following types of piping:

1. Cross-country pipelines: Piping systems that transport fluids over long distances, typically from one region or facility to another.
2. Flowlines: Piping systems that transport fluids from wellheads to processing facilities.
3. Trunklines: Large-diameter pipelines used for the transportation of bulk fluids over long distances.
4. Testlines: Pipelines used for testing purposes, such as pressure testing or flow rate testing.

These requirements apply specifically to line pipe with wall thicknesses ranging from 6.35 mm to 38.1 mm (0.25 to 1.5 inches). The applicable standards for these line pipes are API SPEC 5L, 01-SAMSS-035, and 01-SAMSS-333. These standards provide specifications and guidelines for the manufacturing and testing of line pipes used in transportation piping systems.

The focus of these requirements is to ensure that the line pipes used in off-plot transportation piping have sufficient fracture toughness to resist crack propagation, particularly at temperatures above 0°C. This is crucial for maintaining the integrity and safety of the piping systems during operation.

Testing Requirements for SAES-L-131 PDF Download

According to the standard, the testing requirements for Class IV pipes are as follows:

1. Testing per 01-SAMSS-035: Class IV pipes shall undergo Charpy V-notch testing on the parent metal, heat-affected zone, and weld metal. The testing is performed at 0°C.
2. API SPEC 5L/ISO 3183 absorbed energy values: The transverse Charpy V-notch tests at 0°C should meet or exceed the energy values determined below. The required energy value should not be less than the minimum required value for PSL 2 pipe as given in Table 8 of the current version of API SPEC 5L. The calculated energy values are considered as the average energy of three specimens.

For lean natural gas (>90% Methane) or liquids (with vapor pressure/MAOP < 0.35), the required Charpy V-notch absorbed energy (Cv) is calculated using the following formula:

Cv = (0.0147) * σH^2 (Dt/2)^0.284

Where:

• Cv: Required Charpy V-notch absorbed energy (average of three full-size transverse specimens) per API SPEC 5L/01-SAMSS-035.
• σH: Maximum allowable hoop stress, ksi (typically Design Factor x SMYS)
• D: Outside diameter, inches
• t: Nominal pipe wall thickness, inches

Toughness values listed in Tables 1 through 4 (attached to the standard) are based on the above formula at various design factors and strength levels (up to strength level X65).

For liquids with vapor pressure/MAOP > 0.35, Table 5 provides an alternative formula. However, it is generally recommended to modify the design to increase the design pressure (MAOP) in order to reduce the ratio.

For “rich” gases containing a significant amount of hydrocarbons or gases that do not meet the definition of lean gas, the Materials Engineering Unit of CSD should be contacted for gas decompression and fracture velocity calculation to define the required fracture arrest toughness. The information needed for the calculation includes gas composition, gas temperature and pressure, diameter and wall thickness of the pipe, design factor, and maximum allowable operating pressure (MAOP).

A correction factor should be applied for Charpy V-notch energies greater than 70 ft-lb (95 J) using the provided equation in the standard.

Read Also:

Brittle Fracture | Materials And Corrosion Control

Drainage and Underground Service Pipes