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LEAK BEFORE BREAK, REFERENCE - Coggle Diagram
LEAK BEFORE BREAK
ADVANTAGES OF LBB
In LBB application, it has many advantages such as LBB design ensure that crack growth through the thickness leading to detectable leakage and demonstrate that the crack will stable under the maximun loading condition between the successive inspection.
The LBB concept can be used to eliminate or reducing design provision that have to cope with dynamic effects such as pipe whipping, rapid fluid, transient phenomena that result from postulated high energy pipe ruptures.
In LBB, there is a chance for damage to be detected or for the internal pressure to be relieved before it comes to a sudden catastrophic rupture of vessel.
By improving the monitoring of the plant, the accessibility to non-destructive examination (NDE), or by reducing radiation exposure to plant personnel during ISI and maintenance.
INTRODUCTION
:star: Leak-before-break (LBB) is a term used in reference to a technique for decades that ensures that a leak will be detected before a service fracture occurs. LBB has been applied to missile casings, gas and oil pipelines, pressure vessels, nuclear piping, etc
:star:LBB has several technical definitions as well. For example, for an axial flaw in a pipe, LBB can occur where the penetration of the thickness of the wall results in a stable axial through-wall crack. Under load-controlled conditions, this is LBB. LBB could also occur in a pipe with elevated thermal expansion pressures for a circumferential crack. Under compliant conditions controlled by displacement, this might be LBB.
:star:The main objective of LBB is to ensure the detectable leak occurs before catastrophic fracture in pressurised pipelines. Therefore, LBB behaviour is an important requirement for the safe design and re-assessment of pressure vessels.
DIASADVANTAGES OF LBB
Disadvantages of LBB might arise from the different types of reason such as pure technical reason which linked with the pipework reliability, safety reason linked with the expected margin on certain safety function, global versus local effect choices.
For a plenty reason linked to a historical and national aspect, which is feedback of experience on manufacturing or operation. Regulators should be able to settle "arbitrary" limit to the extent of LBB use.
The analysis of a postulated break lead to global and local effect. Notwithstanding the consistency of the approach, the credit from the LBB might be limited to one category or effects or to part of it.
CONCLUSION
Leak Before Break is a term that has been used for decades in reference to a methodology that means that a leak will be discovered prior to a fracture occuring
LBB also has several techniques for instances where LBB can occurs for on axial flow in a pipe whore. The penetration of the wall thickness will result or a stable axial through wall crack.
Installation of such a leak detection system in accordance with the result of LBB analysis ( critical section, leakage crack size) as well as its careful calibration. Therefore, LBB behavior is an important requirement for the safe design and re-assessment of pressure vessels.
REFERENCE
Irwin, G. R., 1963, “Fracture of Pressure Vessels,” Materials for Missiles and Spacecraft, pp. 204–229, McGraw-Hill, New York, NY.
Pacholkova, S, Taylor, H. Theoretical background of “leak-before-break” as a concept in pressure vessels design. Metal 2002; 14–16.5: 1–8.
Darlaston, BJL . Some aspects of leak before break; their quantification and application. Nucl Eng Des 1985; 84: 225–232.