Creep analyses of a steam pipe system

The International Journal of Advanced Manufacturing Technology, 2020

Materials Today: Proceedings, 2020

Strain, 2009

2014

Site inspections of Hot Reheat Piping system have indentifed cracking at a number locations at butt welds between pipe runs and elbows.Furthermore,it was discovered that pipe runs are instaled with wall thickness of SCH60(ANSI/ASME code[3]),and elbows with wall thickness of SCH30 what is not according to design documentation.This wall thickness discrepancy creates a stress enhancement at the connections between elbows and piping runs.Also,because the elbows are more flexible,there could be a propensity for a creep strains to be concentrated in the elbows as the piping system stresses will be relaxed at these lower strength elbows rather than being distributed throughout the main piping runs.So,a detailed finite element analysis,including elastic and creep analysis, is performed to determine if the secondary stresses during relaxation,or if the stress enhacement of the wall thickness discrepancy,play significant roles in the cracking detected in the piping system.

2016

2019

2011

One of the most common failure modes for elevated temperature piping working in the creep conditions is initiation, growth of cracks in pipe bends that finally leads to the failure. Failure of bends is much more dangerous than appearance of cracks in the piping joint welds or tees due to size of affected areas. It is known that for pipe bends, working in creep range, attention must be paid to imperfections of the cross-section, such as out-of-roundness and different wall-thickness, and their interaction with the internal pressure as well as bending and torsion moments. FE analyses of different bend configuration have been performed to investigate effect of the above factors on the creep damage of this element. It was recognized that out-of-roundness and bending moments are significant contributors to the stress state of pipe bends and hence in the creep cumulative damage. Neglecting of these factors could lead to big uncertainties in the remaining life prediction.

2011

Site inspections of Hot Reheat Piping system have indentifed cracking at a number locations at butt welds between pipe runs and elbows.Furthermore,it was discovered that pipe runs are instaled with wall thickness of SCH60(ANSI/ASME code[3]),and elbows with wall thickness of SCH30 what is not according to design documentation.This wall thickness discrepancy creates a stress enhancement at the connections between elbows and piping runs.Also,because the elbows are more flexible,there could be a propensity for a creep strains to be concentrated in the elbows as the piping system stresses will be relaxed at these lower strength elbows rather than being distributed throughout the main piping runs.So,a detailed finite element analysis,including elastic and creep analysis, is performed to determine if the secondary stresses during relaxation,or if the stress enhacement of the wall thickness discrepancy,play significant roles in the cracking detected in the piping system.

Volume 7: Operations, Applications and Components, 2008

In power station steam plant, experience has shown that portable monitoring equipment is ideal for reliable point-to point measurement of creep strain and also acquisition of strain mapping information. On going laboratory tests have shown positive initial results in that direction; the results being validated against metrology standards. In addition to the monitoring of in-service strain in steam pipes, the study of the effects of strain distribution across welded pipe sections and other known early failure locations on steam pipes and other plant components is growing in interest. An existing strain monitoring method employs the E.ON UK ARCMAC gauge system with a capability of both uniaxial and biaxial strain measurements. For strain mapping, digital image correlation (DIC) is also incorporated and integrated with the ARCMAC system. In an effort to further improve the ARMAC system portability, the use of a digital single-lens reflex (DSLR) camera system is investigated. The scope ...