Analysis and Testing of Freezing Phenomena in Piping Systems

2008 ◽  
Author(s):  
Kenneth M. Smith ◽  
Michael P. Van Bree ◽  
Joseph F. Grzetic
Keyword(s):  
Weak Link ◽  
Frozen Section ◽  
Cooling Water ◽  
Freezing Temperature ◽  
Elevated Pressure ◽  
Piping System ◽  
Actual System ◽  
System Pressure ◽  
Piping Systems ◽  
The Cost

From time to time installed piping systems, including wet sprinkler, potable water and cooling water systems, have failed due to freezing. The cost of such events is significant due to the need for system repair, the loss of service, and the secondary water damage that results. The presumption is often that the pipe was frozen at the point of failure. This paper describes the theory, calculations, and experiments that demonstrate that freezing of a pipe causes pressure in the system to rise between the frozen section of pipe and the blind end of the system. The piping system typically fails at a weak link in the system at a significantly elevated pressure. The location of the breech is almost always at a point in the system where the water is still liquid at the time of the breech. An additional consideration is that the high system pressure depresses the freezing temperature of the water, and a flash-freeze within the pipe occurs when the pressure suddenly drops after a piping system rupture. Armed with this knowledge, the site of the actual system freeze can often be found remote from the point of failure where remedy can be best effected to eliminate the root cause.

Analysis and Testing of Freezing Phenomena in Plastic Piping Systems

2009 ◽  
Author(s):  
Dale B. Edwards ◽  
Kenneth M. Smith ◽  
Donald E. Duvall ◽  
Joseph F. Grzetic
Keyword(s):  
Water Supply ◽  
Weak Link ◽  
Frozen Section ◽  
Pressure Rise ◽  
Critical Length ◽  
Elevated Pressure ◽  
Piping System ◽  
Sprinkler Systems ◽  
Piping Systems ◽  
The Cost

Failure of plastic piping due to freezing occasionally occurs in fire sprinkler systems and water supply lines. The cost of these pipe breaks can be significant, particularly for those that occur in high-rise buildings. The costs may include repair, loss of service, and water damage. In a previous paper, the theory and testing of the freezing failures in metal pipes was investigated, demonstrating that the pipe breaks are due to a pressure rise between the frozen section of the pipe and the blind end of the system. The pipe typically fails at a weak link in the system at a significantly elevated pressure, remote from the freeze area. This paper describes additional testing on plastic pipes, including PVC, CPVC, and PE, that are used in many water supply and sprinkler systems. In the previous study, a critical length of frozen pipe was calculated that would cause the burst due to overpressure remote from the freeze. In the case of plastic piping, the length of time that the pipe is over-pressured also affects the failure due to creep effects. Prior freeze failures in a plastic piping system may cause damage to the remaining non-failed pipe that could lead to future failures even if another freeze event does not occur.

Uncertainty Sampling of Weld Residual Stress Fields in Probabilistic Analysis: Part II — Examples

2016 ◽  
Author(s):  
Robert E. Kurth ◽  
Cédric J. Sallaberry ◽  
Frederick W. Brust ◽  
Elizabeth A. Kurth ◽  
Michael L. Benson ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Residual Stresses ◽  
Assessment Tool ◽  
Lessons Learned ◽  
Piping System ◽  
Primary System ◽  
Cracking Behavior ◽  
System Pressure ◽  
Piping Systems ◽  
Low Probability

NRC Standard Review Plan (SRP) 3.6.3 describes Leak-Before-Break (LBB) assessment procedures that can be used to assess compliance with the 10CFR50 Appendix A, GDC-4 requirement that primary system pressure piping exhibit an extremely low probability of rupture. SRP 3.6.3 does not allow for assessment of piping systems with active degradation mechanisms, such as Primary Water Stress Corrosion Cracking (PWSCC) which is currently occurring in systems that have been granted LBB approvals. US NRC staff, working cooperatively with the Electric Power Research Institute through a memorandum of understanding, conducted a multi-year project that focused on the development of a viable method and approach to address the effects of PWSCC in primary piping systems approved for LBB. This project, called eXtremely Low Probability of Rupture (xLPR) [1], defined the requirements necessary for a modular-based probabilistic fracture mechanics assessment tool to directly assess compliance with the regulations. Using the lessons learned from the pilot study, the production version of this code, designated as Version 2.0, focused on those primary piping systems previously approved for LBB. In this version the appropriate fracture mechanics-based models are employed to model the physical cracking behavior and a variety of computational options are provided to characterize, categorize and propagate problem uncertainties. One of the most influential uncertainty on risk in the xLPR code is the one associated with weld residual stresses (WRS). WRS plays a key role in both crack initiation and crack growth. PWSCC is mainly driven by tensile stresses, whose major contributors are the tensile weld residual stresses that develop during fabrication of the piping system. Handling the uncertainty involved with WRS within a probabilistic framework is quite challenging. A companion paper presents the selected approach to represent uncertainty within the framework of the xLPR code while respecting a set of requirements in term of smoothness of profile, efficiency of (potential) importance sampling and (for axial WRS) equilibrium. This paper illustrate with examples the implementation of the described methods into xLPR v2.0.

Optimization of Module Arrangement in Ship Engine Room

2021 ◽  
Vol 37 (01) ◽  
pp. 54-66
Author(s):  
Gunawan Gunawan ◽  
Allessandro Setyo Anggito Utomo ◽  
Kunihiro Hamada ◽  
Kazetaro Ouchi ◽  
Hiroyuki Yamamoto ◽  
...  
Keyword(s):  
Design Structure Matrix ◽  
Piping System ◽  
Bulk Carrier ◽  
Multiple Series ◽  
New Approach ◽  
Engine Room ◽  
Design Structure ◽  
Room Design ◽  
Piping Systems ◽  
The Cost

This article presents a new approach for engine room design based on the modularization concept including the part arrangement optimization. The characteristics of the proposed methods are as follows. First, attention was paid to piping systems of multiple bulk carrier series of different sizes. The cost and length of the piping system as well as the similarity and the commonness of the modules and arrangements were considered. Second, to define an effective module that could be commonly used in different ships, a design structure matrix was adopted. Third, in the arrangement design, an optimization system was developed using a genetic algorithm to obtain a similar pattern for module arrangement in multiple series ships with specific consideration toward cost and similarity. Some examples using the proposed method are shown at the end of article.

Extremely Low Probability of Rupture (xLPR) Version 1.0 Code: Pilot Study Problem Results

2011 ◽  
Author(s):  
D. Rudland ◽  
C. Harrington
Keyword(s):  
Pilot Study ◽  
Assessment Tool ◽  
Lessons Learned ◽  
Nuclear Industry ◽  
Piping System ◽  
Primary System ◽  
Degradation Mechanisms ◽  
System Pressure ◽  
Piping Systems ◽  
Low Probability

Nuclear Regulatory Commission (NRC) Standard Review Plan (SRP) 3.6.3 describes Leak-Before-Break (LBB) assessment procedures that can be used to demonstrate compliance with the 10CFR50 Appendix A, GDC-4 requirement that primary system pressure piping exhibit an extremely low probability of rupture. SRP 3.6.3 does not allow for assessment of piping systems with active degradation mechanisms, such as Primary Water Stress Corrosion Cracking (PWSCC) which is currently occurring in systems that have been granted LBB approvals. Along with a series of existing qualitative steps to assure safety in LBB-approved lines experiencing PWSCC, NRC staff, working cooperatively with the nuclear industry through a memorandum of understanding with the Electric Power Research Institute, is developing a new, modular based, comprehensive piping system assessment methodology to directly demonstrate compliance with the regulations. This project, called xLPR (eXtremely Low Probability of Rupture), will model the effects and uncertainties of relevant active degradation mechanisms and the associated mitigation activities. The resulting analytical tool will be comprehensive, vetted with respect to the technical bases of models and inputs, flexible enough to permit analysis of a variety of in-service situations and adaptable such as to accommodate evolving and improving knowledge. A multi-year project has begun that will first focus on the development of a viable method and approach to address the effects of PWSCC as well as define the requirements necessary for a modular-based assessment tool. To meet this goal, the first version of this code has been developed as part of a pilot study, which leverages existing fracture mechanics based models and software coupled to both a commercial and an open source code framework to determine the framework and architecture requirements appropriate for building a modular-based code with this complexity. The pilot study focused on PWSCC in pressurizer surge nozzles, and is meant to demonstrate the feasibility of this code and approach and not to determine the absolute values of the probability of rupture. Later development phases will broaden the scope of xLPR to appropriate primary piping systems in pressurized and boiling water reactors (PWR and BWR), using an incremental approach that incorporates the design requirements and lessons learned from previous iterations. This paper specifically examines the xLPR Version 1.0 model, the methods and approach used to couple the deterministic modules within a probabilistic software framework, and the results from the pilot study. A comparison of the results specific to the surge nozzle sample problem is presented. This paper concludes with lessons learned from the pilot study.

Performance Analysis of Thin Shell Bends under High Pressure and Temperature

2015 ◽  
Vol 787 ◽  
pp. 296-300
Author(s):  
P. Govindaraj ◽  
Mouleeswaran Senthilkumar
Keyword(s):  
High Stress ◽  
Fluid Pressure ◽  
Bending Moment ◽  
Piping System ◽  
High Stress Concentration ◽  
Geometrical Imperfection ◽  
Internal Fluid ◽  
Piping Systems ◽  
The Cost ◽  
Work Effect

Around 70% of the cost in piping industry is spent in the pipe manufacturing with optimum design of pipes without defects. Research on design of pipes has gained importance from the last decade. There are numerous methods being developed to improve the efficiency of piping units considering various parameters. The pipe tends to flatten when they are forced to bend, this geometrical changes has a significant role in the acceptability criteria of pipes. It is necessary to bend pipes in order to transmit liquid or gas from one place to other place. In this work special attention is given to pipe bends because of high stress concentration due to various loading conditions. From several kinds of piping systems, process piping systems are chosen for analysis since pipes used here transport important and hazardous materials. Damage to such piping system can cause serious loss to economy and human lives. The geometrical imperfection associated with bending of pipes is ovality. This degree of ovality determines the acceptance of pipes. Thickening and thinning effects cause additional problems like large plastic deformation and loss of flexibility respectively. Hence estimation of the best degree of ovality is required. In this work effect of ovality is estimated by taking the internal fluid pressure and In plane bending moment into account.

scholarly journals Development of Computational Framework and Architecture for Extremely Low Probability of Rupture (XLPR) Code

2010 ◽  
Author(s):  
D. Rudland ◽  
P. Mattie ◽  
R. Kurth ◽  
H. Klasky ◽  
B. Bishop ◽  
...  
Keyword(s):  
Pilot Study ◽  
Nuclear Industry ◽  
Current Status ◽  
Study Phase ◽  
Piping System ◽  
Primary System ◽  
Degradation Mechanisms ◽  
System Pressure ◽  
Piping Systems ◽  
Low Probability

The Nuclear Regulatory Commission (NRC) Standard Review Plan (SRP) 3.6.3 describes Leak-Before-Break (LBB) assessment procedures that can be used to demonstrate compliance with the 10CFR50 Appendix A, GDC-4 requirement that primary system pressure piping exhibit an extremely low probability of rupture. SRP 3.6.3 does not allow for assessment of piping systems with active degradation mechanisms, such as Primary Water Stress Corrosion Cracking (PWSCC) which is currently occurring in systems that have been granted LBB exemptions. Along with the existing qualitative steps to assuring safety in LBB lines with PWSCC, the NRC staff, working cooperatively with the nuclear industry through a memorandum of understanding, is developing a new, modular based, comprehensive piping system assessment methodology to directly demonstrate compliance with the regulations. This tool, called xLPR (eXtremely Low Probability of Rupture), would properly model the effects and uncertainties of both active degradation mechanisms and the associated mitigation activities. The tool will be comprehensive with respect to known challenges, vetted with respect to scientific adequacy of models and inputs, flexible enough to permit analysis of a variety of in-service situations and adaptable such as to accommodate evolving and improving knowledge. A multi-year project has begun that will first focus on the development of a viable method and approach to address the effects of PWSCC as well as define the requirements necessary for a modular-based assessment tool. A prototype xLPR model and pilot study case is first being conducted leveraging existing fracture mechanics models and software coupled to both a commercial and open source code framework to determine the framework and architecture requirements appropriate for building a modular-based code with this complexity. The pilot study phase is focusing on PWSCC in pressurizer surge nozzles. Later development phases will broaden the scope of xLPR to all primary piping systems in pressurized and boiling water reactors (PWR and BWR), using an incremental approach that incorporates the design requirements and lessons learned from previous iterations. This paper specifically examines the prototype xLPR model and includes the methods and approach used to couple existing models and software as modules within a probabilistic software framework. Since the pilot study is currently still ongoing, this paper provides a discussion of the current status and plans to move forward after the pilot study is complete.

Uncertainty Sampling of Weld Residual Stress Fields in Probabilistic Analysis: Part I — Theory

2016 ◽  
Author(s):  
Robert E. Kurth ◽  
Cédric J. Sallaberry ◽  
Frederick W. Brust ◽  
Elizabeth A. Kurth ◽  
Michael L. Benson ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Residual Stresses ◽  
Assessment Tool ◽  
Lessons Learned ◽  
Piping System ◽  
Primary System ◽  
Cracking Behavior ◽  
System Pressure ◽  
Piping Systems ◽  
Low Probability

NRC Standard Review Plan (SRP) 3.6.3 describes Leak-Before-Break (LBB) assessment procedures that can be used to assess compliance with the 10CFR50 Appendix A, GDC-4 requirement that primary system pressure piping exhibit an extremely low probability of rupture. SRP 3.6.3 does not allow for assessment of piping systems with active degradation mechanisms, such as Primary Water Stress Corrosion Cracking (PWSCC) which is currently occurring in systems that have been granted LBB approvals. US NRC staff, working cooperatively with the Electric Power Research Institute through a memorandum of understanding, conducted a multi-year project that focused on the development of a viable method and approach to address the effects of PWSCC in primary piping systems approved for LBB. This project, called eXtremely Low Probability of Rupture (xLPR), defined the requirements necessary for a modular-based probabilistic fracture mechanics assessment tool to directly assess compliance with the regulations [1]. Using the lessons learned from the pilot study [2] the production version of this code, designated as Version 2.0, focused on those primary piping systems previously approved for LBB [3]. In this version the appropriate fracture mechanics-based models are employed to model the physical cracking behavior and a variety of computational options are provided to characterize, categorize and propagate problem uncertainties. One of the most influential sources of uncertainty on risk in the xLPR code is the one associated with weld residual stresses (WRS). WRS plays a key role in both crack initiation and crack growth. PWSCC is mainly driven by tensile stresses, whose major contributors are the tensile weld residual stresses that develop during fabrication of the piping system. Handling the uncertainty involved with WRS within a probabilistic framework is quite challenging. This paper presents the selected approach to represent uncertainty within the framework of the xLPR code while respecting a set of requirements in term of smoothness of profile, efficiency of (potential) importance sampling and (for axial WRS) equilibrium. The current WRS sampling scheme employs correlation in order to smooth the shape of the WRS fields through the thickness of a dissimilar metal weld. This method presents an enrichment of the Cholesky decomposition on the correlation matrix, in order to satisfy the other two requirements.

A SYSTEM FOR PROTECTING AN OIL DIFFUSION PUMP AGAINST FAILURE OF THE MECHANICAL FORE PUMP, COOLING WATER, OR ELECTRICITY

1970 ◽  
Vol 28 ◽  
pp. 344-345
Author(s):  
W. C. Bigelow ◽  
F. B. Drogosz ◽  
S. Nitschke
Keyword(s):  
High Vacuum ◽  
Cooling Water ◽  
Effective Protection ◽  
Pump Line ◽  
Diffusion Pump ◽  
System Pressure ◽  
Control Relay ◽  
Vacuum Systems ◽  
Vacuum Gage ◽  
Pressure Switch

High vacuum systems with oil diffusion pumps usually have a pressure switch to protect against Insufficient cooling water; however, If left unattended for long periods of time, failure of the mechanical fore pump can occur with equally serious results. The device shown schematically in Fig. 1 has been found to give effective protection against both these failures, yet it is inexpensive and relatively simple to build and operate.With this system, pressure in the fore pump line is measured by thermocouple vacuum gage TVG (CVC G.TC-004) whose output is monitored by meter relay MRy (Weston 1092 Sensitrol) which is set to close if the pressure rises above about 0.2 torr. This energizes control relay CRy (Potter & Brumfield KA5Y 120VAC SPDT) cutting off power to solenoid-operated fore line valve Vf (Cenco 94280-4 Norm. Closed) which closes to prevent further leakage of air into the diffusion pump

Non-Linear Design Verification of Nuclear Power Piping According to ASME III NB/NC

2008 ◽  
Author(s):  
Lingfu Zeng ◽  
Lennart G. Jansson
Keyword(s):  
Nuclear Power ◽  
Design Evaluation ◽  
Piping System ◽  
Design Verification ◽  
Intensive Study ◽  
Non Linear ◽  
Piping Systems ◽  
Design Requirements

A nuclear piping system which is found to be disqualified, i.e. overstressed, in design evaluation in accordance with ASME III, can still be qualified if further non-linear design requirements can be satisfied in refined non-linear analyses in which material plasticity and other non-linear conditions are taken into account. This paper attempts first to categorize the design verification according to ASME III into the linear design and non-linear design verifications. Thereafter, the corresponding design requirements, in particular, those non-linear design requirements, are reviewed and examined in detail. The emphasis is placed on our view on several formulations and design requirements in ASME III when applied to nuclear power piping systems that are currently under intensive study in Sweden.

Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane, and Mixed Mode Bending Under Seismic Load: An Experimental Approach

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Dynamic Behavior ◽  
Failure Modes ◽  
Seismic Load ◽  
Piping System ◽  
Shake Table ◽  
Shake Table Tests ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending

Pressurized piping systems used for an extended period may develop degradations such as wall thinning or cracks due to aging. It is important to estimate the effects of degradation on the dynamic behavior and to ascertain the failure modes and remaining strength of the piping systems with degradation through experiments and analyses to ensure the seismic safety of degraded piping systems under destructive seismic events. In order to investigate the influence of degradation on the dynamic behavior and failure modes of piping systems with local wall thinning, shake table tests using 3D piping system models were conducted. About 50% full circumferential wall thinning at elbows was considered in the test. Three types of models were used in the shake table tests. The difference of the models was the applied bending direction to the thinned-wall elbow. The bending direction considered in the tests was either of the in-plane bending, out-of-plane bending, or mixed bending of the in-plane and out-of-plane. These models were excited under the same input acceleration until failure occurred. Through these tests, the vibration characteristic and failure modes of the piping models with wall thinning under seismic load were obtained. The test results showed that the out-of-plane bending is not significant for a sound elbow, but should be considered for a thinned-wall elbow, because the life of the piping models with wall thinning subjected to out-of-plane bending may reduce significantly.

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