Integrity of a piping system is a prerequisite for personnel safety and operational reliability in industries where pipelines are critical means of transferring products from one process point to the other, such as power plants, refinery plants, and chemical industries. An essential aspect of designing a reliable piping system is to design supports of suitable load carrying capacity. This also depends on accurate determination of expected support loads including loads due to vibration of the system. Piping design codes such as ASME B31.3 and B31.1 provide a general framework but do not address vibration and its impact from a detailed perspective. In many situations, the potential impact of vibration is overlooked during support load determination. In recent piping system construction, the effect of vibration has increased due to increase in fluid flow rates and use of high strength thin wall materials. Common factors that contribute to vibration include: turbulent flow (flow induced vibration, FIV), relief valve operation (acoustic induced vibration, AIV), rotating and reciprocating equipment (pulsation induced vibrations, PIV). The effect of vibration depends on the strength of excitation and the flexibility of the piping system. As vibration of the piping system increases, loads transfer to the pipe supports also increase. Catastrophic failure of a piping system can occur if its natural frequency lock-in with the frequency of the excitation source. For holistic system integrity, the loads induced due to vibrations need to be accounted for in the support design. In this paper, we investigate the contributions of the various vibration loads in a piping system, the effect of neglecting the various vibration loads on the system integrity, and an empirical method to readily determine the vibration loads to reduce cost and time require in support design processes.

The piping, welding and its fittings contributes to around 25–35% of the total material [1] of any process plant. The quantity of the piping and fittings required in critical pipes (lines) is largely influenced by the flexibility requirements to comply with applicable codes. Since the pressure and weight driven stresses are primary in nature and taken care by the thickness & supports respectively. The Secondary stresses are mainly caused due to temperature and determines the route of the pipe. Unfortunately, there is no sufficient awareness amongst the Process engineers, who dictate the temperature, about the effect of temperature (listed in line list) on the plant cost. To make the situation worse, very often the pipe stress engineers follow thumb rules, conservative design basis while applying temperature to pipes without questioning process engineers the basis and without having experimental evidences which in turn ends up adding to the cost, labor and time of the plant. Another factor influencing the ‘flexibility need’ is ‘Stress Intensification Factor’ which, as well, incorrectly multiplied by conservative numbers, especially in case of 45° branch fittings. Even ‘Flange leakage analysis’ needs to be performed to ensure safety of the plant. This paper challenges the mis-concepts in temperature distribution of a piping system by analyzing a real-life problem. Also, it provides the actual temperature measurements and compares it with theoretical values. At the end it provides a ‘Temperature de-rating factor, @(Taa)’ which can be used to derive actual expected temperature distribution. Further this paper provides a table to get the actual SIF of Tee and Fittings obtained by FEA. At the end it provides comparison between the results obtained by present industry practices against practical analysis and its effect on cost.

An important step in a pipeline-construction project is confirming that the piping and facilities are adequate for the expected operating pressures. This confirmation is done via a static strength test using a test fluid. All fluids have mass and internal energy. Fluids under pressure have significantly elevated internal energy. All fluids are compressible to some greater or lesser extent, and the fluid added to raise the pressure of the fluid in the bulk volume adds significant energy. The raw mass of a fluid must be considered when evaluating terrain elements and support elements (i.e., pipe stands and pipe racks). The selection process for a test fluid should always endeavor to minimize the total risk of the entire process. There is guidance in the primary pipeline design/construction codes (e.g., ASME B31 series) for many of the important considerations for managing the risk associated with the tests required to perform this confirmation of fitness for purpose. This code-guidance has historically not shown a clear preference for the selection of one particular test-medium over another. Some jurisdictions have written regulations that step away from ASME guidance and do show a clear preference for hydrostatic testing over pneumatic testing. This preference manifests itself in several ways, but the primary representation is the requirement in statutes and regulations that a pneumatic test have an “exclusion zone” around the test to reduce the risk of injury during the test. These documents tend to not have an exclusion-zone requirement for hydrostatic tests. This paper is undertakes to demonstrate the relative risks of liquid vs. gaseous test media and presents a background of why pneumatic tests have been singled out by regulators as higher risk and shows why this regulatory preference can result in actually increasing risk rather than decreasing it.

The evaluation procedures for fatigue initiation of nuclear class 1 components are defined in ASME BPVC Section III NB-3200 (Design by Analysis) and NB-3600 (Piping Design). Design fatigue curves are provided to establish the suitability of a component for cyclic service and define the allowable number of cycles as a function of applied stress amplitude (S-N curves). The number of load cycles at a particular strain range is then divided by the cycles to failure to obtain a partial usage factor., and the cumulative usage factor (CUF) for the component site, calculated from the sum of the partial usage factors, must be less than one. The original fatigue evaluation procedures did not include the effects of the PWR or BWR coolant environments, but laboratory test data indicate that significant fatigue life reductions can occur under such conditions, depending on strain rates and temperatures. These observations led to the formulation of modified procedures, originally published in NUREG-CR/6909 which required the usage factors to be increased by an additional environmental factor, Fen, which accounts for the deleterious effects of high temperature water. An ASME Code Case N-792-1 has now been included in ASME Section III which is based on the NUREG-CR/6909 equations, with some minor modifications. The Fen factors are derived from testing of membrane-loaded solid round tensile or tubular specimens at different strain rates and temperatures. The data were obtained using simple triangular waveforms, i.e. at constant strain rate, and the temperature was also constant for each test. However, for components subject to plant loading, the situation is significantly more complicated, with most major transients being thermal in origin. For a thermal shock transient some key characteristics become apparent. These are (i) temperature is out-of-phase with strain (ii) strain rate and temperature vary through the cycle with a faster strain rate at the top of the cycle (iii) stress decays through the wall of the component. Several assumptions need to be made in order to simplify the assessment of these sorts of transients. Examples of such assumptions include the choice of temperature for the calculation (e.g. maximum or average through the transient) and the method of strain rate calculation (e.g. assumption of constant strain rate, or integration through the cycle, i.e. the modified strain rate approach). These assumptions can be overly conservative and hence very restrictive for plant operators when making safety justifications. Improved models have been developed which weight fatigue damage through the cycle, which is consistent with recent observations from testing under complex load cycles. Although these models can more accurately predict fatigue life for loading that is representative of PWR transients, they still assume membrane loading which is unrealistic for thermal shock transients in thin walled components. Details of a testing capability at Wood (formerly Amec Foster Wheeler) or thermal shock testing in a PWR environment were presented in a previous paper (ASME PVP2018-84923). The predictions of fatigue initiation indicated test durations of 2–3 months based on the latest fatigue models for austenitic stainless steel. The current paper presents the results of the first thermal shock tests carried out on a type 304L stainless steel. The predictions are compared with experimental observations and the accuracy of the models are assessed.

In the 1950’s Markl et al. conducted numerous fatigue test of welded piping components that were later used to develop the ASME B31 and other piping design codes. To analyze low cycle fatigue data, Markl proposed an extrapolation method to obtain the pseudo-elastic stress for fatigue data analysis. In this paper, this extrapolation method is revisited to figure out its underlining mechanism, application scope and limitation. Two sets of fatigue data representing 4 point bending and cantilever bending condition are analyzed to support the study. A structural strain method is then proposed as an improvement and generalization of Markl’s approach, which can correlate large amount weldment fatigue data in both low-cycle and high-cycle regime by defining an equivalent structural strain parameter.

Safety assessment and economy design of piping system at high temperature is highly important in power and nuclear engineering. ASME-NH code considers cyclic failure modes at elevated temperature and provides the rules and damage limits for creep-fatigue interaction. Based on the calculation methods for creep strain increment of ASME-NH code, this paper investigated the creep-fatigue damage of reactor coolant piping in Thorium Molten Salt Reactor-Solid Fuel (TMSR-SF0) loop. By designing different stress cycles, the different creep strain increment and creep-fatigue assessments are systematically conducted. It was found that the creep strain increment of SF0 loop accumulated in one stress cycle time was higher than that accumulated during the entire service life divided by the number of stress cycles. Similarly, the creep-fatigue damage was also lower. And thus, an economical design method for SF0/SF1 loop was given.

The operating environment of polyethylene (PE) gas pipeline is complex and changeable. In the process of pipeline design, construction and operation, there are many fuzzy factors inducing pipeline accidents. In the paper, the fuzzy factors causing pipeline accidents were studied and analyzed, and the risk evaluation factors of PE gas pipeline were determined. According to the theory of fuzzy comprehensive evaluation, the mathematical model of fuzzy comprehensive evaluation for PE pipeline was established. In order to pursue as much accurate results of assessment as possible, the fuzzy analytic hierarchy process was used to determine the weight of each index. The safety evaluation grade of the pipeline was given by using the risk matrix method. And then the evaluation system software of PE gas pipeline risk assessment was developed. The software has been used in the risk inspection of PE gas pipeline, which provides the basis for the risk management of the pipeline.

A Code Case in the framework of JSME Nuclear Codes and Standards is being developed to incorporate a seismic design evaluation methodology for piping by means of advanced elastic-plastic response analysis methods and strain-based fatigue criteria. The Code Case as an alternative seismic design rule over the current rule will provide a more rational seismic design evaluation than the current criteria. This paper demonstrates an application result of the JSME Seismic Code Case to an actual complex piping system. The secondary coolant piping system of Japanese Fast Breeder Reactor, Monju, was selected as a representative of the complex piping systems. The elastic-plastic time history analysis for the piping system was performed and the piping system has been evaluated according to the JSME Seismic Code Case. The evaluation by the Code Case provides a reasonable result in terms of the piping fatigue evaluation that governs seismic integrity of piping systems. Moreover, it is found that the supporting forces and the response accelerations of the piping system obtained by the elastic-plastic response analysis also become more rational results than those with the current elastic response analysis. The contradiction of two requirements in piping design, flexibility for thermal expansion and rigidity for seismic response, can be effectively relaxed by use of the Code Case being developed.

This paper proposes Piping Code rules to address the effects of hydrogen deflagrations inside piping. Previous work proposed a set of criteria for piping subject to detonation loading [PVP2012-78519, PVP2012-78525]. This paper provides criteria to evaluate the effect of deflagrations, which typically have a slower rise time and lower energy, inside the piping. These deflagration criteria, coupled with the previously cited detonation criteria, are being used at the Hanford Tank Waste Treatment and Immobilization Plant to evaluate piping systems subject to hydrogen accumulation. The previous papers did not investigate or propose criteria for deflagrations, as these were known to have lower pressures and slower pressure rise times, but are still of some significance for piping design. Recent work has shown that there exists a scenario in which the deflagration loading may be very significant: deflagrations in small gas pockets surrounded by large waste slugs. Depending on the assumptions used to develop the loading, the unbalanced forces on piping segments in a long piping system can become high during a deflagration event. Thus, for the set of criteria chosen for deflagration, the deflagration event may become the limiting event, especially if it is the more frequent event. The criteria proposed need to recognize this scenario and guide the user to possible solutions. This paper presents the original methodology for evaluating these “slug” events, briefly discusses the recent testing and theory being pursued to reduce the effect of the loading [PVP2015-45970, PVP2016-63260, PVP2016-63262], and then proposes criteria for evaluating deflagration induced stresses and loads.

Waterhammer is the phenomenon which occurs due to rapid valve operation or sudden stop of pumps. When the waterhammer occurs, unbalanced pressure between elbows causes transient load on piping system. In the piping design against the waterhammer, it is necessary to evaluate the strength and the displacement of piping system against the transient load, and required to provide adequate piping supports. In the piping design, dynamic analysis and static analysis with DLF (Dynamic Load Factor) are often conducted to consider dynamic effect of the water hammer load. The piping support often regarded as rigid in the piping system analysis, however, because of support characteristic (flexibility, plastic behavior, sliding friction), the dynamic response of piping system changes from analysis result with rigid support. For this reason, support characteristics shall be considered adequately. Nevertheless, effect of the support characteristics on the piping design has not been discussed sufficiently. In this paper, to clarify the effect of the support characteristics against the waterhammer load, a series of the nonlinear dynamic analyses were conducted. Based on the analysis results, the response spectra and the ductility charts considering the nonlinearities of the piping system were created. the design approach to properly control the displacement of piping system based on the nonlinear response spectra and ductility charts, is proposed, and the dynamic response against waterhammer load in the piping system of LNG loading line is discussed.

Flow-induced acoustic resonances in piping with closed side branches or T-junctions are one of the causes of severe structural vibrations, which sometimes cause fatigue damage to piping and components in a power plant and many engineering applications. In this paper, on the basis of the results of steam flow experiments and calculations, the effects of the liquid phase on the flow-induced acoustic resonance at closed side branches in the steam flow piping of BWRs are described, and some suggestions for the steam piping design of BWRs are also given. The liquid phase in a steam flow forms droplets or liquid film, which may affect the amplitude, frequency and critical Strouhal number of the resonance. From the results of wet steam experiments and CFD calculations, we have found that in some cases the wetness of the steam flow may decrease the resonant amplitude and change the frequency owing to the interaction of the vortex generation or damping by the existence of the liquid film and droplets. Therefore, for the wet steam piping design of BWR, some suggestions for taking these effects into consideration, under actual BWR steam conditions are described.

The Hanford Tank Waste Treatment and Immobilization Plant (WTP) will process waste slurries capable of generating a dispersed non-condensable gas phase. Under postulated conditions, the generated bubbles may coalesce to form flammable gas pockets. Ignition of such a gas pocket may result in a deflagration or detonation that can transmit a pressure pulse into the surrounding gas-liquid slurry. The transmitted pressure pulses will impose structural loads on the piping and associated supports. These loads, and their evolution as the pressure pulse propagates throughout the system, must be considered in the design of WTP piping. Recent work has demonstrated good agreement between experimental data and predictions of the pressure diminishment associated with the propagation of a pressure pulse through a bubbly medium using a simplified onedimensional pursuit model (i.e., model of rarefaction wave overtaking shock front). This paper describes the application of the pursuit model to flammable gas pocket scenarios postulated in the design of WTP piping. The model is adapted to consider the effect of the time-evolution of the ignited gas pocket and parametric simulations are used to demonstrate the effect of key variables on the propagation and diminishment of the pressure pulse in piping. The practical applicability of the pursuit model for WTP piping design / analysis is illustrated through the development of a correlation that appropriately represents the results of the pursuit model for a wide range of conditions and that could be readily incorporated into existing structural analysis tools. Arguments are presented supporting the applicability of the simplified model even for scenarios in which the ignited gas pocket does not satisfy the model’s onedimensional assumption.

In the design of piping systems, there are many options for transitioning between HDPE and metallic piping. One common option is the use of flanged joints. As a result of the visco-elastic nature of HDPE, the use of HDPE-to-metallic flanged joints requires special design considerations. When HDPE-to-metallic flanged joints are used in ASME Class 3 systems, the design is further complicated by the requirements provided in the ASME B&PV Code, Section III for flanged joint analysis. This paper examines the differences between HDPE piping flanged joints and metallic piping flanged joints, including consideration of industry guidance and available industry testing results. The paper provides a proposed methodology for evaluating ASME Class 3 HDPE-to-metallic flanged joints and HDPE-to-HDPE flanged joints, including the determination of required bolt torque values and the determination of the maximum internal pressure that the joint can resist without experiencing leakage.

Different pressure vessel and piping design codes and standards have adopted different fatigue analysis methods. In order to make some contribution to current efforts to harmonize international design codes and standards, a review of fatigue analysis methods for a number of selected nuclear and non-nuclear design codes and standards has been carried out. The selected design codes and standards are ASME Boiler and Pressure Vessel Code Section III Subsection NB and Section VIII Division 2, EN 12952, EN 13445, EN 13480, PD 5500, RCC-M, RCC-MRx, JSME, PNAEG and R5. This paper presents the initial review results. The results of the study could be used as part of the on-going work of the Codes and Standards Task Force of the World Nuclear Association (WNA) Cooperation in Reactor Design Evaluation and Licensing (CORDEL) Working Group.

It is a common challenge for pressure vessel and foundation engineers to determine the effects of piping loads on the foundation and vessel support design and to find out the appropriate design method to be used. Pressure Vessel Codes specify loadings to be considered in the vessel design but limited guidance is provided on the application of piping loads when designing vessel supports. Consideration of piping loads in the design of vessel supports and foundation is left to the engineer’s judgment. Vessel supports are typically designed to withstand the operating weight of the vessel, seismic and wind loading. Pressure vessel literatures provide well-established methodologies in considering these loads in the design of vessel supports. Civil engineering literature, such as the American Society of Civil Engineers (ASCE) Wind Loads for Petrochemical and Other Industrial Facilities [11] or the ASCE Guidelines for Seismic Evaluation and Design of Petrochemical Facilities [17], provide well documented procedures and guidelines for evaluating wind and seismic loads. However, there is limited literature on how to account for external loads from attached piping. Typical major project schedules have vessels and their supports/foundations designed well before the development of the piping design that provides calculated actual nozzle and piping loads on the vessel. This paper reviews the type of piping loads, how the piping loads are translated to the vessel support/foundation and provides a proposal for simplified approach analysis on how to apply these piping loads in the design of the vessel support/foundation. There might be cases where the piping loads will cancel out, but that may not always be the case. Ignoring and not considering nozzle loads in the support design/foundation may not be appropriate for all vessels. The intent of this paper is to also make the Vessel Engineer aware of ways to reduce these loads and to encourage communication with Stress Engineers in regards to flexibilities and other factors used to calculate nozzle/piping loads. In most cases, the vessel shell and nozzles are considered as rigid anchors in the piping stress analysis. By using the proper flexibility at nozzle junctions and the global vessel flexibility, the effect of piping loads in the design of the vessel support can be reduced. There is little or no industry guideline on how to include loads due to the thermal expansion or contraction of piping. Since the thermal loads and calculation of flexibility are the least understood part of the analysis, this paper provides background including examples of how these loads and flexibilities can be calculated. In short, the intent of the paper is to provide a better understanding of how piping loads are translated to the vessel support and to provide some design guidelines that are not readily available in current literature and are not clearly specified in the industry codes or standards.

Sodium-cooled Fast Reactor, SFR is promising candidate of Generation-IV reactor. SFR is operated at high temperature and low pressure. For reducing high thermal stress, thin-walled components and structures are employed for SFR. However, thins-walled components are vulnerable to seismic damage[1]. In this paper, the structural integrity assessment are performed to investigate the effect of piping length on creep-fatigue and seismic damage at elevated temperature. L-shaped elbow is considered for piping design and finite element analyses are conducted to calculate creep-fatigue and seismic damage. The evaluation of creep fatigue damage is carried out according to the elevated temperature design codes of ASME B&PV Sec. III Subsec. NH-3200[2]. Seismic damage are evaluated based ASME B&PV Sec. III Subsec. NB-3600[3] and ASME B&PV Sec. III Div.5 HBB-3200[4]. From the results of creep-fatigue and seismic damage, limit length of piping is determined.

This study proposes a method for designing a water pipeline system against fault displacement by incorporating earthquake resistant ductile iron pipes (ERDIPs). An ERDIP pipeline is capable of absorb the large ground displacements that occur during severe earthquakes by movement of its joint (expansion, contraction and deflection) and the use of the joint locking system. Existing ERDIP pipelines have been exposed to several severe earthquakes such as the 1995 Kobe Earthquake and the 2011 Great East Japan Earthquake, and there has been no documentation of their failure in the last 40 years. In the case of a pipeline that crosses a fault, there is the possibility of the occurrence of a local relative displacement between the pipeline and the ground. It is known that an ERDIP pipeline withstands a fault of axial compression direction by past our study. Hence, this present study was targeted at developing a method for designing an ERDIP pipeline that is capable of withstanding a strike-slip fault of axial tensile direction for a pipeline. This was done by FEM analysis wherein the ERDIPs and spring elements were used to model the soil and ERDIP joints. An ERDIP pipeline can accommodate a fault displacement of about 2 m by joint expansion/contraction and deflection, while maintaining the stress in the pipeline within the elastic limit. However, additional countermeasure is required when the fault displacement exceeds 2 m because such could stress the pipeline beyond the elastic limit. The use of large displacement absorption unit is an effective countermeasure for displacements exceeding 2 m. The expansion/contraction capacity of a unit is 10 times that of an ERDIP joint and it is able to absorb a locally-concentrated axial displacement of the pipeline. It was confirmed in the present study that an ERDIP pipeline with large displacement absorption unit, referred to as a large displacement absorption system, could accommodate fault displacement in excess of 2 m within the elastic stress range of the pipeline.

In geohazard areas, buried pipelines are subjected to permanent ground deformations, which constitute major threats for their structural safety. Geohazards include seismic fault movement, liquefaction-induced lateral spreading and slope instability, and the corresponding deformations induce severe strains in the pipeline. Calculation of these strains is necessary for assessing pipeline integrity. In the present paper, an analytical methodology is presented and compared with existing analytical and numerical methodologies for stress analysis of buried pipelines. The proposed methodology is also compared with full-scale available experimental results and offers significant intuition on the behavior of buried pipelines subjected to permanent ground deformations. Using the proposed analytical methodology, one may predict the strains developed in the pipeline wall quite efficiently and with good accuracy.

Acoustically induced vibration (AIV) is recognized as a vibration of piping systems caused by the acoustic loading at the downstream of the pressure reducing devices. For decades several industrial practices which are derived from past experiences, have been applied for the design of piping system, however it is known that the practices includes uneven design margins. Due to the increase of the large capacity reducing devices, the demands of the development of reasonable screening and design method for AIV are increasing. A detailed assessment of fatigue life using finite element analysis has become popular and clarified the effect of acoustic load on several specific components; however, there are no clear way to explain the susceptibility against AIV depending on its diameter and thickness. Therefore the discussions based on engineering principles are required. In this paper, the vibration of cylindrical shells due to acoustic loading was discussed based on the theory of cylindrical shells. Results of several numerical studies based on the theoretical formulas were presented on the natural frequency and modal stress of vibrating shells on various geometries. Thus, the key factors to affect the vibrating shell stresses were clarified and some simplified formula to evaluate the vibrating shell stress was proposed.

Pipelines are widely accepted to be the most economical method for transporting large volumes of hydrogen, needed to fuel hydrogen-powered vehicles. Some work has been previously conducted on the fatigue crack growth rates of base metals of pipeline materials currently in use for hydrogen transport and on pipeline materials that may be used in the future. However, welds and their heat-affected zones are oftentimes the source and pathway for crack initiation and growth. The heat-affected zones of welds can exhibit low resistance to crack propagation relative to the base metal or the weld itself. Microstructural irregularities such as chemical segregation or grain-size coarsening can lead to this low resistance. Therefore, in order to have adequate information for pipeline design, the microstructures of the heat-affected zones must be characterized, and their mechanical properties must be measured in a hydrogen environment. With that in mind, data on the fatigue crack growth rate is a critical need. We present data on the fatigue crack growth rate of the heat-affected zones for two girth welds and one seam weld from two API 5L X52 pipes. The materials were tested in hydrogen gas pressurized to 5.5 MPa and 34 MPa at a cyclic loading rate of 1 Hz, and an R ratio of 0.5.