Crossover Piping Research Articles

Seismic qualification of crossover piping systems on a sodium-cooled fast reactor with a seismic isolation system

Seismic qualification of crossover piping systems on a sodium-cooled fast reactor with a seismic isolation system

Advances in operating capacity and life time of centrifugal cast pipes for high-temperature pyrolysis of NRC “Kurchatov Institute” – CRISM “Prometey”

On the basis of expert examinations of spent pipes metal operated as coil-pipes at pyrolysis furnaces, heat-resistant alloys and technologies for manufacturing standard products from them have been developed. The service characteristics of the developed alloy 45Kh32N43SB and its welded joints at temperatures of 1100 and 1150°C have been investigated. It is shown that the alloy has structural stability and the ability to resist high-temperature creep at operating temperatures up to 1150°C. A method has been developed for assessing the resource of pipe elements, taking into account the peculiarities of its operation, as well as crack-like defects in the pipe material. The reasons for the significant deformation and damage of the crossover piping, leading to the premature failure of the coils, have been found. The most significant operational factor of damage to the heat exchangers at pyrolysis plants has been identified.

Seismic performance limit of nuclear power plant piping system with seismic isolation system considering measurement points: Low-cycle fatigue life

This paper presents the first part of a two-part investigation on the seismic performance limits of nuclear power plant piping systems with seismic isolation systems considering the measurement points and proposes a scheme for low-cycle fatigue life. This part of the study focuses on pipe elbows, which are components vulnerable to seismic loads in crossover piping systems connecting structures with and without seismic isolation systems in nuclear power plants. The low-cycle fatigue life, which is the seismic performance limit of the pipe elbow, was determined by considering the cyclic loading of the low-frequency characteristics caused by the seismic isolation system. Three-inch test specimens of SCH40, which are typical standards for nuclear power plant piping systems, are fabricated herein consisting of a pipe elbow and straight pipes. In the test specimens, the pipe elbow where the load is concentrated and the lengths of the straight pipes that are connected to the elbow may differ from those in field conditions. Therefore, their effects on the seismic performance limit were analyzed using the relationship between the moment and deformation angle. Cyclic loadings were performed at varying amounts of a constant amplitude, and an imaging system was used to measure the moments and deformation angles. The deformed shapes of the test specimens caused by external forces were compared for each measurement point, and the leakage lines and low-cycle fatigue curves were presented using the relationship between the moment and relative deformation angle.

Seismic performance limit of nuclear power plant piping system with seismic isolation system considering measurement points: Damage index

This paper presents the second part of a two-part investigation on the seismic performance limits of nuclear power plant piping systems with seismic isolation systems considering the measurement points and aims to quantitatively express these limits using a damage index based on the dissipated energy. This part of the study focuses on a method to quantitatively express the seismic performance limits needed for seismic fragility evaluations of crossover piping systems connecting structures with and without seismic isolation systems in nuclear power plants. Test specimens for this study were manufactured by welding straight pipes to both ends of a 90° long pipe elbow. The dissipated energy was calculated using the relationship between the moment measured at the center of the pipe elbow and relative deformation angle at each of the straight pipe’s measurement points using an imaging system; this was compared to the dissipated energy calculated from the relationship between force and displacement, and a suitable length of the straight pipe for low-cycle fatigue tests was found. Further, a method of applying a weighting factor to the yield points, which are needed to calculate the damage index, are examined; thus, it was confirmed that the damage index can be used to quantitatively express the seismic performance limits of thin-walled steel pipe elbows.

Relief Well Challenges and Solutions for Subsea Big-Bore Field Developments

Summary In subsea environments, using large-bore/high-rate well designs is often a key contributor to the economic recovery of hydrocarbon resources. Their use is a necessity for accommodating the huge production capacity of the reservoirs they penetrate, with the major benefit of minimizing the number of wells necessary to develop a subsea field. The enthusiasm for using such well designs, however, must also be tempered by a clear understanding of the considerable well control risk they introduce—that risk being an increased level of difficulty in bringing such a well under control if a blowout were to occur. It is common that multiple relief wells, with their inherent complexities and time investment, would be simultaneously required to bring a big-bore blowout under control. The discussion of this fact is, though, not a common topic in industry literature. Instead, capping stacks have been more the focus. Much recent attention has been trained on ensuring that capping stacks are a viable method for quickly responding to a high-rate subsea blowout. This makes sense in light of the simpler, and publicly more palatable, concept of rapidly installing a capping stack on a blown-out subsea well. Still, a capping stack is only as reliable as the wellhead it must connect to. It is because subsea wellheads have such a high chance of being damaged during a blowout that relief wells will always be relied on as the ultimate backstop for ensuring that a subsea blowout can be brought under control. This reliance on relief wells, as they are traditionally envisioned, has limitations though when addressing a high-rate subsea blowout. Any subsea relief well will have inherent limitations resulting from the architecture of choke and kill lines (flow restrictions) and that of the crossover piping at the blowout preventer (BOP; erosion concerns). In the world of high-rate subsea blowouts, these limitations can sometimes translate into multiple relief wells being required to inject fluid at the rates necessary to affect a dynamic kill. However, the simultaneous use of multiple subsea relief wells to dynamically kill a single blowout has only been tried once in the industry's history. As a result, some countries require that stopping a blowout must be possible by drilling only one relief well. In this paper, we describe methods that can be implemented to transcend traditional relief well limitations via using a relief well injection spool (RWIS), with the ultimate goal of dynamically killing a subsea big-bore blowout using a single relief well. The technique varies with water depth. In both shallow-water (826 ft) and deepwater (8,260 ft) environments, the techniques are presented and analyzed that will allow using a single subsea relief well to perform a dynamic kill using 15 lbm/gal drilling fluid injected at 238 bbl/min. This particularly severe scenario, based on a big-bore gas well development in Western Australia, is chosen so that our results will have applicability to most subsea well control events that might arise in the future.

Method of Seismic Response Reduction for Crossover Piping Using Inertial Mass Element

Method of Seismic Response Reduction for Crossover Piping Using Inertial Mass Element

A Failure Estimation Method of Steel Pipe Elbows under In-plane Cyclic Loading

The relative displacement of a piping system installed between isolated and nonisolated structures in a severe earthquake might be larger when without a seismic isolation system. As a result of the relative displacement, the seismic risks of some components in the building could increase. The possibility of an increase in seismic risks is especially high in the crossover piping system in the buildings. Previous studies found that an elbow which could be ruptured by low-cycle ratcheting fatigue is one of the weakest elements. Fatigue curves for elbows were suggested based on component tests. However, it is hard to find a quantitative evaluation of the ultimate state of piping elbows. Generally, the energy dissipation of a solid structure can be calculated from the relation between displacement and force. Therefore, in this study, the ultimate state of the pipe elbow, normally considered as failure of the pipe elbow, is defined as leakage under in-plane cyclic loading tests, and a failure estimation method is proposed using a damage index based on energy dissipation.

原子力施設の免震技術の開発

The crossover piping is installed between seismically isolated and non-isolated building; the reactor building (RB) is only isolated using seismic isolation systems whereas the turbine building (TB) is non-isolated. The crossover piping supported by both isolated and non-isolated building is calculated in consideration of large relative displacement between the two buildings. The flexible structure is required for crossover piping which allows the relative displacement. It also has to endure the seismic response of itself caused by different seismic excitations from both buildings. The seismic design for crossover piping needs evaluation considering both of the relative displacement and the seismic response. The results of shaking table tests of 1/10 scaled Main Steam (MS) piping model is used to compare the seismic response analyses of crossover piping. In this study, the seismic design methods including design inputs and load combination for the crossover piping design are summarized. In particular, the design shall conservatively consider the effect of stiffness variance of seismic isolator. Based on the discussion, the seismic design method for crossover piping is proposed.

G1000804 原子力施設の免振技術の開発 : 渡り配管 配管設計法の確立

G1000804 原子力施設の免振技術の開発 : 渡り配管 配管設計法の確立

Potential Cracking in Hydrogen Plant with Light Feedstocks (Part II)

This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures, are selected to study the HC thermal cracking. Effect of Crossover Piping Volume on feed thermal cracking is also discussed.

J1010101 原子力施設の免震技術の開発 : 渡り配管要素試験結果に基づく疲労損傷の分析評価([J101-1]耐震・免震・制震 耐震(1))

It is assumed the main steam crossover piping is damaged by the ratcheting deformation based on the relative displacement and the inertia load by the earthquake between the buildings and the internal pressure. This part shows a low cycle ratcheting fatigue test using the scaling model under the combined loadings based on the relative displacement and the inertia load by the earthquake between the buildings and analyses were performed to confirm the failure modes and the fatigue life of the pipe elbow for the fatigue damage of the long-period ground motion.As a result, the fatigue life under combined loads was sufficiently higher than the design criteria and analyses are good match with the test results. So, it confirmed the structural integrity of the crossover piping.

J1010103 原子力施設の免震技術の開発 : 渡り配管の設計手法について([J101-1]耐震・免震・制震 耐震(1))

J1010103 原子力施設の免震技術の開発 : 渡り配管の設計手法について([J101-1]耐震・免震・制震 耐震(1))

J1010105 原子力施設の免震技術の開発 : 渡り配管のフラジリティについて([J101-1]耐震・免震・制震 耐震(1))

J1010105 原子力施設の免震技術の開発 : 渡り配管のフラジリティについて([J101-1]耐震・免震・制震 耐震(1))

Estimate of solid flow rate from pressure measurement in circulating fluidized bed

A method is described to estimate solid mass flow rate based on measurement of pressure drop in horizontal section of circulating fluid bed (CFB). A theoretical model was derived based on momentum balance equation and used to predict the solids flow rate. Several approaches for formulating such models are compared and contrasted. A correlation was developed that predicts the solids flow rate as a function of pressure drop measured in the horizontal section of piping leading from the top of the riser to the cyclone, often referred to as the cross-over. Model validation data was taken from literature data and from steady state, cold flow, CFB tests results of five granular materials with various sizes and densities in which the riser was operated in core-annular and dilute flow regimes. Experimental data were taken from a 0.20 m ID cross-over piping and compared to literature data generated in a 0.10 m ID cross-over pipe. The solids mass flow rate data were taken from statistically designed experiments over a wide range of Froude number U g 2 g D , 25 – 2 00 , load ratio G s ρ g U g , 0. 2 – 23 , Euler number 2 Δ P Horiz ρ g U g 2 ,2 – 5 0 , density ratio ρ p − ρ g ρ g , 6 0 – 2 000 , Reynolds number ρ g U g d p μ g , 6 0 – 16 00 , and Archimedes number ρ s − ρ g ρ g d p 3 μ g 2 , 29 – 95 00 . Several correlations were developed and tested to predict the solids mass flux based on measuring pressure drop in the horizontal section of CFB. It was found that load ratio G s ρ g U g is a linear function of the Euler number 2 Δ P Horiz ρ g U g 2 and that each of these expressions all worked quite well ( R 2 > 95%) for the data within the range of conditions from which the coefficients were estimated.

Metal dusting in the low-point drains of crossover piping system in petrochemical environment

In April, 2008, a leak from a welded elbow was found on the coil inlet piping of an ethane cracking furnace in one of NOVA Chemicals plants. Subsequent examinations identified more potential failure locations, e.g. abandoned thermowells, low-point drains. All these locations were identified as containing confined spaces, which were relatively isolated from the process stream and allowed the buildup of coke. Extensive analysis revealed that metal dusting of the 304H stainless steel was responsible for the material wastage and reduction of wall thickness at these specific locations. This paper describes the analysis on the low-point drains and elaborates on the corresponding mechanism of the metal dusting in these confined spaces. Two 304H stainless steel (SS) low-point drains were analyzed to investigate the root causes of the failure. These failed low-point drains were located in the crossover piping system of an ethane cracking furnace. The failure was in the form of material loss, resulting in the thinning of the plug wall and creating a leak path. The analysis confirmed that the material loss was the result of metal dusting due to excessive carbon deposition and carburization. The metal dusting is proposed to occur in the decoking process, which is an oxidizing environment, rather than the cracking process. Excessive carbon content was detected in the void formed by metal dusting and the crevice between the threads. The coke formation was in the form of catalytic coking, promoted by the existing catalysts (iron and/or nickel) in 304H SS. The metallurgical analysis revealed carburization in the steel and local burns were present simultaneously with the metal dusting. The reduction or disappearance of the original protective layer (Cr 2O 3) allowed a diffusion path of the carbonaceous gases, thus creating carburization and metal dusting. The disappearance of the protective oxide (Cr 2O 3) layer was the result of local excessive temperature causing loss of chromium.

99/03921 Optimization of blast furnace smelting parameters during injection gasification products of low-grade coals: Tovarovskii, I. G. et al. Stal', 1998, (9), 1–6, (In Russian)

In April, 2008, a leak from a welded elbow was found on the coil inlet piping of an ethane cracking furnace in one of NOVA Chemicals plants. Subsequent examinations identified more potential failure locations, e.g. abandoned thermowells, low-point drains. All these locations were identified as containing confined spaces, which were relatively isolated from the process stream and allowed the buildup of coke. Extensive analysis revealed that metal dusting of the 304H stainless steel was responsible for the material wastage and reduction of wall thickness at these specific locations. This paper describes the analysis on the low-point drains and elaborates on the corresponding mechanism of the metal dusting in these confined spaces.Two 304H stainless steel (SS) low-point drains were analyzed to investigate the root causes of the failure. These failed low-point drains were located in the crossover piping system of an ethane cracking furnace. The failure was in the form of material loss, resulting in the thinning of the plug wall and creating a leak path. The analysis confirmed that the material loss was the result of metal dusting due to excessive carbon deposition and carburization. The metal dusting is proposed to occur in the decoking process, which is an oxidizing environment, rather than the cracking process. Excessive carbon content was detected in the void formed by metal dusting and the crevice between the threads. The coke formation was in the form of catalytic coking, promoted by the existing catalysts (iron and/or nickel) in 304H SS. The metallurgical analysis revealed carburization in the steel and local burns were present simultaneously with the metal dusting. The reduction or disappearance of the original protective layer (Cr2O3) allowed a diffusion path of the carbonaceous gases, thus creating carburization and metal dusting. The disappearance of the protective oxide (Cr2O3) layer was the result of local excessive temperature causing loss of chromium.