Adoption of the Composite Reinforced Pressure Vessels (CRPV) Into the ASME BPV Code

Adoption of composite reinforced pressure vessels (CRPV) into the ASME Boiler and Pressure Vessel Code represented advancement in the technology of pressure vessels. The advantage of this construction technique is that the weight of a CRPV for compressed gas service built may be reduced to about one-half conventional pressure vessel of the same capacity. The concept of hoop wrapping fibers in a plastic composite (>90% fiber fill) makes full utilization of the fiber strength as the fibers share the hoop load with a metal cylinder. With reduced hoop stresses in the metal, a substantial reduction in wall thickness is attainable. The process of adoption of this technology presented several challenges and some robust administrative hurdles. These included coordination with ASME BPV Code Section X for the composite application and Section VIII for the steel design and overall acceptance of the Case. The most vexing technical challenge was the inspection of an unfinished weld on the inside of the shell from the outside of the shell. The next challenge was to gain consensus on the testing criteria for the acceptance of finished vessels. Case 2390 was drafted in the winter of 2000 and spring of 2001 and approved for publication after nine revisions with an approval date of October 9, 2002. The Case was subsequently adopted into the body of ASME BPV Code Section VIII, Division 3 [1] (VIII-3) in the 2010 edition.

Ultrasonic Inspection of Dissimilar Metal Welds for Probabilistic Reliability Assessment of Pipe Welds

There are several sources of uncertainties which need to be considered in a probabilistic reliability and lifetime assessment of safety-relevant components. In addition to the probabilistic distribution of material properties, the size and properties of flaws present in a component contribute to uncertainties in the lifetime analysis. In a current reactor safety research project, a methodology for a probabilistic fracture mechanics assessment of reliability for components with austenitic and dissimilar metal welds will be developed using the combined results from statistical evaluation of material properties and ultrasonic inspection (UT). Dissimilar metal welds present a particular challenge for ultrasonic testing due to the effects of the material anisotropy on ultrasonic propagation and scattering. Evaluation of inspection results is typically done using image-based techniques. As there is no simple relationship between UT response and flaw size, criteria for image evaluation and flaw sizing have to be defined taking into account the influence of various factors such as material and flaw properties on the UT response. In this paper, we present results from a study of the influence of grain structure on the ultrasonic inspection results and discuss the challenges of extracting data for probability of detection (POD) analyses.

Gaseous Deflagration in Piping: Part 2 — Proposed Methods and Code Acceptance Criteria

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.

A Novel Defect Location Method for Plate-Like Structure by Using Forward-Scattering Wave and Fuzzy C-Means Clustering

Ultrasonic guided wave technology combined with sparse transducer array provides an efficient and relatively cost-effective means of defect detection and monitoring for rapid interrogation of large in plate-like structures. However, imaging algorithm used baseline subtraction methods may be compromised under mismatched environment and operational conditions. A defect location method based on forward-scattering wave and fuzzy c-means clustering is proposed in this paper. The distance coefficient including location information between sensor pair using exciting and receiving signal and defect is defined to explain feasibility of the method proposed in this paper. A Parallel line array is evaluated using the method to locate defect. Experimental results show that the proposed method can effectively reduce the influence of mismatched environment and operational conditions on the defect location.

Embedded Capacitance Sensor Array for Structural Health Monitoring of Pipeline Systems

Embedded capacitance sensor arrays for Structural Health Monitoring (SHM) of piping is explored. Using a capacitive electrode layer system embedded within Fiber Reinforced Polymer (FRP) layers, to detect potential damage and loading conditions. The sensors are comprised of an electrode array, and allow changes in system capacitance to be monitored. Combined with baseline data points, subsequent measurements can provide indication of applied force changes within composite patched or composite reinforced piping, allowing for repair or reinforcement health status monitoring. Unlike traditional sensors which only measure a single point, the proposed approach incorporates an electrode array technique, while capacitive sensing affords the ability to detect minuscule changes in force on the whole pipe surface. Thus, providing detection and monitoring capabilities beyond those currently employed by industry such as optical fiber or strain gauge.

Multisensor Degradation Data Fusion and Remaining Life Prediction

Multiple sensors are commonly used for degradation monitoring. Since different sensors may be sensitive at different stages of the degradation process and each sensor data contain only partial information of the degraded unit, data fusion approaches that integrate degradation data from multiple sensors can effectively improve degradation modeling and life prediction accuracy. We present a non-parametric approach that assigns weights to each sensor based on dynamic clustering of the sensors observations. A case study that involves a fatigue-crack-growth dataset is implemented in order evaluate the prognostic performance of the unit. Results show that the fused path obtained with the proposed approach outperforms any individual sensor data and other paths obtained with an adaptive threshold clustering algorithm in terms of life prediction accuracy.

Initial Thermal Testing of the Pipe Over-Pack Container With a Combustible Waste Matrix for Los Alamos National Laboratory

Los Alamos National Laboratory (LANL) Technical Area 55 (TA 55) utilizes several different container types to store and transfer special nuclear material and waste for numerous programs. The Pipe Over-pack Container (POC) is a vented carbon steel container with a removable lid designed for storing or transferring nuclear waste. Additionally, TA 55 has been tasked to manage and store all of its Transuranic (TRU) waste for the foreseeable future. Being able to place more material into a single container conserves the physical storage space available at TA 55. Conducting thermal testing with a combustible waste matrix in the POC can benefit stakeholders on increasing the material limits of the container. The results of these measurements will establish new wattage limits to meet LANL’s transportation requirements. The current LANL Transportation Safety Document (TSD) limits the amount of heat source plutonium to 10 grams per POC, corresponding to approximately 5 Watts of heat. Combustible loading consisted of an arrangement of cellulosics, plastics, rubber and other contents such as tape. An initial arbitrary limit was set at 60 °C reflecting previous research on nitrate contaminated cheesecloth within a combustible loaded matrix. The limit will ensure the sensitivity of nitrate contaminated contents is undisturbed. Two tests were conducted on the waste matrix at 9.3 watts and 15 watts payloads. Each test was conducted within an 8 hour work day while observing the transient response to ensure the testing does not exceed the temperature limit. Results show that with a 15 watt payload the temperature at the source reaches the 60 °C limit within 5 hours of testing. Other areas such as the cheesecloth and plywood are under the arbitrary limit. Observations and pictures showed no signs of material degradation from heat loading which allow us to move past the limit and investigate higher payloads. ANSYS numerical modeling has complemented the efforts by producing predictions within 5% error of experimental results. These results along with previous POC thermal testing will be presented to the Packaging and Transportation (OS-PT) group at LANL to assist in raising the heat source plutonium loading limit.

EDS Containment Vessel TNT Equivalence Testing

The V26 containment vessel was procured by the Project Manager, Non-Stockpile Chemical Materiel (PMNSCM) for use on the Phase-2 Explosive Destruction Systems. It was fabricated under Code Case 2564 of the ASME Boiler and Pressure Vessel Code, which provides rules for the design of impulsively loaded vessels [1]. The explosive rating for the vessel, based on the Code Case, is nine (9) pounds TNT-equivalent for up to 637 detonations. This report documents the results of tests that were performed on the vessel at Sandia National Laboratories to qualify the vessel for explosive use [2]. Three of these explosive tests consisted of: (1) 9lbs bare charge of Composition C-4 (equivalent to 11.25lbs TNT); (2) a 7.2lbs bare charge of Composition C-4 (equivalent to 9lbs TNT); (3) a bare charge of 9lbs cast TNT. The results of these tests are compared in order to provide an understanding of how varying charge size affects vessel response when the ratio of free volume to charge volume is small, and in making direct comparisons between TNT and Composition C-4 for TNT equivalency calculations. In a previous paper [3], the 7.2lbs bare charge of Composition C-4, (2) above, was compared to 7.2lbs of Composition C-4 distributed into 6 charges.

Surface Stress Analysis of Internally Corroded Pipes Under External Pressure

Corrosion often leads to the failure of transporting pipelines. The surface stresses on the corroded pipes are related to the failure pressure. In this paper, a double circular arc (DCA) model is developed to calculate the surface stress of the internal corroded pipes under external pressure. In addition, a critical corrosion ratio and a critical thickness-to-diameter ratio are presented to determine the location of the maximum stress. Based on the stress function method and bipolar coordinates, an analytical solution of the DCA model was obtained. And then the stress distributions on the internal and external surfaces of the corroded pipes were determined. Next, the equivalent and hoop stresses at several locations in the cross section of the corroded pipes were discussed. The calculated results were validated using finite element method (FEM). Results show that the maximum stresses vary from the internal surface to the external surface with the increase of the corrosion ratio or the thickness-to-diameter ratio. Our research provides a benchmark for approximate solutions to predict the failure pressure and assess the integrity of the corroded pipelines.