Relationship between the Types of Malocclusion and the Localization of Headaches in Adults

The aim of this study was to investigate the manifestations of headaches in adult patients with types of malocclusion and occlusion deformities. Methods and Results: The study was conducted in 171 adult patients (43 men and 128 women) with malocclusion and occlusion deformities at the age of 18 to 62 years old, who were examined in the orthopedic dentistry clinic. The nature of the dentition closing was studied directly in the patient's oral cavity, and with the help of the "Gnatomat" universal articulator on diagnostic plaster models of the jaws. The occlusal relationships of the teeth were analyzed in the position of the central, anterior, lateral and dynamic occlusions. The biomechanics of the lower jaw movements were studied in 3 mutually perpendicular directions. The detected anomalies and deformities of the occlusion were grouped as sagittal, transversal and vertical. Each group was diagnosed as independent forms of malocclusion, and combined with other anomalies and deformities of the dentoalveolar system. All the subjects were asked to answer the questions of a questionnaire specially developed for our study. The unified questionnaire was developed based on a modified rating questionnaire and the determination of the life disorders index in neck pain. The questionnaire includes blocks of questions aimed at identifying the localization of the headache in the temporal, parietal (in one or both) regions, occipital, frontal regions and in the longitudinal seam region. We identified complaints of patients with pain in adjacent regions of the head. Of the 171 examined adult patients with malocclusion and occlusion deformities, 99 (57.9%) complained of headaches. The presence of a headache in the parietal region of the head was associated most often with sagittal and transversal malocclusions. The presence of a headache in the temporal part of the head was associated often with vertical malocclusion The results of correlation analysis showed that pain in 2 regions of the head was associated with malocclusion: the temporal region (rb=0.9892, P=0.0013) and parietal region (rb=0.9712, P=0.0058). Other regions were not statistically significantly associated with malocclusion. Conclusion: There is a certain relationship between the types of malocclusion, occlusion deformities and localization of headaches in adults. Headaches in the parietal and temporal regions of the head are associated with malocclusion and occlusion deformities more often. The obtained data can serve as a basis for the development of recommendations for appropriate corrective measures in orthodontic practice.

INFLUENCE OF TECHNOLOGICAL PARAMETERS OF STEP FORMING ON STRESS-STRAIN STATE OF PIPE BILLET

The stress-strain state in a pipe billet of longitudinal seam pipes of large diameter made of X70 steel has been studied by the methods of finite element modeling under various technological parameters. The kinetics of the change in the deformation force and reactions of the supports during one step of molding have been determined.

An Improved Methodology for Prioritizing Pipelines With Respect to Fatigue Cracking of Seam Weld Flaws

The threat of pressure cycle induced fatigue cracking of flaws associated with the longitudinal seam weld continues to be a primary concern for pipeline operators. Cyclic pressure loading can cause initial manufacturing flaws in a seam weld to sharpen and grow over time. While this behavior is most prevalent in pre-1979 electric resistance welds (ERW) and electric flash welds (EFW), historical data also shows that submerged arc welds (SAW) have been observed to develop cracks at the toe of the weld, and those cracks have exhibited fatigue growth from transit fatigue, operating pressure cycles, or both. When managing a large pipeline network, it is important to understand which pipelines exhibit higher priority with respect to seam weld fatigue cracking. While there are industry-accepted methodologies used to prioritize pipelines with respect to seam weld integrity (TTO-5 [1] and API RP 1176 [2] being the most well-known), these methodologies can be improved upon when specifically considering fatigue. Saudi Aramco and Quest Integrity developed a detailed methodology to determine a prioritization for a group of pipelines specifically with respect to seam weld fatigue cracking. This improved methodology was specially tailored to consider additional data available in Saudi Aramco’s records to rank the likelihood for a fatigue failure to occur. This initial prioritization will be used to implement a more rigorous program to manage their assets. Additional data gathered in subsequent assessments can be included to refine the prioritization. The primary metrics used to determine the prioritization are pressure cycle aggressiveness, predicted remaining life with respect to recent hydrostatic testing, and the API 1176 Annex B prioritization classification.

Longitudinal Seam Welded Piping Assessment in Refinery Reformer Units

Creep is progressive deformation of material over an extended period when exposed to elevated temperature and stresses below the yield strength. Poor Creep ductility and cracking can be a problem above 900 °F (482°C) in the HAZ of low alloy (Cr-Mo) steel. High stress areas, including supports, hangers and fittings are more vulnerable to cracking. Creep cracking has occurred in longitudinal pipe welds with excessive peaking or welds with poor quality. Numerous incidents of cracking in low alloy (Cr-Mo) steel have been reported in the power industry and in refineries with major concern in longitudinal seam welds as well as highly stressed welds in reactors-heaters interconnecting piping. This paper presents the results of an assessment performed on reactors-heaters interconnecting piping in a catalytic reformer unit with a maximum operating temperature of about 950 °F (510 °C) at 250 psig (1.7 MPa) (> 40 years in-service). Comprehensive inspection including visual, dye penetrant testing, thickness measurements and peaking measurements have been performed. Phased Array Ultrasonic Testing (PAUT) was utilized to detect crack-like defects and flaws. Detailed pipe stress analysis and finite element analyses (FEA) were also performed.

Stress Intensity Factor Solutions for Crack-Like Anomalies in ERW Seam Welded Pipe

In response to the National Transportation Safety Board (NTSB) Recommendation P-09-1, the Department of Transportation (DOT) Pipeline and Hazardous Material Safety Administration (PHMSA) initiated a comprehensive study to identify actions that could be implemented by pipeline operators to significantly reduce longitudinal seam failures in electric resistance weld (ERW) pipe. As part of the project, Task 3 in Phase II was designed to determine more appropriate stress intensity factor solutions for non-standard, axial, crack-like anomalies in ERW seam-welded pipe. The purpose of this paper is to provide an overview of the normalized stress intensity factor solutions for cold weld (CW), selected seam-weld corrosion (SSWC), and hook crack type anomalies. ERW seams with and without weld caps are also included. The limitations on design space are discussed in the context of presenting results and interpolation and extrapolation schemes beyond that space with infinitely long solutions used as a boundary value. Results are presented in the form of surface plots for various combinations of parameters. The reports generated during the project are publicly available and are located on the following PHMSA website: http://primis.phmsa.dot.gov/matrix/PrjHome. rdm?prj=390.

Reelability and Wall Thickness Optimization of HFI Pipeline Against the Sensitivity of Variation in Mismatch Parameters

High frequency Induction welded (HFW/HFI) linepipe is produced by cold forming from steel strip, bent into pipe and longitudinal seam welded. HFW/HFI linepipe has been attractive due to less expensive, improved lead time and tighter wall thickness tolerances and better control of mechanical properties compared to the seamless. Typical design drivers for wall thickness optimization of reeled pipeline are geometric and strength mismatch. HFI pipes gained the attention of reeling contactors because of tighter mismatch tolerances of geometry and strength. However, the limitation of wall thickness in producing the larger diameter pipes needs optimized wall thickness considering the sensitivity of the variation in mismatch properties and stress ratio. The present work is intended to check the capacity of the pipeline against the sensitivity of variation in mismatch parameters. A case study has performed for the reelability of 16” HFW pipe for a selected limiting wall thickness. The different cases of variation in mismatch parameters are considered for the sensitivity check. Finite element (FE) analyses using ABAQUS tool were performed to reel the sections of the pipe joint over the reel hub of the selected installation vessel. The model predictions for axial compressive strain are compared and discussed against the DNV local buckling criterion for displacement control.