ASME B31.3 End of Life Considerations: Corrosion, Mechanical Strength, and Small Bore Geometry

2010 ◽  
Author(s):  
Dennis K. Williams
Keyword(s):  
Mechanical Strength ◽  
End Of Life ◽  
Longitudinal Direction ◽  
Careful Examination ◽  
Tabular Form ◽  
Sectional Area ◽  
Cross Sectional ◽  
Section Modulus ◽  
Process Piping ◽  
Thin Walled

This paper discusses the prescribed requirements contained within the ASME B31.3 Process Piping Code that specifically address the considerations of the design corrosion allowance when coincidently taken into account with the mechanical strength requirements of the same. In particular, the most significant effects of the least favorable corrosion allowances in combination with the mechanical strength requirements of ASME B31.3 are prevalent in thin walled, small bore piping of minimal geometric properties associated with the calculation of component stresses in the longitudinal direction. Careful examination of ASME B31.3 paragraph 302.4 reveals that the minimum required thickness of a piping component include allowances for corrosion and when taken in conjunction with paragraph 302.4.1, which requires that when necessary, the wall thickness shall be increased to prevent overstress, damage, or collapse, due to superimposed loads from handling or other causes. The effects of the aforementioned Code requirements are addressed and examples are presented for small bore piping (nps 2″ and below) that lead to a proposed small bore piping criteria for consideration by piping specification engineers. Finally, the results of the evaluation of various combinations of corrosion allowance and mechanical strength requirements in terms of metal cross sectional area and section modulus are presented in tabular form that support the proposed small bore piping criteria.

scholarly journals Functional Morphology and Morphological Diversification of Hind Limb Cross-Sectional Traits in Mustelid Mammals

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
P Parsi-Pour ◽  
B M Kilbourne
Keyword(s):  
Hind Limb ◽  
Structural Strength ◽  
Aquatic Environments ◽  
Sectional Area ◽  
Cross Sectional ◽  
Phylogenetic Relatedness ◽  
Limb Bone ◽  
Limb Bones ◽  
Section Modulus ◽  
Second Moments

Synopsis Locomotor habits in mammals are strongly tied to limb bones’ lengths, diameters, and proportions. By comparison, fewer studies have examined how limb bone cross-sectional traits relate to locomotor habit. Here, we tested whether climbing, digging, and swimming locomotor habits reflect biomechanically meaningful differences in three cross-sectional traits rendered dimensionless— cross-sectional area (CSA), second moments of area (SMA), and section modulus (MOD)—using femora, tibiae, and fibulae of 28 species of mustelid. CSA and SMA represent resistance to axial compression and bending, respectively, whereas MOD represents structural strength. Given the need to counteract buoyancy in aquatic environments and soil’s high density, we predicted that natatorial and fossorial mustelids have higher values of cross-sectional traits. For all three traits, we found that natatorial mustelids have the highest values, followed by fossorial mustelids, with both of these groups significantly differing from scansorial mustelids. However, phylogenetic relatedness strongly influences diversity in cross-sectional morphology, as locomotor habit strongly correlates with phylogeny. Testing whether hind limb bone cross-sectional traits have evolved adaptively, we fit Ornstein–Uhlenbeck (OU) and Brownian motion (BM) models of trait diversification to cross-sectional traits. The cross-sectional traits of the femur, tibia, and fibula appear to have, respectively, diversified under a multi-rate BM model, a single rate BM model, and a multi-optima OU model. In light of recent studies on mustelid body size and elongation, our findings suggest that the mustelid body plan—and perhaps that of other mammals—is likely the sum of a suite of traits evolving under different models of trait diversification.

scholarly journals Pressure-driven flow in a thin pipe with rough boundary

2020 ◽  
Vol 71 (4) ◽  
Author(s):  
Elena Miroshnikova
Keyword(s):  
Fluid Flow ◽  
Longitudinal Direction ◽  
External Pressure ◽  
General Assumption ◽  
Rough Boundary ◽  
Local Behavior ◽  
Sectional Area ◽  
Cross Sectional ◽  
Incompressible Newtonian Fluid ◽  
Pressure Driven Flow

Abstract Stationary incompressible Newtonian fluid flow governed by external force and external pressure is considered in a thin rough pipe. The transversal size of the pipe is assumed to be of the order $$\varepsilon $$ ε , i.e., cross-sectional area is about $$\varepsilon ^{2}$$ ε 2 , and the wavelength in longitudinal direction is modeled by a small parameter $$\mu $$ μ . Under general assumption $$\varepsilon ,\mu \rightarrow 0$$ ε , μ → 0 , the Poiseuille law is obtained. Depending on $$\varepsilon ,\mu $$ ε , μ -relation ($$\varepsilon \ll \mu $$ ε ≪ μ , $$\varepsilon /\mu \sim \mathrm {constant}$$ ε / μ ∼ constant , $$\varepsilon \gg \mu $$ ε ≫ μ ), different cell problems describing the local behavior of the fluid are deduced and analyzed. Error estimates are presented.

The degradation of the cell walls of lucerne, Italian ryegrass and wheat straw when fed to cattle, sheep and rabbits

2001 ◽  
Vol 137 (3) ◽  
pp. 337-349 ◽  
Author(s):  
N. AHMAD ◽  
D. WILMAN
Keyword(s):  
Wheat Straw ◽  
Cell Walls ◽  
Cross Sectional Area ◽  
Italian Ryegrass ◽  
Sectional Area ◽  
Cross Sectional ◽  
Plant Parts ◽  
Thin Walled ◽  
Cattle And Sheep

Dried lucerne (Medicago sativa), dried Italian ryegrass (Lolium multiflorum) and wheat (Triticum aestivum) straw, in the latter case supplemented with soyabean meal, were each fed to cattle, sheep and rabbits in each of 2 years. In both years, plant parts of the three diets were tested for in vitro digestibility, in both milled and chopped (1 cm lengths) form, and for cell wall content (as NDF). In the first year, the plant parts were analysed for lignin and both the plant parts and the faeces were examined microscopically for the proportions of thick-walled, thin-walled and epidermal cells in cross-sectional area and for the thickness of the cell walls.The plant parts with the lowest proportion of thick-walled cells in cross-sectional area (0·05) were the lucerne leaflets and those with the highest proportion of thick-walled cells (0·68) were the stems of wheat straw. The cell walls of the thick-walled tissues were thinnest (0·7–0·8 μm) in Italian ryegrass leaf blades and sheaths. Within each cell type for the whole crop, the order of cell wall thickness was wheat straw > lucerne > Italian ryegrass. In vitro digestibility of DM was lower (by 0·031–0·085 g digestible DM/g total DM) in chopped than in milled stems of lucerne, ryegrass and wheat and in leaf sheaths of wheat. This suggests incomplete and/or delayed access of rumen microorganisms to some of the cell wall in chopped material in vitro and probably, therefore, also in chewed material in vivo. The concentrations of NDF and lignin in both ryegrass and wheat were in the order leaf blades < leaf sheaths < stems.The lucerne crops were more mature than the ryegrass crops and there was no consistent difference between lucerne and ryegrass in intake of DM or intake of NDF. The intake of wheat straw DM was 0·52 that of lucerne and ryegrass, whereas the intake of straw NDF was 0·89 that of lucerne or ryegrass NDF. Intake of both DM and NDF in relation to metabolic body weight was highest (87–93 g DM and 45–48 g NDF/kg W0·75) with cattle on lucerne and ryegrass and rabbits on ryegrass and lowest (33–34 g DM and 29–30 g NDF/kg W0·75) with sheep and rabbits on straw. The output of faeces/kg W0·75 was particularly high (38–41 g DM and 30–32 g NDF) from rabbits fed lucerne or ryegrass. Digestibility of DM was highest (0·726–0·732 g/g) with cattle and sheep fed ryegrass, followed by cattle and sheep fed lucerne and sheep fed straw. Digestibility of NDF was highest (0·708–0·752 g digestible NDF/g total NDF) with cattle and sheep fed ryegrass and sheep fed straw. Digestibility of NDF with rabbits was lower than with cattle or sheep, but was higher than might have been expected, in a small, hind-gut fermenter, with ryegrass (0·339 g/g) and straw (0·492 g/g).The proportion of thin-walled cells was much lower in the faeces than in the diets, but there was an appreciable proportion (0·10–0·27) of these cells in the cross-sectional area of faecal particles. The cell walls of all cell types were thinner in the faeces than in the diets, e.g. those of the thick-walled cells were thinner by 0·35 μm in lucerne, by 0·11 μm in Italian ryegrass and by 0·41 μm in wheat straw. The faeces from rabbits had higher proportions of thick-walled and epidermal plant cells in cross-sectional area, and a lower proportion of thin-walled cells, than the faeces from cattle and sheep.

scholarly journals Anatomical and morphological features of seedlings of some Cactoideae Eaton (Cactaceae Juss.) species

2016 ◽  
Vol 69 (4) ◽  
Author(s):  
Halyna Kalashnyk ◽  
Nataliia Nuzhyna ◽  
Maryna Gaidarzhy
Keyword(s):  
Calcium Oxalate ◽  
Vascular Tissue ◽  
Morphological Structure ◽  
Morphological Features ◽  
Vascular Bundles ◽  
Sectional Area ◽  
Cross Sectional ◽  
Arid Conditions ◽  
Pith Parenchyma ◽  
Thin Walled

<p>Three-month-old seedlings of 11 species of the subfamily Cactoideae (<em>Melocactus bahiensis</em>, <em>Melocactus curvispinus</em>, <em>Echinopsis eyriesii</em>, <em>E. mirablis</em>, <em>E. peruviana</em>, <em>Oreocereus celsianus</em>, <em>Rebutia flavistyla</em>, <em>Rebutia minuscula</em>, <em>Astrophytum myriostigma</em>, <em>Mamillaria columbiana</em>, and <em>M. prolifera</em>) have been studied. These plants exhibit a uniseriate epidermis, covered by a thin cuticle. Except for <em>E. peruviana</em> and <em>A. myriostigma</em>, no hypodermis could be detected. The shoots of all studied specimens consist mainly of cortex parenchyma with large thin-walled cells. The pith parenchyma is composed of much smaller cells. Due to the fact that the cortex parenchyma comprises the largest portion of the cross-sectional area, it can be concluded that it is the main water-storing tissue. The extent of vascular tissue development varies. Collateral vascular bundles are present in the stele. The studied seedlings contain various ergastic substances, in particular inclusions of calcium oxalate (all studied species), starch (<em>Mammillaria prolifera</em>, <em>E. mirabilis</em>, and the genus <em>Melocactus</em>), inulin-like inclusions, and occasionally lipid drops (some <em>Echinopsis</em> species).</p><p>Thus, it was found that all studied plants have a highly specialized anatomical and morphological structure. At the same time, the epidermis and hypodermis are poorly developed. Accordingly, the adaptation to arid conditions of the examined seedlings involves an increased growth of the water-storing tissue and the production of ergastic substances.</p>

Effect of Electroacupuncture Stimulation on Long-Term Recovery following Achilles Tendon Rupture in a Rat Model

2018 ◽  
Vol 36 (5) ◽  
pp. 327-332
Author(s):  
Miwa Imaeda ◽  
Tatsuya Hojo ◽  
Hiroshi Kitakoji ◽  
Kazuto Tanaka ◽  
Megumi Itoi ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Achilles Tendon ◽  
Tendon Rupture ◽  
Breaking Strength ◽  
Achilles Tendon Rupture ◽  
Cross Sectional Area ◽  
Control Group ◽  
Sectional Area ◽  
Cross Sectional

Aims In this study we examined the effect of electroacupuncture (EA) stimulation on the mechanical strength of the rat Achilles tendon after long-term recovery. Methods Using 20 rats, an Achilles tendon rupture model was created in an invasive manner. The rats were assigned to one of three groups, that received EA treatment (EA group), minimal acupuncture (MA group) or remained untreated (Control group). In the EA group, EA stimulation (5 ms, 50 Hz, 20 µA, 20 min) was applied to the rupture region over a period of 90 days (five times/week). In the MA group, needles were inserted into the same positions as in the EA group but no electrical current was applied. After 90 days the tendon was measured to calculate the cross-sectional area of the rupture region. Then, the mechanical strength of the tendon was measured by tensile testing. Results No significant differences were observed between the three groups in cross-sectional area of the injured tendon. For maximum breaking strength, the EA group showed a significantly higher threshold compared with the Control group (P<0.05) but not the MA group (P=0.24). No significant difference was seen between the MA group and the Control group (P=0.96). Conclusion Given the EA group showed a significant increase in maximum breaking strength, it is likely that EA stimulation increases the mechanical strength of a repaired tendon after long-term recovery, and EA stimulation could be useful for preventing re-rupture.

scholarly journals Evaluation of the Possibility of Performing Cold Backward Extrusion of Axisymmetrical Thinwalled Aluminum Die Stampings with Square Section / Ocena Możliwości Wyciskania Przeciwbieżnego Na Zimno Osiowosymetrycznych Wyprasek Z Cienką Ścianką O Przekroju Kwadratowym Z Aluminium

2015 ◽  
Vol 60 (4) ◽  
pp. 3043-3050 ◽  
Author(s):  
T. Miłek ◽  
B. Kowalik ◽  
B. Kuliński
Keyword(s):  
Mechanical Properties ◽  
Flow Curve ◽  
Computer Modelling ◽  
Cross Sectional Area ◽  
Experimental Investigations ◽  
Sectional Area ◽  
Cross Sectional ◽  
Industrial Practice ◽  
Backward Extrusion ◽  
Thin Walled

The paper presents evaluation of the possibility of performing cold backward extrusion of axisymmetrical thin-walled aluminum (Al 99.50, ENAW-1050A) die stampings with a square section at the strain ε=ln(A0/A1)=2 (where A0 - cross sectional area of the billet, A1 - cross sectional area of the die stamping), and the ratio h1/b=3.6 (where h1 - height of the die stamping in mm, b - width of the base of the die stamping in mm). The analysis was conducted on the basis of the results of computer modelling (FEM) and experimental investigations on backward extrusion. The boundary conditions for numerical calculations were determined experimentally with respect to the flow curve and mechanical properties of aluminum. The results of investigations into backward extrusion of thin-walled square-sectioned aluminum die stampings might be used as guidelines to develop a technological process for industrial practice.

Structural Strength Benefits Observed at the Hip of Premenarcheal Gymnasts Are Maintained Into Young Adulthood 10 Years After Retirement From the Sport

2017 ◽  
Vol 29 (4) ◽  
pp. 476-485 ◽  
Author(s):  
Marta C. Erlandson ◽  
Shonah B. Runalls ◽  
Stefan A. Jackowski ◽  
Robert A. Faulkner ◽  
Adam D.G. Baxter-Jones
Keyword(s):  
Structural Properties ◽  
Bone Structure ◽  
Femoral Shaft ◽  
Cross Sectional Area ◽  
Analysis Of Covariance ◽  
Sectional Area ◽  
Cross Sectional ◽  
Narrow Neck ◽  
Section Modulus ◽  
Buckling Ratio

Purpose: Premenarcheal female gymnasts have been consistently found to have greater bone mass and structural advantages. However, little is known about whether these structural advantages are maintained after the loading stimulus is removed. Therefore, the purpose of this study was to investigate the structural properties at the hip after long-term retirement from gymnastics. Methods: Structural properties were derived from dual-energy X-ray absorptiometry scans using the hip structural analysis program for the same 24 gymnasts and 21 nongymnasts both in adolescence (8–15 y) and adulthood (22–30 y). Structural measures were obtained at the narrow neck, intertrochanter, and femoral shaft and included cross-sectional area, section modulus, and buckling ratio. Multivariate analysis of covariance was used to assess differences between groups in bone measures while controlling for size, age, maturity, and physical activity. Results: Gymnasts were found to have structural advantages at the narrow neck in adolescence (16% greater cross-sectional area, 17% greater section modulus, and 25% lower buckling ratio) and 14 years later (13% greater cross-sectional area and 26% lower buckling ratio). Benefits were also found at the intertrochanter and femoral shaft sites in adolescence and adulthood. Conclusion: Ten years after retirement from gymnastics, former gymnasts’ maintained significantly better hip bone structure than females who did not participate in gymnastics during growth.

Compression tests on square, thin-walled steel tube/bamboo-plywood composite hollow columns

2016 ◽  
Vol 23 (5) ◽  
pp. 511-522
Author(s):  
Weifeng Zhao ◽  
Jing Zhou ◽  
Zhilin Long
Keyword(s):  
Bearing Capacity ◽  
Slenderness Ratio ◽  
Linear Regression Analysis ◽  
Compressive Load ◽  
Steel Tube ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Compression Tests ◽  
Cross Sectional ◽  
Thin Walled

AbstractThin-walled steel tube/bamboo-plywood composite hollow columns (SBCCs) have excellent physical and mechanical properties. The simple cross section of this composite makes it simple to process and suitable for industrial production. In this paper, axial and eccentric compression tests were conducted on 21 specimens to study the failure characteristics and maximum bearing capacity of this composite. The test results showed that compressive failure in an SBCC is primarily characterized by damage from glue failure at the matrix interface at the end of the column, internal damage of the bamboo-plywood material, damage from glue failure on the tension side in the middle of the column, and buckling damage to the plywood material on the compressive side. The overall adhesive strength between the matrixes primarily determined the failure mode. The maximum bearing capacity of the SBCC generally increased with the net cross-sectional area of the bamboo and decreased with the slenderness ratio and eccentricity. The hollow ratio reduced the slenderness ratio of the test specimens with the same net cross-sectional area of the bamboo and increased the critical compressive load, which significantly improved the compressive load capacity, as was reflected in the slenderness ratio. Finally, a model was formulated based on a non-linear regression analysis of the experimental data. The model was used to determine the allowable compressive capacity of an SBCC to provide guidance for engineering applications.

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