Torispherical Head Thickness (ASME)
Calculate the minimum thickness of a torispherical (standard flanged-and-dished) pressure-vessel head, t = (0.885·P·L) ÷ (S·E − 0.1·P), from the internal pressure P (MPa), the spherical crown radius L (mm), the allowable stress S (MPa) and the joint efficiency E. The TORISPHERICAL head is the most COMMON and economical head type in medium-pressure vessels (and universal in shallow tanks): it combines a central spherical crown (radius L) with a toroidal knuckle transition at the edge, joining the cylindrical shell — a form easier and cheaper to stamp than the hemispherical, and more compact (lower height). The 0.885 factor and formula hold for the standard ASME geometry with L ≈ D (crown radius equal to diameter) and the knuckle radius of 6% of the diameter. The price of the economy is a GREATER thickness than the hemispherical (the toroidal transition concentrates stress) and a critical knuckle region, where high bending stresses can arise. The torispherical head is the practical 'middle ground' between the costly hemispherical and the flat (which needs enormous thicknesses). This formula is essential in designing vessels with this head type. Enter the pressure, crown radius, allowable stress and joint efficiency.
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Espessura de tampo toriesférico (ASME)
A espessura mínima de um tampo toriesférico (tipo flanged-and-dished padrão) de vaso de pressão é t = (0,885·P·L) ÷ (S·E − 0,1·P), a partir da pressão interna P, do raio da calota esférica (crown radius) L, da tensão admissível S e da eficiência da junta E. O tampo toriesférico é o tipo de cabeçote mais comum e econômico em vasos de média pressão: ele combina uma calota esférica central (de raio L) com uma transição toroidal (raio de concordância) na borda, ligando-se ao casco — uma forma mais fácil e barata de fabricar por estampagem que o hemisférico, e mais compacta. O fator 0,885 e a fórmula valem para a geometria padrão ASME com L ≈ D e o raio de concordância de 6% do diâmetro. O preço da economia é uma espessura maior que a do hemisférico (a transição toroidal concentra tensões) e uma região crítica na concordância, onde podem surgir tensões de flexão elevadas. O tampo toriesférico é o 'meio-termo' prático entre o caro hemisférico e o plano (que exige espessuras enormes). Esta fórmula é essencial no projeto de vasos com esse tipo de tampo. Informe a pressão, o raio da calota, a tensão admissível e a eficiência da junta.
Related Tools
Hemispherical Head Thickness (ASME)
Calculate the minimum thickness of a pressure-vessel hemispherical head by the ASME Section VIII formula, t = (P·r) ÷ (2·S·E − 0.2·P), from the internal pressure P (MPa), internal radius r (mm), allowable stress S (MPa) and joint efficiency E. Heads close the ends of a pressure vessel's cylindrical shell, and their shape is decisive for structural efficiency. The HEMISPHERICAL (half-sphere) head is the MOST EFFICIENT of all: since the sphere distributes pressure equally in all directions (uniform membrane stress), the hemispherical head needs only about HALF the thickness of the cylindrical shell of the same radius and pressure (compare the '2·S·E' in the denominator with the shell's 'S·E'). So it is the choice for high-pressure vessels. The drawbacks are costlier fabrication and greater height (more space). For moderate pressures and costs, elliptical (2:1) or torispherical heads, intermediate, are used. The head-type choice is a trade-off among thickness/material (cost), space and fabrication ease. This formula is fundamental in the complete vessel design, combining shell and heads. Enter the pressure, internal radius, allowable stress and joint efficiency.
Cylindrical Shell Thickness (ASME)
Calculate the minimum wall thickness of a pressure-vessel cylindrical shell by the ASME Section VIII Division 1 formula, t = (P·r) ÷ (S·E − 0.6·P), from the internal design pressure P (MPa), the internal radius r (mm), the material allowable stress S (MPa) and the welded-joint efficiency E (0-1). The pressure vessel — used in boilers, chemical reactors, heat exchangers, compressed-air and LPG tanks, autoclaves — is a CRITICAL safety component: a failure under pressure can be explosive and catastrophic. So its design is rigorously codified, the ASME BPVC (Boiler and Pressure Vessel Code) being the world's most used. This formula gives the minimum cylindrical-shell thickness to safely resist the circumferential (hoop) stress. The '−0.6·P' term refines the thin-wall formula for moderately thick walls. The joint efficiency E (0.70 to 1.0, per weld type and radiographic-inspection degree) penalizes strength at the welded region — fully radiographed welds have E=1.0, uninspected welds lower E. The corrosion allowance is added to the calculated thickness. This is the central pressure-vessel design calculation, and underestimating is inadmissible. Enter the design pressure, internal radius, allowable stress and joint efficiency.
Hydrostatic Test Pressure
Calculate the hydrostatic test pressure of a pressure vessel by the (simplified) ASME rule, P_test = 1.3 · MAWP, from the maximum allowable working pressure MAWP (MPa). Before entering service (and periodically, at revalidations), every pressure vessel undergoes a HYDROSTATIC TEST: it is filled with WATER (not gas!) and pressurized ABOVE the operating pressure, to verify structural integrity and tightness before entrusting it with a hazardous fluid. ASME VIII Div. 1 (rule UG-99) requires a test pressure of 1.3 times MAWP (corrected by the allowable-stress ratio at test and design temperatures, simplified here). Using WATER is a fundamental safety matter: water is practically incompressible, so it stores very little energy when pressurized — if the vessel ruptures during the test, the failure is localized and relatively safe (it leaks, not explodes); whereas a compressed gas stores enormous energy and a rupture would be EXPLOSIVE, possibly lethal. The 1.3×MAWP test subjects the vessel to higher-than-operating stresses, revealing defects (cracks, bad welds, insufficient thickness) with margin, without reaching general yielding. Passing the hydrostatic test is a condition for the vessel's certification and operation. Enter the MAWP.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.