Ship and Submarine Design

The Drakkar was the Viking war ship, the Dromon that of the Byzantine world.  The Vikings and Byzantines collided, cooperated, fought for and against each other. 

Since the Dromon (and other galleys in the Med) was rowed standing up, perhaps a look at the Drakkar or other Viking style ship did also.

The Dromon went on as galleys up to the 1700's while the Drakkar got fat and short and became the head of long line of sailing ships.

In the Asia-Pacific region, submarine forces have continued to grow, though the greatest number are obsolescent diesel-attack submarines based on late-World War II designs posses by China and North Korea (DPRK). About 139 submarines remain in active service; 109 belong to China (PLAN). The range of submarines includes nuclear-powered and diesel-attack designs, the latter the main focus of Southeast Asian navies.

The aim of the research work was to investigate the position of sail and the
additional notch on tail of a mini submarine to reduce the force resistance. The tail
position parameter was modelled as the ratio of the submarine the total length of the
hull (L) to the sail distance (X), whereas the notch was represented by several notch
designs. Computational Fluid Dynamic (CFD) simulation routines were conducted to
examine the investigated two design parameters, i.e. sail position and notch
configuration. Once the optimal model of the sail position was obtained, the
additional notches model were tried. The simulation results show that the best position
of the sail is when the L/X ratio is 3 and the notch model is T1 (three go around
notches) in standard HT05 airfoil. The selected configurations provide the optimized
sail position and notch model for the designed mini submarine.

The need to build deterrence arises from the fear of being harmed by another nation state with superior capability. This may be harm by way of physical damage or coercion or blackmail to constrain one's ability to pursue foreign policy objectives. This fear forces a nation to acquire the capability to neutralise the threat by building a deterrent force. The Cold War introduced deterrence at the nuclear level, and for the next 50 years, the game of deterrence was aggressively followed with every move at improving nuclear strike capability by the opposite camp being perceived as a threat, and counter-capability being developed as a result. The resultant nuclear deterrence prevented large scale wars for fear of crossing the nuclear threshold.

The aim of the research work was to investigate the position of sail and the additional notch on tail of a mini submarine to reduce the force resistance. The tail position parameter was modelled as the ratio of the submarine the total length of the hull (L) to the sail distance (X), whereas the notch was represented by several notch designs. Computational Fluid Dynamic (CFD) simulation routines were conducted to examine the investigated two design parameters, i.e. sail position and notch configuration. Once the optimal model of the sail position was obtained, the additional notches model were tried. The simulation results show that the best position of the sail is when the L/X ratio is 3 and the notch model is T1 (three go around notches) in standard HT05 airfoil. The selected configurations provide the optimized sail position and notch model for the designed mini submarine. .

In this thrilling adventure tale by the father of science fiction, three men embark on an epic journey under the sea with the mysterious Captain Nemo aboard his submarine, the Nautilus. Over the course of their fantastical voyage, they encounter the lost city of Atlantis, the South Pole, and the corals of the Red Sea. Along the way, they must battle countless adversaries both human and monstrous. This triumphant work of the imagination shows the limitless possibilities of science and the dark depths of the human mind.

Present day ship design is faced with a difficulty to successfully integrate multiple design tools. This paper introduces ng.zine, a new design system intended for conceptual and preliminary ship design, aiming to make the design tool integration easy. ng.zine acts through the flexible XML database, storing and on-demand supplying current and previous values of significant ship parameters and attributes. It does so without a demand for changes in either designers working environment, or in the tools it integrates, leading to the increased flexibility of the design process. ng.zine permits a parallel execution of multiple design tasks. To assure efficient control and management, ng.zine applies concepts of group decision-making. Every designer is supported in choosing the proper parameter values with respect to the particular task responsibility and the global ship performance. Considered concepts allow designers to model in their experiences, knowledge and organizational hierarchy.

Trattare la storia navale comporta non solo parlare di scontri e di uomini, citare le navi e supponerne pregi e difetti, significa approfondire i perché e come delle componenti dello strumento navale …
Componenti che riguardano le navi e la loro affidabilità, aderenza ai requisiti, mantenimento delle capacità e prestazioni.
La maggior parte delle unità militari non è arrivata né arriva mai ad uno scontro, al combattimento, e per quelle poche che ci sono arrivate il combattimento rappresenta un’infima porzione della loro vita operativa.
È la vita operativa, la capability di una nave che va conosciuta e valutata.
Una volta si diceva che la vita media delle navi era di 25 anni, oggi è ampiamente superata, ma anche considerando i minimi di vita, quanto incide il momento dell’azione sull’ intera vita della nave e sul giudizio che si deve dare di essa?   
Anche una nave pessima può dare, casualmente, il meglio e portare dei risultati nell’ effimero dello scontro, ma questo non farà di essa una buona unità, né sarà ricordata dal suo equipaggio come “la nave”.
I navalisti sono più portati al “cosa è successo e come”, più che ai “perché” delle navi.
L’ evoluzione della costruzione, e ancora di più degli apparati motori è stata vertiginosa, con poche evoluzioni e cambi repentini, molto più sostanziali che gli stessi armamenti, eppure si continua a parlare solo di grossi calibri ...
Questo ha fatto si che già a pochi decenni di distanza si siano persi non solo le conoscenze, ma gli stessi rudimenti di tecnologie anche molto sofisticate nel loro momento.
Già è difficile capire la (più vicina e “semplice”) situazione degli apparati della 2^ GM, ed addirittura quelli dell’immediato dopoguerra, e pertanto parlare di apparati motori della 1^ GM è parlare di archeologia industriale, neppure navale.
Questa analisi non è né una rassegna né un catalogo dei motori impiegati, meno un compendio di termodinamica, ma è un tentativo di divulgazione di alcuni dei problemi che afflissero la Regia Marina e soprattutto vorrebbe essere lo spunto per ulteriori approfondimenti sui sistemi di propulsione adottati dalla Regia Marina e sulla tenuta dell’apparato industriale che avrebbe dovuto sostenerla.

Domenica 15 maggio 2022, ore 17.30 Parco di Villa Molaroni, Pesaro
Zrinka Podhraški Čizmek presenterà il volume Navigli adriatici fra le due sponde nel Settecento, Quaderno n. 24 della collana „Rerum maritimarum”
Apertura mostra "Tipologie navali dell’Adriatico nei secoli dell’età moderna" a cura di Maria Lucia De Nicolò, Luigi Divari, Zrinka Podhraški Čizmek
15.5.2022-28.8.2022


In questa edizione vengono presentati tutti i tipi ed elementi distintivi dei navigli menzionati nei primi tre volumi dei Regesti marittimi croati (RMC I-III) che comprendono circa 16.000 documenti riguardanti, tra l’altro, i velieri in uso nell’Adriatico durante il Settecento. Lo studio espone 18.536 menzioni di bastimenti classificati in 79 termini diversi messi a confronto rispetto l’etimologia e caratteristiche peculiari di ogni natante (quali stazza, attrezzatura velica, uso e quant’altro). L’analisi dimostra che i piccoli paroni preferivano velieri più piccoli, dalla portata fra le 20 e 300 t, essendo più veloci e manovrabili con buone capacità di navigazione. Si trattava innanzitutto del trabaccolo con il 14,55% di presenza nei documenti, poi della tartana (11,49%), del pielego (8,06%), della polacca (6,23%), della marciliana (6,18%), della feluca (5,10%), della barca (4,86%), della checcia (2,21%) e della brazzera (2,01%). I velieri minori, ovvero piccoli e medi, di portata inferiore alle 300 t, rappresentavano perfino il 70,82% di tutti i bastimenti nominati, mentre i velieri maggiori, di portata superiore alle 310 t, fra cui le grandi navi/nave ovvero vascelli (15,33%) ed i fregatoni (4,36%) avevano mantenuto il 20,65% del traffico marittimo, soprattutto verso le Isole Ionie ed altri porti mediterranei. Tramite l’analisi comparata delle loro caratteristiche e peculiarità è stato dimostrato che fra i porti delle coste orientali e occidentali dell’Adriatico nel Settecento vi era un intenso commercio quotidiano e che tale traffico era caratterizzato da un forte dinamismo del piccolo e medio ceto imprenditoriale che è riuscito ad imporsi sia nel commercio marittimo che nella costruzione navale che ha interessato ambo le coste adriatiche.


Predstavljanje knjige: Jadranski brodovi između dviju obala u osamnaestom stoljeću. Povijesno-ikonografski pregled

Ovaj povijesno-ikonografski pregled prikazuje sve vrste i glavne karakteristike brodova koji se spominju u prva tri sveska Hrvatskih pomorskih regesta. RMC I–III obuhvaćaju oko 16.000 dokumenata koji se, između ostaloga, odnose na jedrenjake koji su plovili Jadranom i Mediteranom u XVIII. stoljeću. Studija prikazuje 18.536 spomena plovila klasificiranih u 79 različitih naziva koji se uspoređuju s obzirom na njihovu etimologiju i razna obilježja poput nosivosti, jedrilja i namjene. Analiza pokazuje kako su vlasnici brodova radije koristili manje brodove (nosivosti do 300 tona), dobrih maritimnih svojstava, a čiji je brz utovar i istovar išao u prilog ubrzanu ritmu toga stoljeća. Brod koji se najčešće spominje jest trabakul sa svega 14,55% prisutnosti u dokumentima, zatim tartana (11,49%), pelig (8,06%), pulaka (6,23%), marsilijana (6,18%), filjuga (5,10%), barca (4,86%), keč (2,21%) i bracera (2,01%). Čak 70,82% sveukupno navedenih brodova odnosilo se na plovila srednje i manje nosivosti (do 300 t), dok se 20,65% sveukupnoga prometa, izvanjadranskog, mediteranskog (prema Jonskim otocima i dalje) te prema sjevernim morima, odnosio na brodove veće nosivosti (iznad 310 tona) među kojima su nave i vašeli (15,33%) te fregaduni (4,36%). Komparativnom analizom njihovih karakteristika i posebnosti pokazano je da je između luka istočne i zapadne obale Jadrana u osamnaestom stoljeću postojala intenzivna dnevna trgovina čija je glavna značajka bila nevjerojatna dinamičnost maloga i srednjeg poduzetništva koje se uspjelo etablirati kako u pomorskoj trgovini, tako i u brodogradnji, ostavivši golem utjecaj na obje jadranske obale.


Book launch: Adriatic ships between the two shores in the eighteenth century. A historical and iconographic review

This historical and iconographic review outlines all the types and main characteristics of the sailers mentioned in the first three volumes of the Croatian Maritime Regesta (RMC I-III). These three volumes include around 16,000 documents which, among other things, present the sailing ships used in the Adriatic during the eighteenth century. The analysis shows 18,536 mentions of ships classified under 79 different names (types), and compares them with respect to etymology and characteristics such as DWT, sailing equipment, purpose. The analysis demonstrates that small shipowners preferred lighter sailing ships with a DWT of up to 300 t, being faster and more maneuverable with good navigation skills. The dominant type of ship was trabaccolo, which accounts for 14.55% of mentions in the documents, followed by tartane (11.49%), pielego (8.06%), polacre (6.23%), marciliana (6.18%), felucca (5.10%), barca (4.86%), ketch (2.21%), and brazzera (2.01%). Small and medium ships with a DWT of up to 300 t account for 70.82% of all the mentioned sailers. Larger sailing ships, with a DWT over 310 t, including navas/vessels (15.33%) and frigatoons (4.36%), maintained 20.65% of maritime traffic, especially towards the Ionian Islands and other Mediterranean ports. The comparative analysis of their characteristics and peculiarities has indicated that intense daily trade was taking place between the ports of the Eastern and Western coasts of the Adriatic in the eighteenth century, and that this traffic was characterized by a strong dynamism of the small and middle entrepreneurial class which established themselves both in maritime trade and in shipbuilding, and thus left an enormous impact on both Adriatic coasts.

A vehicle operated remotely (ROV) is a submarine robot small, compact, streamlined and tightly designed for extreme depths size, equipped with measuring elements, sensors, cameras, robotic manipulators for scientific, military, exploration, search and rescue work dangerous or entertainment.
The following illustrates the design and development of an ROV, which is a basic and
functional prototype for underwater exploration with omnidirectional movements and at low depths. stages of development are exposed, being an applied and experimental research where knowledge is used in Electronics, Programming, Design Mechatronics and Fluid Mechanics principles related to the design of ROVs.
The results so far are gratifying, there have been analyzes and tests to different
communication systems, propulsion and immersion, has been established mechanical and electronic design. The goal is that once manufactured the prototype meets your preset parameters.

The Indian shipbuilding industry is passing through phase of advancements of IT solutions and infrastructure modernization. In the present Indian and global scenario indigenous shipbuilding requires to be globally competitive through significant capacity enhancement and to produce global quality standards at competitive prices. This necessitates a comprehensive study and debate over various means of achieving above goal. This paper brings out the requirement of modular construction as an essential step in that direction. Various requirements of construction facilities and different methods / options possible for undertaking modular construction have also been discussed and their respective merits vis-à-vis conventional methods have been highlighted.

It has been seen that a great deal of information about submarine performance, and stability and control, can be obtained from a study of the simplified linear equations, of motion despite the many assumptions that have to be made. In order to use these equations we must have available realistic numerical values for the coefficients of the equations, that is, the derivatives. It would obviously be desirable to be able to determine these derivatives in the early stages of the design so that the necessary predictions could be made to check that the design meets the various requirements laid down. At this early stage chances could easily be made to improve the design if it were found that the requirements were not being met.
A method is described below for calculating the derivatives of single-screw submarines.
It is assumed that the derivatives for the complete submarine can be found by adding the contributions of each of the components (hull, propeller, appendages) and including any interference effects between components.

The aspiration to improve submarine Power and Propulsion System (P&PS) performance without hazarding
the platform’s safety continues to challenge the designers of the world’s SSKs.
Technologies are reviewed in this paper which seek to improve performance in the context of the use of more
commercially-based type equipment. Recent technological developments and improvements have created the
potential to improve overall power and propulsion performance and therefore overall submarine capability.
To bring to maturity, prove and ultimately integrate such technology into a submarine design requires a firm
understanding of the actual technology in terms of the benefit it offers and its limitations, complemented by
knowledge of integrating such technology within the host submarine and its operations.
This paper will begin by defining the future challenge for SSK designers and then consider how this could be
translated into P&PS requirements. The technologies that may allow such a requirements set to be met and
the anticipated performance that may be achieved, are demonstrated in an indicative SSK 3,600 tonne design
from BMT Defence Services Limited, known as the Vidar-36.

For minimum resistance, the optimum slenderness (L/D) ratio for an underwater vehicle hull based on a near optimal 'teardrop' hull shape is generally considered to be around six. However, in practice the optimal hull shape is rarely achieved, with most modern underwater vehicles such as submarines and autonomous underwater vehicles (AUV) having parallel mid-body sections. Thus, the optimum L/D ratio is different from that established on the basis of a teardrop shape. This study involves the use of Reynolds-Averaged Navier-Stokes (RANS) Computational Fluid Dynamic (CFD) simulations to quantify the resistance characteristics of three submarine hull shapes with different L/D ratios. The results were used to identify the optimum L/D ratio for minimum resistance for each of the hull forms. The hull forms include the DST generic conventional Joubert submarine geometry, the DARPA standard SUBOFF hull form, and the Teardrop shape that is optimal in terms of hydrodynamic resistance. The CFD simulations were validated against published measurements from captive model experiments. The results presented provide a comparison of the resistance for the shapes and the optimum values of L/D for each different shape are given. The results are also used to establish an approximation technique which can be used to predict the resistance of a hull shape for different L/D ratios. The value of the approximation technique is at the concept stage of a submarine or underwater vehicle design, where it is necessary to have a prediction for the resistance prior to the commissioning of any model tests or CFD simulations, both of which are relatively expensive and time consuming.

The current trend of the United States naval fleet has shifted towards the electrification of next generation vessels. In the case of large actuation systems such as the control surface actuators on submarines, the retrofitting of legacy hydraulic systems with modern electromechanical systems requires keen understanding of all actuation subsystems. This thesis explores two methods of characterization of the actuation and energy storage demands. Each technique relies on the utility of adopting a model basis, and specifically uses a bond graph approach in combination with two-port immittance relations.

This thesis presents a multi-objective optimization model applied to concept design of conventional submarines (i.e. diesel-electric powered boats). A synthesis model that allows the estimation of weights, volume, speed, electrical load and other design features of interest is formulated. The synthesis model is integrated with a multi-objective optimization model based on genetic algorithms (specifically, the NSGA II algorithm). The multi-objective optimization consists of maximizing the submarine’s military effectiveness and minimizing its cost. The military effectiveness is represented by an Overall Measure of Effectiveness (OMOE) established via the Analytic Hierarchy Process (AHP). The submarine’s Basic Construction Cost (BCC) is estimated from its weight groups. At the end of the optimization process, a Pareto Front composed of non-dominated solutions is established. One of these solutions is selected for preliminary refinement and the results are discussed. This work also presents succinct discussion about submarine historical and operational aspects and design methodology. Some Naval Architectural concepts, applied to submarine design, are also discussed.

Keywords: Submarine design. Synthesis models. Multi-objective optimization.

Ao longo do corrente século, as Marinhas de Guerra do mundo viram a evoluçãoo do conceito 'navio capital' deslocar-se dos encouraçados para os navios-aeródromos e destes para os submarinos. Sem dúvida alguma, estas três classes de navios se constituem nos mais sofisticados e complexos produtos da Engenharia Naval.
A primazia do submarino, hoje uma tendência clara, sertamente estará plenamente consolidada no s´culo XXI. A Engenharia Naval deverá então estar preparada para satisfazer, sob os apectos tecnológicos, às demandas de desmepenho operacional destes navios para as próximas décadas, que serão extremamente exigentes.
O presente trabalho visa então apresentar e discutir estas demandas e identificar, através de uma análise de tendências, as soluções técnicas na área de projeto e construção que virão a satisfazê-las.

DISSERTAÇÃO DE MESTRADO
ESCOLA POLITÉCNICA DA USP
OUTUBRO DE 1991

Considers the common misperception that Jules Verne prophesied the modern nuclear attack submarine in 1869 in his novel Twenty Thousand Leagues Under the Sea and examines the actual technology of the Nautilus as envisioned by Verne and how rapid advances in propulsion and submersible hulls rapidly antiquated his creation.

This article presents a study regarding the applicability of genetic algorithms to conceptual submarine design. In this study, the design problem is treated as an optimization problem (single and bi-objective). Three figures of merit are analyzed: 1) Minimizing Drag (R av); 2) Maximizing Deck Area (A total) and 3) Minimizing the Structural Weight/ Displacement ratio (P/Δ). Low and medium fidelity analytical models were used for obtaining R av , A total and P/Δ. A mul-tiobjective optimization routine, based on an adaptation of the NSGA II algorithm, was used to determine a Pareto Front (objectives " 1 " and " 2 "). Subsequently, another optimization routine (objective " 3 "), also based on a genetic algorithm, was applied to the solutions of that Pareto Front. At the end of that process, a set of feasible solutions, in accordance with the constraints and adopted figures of merit, will be available for analysis and comparison.

This paper reports on a theoretical and an experimental investigation into 26 corrugated pressure vessels; which were tested to destruction. The theoretical investigations were carried using the commercial finite element computer program ANSYS, together with an in-house finite element computer program called Conebuck.

Abstract This paper presents CAFE, a new and innovative system for rapid generation of ship concepts. The enhanced and simplified man-model interaction utilizes arbitrary inclined guiding planes. These guides can add, reshape, move or split any entity in a 3D model. In addition, guides can be moved along with all attached plates, girders, stiffeners and brackets. Attached elements change their shape and number of stiffeners if necessary. Another important feature is the magnetic surface concept.

Dette er historien om polarflyveren Sir Hubert Wilkins, hans Forsøk på å nå Nordpolen med ubåt I 1931 og hans vitenskapelige alibi og anseknekt I kampen, Harald U. Sverdrup. Sverdrup var en dyktig oseanograf. Han skrev sin beretning fra ferden, "Hvorledes og hvorfor med Naulus", allerede samme år. Ideen var god. Erobring av Nordpolen, og hydrografisk og oseanografisk kartlegging av Polbassenget fra ubåt, under isdekket, fullstendig uavhengig av isdrift og skrugarder, I temperature over null, mens snøstormene hylte der oppe. Teknologien, en utrangert ubåt fra 1917, bød imidlertid på problemer. Det er også blitt spekulert I at ekspedisjonen ble utsatt for sabotasje. Sverdrups kartlegging og oseanografiske observasjoner, som han publiserte ved MIT I 1933, danner I dag grunnlag for oseanografi og klimastudier I disse områdene

English abstract:
This is the story of the Polar aviator Sir John Wilkins, and his attempt to reach the North Pole by submarine in 1931, and his companion, and scientific alibi, dr. Harald U. Sverdrup. He was a skilled oceanographer, who wrote the story "How and why with the NAUTILUS" the same year. The idea was good. Conquering of the North Pole, and hydrographic and oceanographic mapping of the unknown Polar Basin, under the ice, clear of the ice drift and pressure ridges, in temperature above freezing; while the snowstorms were howling on the surface. The technology, however, was lacking, a de-comissioned uboat from 1917. There were even rumors of sabotage... Sverdrup carried out his scientific program, and published the results at MIT in 1933. These form the basis for oceanographic and  climate studies in the region today.

Under Water Vehicles (UWVs) are extensively being used for variety of operations. Recently, there has been an increased interest in the design of autonomous unmanned underwater vehicles design (UUVs) as future generation submarines. The aim of this study is to investigate the effect of the various design parameters on the rotary coefficients of one such UWV i.e. a submarine SUBOFF model. The rotary coefficient has been calculated using the numerical simulations. The effect the wall roughness, linear velocity, rotation speed has been studied using the steady state Reynolds Averaged Navier-Stokes (RANS) simulations. The study helps to understand the underlying hydrodynamic phenomenon showing the dependence of these parameters on the hydrodynamics of the underwater vehicles.

A part of the reason that the US pulled out of Afghanistan was to focus on China. And we clearly see that with the Washington-Tokyo joint statement issued in April that included a direct reference to Taiwan and the recently unveiled AUKUS trilateral security partnership between Australia, US and UK whose first agenda would be to deliver nuclear submarines to Canberra.

Canavèis Primavera/estate 2017. Editrice Baima & Ronchetti. Castellamonte (Torino). Alice Superiore is a mountain village near Ivrea. Giacomo Cravetto was born here in 1895, during WW1 he was enlisted as a sailor in the royal submarine "Nereide". During a fight with the U5 submarine commanded by Georg Von Trapp, he died with all the crew of the "Nereide" in the Adriatic Sea. The paradox is that its founder became a star in Holliwood Star Sistem.

En la madrugada del 14 de diciembre de 1917 era alcanzado por un torpedo en su lado de babor el mercante británico S.S Coila. El submarino alemán U-64 se encontraba al acecho frente a la costa de Canet (València) cuando perpetró el ataque. Un ejemplo de como la Gran Guerra tuvo lugar en nuestras costas y de como se alteró el comercio de mercancías. Hoy, 100 años después de su hundimiento, el Coila forma parte del Patrimonio Cultural Subacuático de la Comunitat Valenciana. Esta es su historia.

This paper brings a discussion about the challenges involved in the development of a new kind of nuclear facility in Brazil, a naval base for nuclear submarines, with attention to the licensing process and considerations about the risk-informed decision making application to the licensing process. Initially, a model of such a naval base, called in this work, special industrial facility, is proposed, with its systems and respective sets of basic requirements, in order to make it possible the accomplishment of the special industrial facility support function to the nuclear submarine. A discussion about current challenges to overcome in this project is presented: the challenges due to the new characteristics of this type of nuclear facility; existence of several interfaces between the special industrial facilities systems and nuclear submarine systems in design activities; lack of specific regulation in Brazil to allow the licensing process of special industrial facilities by the nuclear safety authority; and comments about the lack of informations from reference nuclear facilities, as is the case with nuclear power reactors (for example, the German Grafenrheinfeld nuclear plant is the reference plant for the Brazilian Angra 2 nuclear plant). Finally, in view of these challenges, an analysis method of special industrial facility operational scenarios to assist the licensing process is proposed. Also, considerations about the application of risk-informed decision making to the special industrial facility activity and licensing process in Brazil are presented.

Initial design considerations of shipboard power distribution grids require a priori load dynamics assumptions for size assessment, power/energy requirements, and system stability considerations. For the analysis of dc micro-grids, power processing units and dynamic loads are often assumed destabilizing constant power loads for simplified stability studies. The constant power load is shown to be valid under certain load conditions, and other potential destabilizing load forms are introduced and discussed. As an example, a hydrodynamic load on a typical shipboard motor is shown to influence the stability characteristics of the power grid. Additionally, a model reduction analysis is proposed for early stage power system stability analysis.

Initial work in developing windows, face ports, lenses and other transparent structures using glassy polymers was often through empirical methods or conservative design tables.  Current minimum standards in ASME PVHO do not require ductility, the key characteristic driving material selection compared to brittle but stronger materials.  Performance-oriented minimums and updated design methods are needed.