Thursday, September 22, 2016

FUSION JOINING without using any intermediate material

Post 144   by Gautam Shah 


Fusion joining without using an intermediate material, are used to join mainly metals and thermoplastics. Fusion joining is a common term used for many different types of welding processes. The welding processes rely on high temperatures that change the phase of materials to be joined aided by pressure (or impact). For phase change, the materials to be joined should have same softening-melting temperature and nearly similar composition.

Raincoat with fused joints > Flickr image by Mantelmann

Fusion joining as a category may include many other nearly similar processes, but which involve an intermediate to form the joint. There are three categories of such fusion joining systems, Soldering and Brazing, where the work pieces are not melted, yet joined using a meltable filler material, Welding the work pieces, and in some instances, the filler material, both are melted, and Chemical fusing or solvent welding (which are actually forms of adhesion fixing), where plastics are joined by solvents to dissolve (soften) the surface areas of the work pieces. The joint is created with or without application of pressure.

Brass vessel making 4 by Forging joining > Flickr image by McKay Savage  (HiH - Enterprises - MSE  )
The first fusion joining process was the forge welding. Blacksmiths used to beat the heated metals like brass, copper etc. for joining. For heating the work pieces, wood, charcoal and later mineral coals were used. Forging: Forging was an ancient process of hammering to shape materials like iron and other malleable metals, or by pressing (or rolling)in their plastic state (by application of heat).

Forged joints of Brass vessel at Madhurawada Visakhapatnam India > Wikipedia image by Asityamadhav83
 Forging has many modern versions. In these variants, the heat is created by electrical resistance, friction, laser beams, etc. Continuous pressure or intermittent impaction is done to fuse the heated components. Forge welding components are in sheet, or small section forms.

Forging created desired form, but also refined the grain size and arrangement, and thereby improve the structure of the metal. Forged metal is stronger and more ductile than cast metal, and exhibits greater resistance to fatigue and impact. Forging is also used to compact materials by removing gases and by packing the cavities.

Butt or spot welding is a widely employed technique for assembling sheet components of metals and plastics like car bodies, cabinets, furniture. It is a type of spot resistance welding. A high electric resistance-heat softens the material close to the melting level, and under pressure (of impact) the thin walls fuse and join. The joint developed has no apparent deformity, except a charred spot.
Wrought iron joints > Pixabay free images by avantrend

Seam or strip welding: Seam or strip welding is also a type of resistance welding method. It is used to join overlapping metal sheets of up to 3 mm thick. Instead of pointed (butt end) electrodes, and wheel-shaped electrodes roll along the work-piece, making a long continuous weld. Weld strength though is lower than other welding methods. The method is suitable for specific uses like formation of seamed pipes, and in terms integrity it is a fairly reliable process.
Blister packing -fusion joining > Wikipedia image by Alex Khimich
Seam or strip welding is also used for joining plastic sheet materials, like raincoats, wind-cheaters, shopping bags, containers, etc. In one process the sheet materials to be joined are pressed by a preheated straight wire, knife or a roller.

Induction welding is a form of resistance welding. Here the materials to be joined are heated by induction (non-touching or a distanced heat source). For this purpose a coil wrapped around a cylinder, causes opposite direction magnetic field in the materials, to melt-join together.

Butt fusion welding creates a joint between pipes gas and water pipe or other sections of doors, windows etc. The ends are pressed against a heated plate, and brought together to form a ‘beaded joint’.

Fusion joining requires a heat source, such as a gas flame, an electric arc, a laser, an electron beam, friction, or ultrasound. Fusion joining sometimes requires a slight to very heavy pressure. Forging is a very noisy process. Fusion joining is done under many different environmental conditions like open air, rain, frost, underwater in vacuum or space and sometimes under the shield of inert gases like Nitrogen, Argon, Helium, Carbon dioxide, etc. Fusion joining in spite of all care is essentially a hazardous procedure. It involves risks of high electric currents, high temperatures, sparks, fumes, and radiation.

Felt Cloth non woven assembly of fibres > Wikipedia image by en:User:Sannse from english WP

There are several other joining systems that use pressure, but not the heat (high enough for softening or melting). Here the (often purposely disarrayed fibres) two surfaces are pressed or rolled together to form a joint. These techniques are used for joining fibrous surfaces like papers, leathers, woven and non-woven fabrics, etc.

Monday, August 29, 2016


Post 143   by Gautam Shah

Making a pot with coil technique > Wikipedia image by Poupou l'quourouce
Clays are fine albuminous products formed by decomposition of igneous rocks. Clays are tenacious and plastic when wet. Clays are highly cohesive, have high capillaries and no internal friction. Clays are smooth to touch, sticky and plastic. Clays can also be classified according to their plasticity, or silt content. Hard clays or stiff clays have low sand content, and are difficult to excavate. Fine clays have medium sand content, and can be excavated with slight effort. Soft clays have coarse texture and are easy to excavate. Pure clays are mostly useless because of the high plasticity and excessive shrinkage on drying. Clays, if very plastic, are called fat clays, whereas less plastic clays are called lean clays.
Top layer or organic soils have substantial amounts of organic matters, from the decomposition of vegetation and human, animals excrete. The presence of organic matters makes a soil light in weight and dark in colour. Organic soils usually show high workability and low shrinkage characteristics. When organic soils are found below an existing layer and are old, contain gallic acid and tannin in small proportions, but sufficient to act as fungicide and mild insecticide.
Incised ceramics in Mexico > Flickr image by Giulian Frisoni

Virgin or non organic soils have negligible amounts of organic matters, and so reflect the basic characteristic of the predominant constituent element present, i.e., lime, silica, or alumina. However, soils do take-on the personality of the other minerals present in it. Non organic soils unless constituted by colloidal particles show very little plasticity. Some mineral constituents of such soils are reactive to water resulting in swelling and leaching. Kaolin or China-clay, is pure mineral clay that is used for making Porcelain. Ball clay is added to other mineral clays for plasticity. Fire clay is used for high heat resistance items, such as for kiln lining bricks.

Clay Deposits Estonia Wikipedia image

Clays are black, white, red, brown and yellow in colour. China Clay is a residual material, contaminated with silica, mica, feldspar and decomposed feldspar. Ball clay is a sedimentary material of fine grain size and some organic contents. It is finer than china clay. Fire clays are formed from feldspar as residual and sedimentary deposit. Brick clays are high in iron content, and impurities of calcium compounds and organic matter.

Unglazed pottery in India > Wikipedia image by McKay Savage from London UK

Clay products forming process is determined by the clay ingredients and the shape or form and size of the object. It is Semi dry or semi plastic process, Wet or plastic process and Liquid processes. Semi plastic processes are adopted where water supply is scarce, and the condition of soil is very plastic, where high density mass by pressing is possible. This is used for forming building blocks. In case of plastic soils, the addition of water causes swelling of the mass and an increase in cracking during drying, so some additives are required. It also needs high degree of compaction, mainly achieved on potters’ wheel and with thin body forms. The item has to be so designed that all parts even cross section thickness, and changeover from one thickness to another, if any, is very gradual. Plastic processes allow sufficient time to a craftsperson to mould and finish an article. Liquid processes are used where through mixing of ingredients is carried out in presence of water. 
Recuay Peru Effigy jar 100-300 BC > Wikipedia image by Helvetiker

Historically, unglazed pottery has been more common than glazed pottery. Unglazed pottery can be produced from wide variety of clays, and is comparatively easy to produce. Unglazed potteries are commonly identified as ‘earthenware and terracottas’. Unglazed potteries were first used for pots and vessels for storage and cooking, and materials’ processing. Later the uses included architectural elements like building blocks, drains and tiles for floors and roofs. Later ages saw development of three basic classes of ceramics. Very thin body or walled pottery produced on wheels, from comparatively good plastic soils, and controlled firing techniques. These were sometimes incised with decorations, or coloured with iron oxide pigments. The next class consisted of non-wheel based formations such as the coil method, used for creating larger storage utilities for grains and water. These were polished with clay slips and appended with clay decorative motifs. The third class consisted of figurines, toys, sculptures, of solid and hollow type, through press-cast and poured in the mould formations.

Brick Production Tanzania > Wikipedia image by Egbert in donker Afrika

Clay-based potteries are also called Terracottas due to the reddish colour, imparted by Iron oxide as ferric and ferrous. Other important colourants are quartz, kaolin, mica etc. Soils show a wide range of colours from off-white to yellow, light brown and chocolate to radish tones.

Terracotta work on Shyamrai Temple Bishnupur India > Wikipedia image by Amartyabag

Clay products are baked at different temperatures depending on the constituent clays, form, shape, size, mass, and the use of the product. Earthenwares are comparatively low temperature (approx. 1000°-1200° C), Stonewares are mid temperature range (1100°-1,300°C), whereas Porcelains are fired in the range of about 1200°-1400°C. An oxidizing atmosphere inside the kiln, allows air and affects the surface and appearance of the products. Whereas by limiting the oxygen in the kiln, some glazes change the colour.

Roman Amphora 520-510 BC Wikipedia image
A ceramic can be decorated before or after firing. Glazing is one such process to make a ceramic product more opaque or less permeable. Glazing process may add colour and lustre. Sewer pipes etc. produced from low-cost materials are salt-glazed during the firing to provide impermeability. Other products are glazed in raw (green) form or after first stage of firing. Building blocks are left unglazed, as porosity increases cement bonding.

Terracotta Etruscan Sarcophagus of the spouses > Wikipedia image by nl:Gebruiker:GerardM
Glaze is a combination of materials, consisting of glass-forming minerals (silica or boron) combined with ‘stiffeners or bodying materials’ (such as clay and fluxes) and melting agents (such as lead or soda). In raw form, glaze can be applied to the unfired pot, or after an initial, or biscuit (or unglazed) firing. Many kinds of glazes are used. Some heighten the colour of the body, and others mask it. Basically, there are four principal kinds of glazes: feldspathic, lead, tin, and salt. Feldspathic, lead, and salt glazes are transparent, tin glaze is an opaque white. Hard porcelain takes a feldspathic glaze, Soft porcelain usually takes lead glaze. There are many other modern glazes that do not fall into any of these categories.

Glazed Celadons Pottery Longquan Zhejiang China 13 C > Wikipedia image by Vassil
Slip (liquefied clay strained of coarse particles) may be used for imparting specific surface finish. Slips are applied to completely dry, or half-dry items by coating or dipping them into the slip of creamy consistency (to which colourant is sometimes added). Slips can be brushed, sprayed, or trailed on with a spouted can or a syringe. Designs can be drawn or incised with a pointed tool into the slip to reveal the body, a technique known as sgraffito.

Dish with Cyprus decorations Iznik, Turkey 1570 > Wikipedia image by deror avi 2011-02-19 07:58:48
Alkaline glazes, popular in the Middle East, are shiny and frequently transparent. They are composed mostly of silica (such as sand) and a form of soda (such as nitre). Lead glazes are transparent, with traditional types made of sand fused with sulphide or lead oxide. They were used on earthenware by Roman, Chinese, and medieval European potters and are still employed on European earthenware. Tin glazes are opaque and white. Metal oxides give colour to glazes. Copper makes a lead glaze green and an alkaline glaze turquoise. Iron produces yellow, brown, grey-green, blue, and with certain minerals, red. Feldspars (natural rocks of alumino-silicates) are used in stoneware and porcelain glazes because they fuse only at high temperatures. Glazes or their firings, if defective show pinholes, bubbles, crazing and peeling. Metal coating, enamelling, minakari, etc. are ceramic like coatings or depositions of metallic and non metallic compounds. Vitreous enamel coatings are glassy but non crystalline coatings are matt.


Tuesday, May 31, 2016


Post 142   by Gautam Shah

Corridors are formal transfer zones in buildings, but sometimes passages get formed with intense movement conditions between two points. Corridors are architecturally articulated built forms, whereas passages are marked or delimited sections. Corridors and passages are distinguished by barricades, flooring differences, sensorial markings, graphics and signages.

Meenakshi temple Corridor Madurai India Flickr image by Jean-Pierre Dalbyra
 A corridor as a built form is highly a formal entity and it is difficult to breach the discipline, but passages have no formal structure, and can be overstepped. A corridor is a passage, but a passage needs to be well modulated to become a corridor. A corridor without the traffic, will still remains a corridor, but a passage without movement just merges in the surrounding space. Corridors are more formal then passages, but passages allow greater public participation, and so ceremonial.
Corbet's Couloir -a ski run or passage Wikipedia image by Enricokamasa

Alleys, arteries, aisles, channels, lanes, couloirs (narrow passageway on a hill), tunnels, paths, lobbies, vestibules, avenues, all have one common element: a linear passageway. A labyrinth and maze, are entwined passageways, where the former one ‘has a single path -unicursal, reaching the centre; and the later is a complex branching -multicursal puzzle, with choices of a path and directions’.

Labyrinth Chartres Cathedral Wikipedia image by Maksim
Corridors and Passages, as transfer systems in buildings are well defined and functionally supported by other systems. Such transfer systems become ineffective, if design definitions are improper, have inaccurate capacities, or lose the validity due to the changed circumstances. When a transfer system becomes ineffectual, many other systems in the building become useless.

Books in Corridor Pixabay image by Unsplash

Corridors, are defined or recognized as passageways, connecting a point to point location, or several ones on the way. Corridors are defined by architectural features, distinctive materials and environment, sensorial recognition of their existence, signage, and preference for the shortest and easiest access route.

Corridors originate at points of transfer such as doors, other branch corridors, stairs, elevators etc. Corridors also occur where conditions for superior and efficient transfers are available, such as: shaded or protected areas, finer floorings, smoother gradient, pleasant surroundings, promise of fulfillment, expectancy, escape from hazards.

Passage Junctions Pixabay image by ujeans

Straight corridors provide a very efficient mode of transfer, but tend to be monotonous. Straight corridors allow continuous acceleration, which may pose problems to other transferees. Corridors with zigzag or variable movement directions heighten the expectancy. Circular or curved corridors tend to align the movement concentrically. Bidirectional movement corridors increase the social interactions among the users. Multi directional and multi velocity movements destroy the character of a corridor.
Main hall Brussels railway station > Wikipedia image by Saber68

Corridors are heavy movement areas, compared to many other spaces used for casual transit. Corridors, due to heavy traffic create environmental interference of noise, vibration, dust and spread pollutants and infections. Corridors enhance the fire hazards and security risks; however, if properly designed, may curtail such risks. A straight corridor can be policed from one point, but so an intruder (terrorist) also can command the entire corridor.

In complex buildings variety of work spaces, each with specific environment and controls are required; corridors as buffer zones isolate such spaces. Corridors create an intermediate or equitable zone of transfer for all such connected units. Corridors provide a strong cohesive identity among apparently very unrelated cells.

Main committee corridor Westminster London > Wikipedia+Flickr image by Mark Kobayashi-Hillary

 Corridors are ideal, if without any encumbrances, like cross passages, doors, and architectural transgressions (projecting out or receding in). But very long corridors, such as at Airports and underground metro services, without intervening interests become boring. Corridors are common utilities, so have several services attached to them, such as, toilets, drinking water fountains, fire fighting systems, emergency exits, air handling units for air-conditioning systems, seats, electrical mains, bulletin boards, exhibitions, first aids, security checkup systems, food and beverage dispensing systems and signs. A Tirupati temple (India) corridors are also used by devotees as a place to sleep, rest, eat, bathe and pray during the long wait for the Darshan.
Parikrama around Girnar Mountain Gujarat India > Wikipedia image by Nileshbandhiya
The word Corridor derives from Italian Corridore =place or space to run, which in turn has derived from correre or Latin currere='to run'. By association courier, meant a man or horse who could run to deliver messages, money or documents. Italian word corridoio is a place, or rather space for the courier (man or horse) to run.

Ponte Vecchio and Vasari Corridor from Galleria degli Uffizi > Wikipedia image by JasonF007

From later part of 16th C. Corridors were strategic spaces or routes of access in fortifications. Couriers and corridors were used for quicker deliveries by the military. It had military ramifications for defence or offense, but very little civilian relate. The space for a faster messaging, the corridoio was not a marked territory or a facilitated ground within a fortification or dense urban setting. It was simply a familiar-well travelled precinct. In late 16th C it denoted a military term for a narrow strip of land along the edge of a ditch or fort-wall sometimes protected by a parapet. It was also a narrow passageway along the slope of a hill and sea. Trails are marked passageways but in the wilderness. Trails are so narrow that most vulnerable or unafraid ones lead the way, and others must trail.
Secret passage between Vatican and Castel SaintAngelo Rome Italy Wikipedia image by Patnaik+ Alessio Damato

Thursday, May 26, 2016


Post 141   by Gautam Shah

Interior Design as a profession is changing at a very fast pace. Today many different forms of interior design practices exist, ranging from

Pure design (only),

Design + Supply,

Design + Supply + Execute (install-fabricate-operate).

Frank Lloyd Wright Pope-Leighey House > Wikipedia image by Cliff from Arlington Virginia USA

These classifications arise due to ethical reasons (professional bodies, governmental regulations, etc.), taxation, traditions and business convenience. There was a time when Interior designer or decorator worked on a site or few sites, within the travelable region. In very large, complex and remotely located projects, however, it was not feasible, for the designer or their representative to be present all the time on a site, and conduct the projects. Interior Designers, as a result, gradually began to limit their work to design matters only, and let other agencies handle the supply and execution. The practice of employing or appointing ‘third party venders or contractors’ serves varying degree of efficiency, reliability and satisfaction, for corporate or government types of organized clients.
Print 1833 of Dome of Rock Jerusalem > Wikipedia image by Georg Dehio/ Gustav von Bezold

In recent years large number of holistic Interior Items and systems have become available. These vendors (such as of modular kitchens, Toilets, Ceiling, Acoustics+Ceiling, Painting and other surfacing, Glazing, etc.) offer complete installation services. So Amateurs and Lay-users prefer services of such supply-install venders.

Vendor-Supply Interior Design Practice through use of Catalogues (by James Shoolbred & Co. 1876) Wikipedia image
 On the other hand, small practice designers found it more convenient to mange execution along with design. Designer self executing their own design often worked, without premeditated scheme. Designers, who lacked the capacity to detail out or document a project, preferred this route. These small time designers or amateurs have a capacity of creating design images (representations like Isometric, perspectives, 3D images, etc.) which are used as presentations for enticing a client. These amateurs rely on known craftspeople who can execute the design from such images and workout the lacking details.
Diagram of three corbel brackets at Chinese Hall by Official and architect Li Jie 1103 Wikipedia image by PericlesofAthens

There was a time when a Designer had to specify raw materials and the process of assembly or manufacturing to generate a product or a functional system. To check the suitability of the delivered product, and operative validity of the system, a series of tests and check parameters are also required. Very often these parameters remain worthless, because neither, the required level of manpower and testing equipments are available at a site, nor is it feasible to take the product or system from site to such locations.
Jasper Morrison Furniture in the Musee des Arts Decoratifs > Wikipedia image by Gael Chardon from Paris France
 Design needs are now documented in terms of ‘performance specifications’ or optimum operative functionality to be attained by the vendor or contractor, with their choice technological input (materials or manufacturing). This type of modern design documentation requires high level of skill input, technological knowledge-ability and professionalism. Amateur or untrained (hobbyists) interior designers do not have such proficiencies.
Documented design by Robert de Cotte 1700s

The separation of design and execution, is also favourable arrangement from point of view of Taxation. Pure Design practice is liable for simple taxation like Service Tax. In Design + Supply practice, a designer may be liable to pay other taxes (Sales Tax, etc.). Design + Build practice, is though an accepted norm in many countries of the world.

McElroy Octagon House on Gough st San Fransisco Cal 1891 Credit Library of Congress Prints & Photographs Division WIS,28-WATO,1-

 Interior Design like any other Design profession, is a dependent profession. Interior designers work in conjunction with other design professionals, needing interior design inputs in their projects, such as Architects, Building engineers, Landscape designers, Furniture and Product designers, Exhibition and Event managers. Interior designers also use expertise of other professionals for their work. These include environmental engineers, ecologists, furnishing experts, textile designers, painters, sculptors, and an array of crafts persons.

Pixabay Free image by stokpic
 Some degree of specialization is becoming apparent in Interior Design. Some of the major fields to have distinct identities within the ambit of Interior Design are: Hospitality or hotel design, Entertainment facilities, Public space design (air ports, railway stations), Exterior design or Street architecture, Exhibitions and events planning, Retail designing, Transport interior design. These fields naturally demand a varied manner of design approach and handling.

Sunday, April 10, 2016


Post 140   by Gautam Shah


Projects or their near independent systems, when nearly ready, begin to function or need to be operated early. Systems, for example, such as the load-bearing entities become operative as soon as installed or the supports are removed. Similarly systems like stairs and elevators or water supply etc. are made operative for use by construction personnel. Some systems need to be run-tested for certification, safety and other guarantees and warrantees to be effective

Towering inferno, a movie of 1974 showed how important are the Operations Manual and Specifications for fighting fires
 A system that is operative also becomes due for regular maintenance, servicing, repair, safety and security observance, and comes under the scope risk-management (such as insurance, fire, etc.). Operations’ Specifications relate to terms and conditions of operating and maintaining various systems of the project. For small, simple and projects of routine nature there may not be any acute need to create a set of such documents. Complex projects, however, require professional operators who may need not be the original contractor or vendors. These third party operators need a formal assignment of their work and responsibilities. The assignments delineating these are the operations manuals. Operations manuals are not just handed to assigned or contracted operators, but placed in an accessible location for emergency reference.

Escalator maintenance Operation > Wikipedia image by Dailongumuneka
Projects of routine and simple nature are distinctly delivered - handed over to the client or user, according to a defined process and schedule. The client or user, thereafter on their own, or through other agencies, manage and operate the system.

In case of complex projects, however, consist of several subsystems which begin to be operative as soon as these are installed. Contractors and vendors use such subsystems during the execution of the project (such as stairs, drainage & water supply system etc.), and sometimes manage them till the project is delivered. In cases like, turnkey projects, some of the subsystems must be operated for trial and verification.

Nose section of Boeing 747 tested with pressure tanks > Wikipedia image by Oliver Cleynen
Operations specification for traditional material specifications+ processes of construction or assembly are different from projects “delivered” through Performance Specifications. Projects conceived through Performance Specifications invariably have many built in provisions for care of the main and subsystems during their emergent phase. For routine projects, in many organizations, the job of operations and maintenance is handled through departmental facilities or out sourced to specialized agencies. In both cases, yet a strategy is required for dealing with probable conditions and also for less-predictable situations (disasters, crisis). Designers of the system may provide such a strategy, or specialist agencies are required to prepare the operational specifications.

Mech+Elec+Plumbing MEP area > Wikipedia image by Eric T Gunther 
Forms of Operations Specifications

Operations specifications become key instructions during crisis. The agency that evolves the operational specifications, such as Owner, Designer, or Operator of the systems, each may adopt a varied strategy, often lacking coordination to deal with the situation. Professionals are now available, who can independently assess a building system, and prepare a set of operations specifications.
During emergency there is little time for understanding a layout > Wikipedia image by Cpl Trent A. Randolph

Operations specifications are often more graphical then written to make its access non technical, and free of language barriers. Many specifications are in the form of signage, instructions or warning signals. These specifications may not occur as a single comprehensive document but distributed across the estate. Repairs and maintenance work, need to be scheduled with other plans of actions. Operations specifications also include methods of observance, supervision and feedback systems.
Complex entities require equally meticulous schemes for operations > Wikipedia image by Reinraum

Conditions for Creating and Providing the Operations Specifications

1          System Designer, System Provider (contractor, fabricator, vendor), and the System Operator, each of the roles should be clearly defined.

2          A System Provider must distinctly (formally) handover (deliver) the System (whole or self-sufficient parts of it) to the Client or appointed System Operators, as provided in the contract.

3     A System Designer and System Provider, together evolve the Operations Specifications. Only one of them is made responsible for Formal Transfer of the Operations Specifications' Documents to the operative agency.

4          System Designer (or the client) must see those necessary guarantees as available from Vendors and Sub contractors, and as provided by the main System Contractor, are transmitted to the Client. Alternatively a third party agency is appointed to create them afresh, and also affect such a transmission of guarantees.

Wednesday, April 6, 2016


Post 139   by Gautam Shah

We need to move, along, away or towards the gravity. These modalities form transfer systems. The transfer systems along the gravity include paths, corridors, passages, etc. Transfer systems away or towards the gravity are perpendicular or inclined, and include firemen sliding poles, garbage chutes, emergency evacuation tubes, steps, stairs, ladders, slides, escalators, ramps and elevators. Some can be of both categories, like automated walkways, cable hung cars, roller coasters, conveyers, etc.
Climbing up the rock face at Angel's landing (Zion National Park) > Wikipedia image by Alex Proimos from Sydney Australia

All movements are essentially directional but transfer systems occur in unison, for two way movements. The other segment, however, manifests in some other situation, occasion, location or format. An escalator as an unidirectional system is more efficient than a mixed movement system like a stair. The gravity accelerates the down-movement, and inclination retards the rate of passage.

Jain Pilgrims on Shatrunjaya hill, Palitana Gujarat India > Flickr image by Arian Zwegers
Regularized transfer systems are uninterrupted services, and have width or passage way as the restrictor. Other restraining factors include speed of movement (goods or people, etc.), acceleration-de-acceleration, intermediate entry-exit openings, and safety. Carriage transports such as elevators are discontinuous services, and restrained by the frequency of service and capacity of the module.
Stairs and Escalators at Cabot Circus Shopping Centre, Bristol England > Wikipedia image by Arpingstone

Stairs and Escalators are stepped and inclined, transfer systems. Both provide uninterrupted transfer services. Use of stairs requires some orthopaedic proficiency and cautious posturing, but automated escalators allow freedom to see around during the passage. Stairs can take mixed traffic of accent and descent, but escalators require different sets. Reverse escalator services are often not provided as stairs are not very strenuous to climb down.
142 Mts long Potemkin stairs Odessa (1834-41) made famous by movie The battle of Potemkin 1925 > Wikipedia image by Dezidor

Film shot of The Battle of Potemkin on Odessa steps
Stairs and escalators are point to point passageways, as there is no midway interference, except at landings. Mountain side steps when comparatively wide show midway disturbance when people climb up diagonally to increase the negotiated distance and thereby reduce the steepness. Escalators are designed to be intermittent systems reaching floor to floor. Escalators transiting multiple floors are not perceived to be safe. Similarly multi floor escalators combined with landing level automated walkways are not favoured.
Streets of Cusco Peru > Road Ramp and matching step gradient > Wikipedia image by Rod Waddington from Kergunyah Australia

Steps and Stairs generally have a pitch higher than ramps. Stairs are safer than ramps provided the person is fully mobile and orthopaedically fit, but ascent or descent over stairs, more strenuous than the ramps. A ramp can have gradually variable pitch, but a stair has to have a one continuous grade of pitch.
Grand Staircase of RMS Olympic > Wikipedia image
The inclination of steps is defined by the relationship of tread versus the riser of the steps. This relationship varies for steps and stairs used for different purposes, ranging from steep ladders to flatter ramps like foot-ways. The dimensions of tread and riser are proportional and can be plotted on a hyperbola. Certain formulas also provide such proportions: 2T + R = 650 to 680 mm or R x T = 43000 to 45000. For steeper pitch the additional effort required to work against the gravity reduces the efficiency.
Steps with alternating treads over steel rock slope of Pinnacles National Park California USA > Wikipedia image by Wing-Chi Poon
Stairs have a pitch of not less than 17.30° (5:16), and of not more than of 48.30° (9:8). Below these limits it becomes a ramp or foot-ways, and above it a ladder. A ladder is not a comfortable utility. Step-ladders are lower in pitch, less than 75° and require flat treads. Risers may be open or closed, for toe accommodation and handrails may or may not be provided. In the ladders’ class of stairs, some are easier to climb than others. Ladders are used for fire escapes, boiler rooms, fly galleries, attics, decks, etc. Rung ladders are pitched more steeply, above 75°, and have extremely narrow treads or round rungs to accommodate the foot. In certain cases, the space to accommodate the knee between steps may be necessary. Rung ladders usually do not require additional handrails as the side members of the ladder can be used for holding grips. Rung ladders are often caged for safety, though such cages are more useful for ascent then for descent. It is safer to climb down facing the ladder. Swimming pools, water tanks, and sewers have rung ladders. Manhole steps are very narrow in widths, but the width is otherwise compensated by its staggered placement. The same holds true, for climbers for bunk beds, whether in railways, buses, barracks or homes.

Temple steps Thanjavur Tamil Nadu India Wikipedia image by Thamizhpparithi Maari

 Steps are components of stairs. Stairs when open (to sky -not covered on sides or top) are considered steps. Steps are freer architectural appendage or inset elements to negotiate small height differences. Steps traditionally have had abutting walls on either side. Steps could have same tread-riser relationship but steps are less steeper. A staircase is an enclosed or caged set of steps to several floors.

High pitch Bathing Ghat steps of ChetSingh Ghar Benaras India > Wikipedia image by Patrick Barry from San Francisco USA
Minimum width required for low intensity unidirectional traffic is 600 mm, however most standards specify 900 as minimum width for escape in a hazardous situation. A two-way lane stair should be at least 11200 mm. Sufficient width space for movement is required at torso level, otherwise at feet level a minimum width of 250 mm is required. Where same step is to be used for placing either one of the feet, both, the step and passage widths of minimum width of 500 mm are necessary. Stairs less than 500 mm width are generally emergency stairs rarely to be used, or service stairs to be used by experienced persons. For single lane traffic 750 mm width is an accepted standard. Most of the building bylaws allow minimum 900 mm widths for private buildings. For public buildings a stair width of 1200 mm to 1500 mm is recommended. For pedestrian over bridges and other public thoroughfares, a stair width of 2400 is recommended. On public thoroughfares where traffic is totally segregated or is only one directional, the minimum stair width could be 1800 mm.
Stepped Caen Hill Locks of the Waterway on Kennet and Avon Canal Devizes Wiltshire England > Wikipedia image
 Many stepping arrangements are used for emergency and special purposes. Simplest is a knotted rope or a rope ladder secured to a wall or column. In many countries older buildings were required to confirm to new bylaws, open iron stairways on the building's exterior were placed. Open iron stairs, though are rendered useless by smoke from windows, so must be placed against a blank wall. One of the best fire escape stairs is a fully enclosed stairway in the building itself or in an adjoining tower. Uncoated or unprotected steel is highly hazardous during a fire as it expands and deforms the stairway. Wood though combustible catches fire slowly, and allows more escape time compared to an unprotected steel stair.
Fire exit stairs in Soho NYC > Wikipedia image by Jorge Royan