Sinan Sever 030070127 10th Week

Knurled Nut

no previous description…

NEW(BETTER)

Common nuts include a jam nut, tightened against a square of hex nut to lock it. A locknut alone dos the same job. A castle nut lets a wheel or other secure part move. A cap nut is decorative and protective. Knurled nuts and wing nuts can be turned by hand. A T-nut goes into one side of a board to receive a bolt coming from the other side. A threaded insert screws into wood to accept a bolt.

(HVAC and Chemical Resistance Handbook for the Engineer and Architect: A Compilation, Tom Arimes, pg. 15-23)

Superalloys

no previous description…

NEW(BETTER)

Superalloys are metallic materials that contain chromium and other elements to enhance resistance to oxidation and corrosion, and to maintain strength at high temperatures.

Superalloys are classified as follows:

·         Iron Based: Iron Based superalloys are hardened by carbides, intermetallic precipitates and/or solid solution strengthening elements such as molybdenum and tungsten.

·         Cobalt Based: These materials contain cobalt as the major constituent with some solid solution strengthening secondary phase carbides or intermetallic compounds.

·         Nickel Based: These heat-resistant alloys contain approximately 30 to 75% Ni, with up to 30% Cr. Small amounts of aluminum, titanium, niobium, molybdenum, and tungsten are added to nickel based superalloys to increase strength, corrosion resistance, or both.

(Asm Metals Reference Book By American Society for Metal, pg. 121)

Single-Crystal Casting

no previous description…

NEW(BETTER)

Certain applications require single-crystal products. Ni superalloy combustion zone turbine blades deliver creep strength if all grain boundaries are eliminated, thereby preventing grain boundary sliding. Strictly speaking, these turbine blades are bot true single crystals since other phases are present in the matrix, but the y-phase matrix is cast to produce a monocrystal.

The Czochralski crystal pulling method produces single-crystal Si for microprocessors. The ultrapure Si must be free of grain boundaries and dislocations to operate properly. This can be achieved by immersing a seed crystal into the surface of a pool of liquid Si under high vacuum and rotating it slowly (about 1 revolution per second) while lifting it vertically. About 80% of Si single crystals are grown by Czochralski method to produce boules up to 380mm in diameter. An alternative process, the flat zone method, simultaneously purifies the polycrystalline starting rod and converts it into a single crystal by slowly moving an induction coil along the length of the rod to melt a small zone immediately under the coil. The coil is started at the intersection of the polycrystalline Si rod and a monocrystal Si seed crystal; as the coil moves away, the Si left behind refreezes b patterning itself on the seed single crystal. Eventually, the entire rod is converted to a single crystal with the same crystallographic alignment as the seed crystal. Impurities in the polycrystalline rod are preferentially rejected into the liquid phase at the solid-liquid interface, so the last few centimeters at the end of the new single crystal contain most of the original rod’s impurities.

(Structure-Property Relations In Nonferrous Metal, Alan M. Russell and Kok Loong Lee, pg. 109)

Clean Steam Generators

OLD

In many facility applications, carryover of boiler treatment chemicals and boiler water is especially prohibited, for example, if steam is to be injected directly into process or if boiler solids would contaminate the airstream in humidification.For these applications, a ,clean steam, generator is appropriate.
(Facility piping systems handbook 2nd edition Michael Frnkel p.11.14)

NEW(BETTER)

Clean steam generation and distribution is a fairly stragihhtforward process. Steam is generated from a pure water source and then distributed throughout the facility. Each usage point for steam typically has a steam trap for condensate removal.

Temperature measurement is required at some use points. Be sure to consult with Sterility Assurance personnel to determine the requirements for temperature measurement. Thermocouples ot RTD’s are most often used.

Clean steam generators are typically supplied as a packaged unit with its own dedicated control system. Distribution systems typically have a custom built steam distribution system. There is little valving or instrumentation; it is possible that al steam distribution valves and instruments can be owned by the unit operation that is drawing the steam. This greatly simplifies the design, testing, and validation.

(Automation Applications in Bio-Pharmaceuticals, George Buckbee, pg. 91)

Electric Steam Generators
OLD
Electric boilers have unique advantages for small facility steam applications:

-They do not require fuel piping
-They have no burner systems or draft blowers
-They do not require flues to carry off the exhaust gas
-They are smaller and easier to install

These boilers must be properly operated and maintained to prevent hot-spots and buildup of solids, which may cause early failure of the boiler.
(Facility piping systems handbook 2nd edition Michael Frnkel p.11.14)

NEW

That electricity, which is generally produced by steam power, should itself be used as a steam-producing agent may seem something of an anomaly, but electric steam generators have much to recommendd them from the point of view of convenience, ease of control, and economy in floor space wen compated with other forms of steam raisers. It is seldom that electricity as a steam-raising medium can compete with a solid fuel plant on fuel costs alone, but the many additional advantages, some of which are indicated above, often turn the balance in favour of electricity.

There are three fundamental designs of electric steam boiler; the design selected for a particular duty is influenced by the steam output required and by the system of electricitysupply available.These three designs are:

·         Immersion heater type

·         Horizontal tubular

·         Electrode

The first two designs are almost identical, the main difference between the being in length of element .

Immersion heaters are made and used as single units up t 3kW rating each, thus best suited to small, low pressure boilers, and may be used either horizontally or vertically.

The tubular type employs long immersion heaters up to, say, 4 feet in length, which are always fitted horizontally.

Except for the difference in element length and that immersion heater boilers have, generally, vertical cylinders, and the tubular type horizontal cylinders, boilers in class (a) and (b) may be regarded as being identical.

(Hot Water and Steam Supply by Electricity, anonymus, pg. 117)