material selection consideration for reactors

8/20/2019 Material Selection Consideration for Reactors

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Material selection consideration for reactorsa) Applicability

i. Mechanical environment: Stress(Load) History, Strain History, Normal, Transient, Accident.

ii. Chemical (lectrochemical) nvironment.iii. Thermal environment.

b) S!itability

i. "!ali#cation $or the !se o$ the !se o$ material on the environment.ii. The e%istence o$ material in the ASM Code.

c) Availability

i. Availability o$ material.ii. &eliable so!rce.iii. Cost o$ the material.

d) 'abricability

i. Thermomechanical processin.ii. Ability to be $abricated $rom material.iii. "!ality ass!rance and !ality control.

e) conomics

i. The c!rrent cost o$ the material and e%pected cost.$) Compromise

The best material $or the constr!ction o$ the reactor is a hih alloy stainless steel.Cast iron is *not a partic!larly stron or to!h str!ct!ral material* accordinto Perry�s Chemical Engineering Handbook + pae +-+ and is not s!itable $or theconditions in the reactor beca!se the reactor operates at /01 psia and 2/1 o'.Carbon steel can not be !sed beca!se accordin to Table 3+-+ in Plant Design andEconomics for Chemical Engineers3, hydroen is not compatible 4ith carbon steel.Several other alloys s!ch as a nic5el-based alloy co!ld be !sed $or the materials and

conditions, b!t 4o!ld not be the most economic materials. High-alloy stainlesssteel is the best material $or constr!ction o$ the reactor

The stainless steelStainless stell is a lo4 carbon steel that consists o$ chromi!m at 367 or moreby 4eiht. Thro!h the addition o$ this chromi!m that ma5es the stainless



steel to has a characteristic o$ corrosion resistance. There are so many typeo$ stainless stell as s!ch there are abo!t 86 rades o$ it and the entire ro!ocan divided into #ve classes. The stainless steel is classi#es and also can beidenti#e by their o4n alloyin elemen. This also a 4ay that each di9erenttype o$ stainless steel has been named.

Benets of stainless steeli. Corrosion resistance

The stainless steel has resistance to4ards atmospheric and o!re 4aterenvironment especially in the lo4er alloy rade. t also has a hihresistance to4ards 4ide rane o$ environments and temperat!res. onany problem o$ the reactor operational environment there 4ill nopresence o$ inter-ran!lar corrosion or inter-ran!lar stress.( 'ol5hard,. 30 )

ii. 'ire and heat resistance

The stainless steel str!ct!re can be e%pected to behold their interritya$ter s!ch a lon period p$ e%pos!re to the hihest temperat!rereached in hydrocarbon #res. 'or e%ample, the alvani;ed mild steelable to 4ithstand #re $or !se$!l time.

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iii. Hyiene

t is easy to clean the stainless steel.

iv. Strenth-to-4eiht advantae

There is sini#cant strenthenin o$ the material $rom cold-4or5inalone and the hih strenth d!ple% rades 4hich enable the materialthic5ness to be red!ced over conventional rades and hence red!cinthe cost and ma5e it more cost savin.

Properties of stainless steelStainless steel can be de#ned as a $erro!s alloy. t has a minim!m o$ 367 o$chromi!m content. As the name says, stainless steel does not stain and asmention be$ore it is resistance to4ards corrosion. t also has a remar5ableresistance to r!stin or o%idation or even to any nat!ral nor man madeenvironments.



Commercial value of stainless steel The stainless steel partic!larly has lo4 maintenance and also relatively notso e%pensive material. t is also resistance to corrosion and stainin also$amiliar l!ster that ma5es it to be an ideal based material $or host o$

commercial application. t is also someho4 an eco-$riendly material sinceabo!t 167 o$ ne4 stainless steel is made !p o$ re-melted scrap metal.

High Alloy Stainless SteelHih alloy stainless steel are those stell 4hich alloy 4ere added in a lare!antities to improve the material characteristics. These materials are heattreated in order to $!rther enhance the mechanical properties andmicrostr!ct!re. t is carried o!t by temperin, normali;in, !enchin or

sol!tionisin. This hih alloy stainless steel has a hih impact resistance as4ell as corrosion resistance.

The typical application o$ this material are:

i. @!mp component - corrosion resistance

ii. mpellers - corrosion resistance

iii. Cr!sher a4s - impact hardenin.

SteelSteel is made !p mainly $rom an iron 4ith a carbon content o$ 6.+7 to +.37by 4eiht. The prod!ction o$ steel are $ro, carbon and other alloyin metals!ch as t!nsten, chromi!m, and mananese. The properties o$ the steelthat is prod!ces are a9ected by the proportions and $orms in 4hich theseelements are !sed.

Properties of steel3. Tensile strenth

The tensile strenth 4hich means the amo!nt o$ stress that as!bstance can ta5e be$ore it str!ct!rally de$ormed. 'or steel, thetensile strenth is comparatively hih and th!s it has a hih $ract!reresistance and brea5ae. This can be a 5ey point $or a str!ct!ralb!ildin.

+. >!ctility



The ability to chane shape 4itho!t $ract!re $or steel is !itesini#cant. The d!ctility o$ steel enables it to be !sed in ma5indi9erent shapes and str!ct!res.

/. Malleability

Closely related to previo!s characteristic, steel has a ood malleability4hich allo4s it to de$ormed !nder compression. This characteristicsenable steel to be compressed into sheets o$ variable thic5ness.

2. >!rability The hardness o$ steel is hih. Bther than that it also lon lastin andhas reat resistance to4ards e%ternal 4ear and tear.

1. Cond!ctivityood cond!ctor o$ electricity and also heat.

8. &!st resistance The steel resistant to r!stin is a9ected by the addition o$ certainelement.

Steel has a reat $ormability and d!rability. Bther than that it also has a oodtensile and yield strentth and also a ood thermal cond!ctivity.'!rthermore, steel also has a hih resistance to4ards corrosion.

References: http://www.tatasteelconstrction.com/en/reference/teaching!resorces/architectral!teaching!resorce/history/the!history!of!iron!and!steel/the!

properties!of!cast!iron!wroght!iron!and!steel

Aluminium The principal ore o$ al!mini!m is ba!%ite 4hich is prod!ced by the4eatherin o$ the al!mini!m silicate roc5s. Al!mini!m has a characteristicso$ so$t and liht4eiht. t is also a lo4 strenth metal and can easily be cast,$ored and machined, $ormed, and 4elded. t is s!itable only in lo4temperat!re applications. This can be e%cepted 4hen it is alloyed 4ithspeci#c elements.

Al!mini!m can be !sed as a deo%idi;er and also can act as a alloyin aent.'or e%ample, tor!e converter p!mp ho!sins, aircra$t str!ct!res, electricaltransmission lines are made o$ al!mini!m. Al!mini!m has a limitation that itsho!ld be !sed at a lo4 temperat!res application.



Cast ironCast iron is an alloy o$ iron and carbon. t has ood compressive strenth b!trelatively poor tensile strenth. Deca!se o$ the imp!rities in cast iron and itscrystalline str!ct!re, altho!h it is a stron material in compression, it is

4ea5 in tension and is very brittle. As a res!lt 4hen it $ailed it did so in ane%plosive manner 4ith little 4arnin.

The castin process enables the prod!ction o$ comple% shapes. Deca!se it isprod!ced by castin, $or e%ample it is made by po!rin into a mo!ld, th!s itis 4ell s!ited to the prod!ction o$ intricate shapes, both str!ct!ral anddecorative. 'or str!ct!ral !se, cast iron 4as best s!ited to elements 4herethe predominant load ca!sed compressionE and so 4as most commonly !sed$or col!mns.

t cannot be $ored. Cast iron is 4or5ed by meltin to a li!id and po!rin inmolds, then by sa4in, #lin, machinin (chip ma5in methods). Thesti9ness and dampenin properties o$ cast iron ma5e it an e%cellent material$or machine tool $rames and parts.

Brittleness

Cast iron is very brittle. The relatively hih carbon content 4hich is 4ithin +to 1 percent 4hich means that the $ormation o$ cast iron is that it is hardens4ith a crystalline str!ct!re that brea5s easily. t also cannot be 4ro!ht that

means it cannot be beaten into di9erent $orms even tho!h 4hen heated.

Tensile strength

The tensile strenth is the meas!re $or ho4 m!ch the p!llin strain 4ithin amaterial can 4ithstand. As $or the cast iron, the tensile strenth is lo4.

Compression strength

This enerally means that the meas!re o$ the amo!nt o$ press!re that thematerial can ta5e be$ore it $ails. 'or cast iron, the compression strenth ishih. Th!s, this ma5e the cast iron !se$!l $or constr!ction.

Corrosion Resistance

The cast iron has a very lo4 resistance to4ards corrosion. Fhen #rstman!$act!red it has a protective #lm on the s!r$ace, 4hich initially increasesits resistance to corrosion. This #lm cannot be relied !pon in the lon term,ho4ever. Fhen e%posed to air and moist!re cast iron rapidly o%idi;es (reacts4ith o%yen in the air), prod!cin the $amiliar red-bro4n iron o%ide 5no4n as



r!st.

References:

http://www.ehow.com/list_7622626_characteristics-cast-iron.html

http://www.gcsescience.com/e"##.htm

material selection consideration for reactors

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