oxyfuel cutting

7/25/2019 Oxyfuel Cutting

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Oxy-fuel cuttingStolen from:

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Oxyfuel cutting - process and fuel gases

Mechanized oxyacetylene cutting

system

he oxy!fuel process is the most "idely applied industrial thermal cutting processbecause it can cut thic#nesses from 0.$mm to 2$00mm the e&uipment is lo" cost

and can be used manually or mechani'ed here are se(eral fuel gas and no''ledesign options that can significantly enhance performance in terms of cut &uality and

cutting speed.

Process fundamentals

he cutting process is illustrated in Fig. 1. )asically a mixture of oxygen and the fuel

gas is used to preheat the metal to its *ignition* temperature "hich for steel is+00,- ! 00,- bright red heat but "ell belo" its melting point. 1 et of pure

oxygen is then directed into the preheated area instigating a (igorous exothermic

chemical reaction bet"een the oxygen and the metal to form iron oxide or slag. heoxygen et blo"s a"ay the slag enabling the et to pierce through the material and

continue to cut through the material.

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he purity of oxygen should be at least .$%. 1 decrease in purity of 4% "ill

typically reduce the cutting speed by 2$% and increase the gas consumption by2$%.

Choice of fuel gas

Fuel gas combustion occurs in t"o distinct 'ones. 7n the inner cone or primary flamethe fuel gas combines "ith oxygen to form carbon monoxide and hydrogen "hich for

acetylene the reaction is gi(en by

2- 28 29 2O 2 -O 9 28 2

-ombustion also continues in the secondary or outer 'one of the flame "ith oxygen

being supplied from the air.

-O928 29;O 2 -O 2928 2O

hus fuel gases are characteri'ed by their

flame temperature ! the hottest part of the flame is at the tip of the primary

flame inner cone

fuel gas to oxygen ratio ! the amount of fuel gas re&uired for combustion but

this "ill (ary according to "hether the flame is neutral oxidi'ing or reducing

heat of combustion ! heat of combustion is greater in the outer part of theflame

he fi(e most commonly used fuel gases are acetylene propane /m ;compared "ith

40;; #>/m ;for propane produce a more intense flame at the surface of the metal

reducing the "idth of the 8eat 1ffected ?one 81? and the degree of distortion.

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Fig..

Oxyacetylene gas!et and nozzle

design

Fig.". Propane gas

!et and nozzle

design

MAPP


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1s /m ; for acetylene. -onse&uently natural gas is the slo"estfor piercing.

For further information contact arcBt"i.co.u#

This Job Knowledge article was originally published in Connect, September!ctober 2""". #t has beenupdated so the web page no longer re$lects e%actly the printed &ersion.

-opyright C200 D7 @td

7nformation and ad(ice from D7 and its partners are pro(ided in good faith and based "here

appropriate on the best engineering #no"ledge a(ailable at the time and incorporated into D7*s "ebsite

in accordance "ith D7*s 7SO 004:2000 accredited status. Ao "arranty expressed or implied is gi(en

regarding the results or effects of applying information or ad(ice obtained from the "ebsite nor is any

responsibility accepted for any conse&uential loss or damage.

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%a&le ' Fuel $as Characteristics

Primary (econdary

1cetylene $+20 ;450 4.2:4 4==0 ;$==2

3ropane $00 2=40 .;:4 40;; =$;2$

oxyfuel cutting

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