Advice, Tips & News

Terry and Graham's Technical Tips
This section is dedicated to incredibly useful tips that should help keep you safe while working and may even save you money through proper use of equipment. Watch out for new tips and you may just find out a useful nugget of information. If you would like more information and specific help on various aspects of buying a welder or buying the right consumables / equipment for your needs then please click through to our Customer Advice Page. There we have various pages all with useful information on.

MIG / MAG Welding Set-up
Most of the very compact and by virtue of their price, lower powered MIG welders will typically have a maximum welding output of say 100 amps to 160 amps these smaller MIG welding machines are really only capable of short circuit or “dip” transfer welding technique.  Short circuit transfer is the most versatile because it may be used in most welding positions and as the process name suggests, “short circuit”  is where the filler wire makes direct contact with the work piece and literally short circuits causing the weakest link – the filler wire – to instantly melt.  Where the filler wire touches the material it also causes the metal to melt.  Due to the speed / frequency with which the “arc shorting” happens this is where we at Noz-Alls describe what we hear as the “buzzing bumble bee” sound or “ sizzling bacon” sound when we have the power and wire feed speed set correctly.  The sought after buzzing sound will typically have a Hertz of between 90 and 200 depending on the material thickness and the power required.  From our perspective when we view the weld it looks like the filler wire is constantly being fed into the molten pool of weld metal.  It is only with an ultra high speed camera the frequency may be observed of the shorting and melting cycles.
Besides protecting the molten metal weld pool from the atmosphere the MIG shielding gas helps to stabilise the arc plus can assist with reducing spatter.
Noz-Alls modern Headux inverter MIG welders have built-in circuitry to help reduce the amount of spatter.  Correct setting also helps to reduce the spatter of course.
How can you set correctly without any data, it is where to begin that helps:-

What MIG Welding Amperage to Use?
In general material thickness determines the welding amperage.
As a guideline, each 1mm of material thickness requires 40 amps of output: 3mm = 120 amps
The wire size you choose to work with is normally the wire that satisfies the majority of your work.  The smaller 0.6mm wire diameter often being reserved for thinner materials where less heat input is required such as automotive bodywork.
Larger wire diameters require a higher welding current
  • 30-130 amps: 0.6mm
  • 40-145 amps: .0.8mm
  • 60-200 amps: 1.0mm
  • 75-250 amps: .1.2mm
What MIG Filler Wire Speed Should I Set?
Setting the wire speed correctly is important as this influences the amperage as well as the weld penetration achieved.  Setting the wire feed rate too high may result in burning through.
In the absence of a welding chart  or weld specification the following calculations help to provide a good starting point which may then be adjusted to meet your requirements
In this example when using 0.8mm filler wire welding 3mm thick steel :-
Multiply 50mm by the amps for 3mm steel = 50 x 120 = 6000 / 1000 = 6 m / min wire speed setting
For wire size Multiply by Ex. using 3mm (120 amps)
0.6mm 90mm  per amp 90 x 120 = 10800 / 1000 = 10.8 m/min
0.8 mm 50mm per amp 50 x 120 = 6000 / 1000 = 6 m/min
1.0 mm 35mm per amp 35 x 120 = 4200 / 1000 = 4.2m / min
1.2mm 25mm per amp 25 x 120 = 3000 / 1000 = 3 m / min

Most Recent
Tungsten Electrodes - What is each one?

TIG Tungsten electrodes come in various types with different purposes for each. The most common are White and Red tips.
Red tungsten electrodes are 2% Thoriated and designed for use with mild steel and stainless steel however because of the radioactive element they are slowly being phased out in favour of the E3 purple tips.
Red tips are referred to as WTh20.
Purple tungsten electrodes have been developed as a 3 in 1 electrode giving improved life and arc characteristics over the Thoriated, Lanthanated and Ceriated electrodes and can be used in both DC and AC. They are a mixed rare earth electrode and are also excellent for automated welding processes.
Purple tips are referred to as E3.
White tungsten electrodes are 0.8% Zirconiated and have been specifically designed for welding aluminium in AC.
White tips are referred to as WZr08.
Green tungsten electrodes are pure tungsten and is mostly a hang over from America where they use this electrode for aluminium welding - the life of this tungsten is less compared to white.
Black, Gold and Blue tungsten electrodes are 1%, 1.5% and 2% Lanthanated, respectively. Lanthanated rods are mainly used for high-alloyed steel, titanium, nickel, copper and magnesium. The higher the percentage the better the ignition characteristics. The life of the tungsten is less than the purple tips.
Lanthanated tips are referred to as WLa10, WLa15 and WLa20.
Grey tungsten electrodes are 2% Ceriated tend to be used for pipe welding but the current carrying capacity is lower than the purple tips.
Ceriated tips are referred to as WCe20.
For the link to this advice page: TIG Tungsten Types.
To shop for Tungsten Electrodes: Shop for TIG Tungsten Electrodes.

How to Practice and Improve Your TIG Welding skills
Basic Practice  - Down hand – horizontal welding – leftward or rightward.
Mild steel sheet  - Set your TIG 
Turn off “pulse” and other special arc functions so you practice with a “standard arc” in DC TIG mode.  Trigger latching 4T may be used if more comfortable than 2T (button held all the time)
Pre-gas set to 1.0 seconds
Slope up set to “0” Slope down set to “0”
Post gas set to 4 seconds
Power level to use will depend on your test sheet thickness
0,8 – 1,0mm mild steel thickness set 40-60 amps
1,0 – 1,6mm mild steel thickness set 55 – 88 Amps
1,6 – 2,4mm mild steel thickness set 60 – 130 Amps
2,4 – 3,2mm mild steel thickness set 100 – 155 Amps
3,2 – 4,2mm mild steel thickness set 110 – 200 Amps
Start with simple items:-
Run Without Filler

Scribe a line on a piece of sheet on which to practice the TIG run
Without using a TIG filler wire initiate the arc and follow the scribed line on the sheet surface. 
Maintain a consistent arc and develop the weld pool, move the arc and weld pool along the scribed line so the melted pool width remains the same width.  Do not melt through the sheet.  The run will appear to be slightly concave on the surface.
Complete the arc run having followed the scribed line – check the run width and practice until you achieve a consistent run line on top of the sheet.  Under the sheet you should have a consistent looking “weld bead” run which proves the arc has sufficient penetration.

Run With a Filler Rod - Practice how to feed the tig rod through your hand / fingers keeping your hand at a constant height.
Now scribe new lines and practice a run using the TIG filler rod as well – only ever put the filler rod into the molten weld pool – the weld pool melts the end of the TIG filler rod not the arc.
Filler rod size is important – too large a diameter and the weld pool will “freeze” too small a filler rod and the amount of feeding into the weld pool is too great.  The top of the weld bead should have a consistent rippled finish along its top surface – each ripple crest is where the filler rod was melted into the weld pool – filling the pool – the arc is moved on and the pool is filled again…………..
Later you will establish that introducing the “pulse” element of the arc achieves more of a ripple effect on the weld bead surface.
Torch & Filler Rod angles
The angle the TIG filler rod touches the weld pool to be melted is also important and will have an effect on the weld pool shape. While welding the filler rod may be kept close to the arc and weld pool but not so close as to impart too much heat into the filler rod prior to being melted into the weld pool.  The angle of the TIG torch is also important start at approximately 10 degrees off from vertical so the TIG tungsten electrode is pointing forward in the direction of welding.  The filler rod will be fed in at approximately 90 degrees to the TIG torch angle.
Once you have mastered a “run” with TIG filler wire which has a consistent width and height on the top as well as a consistent “bead” under the run it is time to join some metal.
 Joining Metal
The first joint to practice is the external closed corner without a filler rod as this is the most simple.
Tack weld some samples sheets together forming a 90 degree angle – with no gap at the joint.
Without using any filler wire – run the TIG arc along the “open corner” maintaining the consistent arc width path already practiced.
The finished arc weld bead should be consistent – neat and not be “lumpy” on the sides of the sheet.  Inside the corner there should be a neat and consistent inner weld bead.  When the above can be achieved then move to the “open corner” joint.
Tack weld the two pieces of sheet together with an open gap along the joint path.  Using a TIG filler wire maintain the weld pool “horse shoe” shape along the joint path and once again fill the pool towards the “middle back” of the pool – once again dipping and melting repeatedly.
What to Look For
When finished the crest of the weld bead should be consistent in height, not lumpy, not running over the edge of the sheets plus there should be a full run inside the weld joint.
Having mastered the “open corner” the next weld to attempt and practice is the “lap joint”, tack the two plates together on both sides – you can then complete both runs. The TIG torch angle has to be very slightly adjusted to compensate for the differing plate heights – slight manipulation of the arc from side to side can assist when welding the lap joint.
Once the “lap joint” has been mastered then move on to a Butt joint.  Tack the two sheets to be joined together – again leaving a joint gap.  Fill and run along the “horse shoe” weld pool in a similar fashion as the open corner – slightly more difficult as the weld pool is more liable to “melt through” and drop out so extra care has to be taken with the Butt joint compared to the open corner or lap joints.  Once again, master this joint and gain consistent weld bead width and shape both on the top of the weld and on the underside.
Getting More Difficult
The next joint to consider is the internal closed corner – once again the angle of the TIG torch changes and is divided equally between the two sheets forming the closed corner.  The arc is now given a distinct weave, in equal proportions getting the heat evenly into both the sides of the internal closed corner joint.
Once this joint has been mastered then move on to a “Tee Fillet” weld – these are the most difficult weld to achieve as the arc now has to be manipulated to distribute the heat into the two pieces of metal in differing proportions.  The vertical sheet joining to the flat base sheet each absorb the heat differently.  The vertical sheet will more easily absorb the most heat so quickly melts the edge of the sheet, the flat base sheet takes longer to absorb the heat as it is more able to conduct the heat away.  Due to the difference in the way the heat is absorbed the arc has to be “aimed” more towards the base sheet so the angle of the arc becomes important this difference in heat input is also gained by “weaving” the arc path as you weld.
Having mastered the various joint types you can now learn how to improve the welding technique by tuning the arc characteristic.
The TIG welder will have “Slope Up” settings which allow a lower initial power to be set along with a time period in seconds before full power set is achieved, this allows for the start of the TIG weld bead to be controlled in a better fashion.
Similarly, as you come to the end of the weld bead, the heat will have built up in the weld joint, to help reduce the possibility of “burn through” at the end of the weld the “slope down” function is used to reduce the TIG welding power allowing a neat finish to the end of the weld bead, the effect is to reduce the crater as the reducing power ensures you have time to fill without excess heat.
TIG arc characteristics may be adjusted to improve your arc control – pulse settings will “slowdown” the welding process which allows more control over the weld bead.  The pulse setting also allows for the specific rod feed and weld pool melting cycles to be synchronised.  
The pulse setting power levels may be chosen so the peak current is sufficient to give a good weld pool melt for the material thickness the lower current or trough current is chosen for the filler dip before the current is once again back at the high setting ready to melt and move forward.
DC TIG Welding current
Tungsten size 1,0mm dia Binzel E3 purple tip       Weld current  20 to 60 amps       
Tungsten size 1,6mm dia Binzel E3 purple tip       Weld current  40 to 100 amps    
Tungsten size 2,4mm dia Binzel E3 purple tip       Weld current  80 to 150 amps    
Tungsten size 3,2mm dia Binzel E3 purple tip       Weld current  100 to 225 amps  
AC TIG Welding current
Tungsten size 1,0mm dia Binzel E3 purple tip       Weld current  20 to 60 amps       
Tungsten size 1,6mm dia Binzel E3 purple tip       Weld current  40 to 100 amps    
Tungsten size 2,4mm dia Binzel E3 purple tip       Weld current  80 to 160 amps    
Tungsten size 3,2mm dia Binzel E3 purple tip       Weld current  100 to 240 amps 

Lead weld like a pro
Ok - so to really weld lead like a pro takes lots of practice and perseverance but all too often budding artisans are setting themselves up to fail before they start by attempting to use the wrong torch type and nozzles. The lead welding Model O torch is the right tool for the job and undoubtedly the best tool for the job.  Noz-Alls Model "O" torch is different to others on the market, our flame will not adjust when in use. 
The issue is however there are lots of 'cheap' versions in the market. I put inverted commas around the word cheap on the basis that there are many welding suppliers selling these cheap Model O torches for a lot of money.
Our own Model O torch is different visually so you may identify it.  All our Model "O" torches are fully stripped down on arrival, modified and machined, fitted with UK O-rings, coated, assembled and tested.
The result is that you get what is becoming recognised as the best on the market and fully conforms to BS EN standards.

What's more, as well as the torch you get a useful information sheet containing Lead codes, weights and thicknesses against which nozzle size is required and for what joint type.

Lead welding information sheet.
Please note that the flame is not and never has been a "ball" the flame is and should be a very short cone - Model "O" size #1 is about 1/2mm in cone length.
the reference to a "ball" flame has been perpetuated by a U-Tube lead welding video where the artisan doesn't know what to call the small bright inner flame and he refers to the flame cone as the "ball flame".
This was simply the fact that he wasn't aware of the correct term for the inner flame cone.

Therefore do not be confused the welding flame cone should not be a ball it is correct as a small cone, a very small cone however!

The blink of an eye
Recently we had a customer come to us for a new ADF Welding helmet. His old mask, was which was working perfectly, ended up sadly having the auto darkening lens cracked.
One of the questions we were asked about our older green style ADF fitted to the CWS ES 5-13 was how quick is it to react.  (The CWS ES5-13 is now obsolete having been replaced by True colour ADF).
The reaction time question got me thinking of how best to explain the reaction time of our own welding helmets.

The blink of an eye is averaged at about 1/3 of a second (0.33) and research has shown that the human eye can detect images in as little as 13 milliseconds (0.0013). Our helmet reacts to the arc in just 4 milliseconds (0.0004). This makes our helmet over 8000 times quicker than the blink of an eye and over 3 times quicker than the human eye / brain can even detect an image.

Make your next helmet a good one and buy from Noz-Alls. Remember - if the helmet doesn't have the spec listed it is probably the seller hiding something.  Check out our range of market leading ADF welding masks with True Colour lenses, from a budget mask to the best on the market.

"I need Stainless MIG Wire..." Fine but come prepared.
We often get approached at the Trade counter by people who are welding stainless steel which is great but so often they don't actually know what type of stainless they are welding. There are many types of stainless steel but often the chances are you will be using 304L or 316L (the L simply stands for low carbon).

Below is a simple table of the most suitable filler materials for the two types of material to be welded. Of course others could be used and the strength of a weld will typically rely more on your own welding ability,

Use the grey cells to match your two pieces of metal to be welded together and then see the filler rods you require for the job. Stainless 410 & 430 typically use 309L filler rod and 310 use 310 rods more often than not. If you are still unsure just give us a call or email.
Mild Steel
Mild Steel
Mild Steel
AGNM or PGNM - Gas gouging a health and safety officer's dream come true
Gouging using gas equipment on mild steel is generally much quieter than using 'carbon arc' or 'arc/air' gouging method plus generally liberates much less fume / dust.
Where Health and Safety requirements are important it makes sense to use oxy / fuel gas gouging process. 
Always wear eye protection and ear defenders for your protection. It is also preferable to wear an approved dust mask - available from  Noz-Alls PPE section of our website.
Gouging will discharge dross a long way from where you are working so stopping the sparks / dross with physical barriers is essential - welding blankets can be useful to cover awkward shapes.
Acetylene The Best Fuel Gas - Safe storage and sensible use
Acetylene cylinders should only be used in the vertical position. If a cylinder has been transported or stored laying flat the cylinder should be stood in an upright position for a minimum of one hour before use begins. Check with your gas supplier as they may require a longer period. If it has been transported at 45 degrees then stand in an upright position for 30 minutes before use.

Dissolved Acetylene - DA
Pure acetylene gas is unstable at high temperature and pressures.  In Europe and the UK acetylene carbide generators are generally not in use anymore , we all use high pressure acetylene  or "DA" = dissolved acetylene.
Modern acetylene cylinders are quite complex and not just empty vessels (like oxygen cylinders).  To enable us to use acetylene safely the acetylene gas is dissolved into a holding agent. - mostly acetone. This liquid solution is itself stored in a monolithic mass, a bit like a solid sponge, which breaks the storeage of the acetone/acetylene mixture into very small compartments so there is not a large mixture volume subject to pressure as the mixture effervesces.

The action is similar to opening a bottle of cola, as the cap is undone and the pressure released above the liquid, the CO2 bubbles out from the cola. This is the same action as when the valve on the acetylene cylinder is opened.

The rate at which the acetylene gas bubbles out of the acetone is the maximum rate at which you can use the acetylene gas from the cylinder. When you draw off acetylene too quickly acetone is drawn off with the gas. To help prevent acetone withdrawal no more than 1/5 of the cylinder contents should be consumed in an hour.  This ratio is based on the "older"  style acetylene cylinders which had a large diameter.  The newer slim type of acetylene cylinders from Linde (BOC)  have a much reduced effervescence rate of only 1/9 of the contents per hour.  Acetone drawn into gas equipment causes damage and malfunction as well as giving operator flame stability problems. Equipment damaged by acetone should be replaced with new equipment.

Small PortaPak size acetylene cylinders should only be used for welding with nozzles up to size #5  - do not use with multi-flame heating or cutting nozzles.
Intermediate size DA cylinders will be able to be used with larger size welding nozzles say #13 or possibly the miniature AFN cutting nozzles but intermediate size DA cylinders should still not be used with full size ANM cutting nozzles or AHT heating nozzles.
Full size DA cylinders with about 8kg contents of acetylene gas may be used with welding nozzles from size #1 to #35, ANM cutitng from 1/32" to 5/64", AGNM #13 (only) and the AHT #25 (only)  larger nozzle sizes will require more than one full size DA cylinder to supply sufficient acetylene flow.

Larger Size Acetylene Nozzles - Noz-Alls  have the equipment you need for safe use.
For your safety and to extend the useful life of your gas equipment system you should note that when using nozzles to cut more than 140 mm  ANM-6 sizes 3/32, 7/64 & 1/8" which cut up to 300mm thick mild steel at least two standard (old shape) 8kg. acetylene cylinders should be manifolded together. However the possibility generally exists to cut for up to 5 minutes in any consecutive half hour period so long as the acetylene cylinder (8kg) is between 3/4 and 1/4 full only.  The rest period is required to allow the acetylene gas to recover.  Extended use will result in an unstable flame due to under running.
Other nozzles which will require more than one full size DA cylinder to supply sufficient gas flow would be:- welding nozzles size 45, 55, 70 & 90 - AHT #50 & AHT #100 - AGNM #19 & AGNM #25 + ANME-10 all sizes
Any questions please give Noz-Alls a call on 01242 681052.

The bRight spark
Only use a proper spark lighter when igniting your nozzle. A spark lighter requires a greater volume of gas to obtain the ignition. Cigarette lighters or flames from another source will ignite the smallest amount of gas and may be the cause of a flashback, igniting the gases before they have begun to flow. Always follow the correct opening and closing down procedures for your safety.
Purge like your life depends on it
Having set the correct operating pressures, and before igniting your nozzle always purge your hoses / torch system. For 10m hoses, open the oxygen valve, count to 3 sec. close the oxygen valve. Now open the fuel gas valve a full turn, count three seconds and light the fuel. When using acetylene continue to open the fuel valve until no black smoke is visible, now introduce the oxygen and adjust to the desired flame characteristic.
Set acetylene sensibly
Acetylene preheat cones should be conical and pointed with a small spherical tip for maximum heat input.
The best heat input is with the cone 1.6mm above the plate surface. 
A single cone on a welding nozzle should be perfect, a cutting nozzle should ideally have 6 equal cones.
Bang, out of order
In normal circumstances when you turn off your torch you should turn off the fuel first, closing the fuel valve completely before closing the preheat oxygen valve.
The flame should not "snap" or "bang" when it is extinguished, if it does your nozzle may have a fault or you may not have sufficient fuel flow to maintain a stable flame. Check your nozzle and fuel supply - NOW!
Check before use
When using injector type cutting torches ensure you have the correct injector type for the fuel you are using. Using acetylene fuel with a torch designed for use with propane will result in an unstable operation and render the torch susceptible to sustained backfire the result of which will be injector damage making further stability problems more likely and may require complete torch replacement.

Gouging Nozzle Applications
Gouging nozzles may be mounted in straight line cutters and set-up to produce "J" edge plate preparation for welding, this requires less filler metal than usual plate preparation.
The smallest of the three sizes of AGNM gouging nozzle  (#13) may be used with a standard cylinder system, one oxy & one acetylene. 
Bothe the larger sizes (#19 & #25) require two full size acetylene cylinders to operate correctly with a stable preheat flame to maintain continuous productivity.
Alternatively switch to the Noz-Alls PGNM #13, #19 or #25 all manufactured from drilled copper  to improve product life.

Make Gouging Easy - Torch Type A
Gouging is generally much more easy to carry out through the use of a torch with a 180 degree or straight head.
To start your gouge the lighted nozzle needs to be angled acutely to the "weld" to be gouged.  As the ignition spot becomes apparent, for backward gouging, move to the furthest edge of the ignition spot introduce and bleed-in the "cutting" oxygen to the ignition spot moving the torch backwards through the spot whilst rotating the torch through an arc so "scooping" out the ignition spot.  Gouging is a skill that needs practice to master so keep practicing!

Make Gouging Easy - Torch Type B
When gouging use a torch that allows you to bleed the gouging oxygen in as you start to gouge.  Typically a torch with a control knob fitted to the lever or a torch that has a rotary cutting oxygen valve instead of the usual lever.  Being able to bleed the oxygen at the start prevents the gouge "running away"  and gives much greater control when gouging.

Hose Joints
Hoses should contain no more than three joins along their length.  Each joint must only be made with the correct brass hose splicer and “O” clips never worm drive clips. 
Never use copper joints with acetylene.  Static gas could form explosive compounds.
Never use steel joints with oxygen.  It is possible to have an oxygen ignition within the steel tube as the oxygen passes through the steel.

Nozzle Use
Nozzles will always function best when used with the correct operating pressures.  Setting pressures too high or too low will be detremental to performance, wasting gas and your time.

Fusion Welding - Oxy / Acetylene
Generally only acetylene fuel gas may be used for welding, there is no alternative.  Other fuel gases are promoted as an "alternative" to acetylene - the truth is that there isn't one.
Acetylene may be used for fusion welding due to the ability to set a "neutral" flame condition, acetylene will normally be set with an oxygen ratio of 1,1::1 - oxygen to acetylene. 
To set the correct flame for fusion welding the correct nozzle size is chosen and the correct operating pressures set - the correct operating pressures are very important, this is because the operating pressure directly affects the welding cone size and force./
Having correctly set the pressures and the yellow soot free acetylene flame the oxygen is introduced which results in the flame turning blue and the inner welding cone becoming increasing visible.  As the oxygen content increases the visable acetylene feather extending from the inner welding cone shortens.  The oxygen content is increased until the inner cone acetylene feather is reduced to nil.  The end of the inner welding cone should not be "crisp" the very tip of the welding cone should exhibit a slight haze to the tip of the inner cone - this is the correct setting for fusion welding.

The welding cone thus set will have the correct characteristics to weld adn develop the weld pool correctly providing the correct amount of heat and control.
When the nozzle size provides too much heat then the setting may generally be reduced by upto 50%  - reduce cone height by half.

Should you require more heat than the given nozzle size - don't increase the operating pressure / flow.  Move up a nozzle size - set correctly for the nozzle size - then reduce the flow to the heat output required.
All the tip the working flame cone should be set with the slight haze at the inner cone tip as this provides the neutral flame required for fusion welding.

Why Can't You Use Propane or Propylene For Welding?
All flame temperatures gained from combusting oxygen mixed with the fuel gas provide enough flame temperature to melt metal - typically the oxy / acetylene neutral flame temperature is 3106C with oxy / propylene giving 2872C and oxy / propane providing 2810C - all very capable of melting steel.  The difference is the volume of oxygen required to burn the fuel effectively - Oxy / acetylene uses almost equal volumes of gases being 1,1::1 whereas oxy / propane requires a mixing ratio of 4::1  (range between 3,75 to 4,3::1) and oxy / propylene would be set between 3,1 to 3,7::1  it is the very oxidising flame setting which precludes the ability to fusion weld.  If you are a good oxy / acetylene welder it is possible to obtain a run / joint - more difficult but possible - however the resultant weld is very brittle and full of porosity, put the place in a vice and bend the metal it fractures and breaks away.
Hence why oxy / propane .......... has never been used for fusion welding.

Brazing / silver soldering / bronze welding and lead welding are all possible with oxy / propane as well as cutting and heating of course.

Gas Equipment Safe & Correct Use
To prolong the life of your gas regulator, plus for the safety of yourself & those around you, you must always check that the regulator pressure adjusting screw is fully wound off, to the zero pressure condition, prior to opening the cylinder valve.
  Artisans that don't follow this procedure put themselves at risk and regularly damage equipment.  The most common consequence of this bad operating practice being regulators that need constant repair due to displaced diaphragms, evident from leaks around the bonnet and vent holes.
The reason  the diaphragm fails is due to the pressure setting of the regulator which holds the valve fully open as the gas pressure decays.  Next time the operator uses the equipment, not checking the pressure setting, the cylinder valve is opened and in that instant full cylinder pressure flows through on to the diaphragm which is easily displaced before the valve has been shut through the pressure  now being applied to the diaphragm. 

Cutting Nozzle Use - PNM-9 / PNME-9
When a two piece nozzle mixing nozzle sustains a backfire, damage to the nozzle can result very quickly. For this reason it is important to shut down the oxygen quickly so the sustained backfire may be extinguished. Turn off the fuel. Cool the nozzle and torch head then remove the nozzle for inspection and check for damage. Before lighting up, find out why you had a sustained backfire.  

HCV - Hose Check Valves
Hose check valves are a one way valve generally fitted to the blowpipe (torch) inlet connections. 
When new the idea is that the HCV help to prevent the back feeding of gases when you have incorrect pressures set or open up in the wrong way.
The HCV will never stop a flashback or backfire from passing through it - the speed of the flashback is so fast that the flash would pass through before the HCV valve has had time to close.
When you ignite a nozzle and it goes "bang" -
A) due to not iginiting correctly but the bang is also a "backfire"  with the flash travelling back along the hose - in the majority of cases it is the fuel hose as the oxygen is typically at a higher operating pressure, back feeds causing the mixture.
B) Incorrect operating pressures are being used for the given nozzle size.
C) Long hoses need to be purged for longer to prevent mixed gases or air and fuel being ignited.
Check your gas equipment for black soot at the mixer connection, torch inlet connections and FBA outlet connection this will show how far the backfire / flashbacks have travelled.
I have seen regulator bodies inside coated with thick black soot (Assumed that no FBA was used).

Many HCV fitted to hose sets do not meet the requirements of BS EN 730 - 2 or now BS EN 5175 -2 the HCV also have a very poor flow rate which causes operating problems with nozzles due to restricted flow.
Compare our HCV to those we tested from major suppliers.
Unfortunately because the hose assembly has been assembled to a standard - BS EN 1256 - it doesn't mean the fittings of HCV meet the relevant standards.
The HCV must be marked with the standard.