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Associate

Join Date: Jan 2010
Location: pipe line project - KSA ( welding inspector - CSWIP 3.1)
Posts: 35

Welding by 7018 Electrode Without Heating

02/12/2010 6:15 AM

I work as consultant welding eng. in office in ksa in pipe line project, and when we started welding in the fitting we started using 7018 elctrode, and we told the contractor to put it in ovens an let it reached 230-300 c and start weld by it, but he said that this elctrode was treated to weld by it without heating.

And he said that if it is a now box and he open it in the start of the day he can weld by it till 8 hours without heating ,and if he will use this box in the next day he will heat it.

Is it true or not.

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Anonymous Poster
#1

Re: welding by 7018 elctrode without heating

02/12/2010 6:39 AM

Pre-heating a welding electrode to 230-300 C must have a purpose. So what is the purpose and where did you get this idea? Some electrodes have a layer of flux on them and this flux has a tendency to absorb moisture from the air. Such a "moist" electrode has an adverse effect on weld quality. It is therefore customary to keep the electrodes in a moderately heated chamber (box) to keep the electrodes dry. Most of the better suppliers of welding accessories have such drying boxes on sale. But the drying temperature is nowhere near to 230-300 C.

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Associate

Join Date: Jan 2010
Location: pipe line project - KSA ( welding inspector - CSWIP 3.1)
Posts: 35
#2
In reply to #1

Re: welding by 7018 elctrode without heating

02/12/2010 7:00 AM

I know from my studies and experience that the 7018 electode ia need to heating , i think that u did not read the title , i am sorry that i did mension that i am talking about 7018 elctrode.

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Anonymous Poster
#4
In reply to #2

Re: welding by 7018 elctrode without heating

02/12/2010 8:08 AM

It is recommended that the 7018 low hydrogen welding electrode be stored in a heated drying box at around 240-250 dg FAHREHEIT. This is to keep it dry. This is around 120 dg Celsius and not 250-300 dg C.

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Anonymous Poster
#3

Re: welding by 7018 elctrode without heating

02/12/2010 7:49 AM

The electrodes are baked at manufacturer's work in desiccating atmosphere and then packed in an hermatically sealed condition, so for all practical purposes they are dry.

After the pack is opened, the ambient will aid in moisture absorption of the highly hygroscopic flux. This obviously be related to the ambient (humidity) and time of exposure. If you are in a relatively low humidity area and can limit the exposure (reseal the pack/ tie the open end immediately after few electrodes are taken out) the rest of the electrodes will remain dry enough.

Another way is to keep these in a desiccant aided box or holding oven with temperature a bit higher than the ambient)

The baking at 3150C is resorted to only when the electrodes were not properly handled/stored and possibility of moisture absorption is high. The main disadvantage is thet there is a limit on the time and number of times these can be baked at this high temperature without adversely affecting the flux.

The electrode ahs to be baked is a mistaken notion. It has to be baked if the storing is improper.

And frankly, there are some of the standards that do allow 9 hrs (with the above conditions) for use without baking after the seal is opened.

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Participant

Join Date: Dec 2011
Posts: 1
#21
In reply to #3

Re: welding by 7018 elctrode without heating

12/21/2011 6:40 AM

The answer above is perfect. Can you please let me know the standards where this 9 hour time is given.

Further I would like to know whether there is any standard which provides the shelf life of such hermitically packed electrodes.

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Guru

Join Date: Aug 2005
Location: Hemel Hempstead, UK
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#22
In reply to #21

Re: welding by 7018 elctrode without heating

12/21/2011 6:57 AM

The post you replied to is over a year old.

I suggest you start a new thread, and, possibly refer back to that post with a link like this http://cr4.globalspec.com/comment/524596/Re-welding-by-7018-elctrode-without-heating

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Commentator

Join Date: Nov 2007
Location: Third Rock from the Sun (?)
Posts: 77
Good Answers: 8
#5

Re: Welding by 7018 Electrode Without Heating

02/12/2010 11:07 PM

You only need to heat the rods to a point warmer than the ambient temperature in order to prevent them from absorbing moisture once you open the can. I've seen some welding shacks that simply had an old refrigerator with a 100 watt light bulb in it to store welding rods in. It works like a charm. Just remember that the compressor should be inoperable. With that said, I've welded on plenty of projects that didn't heat the rods at all. If you are going to use them up in a couple of days they won't absorb enough moisture to make a difference. If the flux is breaking off of the rods then they have too much moisture. When the arc is thousands of degrees a little bit of moisture isn't going to make a whole heck of a lot of difference. inoperable.

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#6

Re: Welding by 7018 Electrode Without Heating

02/13/2010 12:31 AM

Greetings all,

I will throw my two cents worth in simply speaking from experience working in a very damp climate. ( southeast Alaska rainforest ) We normally will simply keep the rod in an o-ring sealed tube made just for rod storage. When you get back to the shop it is kept in an old refrigerator with a light bulb in it like the previous post mentioned. The only time we use the rod oven to bake it is when it has been sitting open too long or otherwise absorbed too much moisture. I might add that we will usually put our root pass in with 6010 or similar and then run with the 7018. There is an awful lot of pipe and structural welded here using this technique. We sometimes have to work with a helper holding a torch to dry or preheat the metal as we go but it always gets done.

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#7

Re: Welding by 7018 Electrode Without Heating

02/13/2010 1:13 AM

Both American Welding Society (AWS) and the American Society of Mechanical Engineers (ASME) have requirements for storing low hydrogen rod in ovens to prevent moisture absorption. How this requirement is implemented is by site specific procedures that can apply the most stringent, or the most lenient interpretation of this requirement. Certainly allowing 7018E shielded metal arc welding (SMAW) rod to be used right out of the can1 is a very carefree interpretation.

I suggest you follow whatever your administrative procedure directs for reporting a deficiency, and if possible issue a stop work order immediately. As the welding engineer; consultant or in-house2, you should write and seek approval for a Welding Rod and Filler Metal Handling and Storage procedure. With regard to this issue; the procedure should have the following requirements as a minimum:

i. Weld rod and other filler material shall be inspected upon delivery to the site.

ii. Low hydrogen electrodes (i.e. 7018E) delivered in undamaged packaging containers shall be placed in a calibrated rod oven for a minimum of 24 hours prior to use. Electrodes delivered with damaged containers shall not be used and any cost associated with replacement or delay shall be at the contractor's expense.

iii. Low hydrogen electrodes shall be transported to the work location in calibrated portable rod ovens where they shall be energized until transported back to the storage area, and transfered to the stationary ovens.

iv. These requirements shall be verified by regular inspection and surveillance by the welding engineer or his/her designee.

No disrespect intended, but this should be a non-issue. If you want a quality product, then make sure the crafts are following the applicable codes and standards. Don't let some contractor bully you around even if you don't know what you're talking about… act like you do. It's all about confidence, show some swagger!

Notes:

  1. Canned food containers are stronger.
  2. Otherwise known as Contractor Scum or Permanent Puke.
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Anonymous Poster
#8

Re: Welding by 7018 Electrode Without Heating

02/13/2010 8:31 AM

Just a correction on the above.

AWS D1.1 is clear if even the low hydrogen electrodes are recieved in a hermetically sealed, undamaged container from the manufacturer, no baking/conditioning is necessary.

Only when the reciept is in damaged condition then the required baking (260oC to 430oC as per AWS D1.1) is required. However the temperature and the cycle will be as recommended by the electrode manufacturer.

Check this

containers. When supplied in undamaged containers, they may be used without any preconditioning, orMany manufacturers now provide electrodes in hermetically sealed vacuum packs with hydrogen levels guaranteed to be less than 5ml/100g weld metal. These are particularly useful in site applications where there is a need to maintain very low hydrogen levels and baking and storage facilities are not available. The electrodes are taken directly from the pack and can be used for up to 12 hours from opening before sufficient moisture has been absorbed to require baking baking, before use. When SMAW electrodes are received in damaged containers or in non-hermetically sealed containers, AWS D1.1 requires that the electrodes be baked prior to use, in the range of 260oC to 430oC (500 to 800°F), to remove any residual moisture picked up from exposure to the atmosphere. The electrode manufacturer's guidelines should be followed to ensure a baking procedure that eliminates retained moisture, and these recommendations may vary from AWS D1.1 provisions.

Lincoln Electric

Low hydrogen stick electrodes must be dry to perform properly. Unopened Lincoln hermetically sealed containers provide excellent protection in good storage conditions. Opened cans should be stored in a cabinet at 250 to 300?F (120 to 150?C).

Electrodes in unopened Lincoln cans or cartons retain the proper moisture content indefinitely when stored in good condition.

Any low hydrogen electrode should be discarded if excessive re-drying causes the coating to become fragile and flake or break off while welding, or if there is a noticeable difference in handling or arc characteristics, such as insufficient arc force.

The AWS specifies in fact that "As recieved diffusible hydrogen content of the weld beads (made from the electrodes) should be less than the classification ratings.

Or here page 84 (11)

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#9
In reply to #8

Re: Welding by 7018 Electrode Without Heating

02/13/2010 11:38 AM

In my response I was referring to storage requirements. I don't have copies of the current codes, (or any welding codes at hand) just some handbooks and field guides. From memory I recall storage requirements for E7018 rod to be to 250°F to 300°F (120°C to 150°C). Storing for 24 hours after receipt, and prior to use is precautionary as those temperatures are not high enough for reconditioning. Reconditioning temperatures; as I recall, are in the 650°F to 750°F (340°C to 400°C) range. I don't remember the soak time. I have verified the preceding temps on the internet

This issue is critical to the performance of welds requiring this electrode, whether they are structural or pressure retaining. Better to have a conservative approach that eliminates the potential for the presence of moisture leading to failures than to have to perform the analysis and remedial actions that will be necessary.

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Anonymous Poster
#10
In reply to #9

Re: Welding by 7018 Electrode Without Heating

02/13/2010 12:25 PM

You are right, I have seen too many times that though we specify the manufacturer and the type of electrode to be "R", the contractor rarely adhere to them (unless caught in the act )

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Commentator

Join Date: Dec 2007
Location: Pekin, IL USA
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#11

Re: Welding by 7018 Electrode Without Heating

02/13/2010 5:36 PM

The conservative approach is the only direction to take with materials that are susceptible to under-bead cracking. Usually whatever code that you are welding to will detail the process. API, AWS or whatever. It's the hydrogen trapped in the weld that makes the difference. Depending upon materials, the defect may not be detectable for several days.

Some codes limit the maximum amount of time that the rod can be out of the oven and do not allow re-bake. You can get by with cutting corners until the pipe line fails. Oops. Preheat of the pipe is a prerequisite unless your welding mild steel.

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#12
In reply to #11

Re: Welding by 7018 Electrode Without Heating

02/13/2010 7:02 PM

Randouli; Thank you for your vote for a conservative approach and for mentioning the different codes.

On the same project or job there may be welding activities under several different codes. AWS D1.1 for structural, ANSI/ASME B31.1 for power piping, or ASME for pressure vessels. The system of welding material control must meet the most stringent requirements of these or there is too high a risk for noncompliance.

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Commentator

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#13

Re: Welding by 7018 Electrode Without Heating

02/15/2010 1:49 AM

The Contractor is right provided the electrodes were supplied in hermetically sealed containers. Preheating is required when electrodes have started producing porosity in weld puddle. This happens only when flux of the electrodes have absorbed moisture from atmosphere. Some time thinner electrodes (3/32" and 1/8" ) are not heated in dry weather for preheating of electrodes is done during welding itself. Slow weaving of welding technique generates resistance in electrodes and the electrodes are preheated before it melts. Preheating of electrodes size 5/32" and 3/16" are preheated the very first day of opening of sealed container. Requirement of preheating depends up on the weather condition.

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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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#14

Re: Welding by 7018 Electrode Without Heating

02/15/2010 12:54 PM

• Low Hydrogen family of filler metals as per ASME code, Section II, Part C, SFA-5.1, Table 1:

E7015 Low hydrogen sodium

E7016 Low hydrogen potassium

E7018 Low hydrogen potassium, iron powder

E7018M Low hydrogen iron powder

E7028 Low hydrogen potassium, iron powder

E7048 Low hydrogen potassium, iron powder

• Table A2 of ASME code, Section II, Part C, SFA-5.1 explains the typical storage and drying conditions for covered arc welding electrodes.

• Very important notes for low hydrogen electrodes:

1. Each welder have a job using low hydrogen electrodes must have a covered electrode can to store a few of electrodes which picked up from the electrode drying oven to maintain the electrodes in a hot condition up to use it in welding.

2. Use the recommended welding direction of that family of low hydrogen electrodes, which mainly for E7018 it must be uphill, and no way for welder to use it downhill.

3. The user of electrodes must read and strictly follow the recommendations of filler metal's producer that located and recorded at electrode box.

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#15
In reply to #14

Re: Welding by 7018 Electrode Without Heating

03/25/2010 1:32 PM

In one way the contractor is right , when he says the electrodes could be used without baking/ re-drying within a prescribed period of hours. The electrodes are baked at manufacturer's end in desiccating atmosphere and then packed in an hermetically sealed condition, so for all practical purposes they are dry.

These electrodes are grouped under the category of AWS SFA 5.1 E 7018 H4R. They are moisture resistant, hydrogen controlled,vacuum packed, basic coated.

Due to vacuum packing they do not require expensive treatment like re-drying at 250 deg. C for 2 hours or at high temperatures.

The hydrogen content of weld deposit when measured in accordance with AWS/ANSI 4.3-86 specification will be 4 ml/100 gms weld deposit. The typical values are between 1.5 to 200 ml/100 gms of weld deposit only. Thus the Hydrogen level is much lower compared to normal level of <15 ml/100 gms. of weld deposit in general category.

The deposited weld metal will meet X-ray quality standards and good for 6G/6GR positions and has a UTS value of 520/580 N/mm2 due to its lower impurities level.

The limitations are, the electrodes should be consumed within a period of 6 hrs. or so when the seal of the container broken. The cost of the electrodes are higher compared to normal category of E 7018 type electrodes.

Sridhar.

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#16
In reply to #15

Re: Welding by 7018 Electrode Without Heating

03/25/2010 1:40 PM

Sorry . There is one correction.

"The typical values are between 1.5 to 200 ml/100 gms of weld deposit only".

It should be read as

"The typical values are between 1.5 to 2.00 ml/100 gms of weld deposit only".

Thank U all.

Sridhar.

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Anonymous Poster
#17
In reply to #15

Re: Welding by 7018 Electrode Without Heating

03/25/2010 1:49 PM

This was covered in #3 and #8 with all relevant informations.

However in this forum, the guests are not heard .

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Anonymous Poster
#18

Re: Welding by 7018 Electrode Without Heating

09/26/2010 3:52 AM

Yes it is true, If it is vacuum pack, it shall be used with out heating for a period of max 12 hours or as per manufacturer's recomendations

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Anonymous Poster
#19

Re: Welding by 7018 Electrode Without Heating

09/26/2010 7:46 AM

It may also be noted that as per quite a few codes (including AWS) the electrodes must be re-baked only once- so if you unnecessarily bake, you may land up with a truck load of rejected electrodes.

UD15

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Join Date: Dec 2007
Location: Pekin, IL USA
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#20
In reply to #19

Re: Welding by 7018 Electrode Without Heating

09/26/2010 12:49 PM

Preheat the oven at 350 degrees F. Put the rods in an oven bag and seal tightly. Bake at 350 degrees for one hour and turn over. Finish baking until the oven bag is dry inside. Remove from the oven and rinse in cold water to cool the rods to the touch. Deposit the rods in the trash and use a MIG or dual shield. Pulse preferred.

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Abdel Halim Galala (1); AbdulWasay (1); Anonymous Poster (8); galal_elden (1); nilay.ball (1); PMoon (3); Randall (1); Randouli (2); Sourdough (1); SRIDHAR (2); vagabond (1)

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