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Hydrogen Control in SMAW 2

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thien2002

thien2002

Mechanical
Aug 13, 2002
110
I have 2 questions from Certification Examination, please help if you have time to share your thought.

1. When hydrogen control is specified for a SMAW project, the electrode would normally be...
a. Cellulose
b. Iron oxide
c. Acid
d. Basic
*I think the answer is b., what do you think and why?

2. A repair organization has a WPS which states it is qualified for P-8 to P-8 material welded with either E308, E308L, E309, E316 Electrodes (SMAW process). The PQR this WPS, states the weld test coupons were.
SA-240 type 304L meterials, welded with E308 electrodes, Is the WPS properly qualified for the base material listed?
a. Yes
b. No
c. Not enough information given
d. Yes, if properly heat treated

Thank you all
Thomas
 
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1)
I have never heard "iron oxide" referred to for typical low hydrogen processes however the remaining choices do not work at all since cellulosic electrode (6010,6011) are not low hydrogen and acid/basic do not refer to SMAW electrode flux types.

The SFA 5.1/5.5 Specs refer to the as "Iron Powder".

2) Yes provided that is the only variables you are questioning and the applicable code is ASME Sec IX.

What kind of certification exam was this?

Gerald Austin
Iuka, Mississippi
 
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1) Iron oxide is the correct answer as the Oxygen acts in the plasma created by the arc as a scavenger for any free Hydrogen...

Gerald Austin asked, "What kind of certification exam was this?" I remember this question from my CWI exam using the AWS D1.1 ...
 
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Thank you both Pipewelder1999 and RJeffery. I think Iron Powder is a product name and Iron Oxide is the chemical name. Sometime it refers to as Iron Oxide Powder.

I don't know if the question no. 2 above should answer as a.YES or d.YES, IF HEAT TREATED PROPERLY.

I don't know if you can answer the question below which was on the FATIGUE FAILURE thread. Thank you so much for your assistance.


1. A fatigue failure is characteristic by the appearance of the fracture surface. It would be:
a. Rough and torn
b. Cheveron - like
c. Smooth
d. Non of the above

2. What constituent is needed in a coating of an electrode to prevent the formation of porosity in welding of rimming?
a. Iron powder
b. calcium fluoride
c. Silicon
d. Calcium carbonate
 
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1.d: Basic coated electrodes or basic electrodes are also known as low hydrogen electrodes: Refer E7016, E7018 and variations.
2.a

Fatigue failure:
1.c smooth with beach marks
2.c

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
 
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The Basic electrode is advised when we wantto control hydrogen . They had to be stored for sometimes at certain temperature.
 
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HYDROGEN
1. When hydrogen control is specified for a SMAW project, the electrode would normally be...
a. Cellulose
b. Iron oxide
c. Acid
d. Basic
*Answer/Explanation -
Rjeffery: b.Iron oxide is the correct answer as the Oxygen acts in the plasma created by the arc as a scavenger for any free Hydrogen... )
sayeeprasadr: d. Basic coated electrodes or basic electrodes are also known as low hydrogen electrodes: Refer E7016, E7018 and variations.

2. A repair organization has a WPS which states it is qualified for P-8 to P-8 material welded with either E308, E308L, E309, E316 Electrodes (SMAW process). The PQR this WPS, states the weld test coupons were.
SA-240 type 304L meterials, welded with E308 electrodes, Is the WPS properly qualified for the base material listed?
a. Yes
b. No
c. Not enough information given
d. Yes, if properly heat treated
*Answer/Explanation -
Rjeffery: a. Yes provided that is the only variables you are questioning and the applicable code is ASME Sec IX.
sayeeprasadr: a. Yes

FATIGUE FAILURE
1. A fatigue failure is characteristic by the appearance of the fracture surface. It would be:
a. Rough and torn
b. Cheveron - like
c. Smooth
d. None of the above
*Answer/Explanation -
sayeeprasadr:c.smooth with beach marks

2. What constituent is needed in a coating of an electrode to prevent the formation of porosity in welding of rimming?
a. Iron powder
b. calcium fluoride
c. Silicon
d. Calcium carbonate
*Answer/Explanation -
sayeeprasadr:c. Silicon
___________________________________________________________
Can you all please check the answers to make sure they have adequate explanation. I sayeeprasadr, I thought that Hydrogen Question no.2 should be a.Iron Powder.


 
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1.we use the low hydrogen electrode when we want to avoid "underbead cracking" and it MUST BE WITH BASIC ELECTRODE. Those electrodes have to be stored at 300°C for a minimum 1 h (generally ask the supplier for accurate parameters).
Iron-powder electrodes can be Low hydrogen, rutile, mineral, .... It's not necessary intended for hydrogen control welds

2.what I understand from your question : WPS qualified for P-8 to P-8 with E..... electrodes. You want to weld SA-240 304L with E308.
the SA-240 304L is a P-8.1. You had to check the other essential variable like thk, current, .... For me the answer is c.
 
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HYDROGEN
1. When hydrogen control is specified for a SMAW project, the electrode would normally be...
a. Cellulose
b. Iron oxide
c. Acid
d. Basic
*Answer/Explanation -
d. Basic coated electrodes or basic electrodes are also known as low hydrogen electrodes: Refer E7016, E7018 and variations. Iron powder is added to electrodes to improve the deposition efficiencies. Note that E7018 is an iron powder basic elctrode whereas E7016 is a basic elctrode without iron powder. The low hydrogen comes from the fact that the basic elcetrodes can be re-dried at 250 -350 Degrees C based on manufacturers reco and then stored in holding ovens at 100 Deg C, eliminating most of the absorbed mositure which is the origin for hydrogen in weldments.(That is why AWS?ASME Sec II C specify a maximum limit of 0.6% moisture in coating for E7016/E7018 but does not specify diffusible hydrogen in weld metal limits. The cellulosic canot be redried and the moisture content in coating is typically 5-10%. So the weld can never be low hydrogen(That is why Hot Pass is used).

2. A repair organization has a WPS which states it is qualified for P-8 to P-8 material welded with either E308, E308L, E309, E316 Electrodes (SMAW process). The PQR this WPS, states the weld test coupons were.
SA-240 type 304L meterials, welded with E308 electrodes, Is the WPS properly qualified for the base material listed?
a. Yes
b. No
c. Not enough information given
d. Yes, if properly heat treated
*Answer/Explanation -
a. Yes provided that is the only variables you are questioning and the applicable code is ASME Sec IX.
Note that the only confusion here should be about the group number. QW403.5 states that a change in group no is a supplemetary essential variable. Since these are stainless steels, impact testing would not be required unless the design temperature is below -100 Deg C. With the above, I would still go for a.

FATIGUE FAILURE
1. A fatigue failure is characteristic by the appearance of the fracture surface. It would be:
a. Rough and torn
b. Cheveron - like
c. Smooth
d. None of the above
*Answer/Explanation -
c.smooth with beach marks


Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
End of all knowledge is the attainment of immortality!
 
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Hi thien2002,
answer of first question:
1-d is correct answer. Basic electrodes (accordance AWS A5.1 and A5.5) are low hydrogen electodes in all fields.For example E7018 is a basic low hydrogen electrode.
(Your answer is incorrect because iron oxide electodes absorb moisture and have low metallurgical properties. You can see AWS handbook)

2-accordance ASME Sec IX qualified this PQR for base materials P No.8 Group No.1 if you don't need toughness conditions you can change group No. to other without requalification.(I must see list of masterials for correct answer)
3- c is correct answer.
4- c is correct answer. Ferro silicon add to cover of electode.
 
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Abver,
Was that message for me?? If so, the name is "Sayee" not "Sayed". Do you need me to give you a star???

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
The whole of science is nothing more than a refinement of everyday thinking!!! [thumbsup]
 
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