Dear all ,
Can some one Tell me that why are we take pneumatic test of RF pad of
pressure vessels nozzle???
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Tuesday, March 31, 2015
[MW:23024] A QUERY CONCERNING TRIMMING/MODIFYING OF ELBOWS
Dear Experts,
A QUERY CONCERNING TRIMMING/MODIFYING OF ELBOWS
Can we use 90 degree elbow as 30 degree elbow by cutting it in aramco project, If any one Knows Aramco standard reference ?
Thanks.
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Monday, March 30, 2015
RE: [MW:23021] HOLDING OF ELECTRODES
GOSWAMI,
Thanks for your general infos.
I am interested in more infos about the influence of CaF2 on the arc stability( metal transfer)in the case when welded at electrode(e.g.E 7018)negative polarity.
In this case the cheracteristic diameter of the droplets increase and CaF2 MIGHT is the cause of this behaviour.We have to take into account ,fluoride ions have high mobility(they have small size) and tend to migrate toward to anode.Fluoride ions react with the layer of positive charges existing there and reduce the cathode spot size.The viscozity of molten metal also play the role in the metal transfer(deoxidizers existing in the electrode coating or electrochemical reactions that occur at the electrode prior to transfer).
Will be nice for us if you have more infos.
GIGI ZEGHEANU
EWE TOTAL E&P
--------------------------------------------
On Sun, 29/3/15, pgoswami <pgoswami@quickclic.net> wrote:
Subject: RE: [MW:23012] HOLDING OF ELECTRODES
To: materials-welding@googlegroups.com
Date: Sunday, 29 March, 2015, 22:00
GIGI ZEGHEANU,
I am not
sure what's your real concern on the coating and arc
stability issue with
respect to basic coated electrodes. This topic had been more
or less like
"proven and frozen truth" and many of the
formulations,
chemical ingredients and their weight percentages in the
coating, is
more of " manufacturer's closely guarded
secret".
Please see
below the extract from a TWI article( it's a 5 part
series). As this is a free
download , its assumed as no-proprietary.Many of such
articles are
downloadable in the web.
The arc
stability , fluidity of the weld puddle all depend on
the combined
effects of the various ingredients. Consumable
manufacturers has
to test electrodes with various formulations to meet AWS
or other
international standards. See the attached article from
Kobelco,which gives a
systematic breakdown of various coating constituents and
their effects.
Generally Low Hydrogen Potassium silicate electrodes are
proven to work equally
well in both DCEP and AC
polarities.
Thanks.
Pradip Goswami,
P.Eng,IWE
Welding & Metallurgical
Specialist
Ontario, Canada
pgoswami@quickclic.net
pradip.goswami@gmail.com
http://ca.linkedin.com/pub/pradip-goswami/5/985/299
http://www.twi-global.com/technical-knowledge/job-knowledge/welding-consumables-part-1-082/
Welding consumables - Part
2
Job Knowledge
Part
1
Part
3
Part
4
Part
5
The previous article, Part 1, dealt
with the cellulosic and rutile
electrodes. This article will cover the basic, iron powder
and acid
electrodes.
The description 'basic'
originates from the chemical
composition of the flux coating which contains up to perhaps
50% of limestone,
calcium carbonate (CaCO3). This decomposes in the
arc to form a gas
shield of carbon monoxide/dioxide.
In addition to the limestone there
may be up to 30% of
calcium fluoride (CaF2) added to lower the
melting point of the
limestone and to reduce its oxidizing effect. Also
deoxidants such as
ferro-manganese, ferro-silicon and ferro-titanium are added
to provide
de-oxidation of the weld pool.
Other alloying elements such as
ferro-chromium,
ferro-molybdenum or ferro-nickel may be added to provide an
alloy steel deposit.
Binders may be sodium silicate, only for use on DC+ve
current, or potassium
silicate which enables the electrodes to operate on both
direct and alternating
current.
The gas shield from basic electrodes is not as efficient
as that from the
rutile or cellulosic types and it is necessary to maintain a
constant short arc
if porosity from atmospheric contamination is not to be a
problem. The
electrodes are particularly sensitive to start porosity
because of the length of
time taken to establish an efficient protective shield. An
essential part of
welder training is familiarisation with the technique of
starting the weld ahead
of the required start position and moving back before
proceeding in the
direction of welding.
The penetration characteristics of basic electrodes are
similar to those of
rutile electrodes although the surface finish is not as
good. The slag cover is
heavier than rutile electrodes but is easily controlled,
enabling the electrodes
to be used in all positions. High limestone coatings have
been developed that
enable a limited range of electrodes to be used in the
vertical-down (PG)
position. The weld pool blends smoothly into the parent
metal and undercutting
should not occur.
The slag is not as easily removed as with rutile or
cellulosic electrodes but
the low melting point means that slag entrapment is less
likely. The chemical
action of the basic slag also provides very clean, high
quality weld metal with
mechanical properties, particularly notch toughness, better
than that provided
by the other electrode types. A further feature of these
electrodes is that the
welds are more resistant to solidification cracking,
tolerating higher levels of
sulphur than a rutile or cellulosic electrode. This makes
them valuable if it
becomes necessary to weld free cutting steels.
The basic electrode is also known
as a low hydrogen rod
('lo-hi'). The coating contains no cellulose and
little or no moisture provided
the electrodes are correctly handled. When exposed to the
atmosphere, moisture
pick-up can berapid. However, baking the electrodes at the
manufacturers'
recommended baking temperature, generally around 400°C,
will drive off any
moisture and should provide hydrogen levels of less than
5ml/100g weld metal.
After baking the electrodes need to be carefully stored in a
holding oven at a
temperature of some 120°C to prevent moisture
pick-up.
Many 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.
Basic, low hydrogen electrodes are therefore widely used
in a variety of
applications where clean weld metal and good mechanical
properties are required.
They can be obtained with alloyed core wires and/or
ferro-alloy additions to the
coating to give very wide selection of weld metal
compositions, ranging from
conventional carbon steels, creep resistant and cryogenic
steels and duplex and
stainless steels. Where high quality, radiographically or
ultrasonically clean
weld metal is a requirement, such as on offshore structures
and pressure
vessels, basic electrodes will be used.
Developments over the last 20 or so years have enabled
carbon-manganese steel
consumables to give good Charpy-V and CTOD values at
temperatures down to
-50oC. The low hydrogen capabilities also mean
that basic electrodes
would be used for the welding of thick section carbon steels
and high strength,
high carbon and low alloy steels where cold cracking is a
risk (see Job
knowledge articles Nos. 45 and 46).
In addition to the 'standard' cellulosic, rutile
and basic electrodes
discussed above, electrodes may be classified as 'high
recovery'.
By adding substantial amounts of iron powder, up to 50%
of the weight of the
flux coating, to either basic and rutile electrode coatings
it is possible to
deposit a greater weight of weld metal than is contained in
the core wire. These
electrodes are described as having an efficiency above 100%
eg 120%, 140% etc
and this 3 digit figure is often included in the electrode
classification.
The electrodes have thicker coatings than the
'standard' electrodes which can
make them difficult to use in restricted access conditions.
They are, however,
welder friendly with good running characteristics and a
smooth stable arc. The
iron powder not only melts in the heat of the arc to
increase deposition rate
but also enables the electrode to carry a higher welding
current than a
'standard' electrode.
The iron powder is electrically conducting, so allowing
some of the welding
current to pass through the coating. High welding currents
can therefore be used
without the risk of the core wire overheating, thus
increasing both the burn-off
and the deposition rates. The high recovery electrodes are
ideally suited for
fillet welding, giving a smooth, finely rippled surface with
a smooth blend at
the weld toes. They are generally more tolerant to
variations in fit-up and
their stability on low open circuit voltages means that they
are very good at
bridging wide gaps. However, the large weld pool means that
they are not suited
to positional welding and are generally confined to welding
in the flat (PA) and
horizontal-vertical (PC) positions.
The last type of electrode covering is described as
'acid'. These electrodes
have large amounts of iron oxides in the flux coating which
would result in a
high oxygen content in the weld metal and poor mechanical
properties. It is
therefore necessary to incorporate large amounts of
de-oxidants such as
ferro-manganese and ferro-silicon in the flux. Although they
produce smooth flat
weld beads of good appearance and can be used on rusty and
scaled steel items
the mechanical properties tend to be inferior to the rutile
and basic coated
electrodes. They are also more sensitive to solidification
cracking and are
therefore little used.
The next articles will cover specification and
classification of MMA (SMAW)
electrodes.
Part 3
Part 4
Part 5
From:
materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com]
Sent: Sunday, March 29,
2015 12:14 PM
To:
materials-welding@googlegroups.com
Cc:
pgoswami@quickclic.net
Subject: Re:
[MW:23011] HOLDING OF
ELECTRODES
Dear
all,
As
it's knows the coating of Low
Hydrogen Electrodes (basic electrodes) include CaCO3 and
CaF2(Calcium
Fluoride),ferroalloys (ferrosillicium, ferromaganese) and
iron
powder.
I would
like to open a discussion about
the arc(DCEN,DCEP) stability (effect of the CaF2,CaCo3
content of
coating):
-the arc
stability evaluated by conductivity
of the arc gap B (B=I/Ut where I,U and T are respectively
the current(A)
Voltage(V)and ignition time(sec)of the arc.)
-CaCo3/CaF2
ratio influence of arc
stability
-since the
slag of these electrodes contain
SiO2 and TiO2 oxides .melting of the electrodes has as
result intensive
interacation of these oxides with CaF2 with formation of
gaseous with influence
of arc stability.
Could
somebody provide more explanation/infos
concerning the above subjects?
GIGI
ZEGHEANU
EWE -
TOTAL E&P
From: pgoswami
<pgoswami@quickclic.net>
To:
materials-welding@googlegroups.com
Cc:
mechsivachidambaram@gmail.com
Sent: Sunday, 29 March
2015,
17:13
Subject: RE: [MW:23010]
HOLDING OF ELECTRODES
Mr.
Sivachidambaram,
Please see
the attached document for your guidance. If
these electrodes are
in " hermetically
sealed" packs, one may avoid rebaking.
There is no
specific time limits for
storage @ 150 Deg C, however
storing for months
would not be advisable.
You need to go with your electrode
manufacture's
recommendations.
Thanks.
Pradip Goswami,
P.Eng,IWE
Welding & Metallurgical
Specialist
Ontario, Canada
pgoswami@quickclic.net
pradip.goswami@gmail.com
http://ca.linkedin.com/pub/pradip-goswami/5/985/299
-----Original
Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com]
On Behalf Of safad pp
Sent: Sunday, March
29, 2015 2:12 AM
To: materials-welding@googlegroups.com
Subject:
Re: [MW:23009] HOLDING OF ELECTRODES
Dear
SIvachidambaram,
You can
keep it for continuously @ 150
deg .
Before that theses electrodes
shall be baked @ 250-300 deg for 2
hours
.Once should we take care
that, the required quantities of electrodes
should be taken for baking ,then
long time holding can be avoided . And also
when baked electrodes contact
with
room temp for more than 4 hours ,then
again re-bake required
.
Shafad P.P
CSWIP3.1 /AWS -CWI
On Sun, Mar 29, 2015 at 10:51
AM, Siva Chidambaram
<mechsivachidambaram@gmail.com>
wrote:
> Hi Friends,
>
> Can anybody guide me
that how long
shall i keep Low Hydrogen electrode
> on
a Holding oven at a temperature
of 150deg Cel.
>
>
> Regards,
> M.
SIvachidambaram
>
>
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Thanks for your general infos.
I am interested in more infos about the influence of CaF2 on the arc stability( metal transfer)in the case when welded at electrode(e.g.E 7018)negative polarity.
In this case the cheracteristic diameter of the droplets increase and CaF2 MIGHT is the cause of this behaviour.We have to take into account ,fluoride ions have high mobility(they have small size) and tend to migrate toward to anode.Fluoride ions react with the layer of positive charges existing there and reduce the cathode spot size.The viscozity of molten metal also play the role in the metal transfer(deoxidizers existing in the electrode coating or electrochemical reactions that occur at the electrode prior to transfer).
Will be nice for us if you have more infos.
GIGI ZEGHEANU
EWE TOTAL E&P
--------------------------------------------
On Sun, 29/3/15, pgoswami <pgoswami@quickclic.net> wrote:
Subject: RE: [MW:23012] HOLDING OF ELECTRODES
To: materials-welding@googlegroups.com
Date: Sunday, 29 March, 2015, 22:00
GIGI ZEGHEANU,
I am not
sure what's your real concern on the coating and arc
stability issue with
respect to basic coated electrodes. This topic had been more
or less like
"proven and frozen truth" and many of the
formulations,
chemical ingredients and their weight percentages in the
coating, is
more of " manufacturer's closely guarded
secret".
Please see
below the extract from a TWI article( it's a 5 part
series). As this is a free
download , its assumed as no-proprietary.Many of such
articles are
downloadable in the web.
The arc
stability , fluidity of the weld puddle all depend on
the combined
effects of the various ingredients. Consumable
manufacturers has
to test electrodes with various formulations to meet AWS
or other
international standards. See the attached article from
Kobelco,which gives a
systematic breakdown of various coating constituents and
their effects.
Generally Low Hydrogen Potassium silicate electrodes are
proven to work equally
well in both DCEP and AC
polarities.
Thanks.
Pradip Goswami,
P.Eng,IWE
Welding & Metallurgical
Specialist
Ontario, Canada
pgoswami@quickclic.net
pradip.goswami@gmail.com
http://ca.linkedin.com/pub/pradip-goswami/5/985/299
http://www.twi-global.com/technical-knowledge/job-knowledge/welding-consumables-part-1-082/
Welding consumables - Part
2
Job Knowledge
Part
1
Part
3
Part
4
Part
5
The previous article, Part 1, dealt
with the cellulosic and rutile
electrodes. This article will cover the basic, iron powder
and acid
electrodes.
The description 'basic'
originates from the chemical
composition of the flux coating which contains up to perhaps
50% of limestone,
calcium carbonate (CaCO3). This decomposes in the
arc to form a gas
shield of carbon monoxide/dioxide.
In addition to the limestone there
may be up to 30% of
calcium fluoride (CaF2) added to lower the
melting point of the
limestone and to reduce its oxidizing effect. Also
deoxidants such as
ferro-manganese, ferro-silicon and ferro-titanium are added
to provide
de-oxidation of the weld pool.
Other alloying elements such as
ferro-chromium,
ferro-molybdenum or ferro-nickel may be added to provide an
alloy steel deposit.
Binders may be sodium silicate, only for use on DC+ve
current, or potassium
silicate which enables the electrodes to operate on both
direct and alternating
current.
The gas shield from basic electrodes is not as efficient
as that from the
rutile or cellulosic types and it is necessary to maintain a
constant short arc
if porosity from atmospheric contamination is not to be a
problem. The
electrodes are particularly sensitive to start porosity
because of the length of
time taken to establish an efficient protective shield. An
essential part of
welder training is familiarisation with the technique of
starting the weld ahead
of the required start position and moving back before
proceeding in the
direction of welding.
The penetration characteristics of basic electrodes are
similar to those of
rutile electrodes although the surface finish is not as
good. The slag cover is
heavier than rutile electrodes but is easily controlled,
enabling the electrodes
to be used in all positions. High limestone coatings have
been developed that
enable a limited range of electrodes to be used in the
vertical-down (PG)
position. The weld pool blends smoothly into the parent
metal and undercutting
should not occur.
The slag is not as easily removed as with rutile or
cellulosic electrodes but
the low melting point means that slag entrapment is less
likely. The chemical
action of the basic slag also provides very clean, high
quality weld metal with
mechanical properties, particularly notch toughness, better
than that provided
by the other electrode types. A further feature of these
electrodes is that the
welds are more resistant to solidification cracking,
tolerating higher levels of
sulphur than a rutile or cellulosic electrode. This makes
them valuable if it
becomes necessary to weld free cutting steels.
The basic electrode is also known
as a low hydrogen rod
('lo-hi'). The coating contains no cellulose and
little or no moisture provided
the electrodes are correctly handled. When exposed to the
atmosphere, moisture
pick-up can berapid. However, baking the electrodes at the
manufacturers'
recommended baking temperature, generally around 400°C,
will drive off any
moisture and should provide hydrogen levels of less than
5ml/100g weld metal.
After baking the electrodes need to be carefully stored in a
holding oven at a
temperature of some 120°C to prevent moisture
pick-up.
Many 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.
Basic, low hydrogen electrodes are therefore widely used
in a variety of
applications where clean weld metal and good mechanical
properties are required.
They can be obtained with alloyed core wires and/or
ferro-alloy additions to the
coating to give very wide selection of weld metal
compositions, ranging from
conventional carbon steels, creep resistant and cryogenic
steels and duplex and
stainless steels. Where high quality, radiographically or
ultrasonically clean
weld metal is a requirement, such as on offshore structures
and pressure
vessels, basic electrodes will be used.
Developments over the last 20 or so years have enabled
carbon-manganese steel
consumables to give good Charpy-V and CTOD values at
temperatures down to
-50oC. The low hydrogen capabilities also mean
that basic electrodes
would be used for the welding of thick section carbon steels
and high strength,
high carbon and low alloy steels where cold cracking is a
risk (see Job
knowledge articles Nos. 45 and 46).
In addition to the 'standard' cellulosic, rutile
and basic electrodes
discussed above, electrodes may be classified as 'high
recovery'.
By adding substantial amounts of iron powder, up to 50%
of the weight of the
flux coating, to either basic and rutile electrode coatings
it is possible to
deposit a greater weight of weld metal than is contained in
the core wire. These
electrodes are described as having an efficiency above 100%
eg 120%, 140% etc
and this 3 digit figure is often included in the electrode
classification.
The electrodes have thicker coatings than the
'standard' electrodes which can
make them difficult to use in restricted access conditions.
They are, however,
welder friendly with good running characteristics and a
smooth stable arc. The
iron powder not only melts in the heat of the arc to
increase deposition rate
but also enables the electrode to carry a higher welding
current than a
'standard' electrode.
The iron powder is electrically conducting, so allowing
some of the welding
current to pass through the coating. High welding currents
can therefore be used
without the risk of the core wire overheating, thus
increasing both the burn-off
and the deposition rates. The high recovery electrodes are
ideally suited for
fillet welding, giving a smooth, finely rippled surface with
a smooth blend at
the weld toes. They are generally more tolerant to
variations in fit-up and
their stability on low open circuit voltages means that they
are very good at
bridging wide gaps. However, the large weld pool means that
they are not suited
to positional welding and are generally confined to welding
in the flat (PA) and
horizontal-vertical (PC) positions.
The last type of electrode covering is described as
'acid'. These electrodes
have large amounts of iron oxides in the flux coating which
would result in a
high oxygen content in the weld metal and poor mechanical
properties. It is
therefore necessary to incorporate large amounts of
de-oxidants such as
ferro-manganese and ferro-silicon in the flux. Although they
produce smooth flat
weld beads of good appearance and can be used on rusty and
scaled steel items
the mechanical properties tend to be inferior to the rutile
and basic coated
electrodes. They are also more sensitive to solidification
cracking and are
therefore little used.
The next articles will cover specification and
classification of MMA (SMAW)
electrodes.
Part 3
Part 4
Part 5
From:
materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com]
Sent: Sunday, March 29,
2015 12:14 PM
To:
materials-welding@googlegroups.com
Cc:
pgoswami@quickclic.net
Subject: Re:
[MW:23011] HOLDING OF
ELECTRODES
Dear
all,
As
it's knows the coating of Low
Hydrogen Electrodes (basic electrodes) include CaCO3 and
CaF2(Calcium
Fluoride),ferroalloys (ferrosillicium, ferromaganese) and
iron
powder.
I would
like to open a discussion about
the arc(DCEN,DCEP) stability (effect of the CaF2,CaCo3
content of
coating):
-the arc
stability evaluated by conductivity
of the arc gap B (B=I/Ut where I,U and T are respectively
the current(A)
Voltage(V)and ignition time(sec)of the arc.)
-CaCo3/CaF2
ratio influence of arc
stability
-since the
slag of these electrodes contain
SiO2 and TiO2 oxides .melting of the electrodes has as
result intensive
interacation of these oxides with CaF2 with formation of
gaseous with influence
of arc stability.
Could
somebody provide more explanation/infos
concerning the above subjects?
GIGI
ZEGHEANU
EWE -
TOTAL E&P
From: pgoswami
<pgoswami@quickclic.net>
To:
materials-welding@googlegroups.com
Cc:
mechsivachidambaram@gmail.com
Sent: Sunday, 29 March
2015,
17:13
Subject: RE: [MW:23010]
HOLDING OF ELECTRODES
Mr.
Sivachidambaram,
Please see
the attached document for your guidance. If
these electrodes are
in " hermetically
sealed" packs, one may avoid rebaking.
There is no
specific time limits for
storage @ 150 Deg C, however
storing for months
would not be advisable.
You need to go with your electrode
manufacture's
recommendations.
Thanks.
Pradip Goswami,
P.Eng,IWE
Welding & Metallurgical
Specialist
Ontario, Canada
pgoswami@quickclic.net
pradip.goswami@gmail.com
http://ca.linkedin.com/pub/pradip-goswami/5/985/299
-----Original
Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com]
On Behalf Of safad pp
Sent: Sunday, March
29, 2015 2:12 AM
To: materials-welding@googlegroups.com
Subject:
Re: [MW:23009] HOLDING OF ELECTRODES
Dear
SIvachidambaram,
You can
keep it for continuously @ 150
deg .
Before that theses electrodes
shall be baked @ 250-300 deg for 2
hours
.Once should we take care
that, the required quantities of electrodes
should be taken for baking ,then
long time holding can be avoided . And also
when baked electrodes contact
with
room temp for more than 4 hours ,then
again re-bake required
.
Shafad P.P
CSWIP3.1 /AWS -CWI
On Sun, Mar 29, 2015 at 10:51
AM, Siva Chidambaram
<mechsivachidambaram@gmail.com>
wrote:
> Hi Friends,
>
> Can anybody guide me
that how long
shall i keep Low Hydrogen electrode
> on
a Holding oven at a temperature
of 150deg Cel.
>
>
> Regards,
> M.
SIvachidambaram
>
>
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[MW:23022] How to protect Serration of Flanges during Hot dip galvanization
Dear Sirs,
Presently we are doing hot dip galvanization of pipe spools where we
have to protect the serration of flanges during galvanization.
Can any body suggest what can be applied on serration to protect it
from adhesion of ZINC on serration.
Please Advise.
Regards
Arvind
--
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Presently we are doing hot dip galvanization of pipe spools where we
have to protect the serration of flanges during galvanization.
Can any body suggest what can be applied on serration to protect it
from adhesion of ZINC on serration.
Please Advise.
Regards
Arvind
--
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Re: [MW:23023] Dillmax 690 weld cracks
hi..thanks.
read these docs...no clue on reasons on where we went wrong?
On Monday, 30 March 2015 14:27:08 UTC+5:30, Lalu r p wrote:
Hi,With all high strength, quenched and tempered fine grained structural steels, DILLIMAX steels are susceptible to cracking (Cold cracking) in the weld area if the conditions are unfavorable AND these cracks may not appear until 48 hours after welding. In order to ensure that the tensile strength of the weld metal fulfills the requirements of the base metal, the heat input and interpass temperature must be limited during welding. Please refer the attached data sheets for more information.regards,LALULINKS MIDDLE EASTABU DHABI, UAEOn Mon, Mar 30, 2015 at 11:00 AM, RK <krishn...@gmail.com> wrote:--Hi..We have used Dillimax 690PE material for our penstocks under construction.Experienced delayed cracking in welds (after a month or so) in all most all the welds...in all 3 welding processes used SAW, SMAW, FCAW...cracks are only in the welds!!!Process is PH 100-150 DegC, Interpass 200 Deg C and DHT 200-250 DegC for 3 hrs.Can anyone have any idea what could be the reasons?? we are in soup...and not able to proceed further..rgds
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Re: [MW:23020] Dillmax 690 weld cracks
The stresses appeared quite late. Usually cold cracks appear after 2 days. Are you sure for the correcteness of the stress analysis on which the joint design is based
From: LALU RAJENDRAN [lalucpt@gmail.com]
Sent: 03/30/2015 12:51 PM ZE4
To: "materials-welding@googlegroups.com" <materials-welding@googlegroups.com>
Subject: Re: [MW:23018] Dillmax 690 weld cracks
Hi,
With all high strength, quenched and tempered fine grained structural steels, DILLIMAX steels are susceptible to cracking (Cold cracking) in the weld area if the conditions are unfavorable AND these cracks may not appear until 48 hours after welding. In order to ensure that the tensile strength of the weld metal fulfills the requirements of the base metal, the heat input and interpass temperature must be limited during welding. Please refer the attached data sheets for more information.
regards,
LALU
LINKS MIDDLE EAST
ABU DHABI, UAE
On Mon, Mar 30, 2015 at 11:00 AM, RK <krishna.4969@gmail.com> wrote:
--Hi..We have used Dillimax 690PE material for our penstocks under construction.Experienced delayed cracking in welds (after a month or so) in all most all the welds...in all 3 welding processes used SAW, SMAW, FCAW...cracks are only in the welds!!!Process is PH 100-150 DegC, Interpass 200 Deg C and DHT 200-250 DegC for 3 hrs.Can anyone have any idea what could be the reasons?? we are in soup...and not able to proceed further..rgds
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This message contains confidential information. To know more, please click on the following link: http://disclaimer.bureauveritas.com --
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Re: [MW:23018] Dillmax 690 weld cracks
Gas cutting & grinding...
thickness 40 to 48 mm
photo i'm sending to your mail id..
thanks..
On Monday, 30 March 2015 14:13:56 UTC+5:30, vanchi wrote:
what method was used for joint preparation? gas cutting, grinding , machining ? what is the thk of joint.? can you take a photo of cracked joint and send. my mail id : vanchinaths @gmail.comOn Mon, Mar 30, 2015 at 12:30 PM, RK <krishn...@gmail.com> wrote:--Hi..We have used Dillimax 690PE material for our penstocks under construction.Experienced delayed cracking in welds (after a month or so) in all most all the welds...in all 3 welding processes used SAW, SMAW, FCAW...cracks are only in the welds!!!Process is PH 100-150 DegC, Interpass 200 Deg C and DHT 200-250 DegC for 3 hrs.Can anyone have any idea what could be the reasons?? we are in soup...and not able to proceed further..rgds
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Re: [MW:23018] Dillmax 690 weld cracks
Hi,
With all high strength, quenched and tempered fine grained structural steels, DILLIMAX steels are susceptible to cracking (Cold cracking) in the weld area if the conditions are unfavorable AND these cracks may not appear until 48 hours after welding. In order to ensure that the tensile strength of the weld metal fulfills the requirements of the base metal, the heat input and interpass temperature must be limited during welding. Please refer the attached data sheets for more information.
regards,
LALU
LINKS MIDDLE EAST
ABU DHABI, UAE
On Mon, Mar 30, 2015 at 11:00 AM, RK <krishna.4969@gmail.com> wrote:
--Hi..We have used Dillimax 690PE material for our penstocks under construction.Experienced delayed cracking in welds (after a month or so) in all most all the welds...in all 3 welding processes used SAW, SMAW, FCAW...cracks are only in the welds!!!Process is PH 100-150 DegC, Interpass 200 Deg C and DHT 200-250 DegC for 3 hrs.Can anyone have any idea what could be the reasons?? we are in soup...and not able to proceed further..rgds
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Re: [MW:23017] Dillmax 690 weld cracks
what method was used for joint preparation? gas cutting, grinding , machining ? what is the thk of joint.? can you take a photo of cracked joint and send. my mail id : vanchinaths @gmail.com
On Mon, Mar 30, 2015 at 12:30 PM, RK <krishna.4969@gmail.com> wrote:
--Hi..We have used Dillimax 690PE material for our penstocks under construction.Experienced delayed cracking in welds (after a month or so) in all most all the welds...in all 3 welding processes used SAW, SMAW, FCAW...cracks are only in the welds!!!Process is PH 100-150 DegC, Interpass 200 Deg C and DHT 200-250 DegC for 3 hrs.Can anyone have any idea what could be the reasons?? we are in soup...and not able to proceed further..rgds
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[MW:23015] Requesting to conform the material grade
Dear Sir,
I have a 2 chemical compositions one is Italian material another one is Brazilan material, Requesting you to conform the grade or any equivalent material in Indian grade.
Italy chemical composition
ELEMENTS % BY WT
C 0.243
Si 0.26
Mn 1.19
P 0.012
S 0.008
Cr 0.32
Ni 0.16
Mo 0.05
HARDNESS HRC: 43.7
Brazil chemical composition
ELEMENTS % BY WT
C 0.183
Si 0.80
Mn 1.34
P 0.026
S 0.014
Cr 0.14
Ni 0.11
Mo 0.04
HARDNESS HRC: 41.7
Anyone Please help me....
Regards
Vinay
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[MW:23015] Dillmax 690 weld cracks
Hi..
We have used Dillimax 690PE material for our penstocks under construction.
Experienced delayed cracking in welds (after a month or so) in all most all the welds...in all 3 welding processes used SAW, SMAW, FCAW...cracks are only in the welds!!!
Process is PH 100-150 DegC, Interpass 200 Deg C and DHT 200-250 DegC for 3 hrs.
Can anyone have any idea what could be the reasons?? we are in soup...and not able to proceed further..
rgds
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RE: [MW:23012] HOLDING OF ELECTRODES
GIGI ZEGHEANU,
I am not sure what's your real concern on the coating and arc stability issue with respect to basic coated electrodes. This topic had been more or less like "proven and frozen truth" and many of the formulations, chemical ingredients and their weight percentages in the coating, is more of " manufacturer's closely guarded secret".
Please see below the extract from a TWI article( it's a 5 part series). As this is a free download , its assumed as no-proprietary.Many of such articles are downloadable in the web.
The arc stability , fluidity of the weld puddle all depend on the combined effects of the various ingredients. Consumable manufacturers has to test electrodes with various formulations to meet AWS or other international standards. See the attached article from Kobelco,which gives a systematic breakdown of various coating constituents and their effects. Generally Low Hydrogen Potassium silicate electrodes are proven to work equally well in both DCEP and AC polarities.
Thanks.
Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Specialist
Ontario, Canada
Welding consumables - Part 2
Job Knowledge
The previous article, Part 1, dealt with the cellulosic and rutile electrodes. This article will cover the basic, iron powder and acid electrodes.
The description 'basic' originates from the chemical composition of the flux coating which contains up to perhaps 50% of limestone, calcium carbonate (CaCO3). This decomposes in the arc to form a gas shield of carbon monoxide/dioxide.
In addition to the limestone there may be up to 30% of calcium fluoride (CaF2) added to lower the melting point of the limestone and to reduce its oxidizing effect. Also deoxidants such as ferro-manganese, ferro-silicon and ferro-titanium are added to provide de-oxidation of the weld pool.
Other alloying elements such as ferro-chromium, ferro-molybdenum or ferro-nickel may be added to provide an alloy steel deposit. Binders may be sodium silicate, only for use on DC+ve current, or potassium silicate which enables the electrodes to operate on both direct and alternating current.
The gas shield from basic electrodes is not as efficient as that from the rutile or cellulosic types and it is necessary to maintain a constant short arc if porosity from atmospheric contamination is not to be a problem. The electrodes are particularly sensitive to start porosity because of the length of time taken to establish an efficient protective shield. An essential part of welder training is familiarisation with the technique of starting the weld ahead of the required start position and moving back before proceeding in the direction of welding.
The penetration characteristics of basic electrodes are similar to those of rutile electrodes although the surface finish is not as good. The slag cover is heavier than rutile electrodes but is easily controlled, enabling the electrodes to be used in all positions. High limestone coatings have been developed that enable a limited range of electrodes to be used in the vertical-down (PG) position. The weld pool blends smoothly into the parent metal and undercutting should not occur.
The slag is not as easily removed as with rutile or cellulosic electrodes but the low melting point means that slag entrapment is less likely. The chemical action of the basic slag also provides very clean, high quality weld metal with mechanical properties, particularly notch toughness, better than that provided by the other electrode types. A further feature of these electrodes is that the welds are more resistant to solidification cracking, tolerating higher levels of sulphur than a rutile or cellulosic electrode. This makes them valuable if it becomes necessary to weld free cutting steels.
The basic electrode is also known as a low hydrogen rod ('lo-hi'). The coating contains no cellulose and little or no moisture provided the electrodes are correctly handled. When exposed to the atmosphere, moisture pick-up can berapid. However, baking the electrodes at the manufacturers' recommended baking temperature, generally around 400°C, will drive off any moisture and should provide hydrogen levels of less than 5ml/100g weld metal. After baking the electrodes need to be carefully stored in a holding oven at a temperature of some 120°C to prevent moisture pick-up.
Many 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.
Basic, low hydrogen electrodes are therefore widely used in a variety of applications where clean weld metal and good mechanical properties are required. They can be obtained with alloyed core wires and/or ferro-alloy additions to the coating to give very wide selection of weld metal compositions, ranging from conventional carbon steels, creep resistant and cryogenic steels and duplex and stainless steels. Where high quality, radiographically or ultrasonically clean weld metal is a requirement, such as on offshore structures and pressure vessels, basic electrodes will be used.
Developments over the last 20 or so years have enabled carbon-manganese steel consumables to give good Charpy-V and CTOD values at temperatures down to -50oC. The low hydrogen capabilities also mean that basic electrodes would be used for the welding of thick section carbon steels and high strength, high carbon and low alloy steels where cold cracking is a risk (see Job knowledge articles Nos. 45 and 46).
In addition to the 'standard' cellulosic, rutile and basic electrodes discussed above, electrodes may be classified as 'high recovery'.
By adding substantial amounts of iron powder, up to 50% of the weight of the flux coating, to either basic and rutile electrode coatings it is possible to deposit a greater weight of weld metal than is contained in the core wire. These electrodes are described as having an efficiency above 100% eg 120%, 140% etc and this 3 digit figure is often included in the electrode classification.
The electrodes have thicker coatings than the 'standard' electrodes which can make them difficult to use in restricted access conditions. They are, however, welder friendly with good running characteristics and a smooth stable arc. The iron powder not only melts in the heat of the arc to increase deposition rate but also enables the electrode to carry a higher welding current than a 'standard' electrode.
The iron powder is electrically conducting, so allowing some of the welding current to pass through the coating. High welding currents can therefore be used without the risk of the core wire overheating, thus increasing both the burn-off and the deposition rates. The high recovery electrodes are ideally suited for fillet welding, giving a smooth, finely rippled surface with a smooth blend at the weld toes. They are generally more tolerant to variations in fit-up and their stability on low open circuit voltages means that they are very good at bridging wide gaps. However, the large weld pool means that they are not suited to positional welding and are generally confined to welding in the flat (PA) and horizontal-vertical (PC) positions.
The last type of electrode covering is described as 'acid'. These electrodes have large amounts of iron oxides in the flux coating which would result in a high oxygen content in the weld metal and poor mechanical properties. It is therefore necessary to incorporate large amounts of de-oxidants such as ferro-manganese and ferro-silicon in the flux. Although they produce smooth flat weld beads of good appearance and can be used on rusty and scaled steel items the mechanical properties tend to be inferior to the rutile and basic coated electrodes. They are also more sensitive to solidification cracking and are therefore little used.
The next articles will cover specification and classification of MMA (SMAW) electrodes.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com]
Sent: Sunday, March 29, 2015 12:14 PM
To: materials-welding@googlegroups.com
Cc: pgoswami@quickclic.net
Subject: Re: [MW:23011] HOLDING OF ELECTRODES
Dear all,
As it's knows the coating of Low Hydrogen Electrodes (basic electrodes) include CaCO3 and CaF2(Calcium Fluoride),ferroalloys (ferrosillicium, ferromaganese) and iron powder.
I would like to open a discussion about the arc(DCEN,DCEP) stability (effect of the CaF2,CaCo3 content of coating):
-the arc stability evaluated by conductivity of the arc gap B (B=I/Ut where I,U and T are respectively the current(A) Voltage(V)and ignition time(sec)of the arc.)
-CaCo3/CaF2 ratio influence of arc stability
-since the slag of these electrodes contain SiO2 and TiO2 oxides .melting of the electrodes has as result intensive interacation of these oxides with CaF2 with formation of gaseous with influence of arc stability.
Could somebody provide more explanation/infos concerning the above subjects?
GIGI ZEGHEANU
EWE - TOTAL E&P
From: pgoswami <pgoswami@quickclic.net>
To: materials-welding@googlegroups.com
Cc: mechsivachidambaram@gmail.com
Sent: Sunday, 29 March 2015, 17:13
Subject: RE: [MW:23010] HOLDING OF ELECTRODES
Mr. Sivachidambaram,
Please see the attached document for your guidance. If these electrodes are
in " hermetically sealed" packs, one may avoid rebaking. There is no
specific time limits for storage @ 150 Deg C, however storing for months
would not be advisable. You need to go with your electrode manufacture's
recommendations.
Thanks.
Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Specialist
Ontario, Canada
pgoswami@quickclic.net
pradip.goswami@gmail.com
http://ca.linkedin.com/pub/pradip-goswami/5/985/299
-----Original Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com] On Behalf Of safad pp
Sent: Sunday, March 29, 2015 2:12 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:23009] HOLDING OF ELECTRODES
Dear SIvachidambaram,
You can keep it for continuously @ 150
deg . Before that theses electrodes shall be baked @ 250-300 deg for 2
hours .Once should we take care that, the required quantities of electrodes
should be taken for baking ,then long time holding can be avoided . And also
when baked electrodes contact with
room temp for more than 4 hours ,then again re-bake required .
Shafad P.P
CSWIP3.1 /AWS -CWI
On Sun, Mar 29, 2015 at 10:51 AM, Siva Chidambaram
<mechsivachidambaram@gmail.com> wrote:
> Hi Friends,
>
> Can anybody guide me that how long shall i keep Low Hydrogen electrode
> on a Holding oven at a temperature of 150deg Cel.
>
>
> Regards,
> M. SIvachidambaram
>
> --
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[MW:23013] CS to SS PQR Qualification in AWS D 1.6
need to qualify a PQR of CS to SS in AWS D1.6.
-- Can you gentlemen please guide me with your expertise and knowledge.
Also a SAMPLE pWPS FORMAT would help a lot.
Thanks in advance :)
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Sunday, March 29, 2015
Re: [MW:23014] Reg - Etchant for Aluminum material
The following etching reagents and directions for their use are suggested for revealing
the macro structure.
Aluminum and Aluminum-Base Alloys
Hydrochloric acid (concentrated) 15 ml
Hydrofluoric acid (48%) 10 ml
Water 85 ml
This solution is to be used at room temperature, and etching is accomplished by either
Aluminum and Aluminum-Base Alloys
Hydrochloric acid (concentrated) 15 ml
Hydrofluoric acid (48%) 10 ml
Water 85 ml
This solution is to be used at room temperature, and etching is accomplished by either
swabbing or immersing the specimen.
U cane also refer to following:
| Etchant | Conc. | Conditions | Comments |
| Kellers Etch Distilled water Nitric acid Hydrochloric acid Hydrofluoric acid | 190 ml 5 ml 3 ml 2 ml | 10-30 second immersion Use fresh | For most aluminum and aluminum alloys |
| Methanol Hydrochloric acid Nitric acid Hydrofluoric acid | 25 ml 25 ml 25 ml 1 drop | 10-60 seconds | Pure aluminum, aluminum-magnesium, and aluminum-magnesium-silicon alloys |
| Krolls Reagent Distilled water Nitric acid Hydrofluoric acid | 92 ml 6 ml 2 ml | 15 seconds | Aluminum-copper alloys |
C Sridhar.
Technical Adviser - Welding,
for Alsta Pristine Engineering Private Limited,. Bangalore
( SS, AL fabricators & A venture of Advance Eng. Training & Inspection Services). Chennai,
Mobile nos: 0 94449 71097, 0 7406 326326, 0 94445 21267.
Technical Adviser - Welding,
for Alsta Pristine Engineering Private Limited,. Bangalore
( SS, AL fabricators & A venture of Advance Eng. Training & Inspection Services). Chennai,
Mobile nos: 0 94449 71097, 0 7406 326326, 0 94445 21267.
Please don't print this e-mail unless you really need to. Save the environment.
From: anand babloo <bravanand@gmail.com>
To: materials-welding@googlegroups.com
Sent: Wednesday, 25 March 2015 12:53 PM
Subject: [MW:23002] Reg - Etchant for Aluminum material
Dear Experts,
-- I need certain Aluminum weld samples to be Macro etched .
The grades of Aluminum are ALU 5052 & ALU 1050.
Kindly advice me that which etchant has to be used to reveal proper weld fusion.
Thanks in advance :)
Awaiting experts advice.
With regards,
R.Anand Raj
CSWIP 3.1 Welding Inspector
ASNT LEVEL II
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