Mr. Andrews,
Answers are elaborate. To shorten it,
1.what are all the Quality check points while welding with SS?
a. Welding of SS special compared to CS.. Do not mix up CS with SS welding. Avoid using same hand gloves, grinding wheel, tongs or even the
same work area used for CS to avoid Carbon migration on SS . Handle SS carefully. Stake it vertically to avoid walking over it which forms serrations.
All above may lead to corrosion.. Use special SS grinding wheel to avoid clogging of gr. wheels. Do not use yellow-oil chalks(sulphur rich) for writing
on SS to avoid corrosion. Check currents as recommended by the manufacturers. Pickle and passivate S after welding. There are plenty more..
From: James cyrilandrew <jcyrilandrew@gmail.com>
To: Material welding groups <materials-welding@googlegroups.com>
Sent: Friday, 30 November 2012 10:51 PM
Subject: [MW:16095] Stainless Welding...
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Answers are elaborate. To shorten it,
1.what are all the Quality check points while welding with SS?
a. Welding of SS special compared to CS.. Do not mix up CS with SS welding. Avoid using same hand gloves, grinding wheel, tongs or even the
same work area used for CS to avoid Carbon migration on SS . Handle SS carefully. Stake it vertically to avoid walking over it which forms serrations.
All above may lead to corrosion.. Use special SS grinding wheel to avoid clogging of gr. wheels. Do not use yellow-oil chalks(sulphur rich) for writing
on SS to avoid corrosion. Check currents as recommended by the manufacturers. Pickle and passivate S after welding. There are plenty more..
2.how to check the discoloration while welding?
a.Use low currents (15 % or less) compared to MS welding. The weld or HAZ should not turn to blue, which means depletion of chromium (reaction with
Oxygen to form Cr -Oxides) The weld should be straw / light yellow, white to show non reaction. Stop the welding if required, to avoid over heating while welding..
3. purge time calculation?
a. It is difficult as it depends up on the length of plate, pipe dia etc. Purge till you make sure the oxygen is removed fully. Use a burning match stick (easier
method) to check the out flow of gas. Any left out oxygen may create oxidation at the root side and is not acceptable..
a.Use low currents (15 % or less) compared to MS welding. The weld or HAZ should not turn to blue, which means depletion of chromium (reaction with
Oxygen to form Cr -Oxides) The weld should be straw / light yellow, white to show non reaction. Stop the welding if required, to avoid over heating while welding..
3. purge time calculation?
a. It is difficult as it depends up on the length of plate, pipe dia etc. Purge till you make sure the oxygen is removed fully. Use a burning match stick (easier
method) to check the out flow of gas. Any left out oxygen may create oxidation at the root side and is not acceptable..
4. if thickness of the base material is less than 3mm what are all aspects shall be followed to maintain a good welding?
a. Use Pulsed TIG welding processes as it is gives very low heat input compared to normal /continuous weld.Pulsing is good for higher thicknesses also.
a. Use Pulsed TIG welding processes as it is gives very low heat input compared to normal /continuous weld.Pulsing is good for higher thicknesses also.
5. what is the distance calculation for purging?
a. Purging could be localized or to full length of the pipe if required. Purging could be 40 -50 % less to shielding pressure. gas inlet end could be around
50 to 75 mm or so from the weld cir-seam end if it is a pipe.
a. Purging could be localized or to full length of the pipe if required. Purging could be 40 -50 % less to shielding pressure. gas inlet end could be around
50 to 75 mm or so from the weld cir-seam end if it is a pipe.
6.how to determine the electrical parameter and shielding gas parameters,preheating details for GTAW while preparing proposed WPS for SS and NON FERROUS
MATERIALS?
a.SS do not require any pre heating. The inter pass temp. could be around 75 to 100 deg.C max.. The total heat input should be less or nearer to 1.0 Kj /mm.
Use stringer runs only. Do not use weave pass to avoid more heat input. The shielding gas pressure could be bet. 8 -10 -12 LPM. For non ferrous metals, heat
input could be around 2.0 Kj/mm. Use only DC EN for both SS & MS.
MATERIALS?
a.SS do not require any pre heating. The inter pass temp. could be around 75 to 100 deg.C max.. The total heat input should be less or nearer to 1.0 Kj /mm.
Use stringer runs only. Do not use weave pass to avoid more heat input. The shielding gas pressure could be bet. 8 -10 -12 LPM. For non ferrous metals, heat
input could be around 2.0 Kj/mm. Use only DC EN for both SS & MS.
(i checked with the AWS Sec II part c but i could not get it.)y
a. Codes do not spell these things. It is by experience and also available in the welding hand books.
Sridhar.
a. Codes do not spell these things. It is by experience and also available in the welding hand books.
Sridhar.
From: James cyrilandrew <jcyrilandrew@gmail.com>
To: Material welding groups <materials-welding@googlegroups.com>
Sent: Friday, 30 November 2012 10:51 PM
Subject: [MW:16095] Stainless Welding...
Dear all,
-- thanks for the support and clarifications for the past years with this group.
1.what are all the Quality check points while welding with SS?
2.how to check the discoloration while welding?
3. purge time calculation?
4. if thickness of the base material is less than 3mm what are all aspects shall be followed to maintain a good welding?
5. what is the distance calculation for purging?
6.how to determine the electrical parameter and shielding gas parameters,preheating details for GTAW while preparing proposed WPS for SS and NON FERROUS MATERIALS?
(i checked with the AWS Sec II part c but i could not get it.)
eagerly waiting for reply.
--
Regards,
J.C.Andrews
QA/QC Engineer
Doha-Qatar.
To post to this group, send email to materials-welding@googlegroups.com
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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