Hello
Nadeem,
Backing Gas Purge Times for Stainless Steel Pipe
Nominal Pipe Size
Purge Time (minimum)
2 inch NS
0.5 minutes
4
2 minutes
6
4 minutes
8
7 minutes
10
10 minutes
12
15 minutes
16
25 minutes
Assumes use of argon gas at a flow rate of 20 CFH (9 lpm).
Listed times are for each 300 mm of pipe length to be purged (multiply by actual length). Use the values for 300 mm for any shorter length.
Purge Time (minimum)
2 inch NS
0.5 minutes
4
2 minutes
6
4 minutes
8
7 minutes
10
10 minutes
12
15 minutes
16
25 minutes
Assumes use of argon gas at a flow rate of 20 CFH (9 lpm).
Listed times are for each 300 mm of pipe length to be purged (multiply by actual length). Use the values for 300 mm for any shorter length.
as per standards ASME
In order to obtain a suitably smooth,
uniform under side weld surface without crevices or oxidation,
a purge must be established using a suitable protective
gas. Since the second and third passes in the joint may
take the previously deposited consumable insert root pass
above the oxidizing temperature of the base and filler metal,
it may be necessary to maintain the purge until three layers
or 3⁄16 in. (4.8 mm) root thickness is obtained.
uniform under side weld surface without crevices or oxidation,
a purge must be established using a suitable protective
gas. Since the second and third passes in the joint may
take the previously deposited consumable insert root pass
above the oxidizing temperature of the base and filler metal,
it may be necessary to maintain the purge until three layers
or 3⁄16 in. (4.8 mm) root thickness is obtained.
most cases ,refer to project specifications from client (DGS)
T&R
Shyamal
On 31 January 2018 at 07:01, nadeem baig <mirzaanadeembaig@gmail.com> wrote:
Dear Friends--I need help regarding the reference from international standards for purging of stainless steel and alloy steel welding.RegardsNadeem
https://materials-welding.blogspot.com/
https://www.linkedin.com/groups/122787
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