Weld porosity problem
Weld porosity problem
(OP)
Dear welding experts,
we are manufacturing longitudinal saw weld pipes of api 5l
weld groove: double v(internal saw and external saw)
recently we have weld 50 nos(12.2Meter length)of pipe of size dia.32"Xthi.39mm
we have done 100% Rt of each pipe & results no any porosity found. but after few days we have weld pipe size dia24"Xthi.38mm & rt results found porosity in every pipes.
both pipe size grade(Api 5l x-65) is same, joint geometry is same, saw welding consumables is same,same preheating temp and also we are taking extra care like cleaning of pipe , heating of flux in pipe size 24"X38mm.
then why porosity come in pipe size 24"x38mm in internal saw welding
we are manufacturing longitudinal saw weld pipes of api 5l
weld groove: double v(internal saw and external saw)
recently we have weld 50 nos(12.2Meter length)of pipe of size dia.32"Xthi.39mm
we have done 100% Rt of each pipe & results no any porosity found. but after few days we have weld pipe size dia24"Xthi.38mm & rt results found porosity in every pipes.
both pipe size grade(Api 5l x-65) is same, joint geometry is same, saw welding consumables is same,same preheating temp and also we are taking extra care like cleaning of pipe , heating of flux in pipe size 24"X38mm.
then why porosity come in pipe size 24"x38mm in internal saw welding





RE: Weld porosity problem
http://www.thefabricator.com/article/arcwelding/22...
RE: Weld porosity problem
Certainly seems like a problem with the material.
Is it from the same manufacturer ?
If so, is it same heat number ?
Do you have any off-cuts ?
If so put a 32" and 24" pup piece together with the longitudinal seams lining up.
Weld the SAW along both pipes at the same time and if one is OK and the other is full of porosity it is time to reject the 24".
Hope that helps,
Regards,
DD
RE: Weld porosity problem
Go to the source;
http://www.twi.co.uk/technical-knowledge/faqs/proc...
RE: Weld porosity problem
Best regards - Al
RE: Weld porosity problem
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Weld porosity problem
3. Insufficient flux burden can expose the arc and molten weld pool to atmospheric contamination.
RE: Weld porosity problem
we are using saw three tandam arc automatic welding and following steps I have all ready taken...
1. baking of flux as permanufacture recommendation( same flux batch for both size)
2. I throuly clean the pipe from internal side and external side by grinding and buffing.
3. machin taken for operation and electrical maintenance in which we have check all parameter, instrument and littel damage part replace by new.
4. I have raise preheating temp. 125C instead of 85C.
but stil two to three points of poro is coming in each pipe.
I have doute in following points.
1. due to lower dia of pipe generation of megnetic field is effect arc and resultant in arc blow may be entrept gases.
2. joint jeometry double v (means narrow gap between upper face and lowerface of two edges and no rootface gap )
is it root cause for porosity..????
RE: Weld porosity problem
we are using saw three tandam arc automatic welding and following steps I have all ready taken...
1. baking of flux as permanufacture recommendation( same flux batch for both size)
2. I throuly clean the pipe from internal side and external side by grinding and buffing.
3. machin taken for operation and electrical maintenance in which we have check all parameter, instrument and littel damage part replace by new.
4. I have raise preheating temp. 125C instead of 85C.
but stil two to three points of poro is coming in each pipe.
I have doute in following points.
1. due to lower dia of pipe generation of megnetic field is effect arc and resultant in arc blow may be entrept gases.
2. joint jeometry double v (means narrow gap between upper face and lowerface of two edges and no rootface gap )
is it root cause for porosity..????
RE: Weld porosity problem
Good luck getting to the root of the problem! These things can be exasperating sometimes.
http://www.lincolnelectric.com/en-us/support/weldi...
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Weld porosity problem
I realy need more guidance...