Austeninate Stainless Steel(ASTM 304, 316) Welding in Field

[ryu.changmyong]

Hi, Concerned person
Recently, I surprised when I heard of happening welding crack in area of stainless steel
since about 3 years of S.Steel welding in small size of 2-1/2"
When I review technical specification in feed water line where pressure is less than 50 psi.
it allowed to install pipe spool with
non-wleding method (compressing mechine) less than 2-1/2" size in order to avoid
any possible wleding crack.
so nowdays all most pipe welding below 2-1/2" pipe size is to do non-welding method.
So, I wonder that which method is more better between welding and pressing in a low pressure pipe line.

Kind regards,

ChangMyong

 

Do not attempt mitigation or repair until you understand the reason for failure. Based on the incomplete information there can be any number of causes.
Strongly recommend you retain a failure analyst who will examine the actual material, instead of asking the internet to speculate.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

There are many issues that cause cracking of SS welds.
But that said I have work on projects with more than 10,000 welds installed with zero cracks and zero leaks.
Swagged fittings may take less skill, but they still require special training to do correctly. And they don't like systems with deep thermal cycling.

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P.E. Metallurgy

 

[TugboatEng]

I assume you're referring to a press on system such as Viega Megapress. I see crevice corrosion being an issue with this system. Correct selection of sealing elements is essential. The biting ring is 420 stainless steel and may have issues in externally corrosive environment. The piping system is also available in copper nickel.

 

[EdStainless]

And in VicPress they are all 304 or 316 but there is an elastomer that will degrade over time. The o-ring isn't the primary seal but it can cause issues.

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P.E. Metallurgy