welding in h2s (& maybe wet) service...in addition to NACE requirement

[engr2GW]

Hi all,
In a sour service (especially h2s) in O&G production. I have prepared the following:
WPS qualified with low hydrogen electrodes, NACE qualified with Vickers' hardness test, and pipe material used in production are most A 106 grade B or equivalent.
Is this enough to be used for sour service and the MAIN QUESTION IS;
What level of h2s (and may be C02) do I have to worry about additonal masures on the welding, e.g. pre-heat, PWHT, etc.

Thank you.

 

[blacksmith37]

If your conditions are on the "wrong" side of figure 1 or 2 ,it is NACE sour. There is no "more sour". The welding parameters (thickness, chemical comp. etc) are used to control hardness to pass the Vickers test.

 

[engr2GW]

@blacksmith37; I'm trying to figure out what you mean by thickness, chemical composition, etc. Is that for the electrode or the filler metals...?

lets say it's sour, and the WPS used have been tested for vickers hardness and meets NACE hardness number requirement, fill and cap electrodes are low hydrogen. Pipe material is A106 grade B type or equivalent.

At what point do I begin to require additional actions like; requiring pre-heat, material change (carbone equivalent) and what the actual C.E should be limited to. this is for sour service

 

[vesselfab]

I would think he is talking chemicals for plate.

HIC type plate.

we normally use Hic Quality, not certified, normalized, UT'd, CE of less than .42 and low carbon content.

Normalized flanges and forgings and 333-6 seamless pipe

 

[blacksmith37]

You need to adjust welding parameters when the hardness gets too high. ( I meant thickness ,chemistry of the base metal. Steels from "mini-mills" may conform to A 106, and have "high" residual alloy from the scrap.)
I suggest performing some hardness tests on production welds, not relying only on WPS/PQR coupons. Of course field hardness testing of weldments is a whole new adventure.