304 or 316SS for chemical injection skid 2

[chemg]

Hi

We're checking the material requirement for one skid to feed bactericide into some process lines ( 45°C/113°F; 218psi), around 10l/h of Glutaraldehyde, Quaternary amine and THPS, each one for 6 days.

Currently, our standard is to use 304SS, but due to a fail in one weld we started to think a little more.

The Quaternary amine is pH 4-5 using ASTM E70, and the IATA is Class 8 packing group III
The THPS is pH 4 using ASTM E70, and the IATA is Class 8 packing group III
The Glutaraldehyde is pH 7 using ASTM E70, and the IATA is Class 8 packing group III

I supouse that we need is a material selection index, so if anyone known a good one it will be very helpfull.

Regards

AVC

 

[rustbuster]

Was it the 304 or 304L. What was the failure?

Try

http://www.corrosionist.com/

Resitance tables are good.

Good luck

 

[chemg]

The fail was due to acid attack on a weld...

Some of my coleagues said it's no reason to change it, because the fail might be in the weld and not due the material.

The material is 304, not L.

 

[Latexman]

I'm used to a batch-wise biocide system, where a water flush at the end of the addition is used to shorten the contact time of the biocides with the SS. Even with this water flush on biocides, we standardize on seamless tubing/pipe and forged fittings made of 316L for the same reason as you, we saw corrosion and failure at 304 and 304L welds after a few years (for us).

Sounds like you use biocides continuously. Not sure how that will factor in on a recommended material change, but I'd guess it makes your application tougher than mine.

Good luck,
Latexman

 

[mfelzien]

If your are having second thoughts due to a weld failure wouldn't you look at the type of welding-joints used and what welding process was used (SMAW or whatever) and the type of weld stick (Filler metal) was used? The failure wasn't in the actual 304SS.

In the petroleum industry each weld has a history such as RT/UT inspection and testing and weld method. The mechanical company usually has copies of this information (which is usually not given to the client). So, you would be able to find information on this particular failure.

Why revisit and change your company standards for one weld failure that may have not been up to the standards in the first place.

-MF

 

[europipe]

Saw that too, welds rusting through.
Sometimes nothing to do about it, even thoroughly pickling and passivating.
You can use pvdf or ptfe lined pipe.
Check chemical resistance.

 

[SJones]

Was the failure from the inside even? S30400 is falling down the league table of preferred materials in upstream and midstream oil and gas, principally because of its poor performance in respect of external corrosion. You will note that it does not feature in ISO 21457 Materials selection and corrosion control for oil and gas production systems.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04