Amine service and stainless steel

[marianito]

I'm not a material specialist, but in the office they give me a problem retaled with.
In a amine plant, using DIPA, the low temp/low pressure part of the plant is designed with ASTM A 516 Gr B, according to NACE 0103 (it's refinery), but in the high temperature part (after lean/rich exchanger) the piping (rich amine and lean amine section) is made with AISI 316, but without taking NACE/customer's sour service guidelines in account (PWHT/HB below 250 aprox).
Is it correct? Should we use NACE in this part too?

best regards

mariano suarez

mariano

 

[gr2vessels]

Marianito,
Are you the Client specifying the NACE MR0103 or the fabricator apllying the relevant Clauses?
Below is an excerpt from NACE MR0103, which refers to the responsibility of applying / using this standard;-
"1.2 Applicability
Clause 1.2.1
This standard applies to all components of equipment exposed to sour refinery environments (as defined in Paragraph 1.3) where failure by SSC would:
(1) compromise the integrity of the pressurecontainment
system, (2) prevent the basic function of the equipment, and/or (3) prevent the equipment from being restored to an operating condition while continuing to contain pressure.
Clause 1.2.2
It is the responsibility of the user to determine the operating conditions and to specify when this
standard applies.
Clause 1.2.3
It is the user’s responsibility to ensure that a material will be satisfactory in the intended environment."
Read also Clause 1.3.8, it is important.
The "NACE" standards are an indicative collection of recommendations and are not intended to prescribe a particular material to be used in a particular application. It helps, however, to guide the engineer in selecting the most suitable type of material for his application.
If you noticed a "hole" in the material selection process, you should flagged to the material selection people.
Please refer also to a previous thread338-183730 (sh*#@!!, I still don't know how to post a link!).
cheers,
gr2vessels

 

[marianito]

gr2vessels:
first, thank for your fast answer.
the problem/point is (maybe I didn't write as good as I have to) that in the rich amine zone, the basic eng provider says that no "special conditions" are requiered for the piping, because they're using AISI 316, with 0 mm of CA!!!
the rest of the plant, including the equipment associated with rich amine (strippers/pumps/reboilers) are NACE compliant, but they don't say anything about the piping, and that's what I think, it's because H2S has been absorbed by the DIPA, and there's no H2S free, but in the case of flashing, you have it again.....
In our opinion (EPC contractor) this piping has to be NACE compliant, but up tp now, we don't have the customer approval, and in this case, it means a lot of money....you know

thank you in advance

best regards

mariano

 

[gr2vessels]

marianito,
I'm unable to see what's your problem. It appears to me that your material selection for the rich amine section (austenitic stainless steel, grade 316;- perhaps 316L for fabrication)is correct and safe. The corrosion allowance of 0 mm is perhaps "lean", but is not unheard of. And all this is fully NACE MR 0103 compliant. Remember that most of the problems (cracking) are expected at rather lower temperature, even ambient, during the shut downs, not necessary at elevated temperature.
gr2vessels

 

[SJones]

Errrr - excuse me for asking, but why would you want a corrosion allowance on 316 stanless steel?

In addition, just adding a hardness limit to a 316 purchase specification should not add any cash to the bill.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/

 

[rustbuster]

Marianito,

316L is the best choice of material for the rich and hot lean piping with 0 CA. These systems are prone to flow accelerated corrosion < 3fs and ASCC in non PWHT CS.

SS affords higher fluid velocities and greater corrosion resistance. From much experience, (many failures)it is the right choice.

Regards

 

[marianito]

Thank you everybody for the answers.
Another question, always about the same is about the block valves and the amine drain system (control valves are NACE 0103).
Should the valves be requested as NACE compliant, in the rich amine circuit, before Lean/rich heat exchanger? How about the drains?
In the basic design package we' ve received, this part (including process drainage system) is NOT requested as NACE compliant. Is it correct? Or it has to be NACE, even the [H2S] is under the NACE aplication value?

Thank in advance

best regards

mariano

 

[gr2vessels]

marianito,
The system you are looking at is supposedly covered by the same specification;- all the process lines, including valves, pumps, etc must be "NACE" compliant. Please note that I'm including the wetted parts only. Perhaps your engineering supplier has already specified the correct valving materials, NACE MR0193 compliant and therefore has not added unnecessary comments of compliance.
The drainage system should normally be covered by the same specification, however it is up to the designer to evaluate the consequences of the drainage system failure and to specify the suitable materials accordingly.
cheers,
gr2vessels

 

[TomEun]

Why don’t you find API RP945 and API RP571, para.5.1.1.1.