RE: [MW:23590] Re: NEED ADVISE CORROSION IN INHIBITOR TANK REGD

1 -Should try passivization after pickling 

Nitric Acid Passivation of Stainless Steels
—Chromium-Nickel Grades (300 Series) —Grades with 17% Chromium or more (except 440 Series)	20% by vol. nitric acid at 120/140°F (49/60°C) for 30 minutes
—Straight Chromium Grades    (12-14% Chromium) —High Carbon-High Chromium Grads (440 Series) —Precipitation Hardening Stainless	20% by vol. nitric acid + 3 oz. per gallon (22 g/liter) sodium dichromate at 120/140°F (49/60°C) for 30 minutes or 50% by vol. nitric acid at 120/140F (49/60°C) for 30 min.

Passivation is a post-fabrication method of maximizing the inherent corrosion resistance of the stainless alloy .

2 -Painting option :

a)surface preparation :

Abrasive blasting can be accomplished by using clean, fine, hard non-metallic abrasive particles (e.g. alumina or silicon carbide). The abrasive medium must be iron-free to avoid contamination, which can result in rust staining on the surface prior to coating and the compressed air carrying the abrasive medium must be free of compressor oil.

b) Prior to coating, all stainless steel surfaces must be dry and free from rust, other foreign materials, oil and grease. The presence of such contaminants may lead to failure of the coating system.

c) coating application and system 

he table below gives details of paint systems suitable for coating stainless steels and, in accordance with ISO 12944 and ISO 9223, classifies them in terms of the severity of the envisaged service environment.

Exterior Environment			Coating System
Category	Corrosion Risk	Location	.
C3	Medium	Rural and urban areas with low sulphur dioxide, acid, alkali and salt pollution	Two pack epoxy or polyurethane primer suitable for stainless steel at 30-50 micron dry, FOLLOWED BY High solids polyurethane finish at 100 micron dry
C4	High	Urban and industrial areas with moderate sulphur dioxide and/or coastal areas with low salinity	Two pack epoxy or polyurethane primer suitable for stainless steel at 30-50 micron dry, FOLLOWED BY High build epoxy MIO* at 100 mm dry, FOLLOWED BY Re-coatable polyurethane finish at 60 micron dry
C5I	Very High	Industrial areas with high humidity and aggressive atmospheres	Two pack epoxy or polyurethane primer suitable for stainless steel at 30-50 micron dry, FOLLOWED BY High build epoxy MIO* at 200 micron dry (one or two coats), FOLLOWED BY Re-coatable polyurethane finish at 60 micron dry
C5M	Very High	Coastal and offshore areas with high salinity	Two pack epoxy or polyurethane primer suitable for stainless steel at 30-50 micron dry, FOLLOWED BY High build epoxy MIO* at 200 micron dry (one or two coats), FOLLOWED BY Re-coatable polyurethane finish at 60 micron dry

MIO = Micaeous Iron Oxide

Cleanliness is extremely important in the successful application of paint coatings to stainless steels surfaces. Paint coatings should be applied in clean, dust-free conditions to clean, dry stainless steel surfaces.

If the correct precautions are taken, the complete coating systems suggested in the table can be applied in 'on-site'.

Best Regards 

Elias 

---

Subject: [MW:23584] Re: NEED ADVISE CORROSION IN INHIBITOR TANK REGD
To: neilashkumar@yahoo.com
CC: materials-welding@googlegroups.com
From: george.dilintas@gr.bureauveritas.com
Date: Tue, 29 Sep 2015 10:04:06 +0300

It looks like iron contamination.
Actions to implement:

1. Removal of rust by stainless steel compatible brushes/disks.
2. Pickling
3. Avoid contact with carbon steel tools, jigs etc

best regards

Dr. Georgios Dilintas

Authorized Nuclear Inspector
Authorized Inspector Supervisor

I&F REGIONAL TECHNICAL MANAGER
BUREAU VERITAS PIRAEUS - GREECE

Tel: +30 210 40 63 113 /4 /5
Fax: +30 210 40 63 118
Cell: +30 69 44 64 62 04


Neilash Kumar ---29/09/2015 09:56:39--- Dear Sir, Good Morning, please find the attached tank drawing

From: Neilash Kumar <neilashkumar@yahoo.com>
To: George H Dilintas/GRC/VERITAS@VERITAS, Welding Groups <materials-welding@googlegroups.com>
Date: 29/09/2015 09:56
Subject: NEED ADVISE CORROSION IN INHIBITOR TANK REGD

---

 Dear Sir,

Good Morning, please find the attached tank drawing
fabricated by us for our client & it is corroded fully ,
Can you please clarify,
1. Why the tank are corroded So fast?
2. Can you please advise us the method to stop /reduce the rate of corrosion by applying a top coat &  what
type of coating to be applied?

please advise me . Material is 316L tank.

Regards
P.Neilashkumar[attachment "20150909_102338.jpg" deleted by George H Dilintas/GRC/VERITAS] [attachment "20150909_102358.jpg" deleted by George H Dilintas/GRC/VERITAS]
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