Re: [MW:16819] Pitting Corrosion Resistance Failure in DSS

Dear Mani,

1. Before planning for PQR, You have to confirm from Consumable Manufacturer that, Do they grantee their consumable to pass Corrosion test in accordance with ASTM 923 C, As most of Consumable Manufacturers prefer to test according to the ASTM G 48 Method (Which is actually standard for Pitting Corrosion Test, While ASTM 923 C is for Intergranular Corrosion Test).

2. Does your Project specification calls for Corrosion Test as per ASTM 923 Method C. If not, then go for ASTM G 48 C?

3. If ASTM 923 C is the requirement, then I shall suggest you to change Consumable Brand ( You may select Sandvik)

4. Which Welding Process, did you use?, If possible MIG can be useful, But there is no special restriction for using GTAW, SMAW or SAW. 

5. Conduct PQR Wedling according to all the recommendations of Consumable Manufacturer including those, shielding / purging gases & current ranges etc.

6. There is special technique with DSS & SDSS, depositing thick root pass and thin cold pass (as fast as welder can weld it).

7. Did you monitor Oxygen Level in Backing gas (if used) during welding, It should be less than 50ppm or according to Consumable manufacturer?

Regards

Tariq Hussain.

On Wed, Feb 20, 2013 at 6:08 AM, E.S.Mani <maniesbk@gmail.com> wrote:

Dear Experts,

We are welded DSS A790 UNS S31803 Pipe to pipe PQR welding and we sent it for Mechanical test. But we found PITTING.

The details are below and i attached the test result also.

Material                         :           A 790 UNS S31803 (Pipe to Pipe)

Size                              :           4" X 8.56mm

Filler Used                     :           ER2209 (Metrode) 2.4mm

Max. Interpass               :           Below 50ºC

Max. Heat Input             :           1.2 KJ/MM

Test Method                  :           ASTM 923 Methode C (22ºC – 24HRS)

Now we are planning to do the PQR again. So please give me you idea to avoid the failure again.

Thanks.

--

Regards,

E.Subramanian

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