FW: Welding Superduplex

[BILLY TAN]

Dear Experts,

I have try to qualified repair procedure  14’inch superduplex pipe 30 mm thickness(UNS32750) where using purging and shielding gas 98% Ar and 2% N2.Unfortunately I failed on the pitting  corrosion testing(35⁰C)5g/m2 weigh loss(test required 4g/m2)G48 method A. Original weld pass at 0gram weigh loss. Piting was found at side(near excavation area) and root weld where the side of test piece is more severe . Heat input for root around 1.2KJ/mm and the rest passes are 0.8-1.1kjmm. Filler wire used is ER2594.

 

a)Can you guys provide information for the purging usually used( I am using only span), suitable environment for welding superduplex? 

b)Do we need to cut off the tip of the filler wire if it is oxidized(reused wire)?

c) Can we use power brush for interpass cleaningexclude capping?

d.) The deposite thickness is thin for every pass in order to get high travel speed/low heat input?

e)  I am using cleaning agent acetone to clean the bevel , does this matter?

  Please let me know if any goes wrong.

 

Weld details

1.)    Single V joint

2.)    Sample extract from to position. Welded 6G position.

3.)    Repair procedure. Excavation up to 6mm root ligament where as per drawing.

4.)   

5.)    Pitting corrosion picture

6.)    Interpass temperature <100⁰C

7.)    Oxygen level <50ppm, excavation method grinding.

8.)    Interpass cleaning, power brush.

9.)   

10.)

 

 

[ahmad elsharkawy]

Could you please what happen after that and what is the parameter you used to pass the corrosion test?

[Babur Khan]

Greetings,

Below here is major factors:

1. Mixture of Shielding gases (Or + N).

2. Cold Pass Techniques (second pass should be lesser heat input from root pass approximately 75% ).

3. Control heat input with normal root penetration and excess weld-metal.

  4. Filler wire with minimum diameter to reduce heat input.

Muhammad Babur Khan

Sr. Welding Inspector 

(CSWIP 3.2.2)

Sent from my iPhone

On 19 Sep 2022, at 9:33 AM, ahmad elsharkawy <ahmad.sh...@gmail.com> wrote:

[Muhammad Azeem]

Hi Ahmed,

We also suffer a lot of rejection for Super DUplex with same reason of COrrosion, Its better to revise the Gas mixture combination and control of heat inputs ..

Welding environments effects as well, Just arrange the area dust free ,humidity free. 

Regards,

Muhammad Azeem Iqbal

Welding Inspector Aramco Approved

053110-8577/0554453626/0590071467

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[J Prinsen]

Muhammad:

For Super Duplex: 

Use high Nitrogen containing backing/purge gas Ar/N2 80/20 or even full Nitrogen backing

Use root gap of 4 mm (to get enough filler (with higher Ni content) in the root)

First layer , rel thick (3mm) with heat input around 1.5 kJ/mm

Use interpass of 75 centigrade for root for second layer (cold pass) 

Second layer/Coldpass shall be thin, run fast, low heat input (1kJ/mm) to avoid baby austenite, which kills the corrosion resistance during the test

Keep interpass as low as possible (125 centrigrade)

This has been proven in the past

Regards

Jurgen Prinsen IWE/MSc

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Van: "Muhammad Azeem" <azee...@gmail.com>
Aan: "materials-welding" <material...@googlegroups.com>
Verzonden: Maandag 10 oktober 2022 11:31:22
Onderwerp: Re: [MW:33574] Re: FW: Welding Superduplex

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CAHqH7yD3p7Hu2crBrW9B%3DSfCeM2ggv7si2dfX%2BzfqUooEPTP5Q%40mail.gmail.com.