ASTM A790 UNS 31803 IMPACT TESTING

[AHMAD&MOHAMAD REDA]

Is it possible to make an impact test for PQR using ASTM A790 UNS 31803 AT -50C? PLEASE ADVICE

and if true and the specimen fails to met the requirement what can we do?
IS THE PWHT POSSIBLE TO MAKE THE SPECIMEN PASS THE TEST

thanks for your co operation and quick reply will be highly apprechiated

[pgoswami]

Hi Ahmad,

 

Passing impact test for DSS 31803 @ -50 Deg C could be tough.  A lot would depend  how the engineering variables for passing impact test  are taken into consideration at the first place as mentioned below:-

1. was the base material procured with impact test @ -51Deg C, if so what're the impact test  values
2. the same for filler wire or welding electrodes
3. welding process adopted, if it's GTAW the chances could be fair, SMAW touch and go , FCAW-No.

Only with the above considerations  one should proceed for impact test of DSS.

 

PWHT (say Stress Relieve) is not called for  while welding DSS. The only PWHT allowed is Soln Anneal, however you can't  solution anneal every weld joint. Soln anneal would definitely improve the impact properties.

 

See below the extract from API -TR-938C on impact testing of DSS.

 

 

What's the design code vs. the impact acceptance criteria asked for

 

Appreciate your feedback.

 

Thanks.

 

 

Pradip Goswami, P.Eng,IWE

Welding & Metallurgical Specialist

Ontario, Canada

pgos...@quickclic.net

pradip....@gmail.com

pradip_...@yahoo.ca

 

4.4 Low and High Temperature Properties

DSS with the proper structure can have adequate toughness for arctic ambient temperatures, but not for cryogenic applications. Minimum allowable temperatures are –51 °C (–60 °F) in the B31.3 Code and –29 °C (–20 °F) for some cases in the ASME Code Section VIII. These limits have qualifiers involving thickness, etc., and lower temperatures can be used by impact testing the material. Hence, actual limits are determined by reviewing the applicable Code.

The ASME Section VIII requirements for impact testing for DSS base and weld metals are given in UHA-51(d)(3).  They require impact testing of all DSS thicker than 10 mm (3/8 in.) or those with an MDMT less than –29 °C (–20 °F).

The toughness of weld deposits varies by the welding process due to the differences in the amount of oxygen in the weld typical for each process.Higher toughness is generally achieved with GTAW, PAW and GMAW than with SMAW, SAW and FCAW

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Sent: Wednesday, April 09, 2014 4:58 PM
To: material...@googlegroups.com
Subject: [MW:20549] ASTM A790 UNS 31803 IMPACT TESTING

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[Ramin Kondori]

Hi Ahmad:

My advise is that you need to be at lower acceptable ferrite levels to pass such impact. On the other hand, it is not recommended to achieve this with higher heat input. Use low heat input GTAW (or even Pulsed MIG if you can) and introduce N2 in your shielding gas in order to achieve higher austenite. Also be critical in following recommended practice for DSS welding (cleaning etc.).
  

Best Regards

Ramin Kondori

Sr. QA/QC engineer

Yadavaran Oilfield Project

SIPC (SINOPEC)

[Amitabha.B...@voestalpine.com]

Hi Ahmed,

Your attention is drawn to the  attached PDS of Avesta 2205 HF. This may help.

Thanks

 

With Regards

Amitabha Bhattacharya

voestalpine Bohler Welding India Pvt. Ltd.

voestalpine Bohler Application Technology Centre

M. +91-98 33998246

www.voestalpine.com/welding

[AHMAD&MOHAMAD REDA]

hi pgoswami

thank you sir for your co operation and quick reply the design code is ASME B31.3 AND  the acceptance criteria is 70j@-50 for individual specimen                          any way before your reply i asked for the mill certificate

(they take this condition because they said that the blow down for this line well be @-35 and this is a gas compression station)

thank u again and i hope to keep in touch with u

[pgoswami]

Hi Ahmed,

 

Please see the attached  data sheet on  DSS-31803  Grades form Norsok-M-630. Norsok standards are very specific and well accepted standards in upstream oil and gas industry. Impact test is specified  for both  DSS and SDSS grades @-46 DegC, with 45J Average and 35 J Minm for single specimen.

 

The requirements of  70 J @ -50 Deg C as specified below are extremely high.

 

Are your  vendors are in a position to comply 70 J @ -50 Deg C  requirements ?? With proper heat treatments one may get the same in base metal. However with matching welding consumables for DSS- 31803 it would be extreme Ely difficult to achieve the above impact values in  the welds in as welded condition.One may have to think about using over alloyed consumable ( as required).

 

The other option may be to switch to 254 type base metal. However this would be quite expensive.

 

My advise would be to revisit the impact test temperature. If the blow down line goes to -35 deg C max, while in operation, then why ask for impact @-50 Deg C.

 

Incidentally B-31.3 code allows lowest permissible design  temperature of -60 Deg F(-51 Deg C)  for DSS 31803, with 27J (Av) and 20 J  Min  impact values.

 

Thanks.

 

Pradip Goswami, P.Eng,IWE

Welding & Metallurgical Specialist

Ontario, Canada

pgos...@quickclic.net

pradip....@gmail.com

pradip_...@yahoo.ca

 

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From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of AHMAD&MOHAMAD REDA
Sent: Saturday, April 12, 2014 3:24 AM
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Cc: amred...@gmail.com; Amitabha.B...@voestalpine.com
Subject: Re: [MW:20568] RE: 20549] ASTM A790 UNS 31803 IMPACT TESTING