[MW:8108] RE: USE OF ER80S-Ni1 FOR WELDING IN SERVICE WHICH CONTAIN CO2

Phillip,

 

ER 80SNi-1 filler contains around 1% Nickel.For low temperature impact toughness on Carbon steel welds this consumable could be a perfect choice. In offshore oil and gas CO2 corrosion is quite prevalent, subject to the pressure, temperature and the concentration (Mol fraction ) of the gas and presence of Nacl and H2S.

Though theoretically ER 80SNi-1 weld is superior to base metal with respect to mechanical and chemical properties , there are  many instances of Preferential Weld Corrosion (PWC) of such welds in wet CO2 for offshore oil and gas services. Alloyed consumables containing only "Ni" as alloying element may not withstand the service environment. I would say a change has to be fully scrutinized,until and unless the welds have passed the client specified  CO2corrosion tests and are duly accepted.

 

In such cases matching chemistry ER-70S2/S3/S6 filer or ER-80S-G filler(Containing Cr,Ni and or Mo-see below) may be better choices. If could send me more details and welding  requirements  I can send more advice to you.

 

If the design conditions are for onshore process plants, then ER-80S-Ni1 could be used subject to the facts that it should meet the construction code requirements.

 

Meantime  the attached  documents( both from TWI-UK) would provide you some form of guidance.

 

Thanks

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Specialist & Consultant

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

Preferential weld corrosion: Effects of weldment microstructure and

composition

C-M Lee, S Bond and P Woollin

TWI Ltd

Great Abington

Cambridge CB1 6AL

UK

Paper presented at NACE 2005 Houston, Texas, 3-7 April 2005

Abstract

Preferential weldment corrosion (PWC) of carbon and low alloy steels used for pipelines and process piping systems in CO 2 -containing media has been observed increasingly in recent years. In particular, this has been on weldments made by the manual metal arc (MMA) process using electrodes containing Ni or Ni plusCu. This paper presents the results of a joint industry research programme which was conductedcollaboratively by three research organisations to investigate this corrosion mechanism and to seekpractical solutions.

The effect of composition and microstructure on PWC in CO 2 -containing media was investigated on 12weldments produced in X52 and X65 grade pipe materials using TIG and MMA processes. Corrosion tests were conducted in a re-circulating vessel on segmented weld electrodes in

CO 2 -containing media, with two levels of chloride content. The addition of increased amounts of nickel and silicon was detrimental,whilst additions of molybdenum and chromium (of up to 0.7wt%) did not give improvements in PWC behaviour. Autogenous weldments, made without filler additions, and weldments made with matchingcomposition consumables gave the best PWC resistance. It is also shown that empirical relationships existbetween PWC and hardness levels and microstructure, with unrefined microstructures, having highhardness, being detrimental. The implications of the data for design of welding procedures to minimise PWC are considered.

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From: Philip Drisu [mailto:darephilip@yahoo.com]
Sent: Friday, November 05, 2010 3:00 PM
To: materials-welding@googlegroups.com
Cc: pgoswami@sympatico.ca; pgoswami@quickclic.net
Subject: USE OF ER80S-Ni1 FOR WELDING IN SERVICE WHICH CONTAIN CO2

Hello  gents  in the  House,

 

 is  the  Use of ER80S-Ni1  consumable  for welding GTAW  process  not acceptable in services which may contain wet CO₂   

 for welding  basemetal, P1 Group 1 to  P1 Group 1.

 

Best Regds

Oluwadare.