Thanks for all response.
I did some study and I found that both ERW and DSAW pipe have been involved in SCC-related failures. There is no obvious unique metallurgical characteristics associated with the failures.
For the time being, I won't consider their corrosion resistance difference anymore.
Thanks for response. It is cooling water pipeline. Ambient temperature and low pressure. Our vendor want to use ERW pipes to substitute DSAW pipes. My concern is their corrosion resistance difference. If there is no much difference I think the substitution should be OK. How do you think?