Abstract: According to the need of a certain gas transmission pipeline project, a Φ610 mm×18 mm L290M SAWH pipe with ultra large SDR is researched and developed by a certain domestic company.Described here in the paper are the difficulties as concerned with the formation and welding operations which are encountered during the trial production process of the said SAWH pipe, and relevant adjustment and control measures as taken.Also analyzed are the physiochemical properties, the welding quality and the welding difficulties, etc.of the pipe.The results of the tests and inspections as made to the pipe show that all the technical indexes of the pipe are up to the applicable technical requirements.