The results of a major TWI project are already helping the oil and gas industry to cut costs. One operator has saved about half amillion pounds by demonstrating fitness-for-purpose using current data.
The project, sponsored by a group of companies, evaluated safe hardness levels for welded C-Mn and low alloy steels exposed to mildly sour environments.
The work showed that hardness levels above 22 HRC equivalent can be tolerated in many environments up to at least ten times the NACE MR0175 limit of 0.05psi partial pressure H2S, depending on other environmental variables, mostimportant of these being pH.
The results are in general agreement with recent EFC guidelines, but there are important differences in specific hardness limits recommended. Furthermore, an effect of total system pressure was noted in this work, which is believedto be the first major programme in this area to have been carried out at elevated pressure (mostly 500psi).
In view of the very significant potential financial and safety implications of these findings, the Sponsor Group has decided that the database should be strengthened. Further work, concentrating on the effects of total systempressure and ambient temperature is now proceeding.
Any new Sponsors participating in this further work will receive the final report for the first programme, (total value greater than 400 000 pounds) for no additional cost.
For further information on this excellent value joint-funded deal, contact Richard Pargeter: richard.pargeter@twi.co.uk
