The members of the Lower Olefins sector group have adopted guidelines on the standardization of couplings for the transport of butadiene by railcars in order to ensure safety.  LOSG members have now committed to eliminate flange couplings for transporting butadiene by the end of 2025 as it can result in leakages when not used properly. They strongly encourage other producers and consumers of butadiene to do the same.

Butadiene is a well-known carcinogen with a binding EU Occupational exposure limit of 1ppm and as such must be handled with particular care. Three type of couplings are currently used: flanged couplings, WECO couplings and dry-disconnect couplings. Although they are all acceptable for the loading and unloading of railcars from an exposure point of view when used properly, the error rate is higher for flange systems resulting in leakages of butadiene into the atmosphere. LOSG members currently believe that both WECO and Dry-disconnect are valid alternative couplings to flanges. A guideline document is available on the LOSG website outlining advantages and disadvantages for both systems.

To ensure flexibility and multipurpose use and to avoid the need for a dedicated fleet of butadiene, LOSG members will consider extending these recommendations to C3-C4 olefinic streams by the end of 2023.