# 1995 Edinburgh
Polybutylene-l (PB) for pipe applications was first developed by Chemische Werke Huls in Germany in the early 1960's. 1965 several manufacturers were chosen by Huls to extrude pipes for trial installations - one of them was SALEN (today PIPELLFE) in Austria.
Hiils sold it's PB-know how early 1970's. Mobil Chemical Co. and Witco Chemical Corp. worked on PB in the USA before SHELL took over the PB-plant. Since then SHELL improved Polybutylene significantly and supplied major companies in USA and Europe with new grades of PB especially formulated for underfloor - heating and radiator connections.
In 1982 SHELL introduced the brand new grade PB 4137 . which is stabilised for elevated temperatures and approved for drinking water as well. This type is now successfully used since and passed all required tests in various testing institutions.