The Award winning (ASME Design Award 2002) Twin-Blok II or "TB" range of double block and bleed valves are designed to enable engineers to utilise a double barrier valve isolation instead of single isolate units.
Twin-Blok II saves money by eliminating the cost of pipework modifications due to it’s compact overall length which conforms to ANSI standard lengths of single ball valves (as shown).
The TB type valve simply retrofits into the space left by a standard isolation ball valve that is to ANSI length. Twin-Blok II has the added advantage of having the unique non-blocking annulus venting facility and only one body joint from end to end - less joints means less potential leak paths.
Modern pipeline safety standards and practices require that the pipeline is provided with double barrier isolation between the live process and the outlet of a valve i.e. DBB. The traditional methods have resulted in space wastage due to the heavy and bulky utilisation of two gate or ball valves. This method brings along with it many additional joints where the valves meet. Also by using several single valves brought together there is a weight penalty. Great consideration should be given where weight, size and pipeline stress are important i.e. FPSO / offshore installations. The TB valve has been used in flow-line, level gauge and other instrumentation applications around the world.