The well-control stack system is a critical part of the coiled tubing (CT) unit pressure containment package and is composed of a stripper assembly and hydraulically operated rams, which perform the functions described next. Figure 1--Typical quad-ram well-control stack configuration (courtesy of SAS Industries Inc.). The blind rams are used to seal the wellbore off at the surface when well control is lost. Sealing of the blind rams occurs when the elastomer elements in the rams are compressed against each other. For the blind rams to work properly, the tubing or other obstructions across the ram bonnets must be removed.