Abstract: An apparatus for aiding in welding a pipe structure is provided. The apparatus includes first and second expandable spaced apart seals adapted to be positioned in the pipe structure and on opposed sides of a region subjected to a welding process. Each of the spaced apart seals has a circular exterior surface selectively expandable to contact and form a seal with an interior surface of the piping structure, and a circular inner surface. A light-transmitting tubular shield support extends between the first and second seals and mates with the circular inner surfaces to position the first and second seals in spaced relationship with each other. An optical device has a selectable field of view supported within the interior of the tubular support, and is rotatable about the major axis of the tubular support for producing an image of the portion of the inner surface of the piping structure that is within the field of view of the optical device.

Abstract: Apparatus for positioning an image receptor, such as X-ray film, within a patient's mouth in predetermined relation to an energy beam, such as an X-ray beam, generated externally of the patient's mouth, includes rigid structure supporting an image receptor and connecting it to the source of the energy beam, and a bite block removably attached to the rigid structure in a position such that the portion of the patient's maxilla and mandible gripping the bite block is removed from the portion being studied with the energy beam. The attachment system further provides for attachment of the bite block at any of a plurality of discrete sites relative to the image receptor. Bite registration material is preferably provided on the bite block surfaces to allow precise repositioning of the bite block in a series of successive exposures. The apparatus allows a plurality of target areas to be studied using one bite block position within the patient's mouth.