Abstract: The invention relates to a borosilicate glass of high chemical resistance and low viscosity which contains zirconium oxide and lithium oxide. The borosilicate glass has hydrolytic resistance (in accordance with DIN ISO 719), class 1 acid resistance (in accordance with DIN 12116), and class 1 alkali resistance (in accordance with DIN ISO 659), and with a low operating temperature V.sub.A of between 1180.degree. C. to 1230.degree. C. and a coefficient of thermal expansion .alpha..sub.20/300 of 4.9.times.10.sup.-6 K.sup.-1. The borosilicate glass has the composition (in % by weight, based on oxide): SiO.sub.2 73-75; B.sub.2 0.sub.3 7-10; Al.sub.2 0.sub.3 5-7; ZrO.sub.2 1-3; Li.sub.2 0 0.5-1.5; Na.sub.2 0 0-10; K.sub.2 0 0-10; MgO 0-3; CaO 0-3; BaO 0-3; SrO 0-3; ZnO 0-3; ratio of SiO.sub.2 /B.sub.2 0.sub.3 .gtoreq.7.5; .SIGMA. SiO.sub.2 +Al.sub.2 0.sub.3 +ZrO.sub.2 80-83 and .SIGMA. MgO+CaO+BaO+SrO+ZnO.ltoreq.3, and fluorides 0-3.

Abstract: The invention is directed to a method for controlling the free deformation of thermoplastic material in an automated process for processing the material to form articles. These articles are especially ampules, small bottles and the like produced from glass tubes. In this method, in order to obtain a high dimensional accuracy of the article, a corrective action is carried out by applying heat to the starting material in the deformation region in the heating phase. This corrective action takes place in dependence on a desired-value/actual-value comparison of the deformation of a workpiece achieved in a predetermined working step. In order to exclude interference influences in the development of the deformation, the measurement of the deformation achieved, the desired-value/actual-value comparison and the corrective action are carried out in situ on one and the same workpiece during shaping of the deformation in the heating phase.

Abstract: The invention refers to a process and an arrangement to connect and seal tubes (2, 4) made of glass, metal or ceramic materials, that are joined to form flue-gas pipes. The sealing system according to the invention is distinguished by the fact that it can be used for exhaust gas pipes as well as for diminished cross-sections for chimneys, for example, since the sealing material is used in such a way that the overlapping pipes (2, 4) are connected in gas-tight manner even in the case of varying pressure conditions, and that the sealing material (8) is sufficiently resistant to acid, water and temperature to be used in the removal of hot, acid gases. In a preferred form of construction, the pipes (2, 4) are fixed together before applying the anorganic sealing material (8). The pipes are either fixed by punctually applied, quick-setting adhesive (6) or secured together by a pipe clamp (14) attached at the circumference of the pipes.