GB716493A - Improvements in and relating to tube testing machines - Google Patents

Abstract

716,493. Testing strength of pipes. HYDROPRESS, Inc. April 16, 1951 [April 26, 1950], No. 8772/51. Class 106 (2) A machine for subjecting tubes to internal fluid pressure tests has a compensating device enabling the relationship of the tube sealing heads to the tube ends to remain fixed irrespective of changes in length of the tube or the testing machine during a test. The tube to be tested is placed between sealing heads, at least one of which is movable inwardly relative to the other by a hydraulic motor so as to cause the tube to be engaged and sealed between the sealing heads. The compensating means is separate from said hydraulic motor and comprises a sealing head 14, Fig. 3, acting as a movable cylinder 21 on a plunger 24 secured to the sealing head carrier 25 at one end of the machine. As fluid is supplied under pressure through a bore 34 in the plunger 24 to a tube 14A under test, the said fluid pressure is caused to act on the cylinder in a manner moving it away from the plunger 24 should the test machine increase in length or the tube 14A decrease in length during a test. For this purpose the bore of the plunger 24 is larger than the exterior diameter of the tube 14A. A sealing ring 23 engages the exterior surface of the tube 14A and auxiliary pressure operated compensating means 36 are mounted on either side of the test head 21 to assist in the relative movement of the compensating device with respect to the sealing head carrier 25. A passage 35 in the plunger 24 provides an outlet for the test fluid should the cylinder 21 reach a predetermined position with respect to the plunger 24. In Fig. 5 a tube 47 under test embraces sealing elements 48 on a cylinder 46 movably mounted on a plunger 43. The internal fluid pressure in the tube 47 serves to move the cylinder 46 relatively to the plunger 43 should the stresses occuring during a test change the length of the tube or testing machine. If a tube 55, Fig. 6, with a coupling 56 at its end is to be tested, the sealing head 57 is provided with a coupling clamping mechanism 59 adapted to relieve the tube 55 of the end thrust set up on the coupling 56 by the pressure of the fluid on its end.