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Metal Winding O-rings On The Tube Box Installation Method Steps

Doit Rubber Products Co.,Ltd | Updated: Nov 06, 2017

Metal winding O-rings on the tube box installation method steps
First, the flange sealing surface clean, and will not remove the plastic packing tape O-rings and tube flange pre-assembled to ensure that the O-rings in place, and in the metal O-rings stainless steel inner ring and Tube flange with 4 uniform positioning holes. Then, carefully remove the plastic packing tape of the metal O-rings and inspect the O-rings without any defects such as radial scratches. Lastly, the metal O-rings is secured to the tube flange using a resilient cylindrical pin, followed by assembly of the tube assembly with the tube sheet.
After the tube box assembly and the tube plate assembly, the following key processes on the seal play a key role.
(1) Bolt fastening order requirements. Bolt and nut thread must be clean, not allowed to adhere to mechanical impurities, tighten the nut force evenly, the tight symmetry of the bolt should be uniform, and when the bolt should be gradually and evenly divided round, each round should be Tighten the bolts to 1/3 of the final tightening torque, starting from each wheel should be offset by 120. , O-rings pressure evenly.
(2) Bolt tightening torque requirements. According to the general rules of screw fasteners fastening and practical experience at home and abroad, the recommended torque of M64 × 3 bolts is 8500N · m. When tightening the bolt torque, the torque needs to be gradually increased to the specified torque value in three rounds, Can not be fastened in place once. Relevant statistics show that about 80% of the domestic pre-tight seal is based on experience and can guarantee the reliability of the seal is only 22.3%, so in accordance with the bolt tightening torque and the choice of a suitable torque wrench is to ensure that sealing an important factor.
(3) Choose a reasonable amount of metal winding O-rings compression. At present, there are mainly two ways to control the pre-tightening force of the metal-wrapped O-rings: one is to use a torque wrench; the other is to control the amount of metal-wrapped O-rings to be compressed by measuring the clearance of the sealing surface of the flange. Such as 4.5trim thick metal O-rings, the amount of compression is appropriate about 1.2mm, preload bolts should also be taken to be symmetrical, to prevent tight bias.
Based on the assembly requirements described above, the tightening torque of the bolt and the amount of compression of the metal O-rings are controlled from the fastening order of the bolt (the tightening torque of the bolt is the main and the compression is supplemented), and the torque of the bolt From 9500N · m down to 8000 ~ 8500N · m; In the hydrostatic test, the pressure test passed, there is no leak at the flange seal; these experiences are successfully copied to another same heat exchanger, the pressure test Pass at once
Due to the positioning hole drilled in the inner ring of the metal O-rings in the flange of the pipe box, if the equipment is repaired to the customer's site or the customer needs overhaul and needs to replace the metal O-rings, the method described in this article can be adopted. O-rings removed, drilling hole in the new metal O-rings on the installation site does not have any impact.
The phenomenon of radial inward buckling of metal wound O-rings has been found on the site for many years and is observed for O-rings of different diameters and under various operating and mounting conditions. However, certain diameter ranges of metal-wrapped O-rings are particularly sensitive to this type of buckling under certain operating conditions. These include: (1) Coiled O-rings made of asbestos, rock or other rock wool material at a relatively high temperature, with a larger diameter 304, 316 stainless steel band; (2) In severe thermal transient conditions Under the work of winding O-rings; (3) pre-tightening PTFE (PTFE) wrapped O-rings.