14 May 2021, 4:18pm
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Pipelines

For sealing threaded and flanged compounds allowed the use of other sealing materials, providing leaks. the situation. The flanges are connected with pipes welding. Deviation from perpendicularity welded to the pipe flange relative to the tube axis is allowed up to 1% of outer diameter of flange, but no more than 2 mm. Not allowed embedment heads of bolts and nuts into the holes of flanges. Head bolts should be placed on one side of the connection. On the vertical sections Pipelines must be located at the bottom nuts. The ends of the bolts should not protrude from the nuts by more than half the diameter of the bolt or three steps of the thread.

End of the tube, including the seam weld the flanges to the pipe must not protrude behind the mirror flange. Gaskets in flanged connections must not overlap the bolt holes. Installation between flanges more or beveled strips are not allowed. Deviation of the linear dimensions of the collected sites should not be exceed 3 mm in length and 1 m and 1 mm for each subsequent meter. Nodes pipeline engineering systems must be tested for leaks at the site of their manufacture. Knots of gas pipelines and piping systems, heating, heating, domestic hot and cold water, including those designed to seal in the heating panels, the cluster pans, taps, valves, sumps, air tanks, silos, etc., should be subjected to Test- hydrostatic (hydraulic) by at least 3 minutes or bubble (pneumatic) by a period of not less than 30 s in accordance with gost 25136 and gost 24054. Under hydrostatic test method for leakage from nodes completely remove the air is filled with water with temperature below 5 C and maintained under positive pressure test pnp = 1,5 Py, where Py – conditional excess pressure that can maintain connections with normal temperature of the working environment in the operating conditions. Nodes and internal sewer drainage steel pipe should withstand a test overpressure of 0.2 MPa for at least 3 minutes. The pressure drop is controlled technical means. The pressure drop in the tests are not allowed.

 
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