How to set up the backflow and vent valves for the hydraulic testing of long pipes in utility tunnels
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In long-distance pipelines within pipe galleries, guide valves and drain valves are generally not included in the original design; therefore, during hydrostatic testing, it is necessary to install valves for venting at the high points and draining at the low points. For pipes that are non-toxic and harmless, we generally use openings with valves; after testing, they are cut, then ground and rewelded, followed by coloring inspection. This leads to the issue of having to weld the system again after the hydrostatic test ； Toxic and hazardous pipelines, as well as those operating under high temperature and pressure, are equipped with drain valves and flange covers during construction to be used as permanent components; this alters the original design and increases the number of potential leakage points. Do you all have any good methods for construction?
This post was last edited by ylb913 on 2015-12-31 at 10:09. We keep them during the design phase permanently; those with flange covers are more common, while those with valves are less so.
The design takes into account the need for additional high-point venting and low-point drainage during hydrotesting. After cutting in the test, grind it and then weld it back in place.
I agree with you; design should take into account both testing and operation. If that isn’t considered, it’s a flaw in the design
Remelting has an impact on the properties of the base material; it is recommended to use a flange cover
This post was last edited by Grizzly on 2016-1-3 at 18:49. The points raised by the people above are quite reasonable; let me explain it more systematically: During the 90% model review, the piping engineer should determine the locations for venting and drainage, reflect these in the model and ISO documents, mark the master PID, and then send it back to the process team. When generating the diagrams, the latest venting and drainage systems are already marked on the PID. (In some projects, the PID only shows the process-related venting and drainage systems, but this approach seems outdated; our current requirement is to display everything.) ), new venting and drainage points have been added to both the ISO for the piping layout and the pipe layout diagram, and they have been included in the checklist for verification. The problem encountered by the poster is actually due to inadequate design management; making changes during construction would certainly require a great deal of work. It’s better to do things properly during the design phase than to have workers work with fire on site. Especially for EPC projects, since everything is related to us anyway, it’s better to handle it all at once.