I encountered the the turbo butterfly valve with PP-R pipe connection exists, for example, a brief description.
1. Problems and phenomena
In October 2010, my unit replace the outdoor water supply pipeline, trunk 1.6MPaPP-RΦ160 × 17.9-tube, the front of the building the feeder using 1.6MPaPP-RΦ90 × 10.1 tube, instead of original serious corrosion of steel pipe line, for 12 residential buildings domestic water, including water supply trunk of six residential buildings with a turbine, butterfly regional control. Pipeline flushing, after passing the pressure test, found six residential buildings feedwater pressure start normal water supply, a lot smaller than the original, brought a lot of inconvenience to the lives of the residents.
Find out the reasons
First, find the design reasons. We promptly get in touch with the design institute, Design Institute of designers, after careful calculation and on-site field trips, after repeated demonstrations to prove that there is no problem with the design.
Find construction reasons, after the normal flushing the pipeline, can ensure that the construction process, the pipeline there is no clogging, pressure test results normal.
Then we suspected PP-RΦ160, the the PP-RΦ90 pipeline construction, hot-melt interface at the remnants of too much, resulting in smaller pipeline diameter, forming a bottleneck. After observing the residents in the floor in front of the building branch line at the flange connection, not too hot melt remnants pipeline hot-melt interface, and will not become a bottleneck.
Construction causes for design reasons, we suspect that the reason of the materials and equipment.
First, for a small part of the residential building water supply pressure, water supply pumping station and the center of the cell, confirmed the feedwater pressure no abnormal; then we suspect PP-RΦ160 × 17.9 turbine butterfly valve to the water pipe line (D371X-16DN150). Although its external signage for maximum open state, but the internal really fully open it? Removing turbine immediately butterfly found butterfly plate open only to a maximum value of 1/3, PP-R line end surfaces and the inner wall and connected thereto have been squeezed trace of damage.
Herein the turbo butterfly valve on each side of the installation of a soft connection, another replacement, a new butterfly valve, normal water pressure of all residential buildings.
3 Cause Analysis
The cause of the failure are many, except for the construction managers, construction team technical staff construction experience less, mainly materials and equipment reasons.
(1) The existing GB PP-RΦ160 water supply, the the heating pipeline specifications butterfly valve specifications do not match. PP-R water supply, heating pipeline specification model representation of the outside diameter × thickness, butterfly valves and other valves representation of the nominal diameter.
To the PP-RΦ160 pipeline, for example, for 1.25MPaΦ160 × 14.6,1.6 MPaΦ160 × 17.9,2.0 MPaΦ160 × 21.9 line, the wall thickness is too large due to its pipeline, hinder the normal opening of the butterfly valve disc (Figure 1). In accordance with the general method of construction, the butterfly valve can open only about 1/3, or can not open.
(2) construction specification. Later confirmed in the the my unit water supply trunk actual construction process, the construction team butterfly valve turbo turbo force to reverse its surface signage, point of maximum open state, while the the turbo butterfly valve internal disc and no corresponding open, leading to the turbine butterfly valve damage.
4. Countermeasures based on years of on-site construction experience for PP-R pipe diameter pipeline in the actual construction process, but also may encounter the phenomenon of the butterfly valve disc not open. Therefore, when the PP-R pipeline construction, in order to enable construction to achieve the desired effect, it is recommended to use the gate valve control, if you do need to use the butterfly valve is recommended as follows are several ways.
(1) on both sides of the butterfly valve, the installation of a short embalmed steel pipeline, steel pipe line butterfly valve via a flange connection. Steel pipeline susceptible to corrosion, easy to maneuver, and moderate cost.
(2) on both sides of the butterfly valve, the installation of a soft connection, a remission PPR Water Pipelines thermal expansion stress the dangers of the pipeline and its annexes, two can make the butterfly valve normally open. Soft connection is easy to operate, durable and difficult to corrosion, and a slightly higher cost.
(3) be installed on both sides of the butterfly valve gasket group. The first the corresponding specifications gasket about 10, with the raw material with Soft thing gaskets intertwined to form a whole; using this method produced two large Gaskets. Large Gaskets on the butterfly valve and the the PP-RΦ160 line flange connection between the fastening bolts to complete the butterfly valve installation and construction. Gaskets are easy to operate, the lowest cost.
Other PP-R pipe diameter pipeline construction process, if using a butterfly valve, butterfly valve in the installation when first butterfly valve to open to the maximum open state, closing butterfly valve to be installed, and then, finally, open to the maximum open state, in order to ensure the smooth construction and butterfly normal use.
