Tag:waterway=pressurised

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Public-images-osm logo.svg waterway = pressurised
Waterway pipe flow tunnel.png
Description
An artificial waterway where water flows in a closed space without air Show/edit corresponding data item.
Group: waterways
Used on these elements
should not be used on nodesmay be used on waysshould not be used on areasshould not be used on relations (except multipolygon relations)
Useful combination
Status: approvedPage for proposal

The waterway=pressurised key maps artificial conduits where water flows in a permanently closed space, without air. As water is filling all space available, it applies a positive static pressure on the conduit walls.

The conduit can be either a pipeline or a tunnel. This is specified by adding man_made=pipeline or tunnel=* to the way tagged waterway=pressurised.

Pressurised waterways require an intake below the water level at all time as to prevent any air to get inside the conduit. It's not only a physical constraint but air can cause heavy damages on equipment expected to run with no air. There is usually no change in flowing regime as pressurised waterways require special design to run.

A "pipe flow regime" is one of the three main flow regimes of liquid water. This regime is obtained by design when the intake of the conduit is built below the lowest water level the source can reach.

How to map

Waterways are mapped as ways: draw a line, starting at the intake, in the direction of the flow of water. Tag with waterway=pressurised. Then, add man_made=pipeline, tunnel=culvert or tunnel=flooded depending of the nature of the conduit. Look at those keys pages for more information. Remember that the water conduit must start at an intake placed below water level.

Pressurised waterways can be added as a member of Relation:waterway with the role side_stream or main_stream depending of the situation.

There is actually no problem to use pressurised consecutively with any other waterway=* value depending of successive regimes found along the watercourse.

Usage

Such waterways are found in water transmission, irrigation and hydropower systems which need large amount of water. This is specified with an optional usage=* with one of the values:

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Examples

Headraces

Photo Tagging Note
Headrace tunnels map

waterway=pressurised
tunnel=flooded
usage=headrace
location=underground
diameter=4900
operator=*

Horizontal tunnels carrying water from intakes to penstocks. Such ways have a pipe flow regime, their inlet are always below the water level and no air can get inside.
Headrace pipeline in a tunnel

waterway=pressurised
man_made=pipeline
substance=water
usage=headrace
tunnel=yes
location=underground
operator=*
access=private

The most complete case with a headrace pipeline hosted in a human accessible tunnel in operation.
This is the only situation where man_made=pipeline is used in combination with tunnel=* on the same way.
Water siphon

On all parts, use:

waterway=pressurised
man_made=pipeline
substance=water
usage=headrace


operator=*

On the bridge part, use:
location=overhead

On the underground part, use:
location=underground

A big siphon allowing water to cross a valley. Only half side is visible on the picture, tunnels or pipelines are connecting each side at equivalent altitudes. The siphon is a pipe flow waterway.

Penstocks

Photo Tagging Note
Pipeline penstocks

waterway=pressurised
man_made=pipeline
substance=water
usage=penstock
operator=*
location=overground
diameter=1200
pressure=70 bar

Metallic penstocks feeding a power plant down the mountain. No air can get inside and water goes pipe flow
Construction of a pressure shaft

waterway=pressurised
operator=*
man_made=pipeline
substance=water
usage=penstock
location=underground
diameter=2800
direction=both

Vertical or inclined pressure shafts are shielded as pipeline without tubes. Pipes are connected upstream and downstream.

See the two vertical shafts on the power plant digital model and some pics of how it was built with a raise drill machine.
Since Nant de Drance power plant can pump water back, penstocks, tunnels and shafts get direction=both.