Materials
Handling and Transfer
“Piping Systems”
Piping System Definition:
Interconnected piping subjected to the same design conditions.
Piping system components
1. Pipes
2. Fittings (flanges, threaded, welded) 3. Valves
4. Expansion joints 5. Strainers
6. Traps
7. Inline instruments 8. Supports (anchors)
Identification Systems
ASTM System
PVC pipes take the letter D
Pipes specifications:
Pipes are specified according to wall thickness by a standard formula for schedule number
On increasing schedule number, the pipe wall thickness increase
What is the nominal diameter?
The ND code is a code that rounds off the diameter of the pipe to get an even number to work with, not the exact diameter. The American version is called NPS (Nominal Pipe Size) and is in English units. ND is the European version and is based on millimeters. For example, If you want 2" Pipe, NPS calls it 2" and ND calls it 50 mm. but the actual outside diameter is neither 2" or 50 mm. They just use these nice round numbers cause it is easier.
Pipe Sizing
1- Wall Thickness
tm: is the minimum required thickness Dm: mean diameter
2- Optimum Diameter
Fittings and other piping auxiliaries.
Are used to:
A- Connect pieces of pipes together B- Change the flow direction
C- Regulate the flow
D- Obtain desired conditions in a flow system
Types of fittings
1- Threaded fittings( screwed) [for small size]
2- Flanges [for diameter 3 in.]
3- Welding
Threaded (screwed) fittings
Threaded (screwed) fittings
Flanged fittings
Flanged fittings
Piping Systems Problems
1- Solidification and corrosion 2- Thermal expansion
3- Liquid pockets
Liquid pockets
They can be caused by gas/liquid getting into a liquid/gas pipe. Sometimes the pressure or temperature of the fluid within a pipe will change and that can allow phase change, or gases to escape out of a liquid, or gases to condense. e.g. Steam lines contain hot gaseous steam, but as this steam cools down, condensate(liquid water) starts forming. If water within a pipe gets hot some may boil (causes "boiler rumbling"). Carbonated drinks hold a lot gas when under pressure, when it's realized the gas/liquid separate.
Air holds a fair bit of moisture, Increase it's pressure, or drop it's temperature and moisture will drop of it. Similar thing with natural gas.
liquid pockets can cause problems as slug of liquid can then be forced down the pipe at high speed. When it hits something, it's comes to a very quick stop. The liquid is effectively incompressible and so it's KE is converted into a VERY fast rise in pressure, and that can rupture the pipe/fitting (Water hammer).
Steam trap
A steam trap is a device used to discharge condensate and non condensable gases with a negligible consumption or loss of live steam. Most steam traps are nothing more than automatic valves. They open, close or modulate automatically.
The three important functions of steam traps are:
Discharge condensate as soon as it is formed.
Have a negligible steam consumption.
Have the capability of discharging air and other non-condensable gases.
Pipe Launcher
How to overcome the solidification problem in pipelines?
Smart Pig
Smart Pig
Smart Pig Inside the Pipe
Magnetic sensor Pipe wall
Pig body
Pipe Expansion and Support
Any piping system must be fully supported, able to expand during operation and sufficiently flexible to allow movement as a result.
All pipes will be installed at ambient temperature.
Pipes carrying hot fluids such as water or steam operate at higher temperatures.
It follows that they expand, especially in length, with an increase from ambient to working temperatures.
This will create stress upon certain areas within the distribution system, such as pipe joints, which, in the extreme, could fracture.
Calculation of the amount of expansion
The amount of the expansion is readily calculated using Equations, or read from an appropriate chart
.
Expansion coefficients (α) (mm/m °C x 103)
A chart showing the expansion in various steel pipe lengths at various temperature differences
The fixed or 'anchor' points 'A' provide a datum position from which expansion takes place.
The sliding support points 'B' allow free movement for expansion of the pipe work, while keeping the pipeline in alignment.
The expansion device at point 'C' is to accommodate the expansion and contraction of the pipe.
Pipe Support
Chair and roller Chair roller and saddle
Expansion Fittings
Full loop
This is simply one complete turn of the pipe and, on steam pipe work, should preferably be fitted in a horizontal rather than a vertical position to prevent condensate accumulating on the upstream side.
1- Full loop
2 Horseshoe or lyre loop -
Horseshoe or lyre loop
3 Expansion loops -
Expansion loop
Expansion loop capacity for carbon steel pipes
4 Sliding joint -
Sliding joint
5 Expansion bellows -
Simple expansion bellows
An expansion bellows, has the advantage that it requires no packing as does the sliding joint type.
Expansion bellows
Expansion bellows
Bellows may incorporate limit rods, which limit over-compression and over-extension of the element.