E1 - Describe Gas piping and Tubing Flashcards
How does gas flow?
From high to low
How is the amount of pressure in a pipeline measured?
psi
What is the safest + most reliable way to deliver gas?
pipeline
What is a “Christmas Tree”?
a production tubing that connects valves, pressure gauges to flow line connectors
What is a major by product of NG?
Sulphur
What does NG get compressed down to when transported?
5500 - 8000 kPa (800 - 1200psi)
What speeds does NG travel at through pipelines?
11 - 32 km /h
What reduces NG speed through pipelines? (FED)
distance, friction and elevation differences
True or False: dt pressure decrease along pipelines –> pump boosters have to be used to increase pressure + speed
True
How far apart are booster pumps placed?
80 -100 km
Who is responsible for pipeline maintenance?
transmission companies
Are LP gases transported in their gaseous state?
No, liquid state under pressure
Before local utility can distribute the gas to customers, what has to happen?
Gas pressure has to be reduced
How does the pressure reduction happen?
gas passes through a city or town gate
What do the city gate stations control? (MOP)
metering, pressure limiting and odourization of gas
What is added to NG to give it it’s distinct odor?
Mercaptan
(Mercaptan my captain)
What does the pressure get reduced down to at the gate stations?
690 kPa (100 psi)
What do storage tanks act as?
A buffer between transportation and distribution
What is a base load?
Seasonal demand shifts
What are peak loads?
unexpected demand surges
What are 3 main types of underground storage? (SAD)
1) depleted gas reservoirs
2) aquifers
3) salt caverns
True or False: LNG stored above ground occupies 600 times less space then being stored underground
True
What is auto - refrigeration?
The release of gas from the liquid storage is also used to maintain remaining stored liquid at low temp.
What is the Gas utility responsible for?
Installs and maintenance of gas service
(service line, riser, service stop (valve) service regulator and meter)
What is the max pressure allowed for a single family dwelling?
2 psig (14 kPa)
What is the max pressure allowed for an idustrial / commercial buildings?
5 - 20 psig (35 - 140 kPa)
What types of pipe are allowed in gas applications?
Black iron, CSST, copper tubing, polyethylene plastic
What is the gas fitter responsible for?
designing a piping system
What is fluid dynamics?
the physics of the flow of fluid
What is important when thinking about flow rates?
Affect of the gas pressure energy
Flow in pipe is created by what?
energy loss dt friction
How can one measure friction loss?
With 2 gauges at different points in the system
Where would friction pressure drop be measured from on a system you’re working from?
From the gas supply (metered or pressure regulator) and the most distant appliance
What is the driving force that moves gas through a pipe?
pressure difference
The greater the pressure difference, the greater the….
- volume and velocity of flow
What are the 5 flow factors to consider?
1) Velocity
2) Pipe size
3) Density (SG)
4) Pipe Material
5) Fittings
Friction loss in uniform, straight sections of pipe are greatly affected by?
Velocity of fluid
What are 2 types of flow?
Laminar flow
Turbulent flow
Describe Laminar flow
- Flow is smooth –> streamline
Where does laminar flow occur?
At lower velocities
What type of flow has an energy loss?
Laminar
Explain turbulent flow
- Has a rough flow
What is a characteristic of turbulent flow?
Eddies or small pockets of fluid particles. (results in lateral mixing)
What kind of flow increases friction loss?
Turbulent
True or False: changing pipe size will change gas velocity
True
What is the Shear rate?
it’s the measure of fluids viscosity or slipperiness.
Fluids w/ higher density require more what to move them?
Energy (and shear less easily)
Specific gravity of a gas describes its density relative to what?
Air
What is the SG of propane?
1.5
What is the SG of NG?
0.6
What is the SG of Butane?
2.0
True or False: Less dense gases are easier to more.
True
The amount of roughness on the inside of a pipe affects what?
Drag of the fluid
When are eddies produced?
When the fluid is forced to change direction or go around a disruption
Eddies produce what?
additional pressure loss
What are the 3 different way to account for the friction loss of fittings?
1) Percentage of length
2) Pressure drop calculations
3) Equivalent length table
Why is 20% added to the measured length?
It’s a given allowance to account for the friction loss caused by fittings (It’s a guess-tamation)
Material not listed in the Gas code can be used if what?
-They conform to nationally recognized standards
- A test report of a nationally recognized certification organization
Steel piping is also called what?
Carbon steel or black iron pipe
What wall thickness must steel pipe have?
schedule 40 or schedule 80 or standard weight depending on the application or size
Can hot zinc coated pipe / fittings be used?
Yes
What kind of copper is approved for gas use?
Type G, K, L
What application are type G, K, and L only approved for?
Above ground and can’t exceed 1 3/8” OD size
Does the pipe sizes in the Gas code book go off OD or ID sizes?
OD
True or False: Type K and L nominal tube size is 1/8” larger than its nominal size.
True
What type of copper is approved for underground use?
Type K - must be soft annealed
In order for Type L or G to be used underground, what must be applied to it?
External poly coating
Can steel piping be used for gas systems?
yes but not common
What is the pressure rating of a PE medium density pipe?
100 psi
What is plastic pipe approved for only?
for outdoor, underground only
What applications is plastic pipe good for?
gas mains, house service lines and after meter on premise underground lines
When is plastic pipe to be inspected?
Before and after installation
If there are any defects on the plastic pipe or fittings, what needs to be done?
It needs to be cut out and replaced
Is PE thermoplastic?
Yes
What does thermoplastic mean?
Softens when heated / solidifies when cooled
(No chemical reaction takes place)
PE piping is fused by applying what?
Heat and pressure
Plain ended pipe is joined how?
butt fusion
PE fittings are typically joined how?
socket fused
How are tees often formed?
Saddle fusion
Marking on PE should be at what intervals?
max 1.5m (4.9’)
What do the 4 digits on PE pipe represent?
1st number = density of pipe
2nd number = melt rating
3rd / 4th numbers = strength for density
Is corrugated stainless steel tubing approved for gas?
Yes
Up to what psi is corrugated stainless steel approved for?
5 psig
What size of pipe does CSST come in?
3/8” - 2”
What is a distinguishable feat of CSST pipe?
its yellow PE jacket on the outside
How should CSST be installed?
As per manufacturer’s instructions
Do you have to take a training program prior to installing CSST?
Yes
What is a benefit of using CSST pipe?
it’s easy to weave through obstacles in one con’t run
What does black CSST pipe indicate?
That it’s lightning - resistant
What can’t CSST pipe be used for?
as a gas connector
What do gas connectors require?
flexible connection to connect to rigid permanently installed gas supply piping
Choosing the correct connector depends on what? (Mo/dis/re/out)
- if there is repeat movement
- repeat dis/reconnection requirements
- be used outdoors
What is the min working pressure that hose / hose fittings must have?
350 psig (2400kPa)
