E2: Install Gas Piping and Tubing Systems Flashcards
What is included in a piping system?
pipe, tube, connector, hose or fitting used to carry fuel gas from supply –> appliance
What is required when jointing sealant is used?
- Apply to male ends
How should T-tape be used?
Tape has to be stretched and applied in a clockwise direction
- have a 50% overlap
- Leave the first 2 started threads bare
How are steel pipe seized 2 1/2” and over connected?
With welded joints
What must threaded fittings be made of?
malleable iron or steel construction
Why can’t cast iron threaded fittings be used?
more susceptible to cracking
How are cast iron fittings differentiated from malleable fittings?
Cast iron hubs are larger (“heavier reinforced bead”)
All pipe thread have to be free of what?
burrs, scale and defects
Do all pipe ends have to be reamed?
Yes
How are press fittings designed?
If there are any un-pressed connections, it will leak past the internal sealing element (
What fittings are NOT approved for steel pipe?
-Fittings w/ running threads (thread protectors)
-Close nipples
- Street elbows
- Fittings w/ right or left hand threads
What kind of bushing is used when there is 1 pipe size change?
Forged steel bushing
What type of material is used when reducing to min 2 pipe sizes?
Malleable iron or steel
What is nesting mean?
using multiple bushings together
What type of fittings can be used with Copper pipe?
flared
brazed
press - connect
Can compression fittings be used with copper pipe?
If AHJ approves
What type of flare fittings has to be used?
- use soft annealed copper
- 45 degree type
- does not come with nuts (have to purchase separately)
What are flared fittings made of? (BF)
Brass forged type
Can externally machined nuts be used?
No, they are not strong –> wall thickness decreased dt machining process
How are CSST tubing connected?
By using self-flaring brass fittings –> creates a metal to metal seal when tightened.
True or False: only manufactured certified fittings can be used with CSST pipe
True
Adapter fittings used for CSST pipe have what kind of threads?
standard NPT
What can be used in place of fusion fittings for PE pipe?
PE compression slab lock fittings
Manual shut offs are required where?
for each appliance / must be readily accessible
If a manifold is being used, where can shut off valves be placed?
at the manifold.
If AHJ approves
Where are manual shut offs installed?
upstream of any line pressure regulators that in the system or any underground section of pipe
What kind of turn must a manual shut off have?
A quarter
What type of valves can be used for shut offs?
- ball
- plug
- eccentric type
Shut off valves can be used as long as they are rated for what?
for the pressure and temperature they are being used for
What is the most common shut off used?
ball valve
Where would you find a lubricated plug valve?
Utilities meter set
Where are eccentric style valves seen?
larger applications –> over 2” in size
What is a benefit of the offset half plug?
Creates less friction = lower operating torque needed for large valves
Quick disconnects has what kind of internal device?
shut off
What must be installed in addition to a quick disconnect shut off?
manual shut off valve installed upstream of quick -disconnect device
What is a gas convenience outlet?
It is a combined units w/ the quick disconnect + manual shut off supplied as a unit
What additional feat does a manually operated gas valve have?
a handle designed so that disconnection can be accomplished only when the gas valve is in the closed position
Where can we see Dirt pockets?
- inlet to an appliance regulator
- at the base of a vertical drop to an appliance
How does a dirt pocket work?
- designed to capture dust before it enters the appliance
- reduces the chance of clogged gas valves or orifices
Drip pockets have to be provided where?
at all points in a piping system where condensation can collect
(ex: wide ranges or sudden temp changes)
True or False: drip / dirt pocket names are used interchangeable.
True
Why must piping or tubing be mounted, braced and supported?
To provide for expansion, contraction, jarring, vibration / settling = no wear or strain on the piping.
What are the additional considerations for commercial or industrial roof tops?
pipe movement caused by thermal expansion / contraction
How are thermal expansion / contraction supported?
through designed pipe bends, loops, offsets or expansion joints
True or False: pipes have to be anchored at appropriate locations to control direction or expansion / contraction
True
Can gas piping enter the building from underground?
No, it has to rise above grade before entry unless otherwise permitted by AHJ
What must happen when gas lines pass through an exterior wall above ground?
- must be sealed in a watertight / portion running through the wall sleeved or double wrapped w/ a waterproof wrap
Joints or Fittings must be what before being covered up?
tested / inspected
Where can’t gas pipes be installed?
- stairwell (unless chase available)
- chimney, dumbwaiter
- heating or vent plenum, duct, shaft
- cinders, ashes, corrosive materials
- under a foundation wall
What happens if gas pipe has to be installed in concrete?
it has to be laid in channels / encased in ventilated ducts so there are free air space around
What are the rules for a vertical chase?
- has to have an opening at the top / bottom
- openings have to be 1” in diameter around the pipe
Damaged pipe results in
reduced life expectancy
failure of the piping system
What are 3 basic methods to protect pipes?
1) protective coatings
2) physical/ mechanical damage protection
3) cathodic protection
Why is coating or wrapped gas piping not recommended?
due to exposure to sunlight / rain / snow = thermal expansion / contraction
How can you avoid galvanic corrosion?
install pipe so that it is not in contact with dissimilar metals
Why must piping be sleeved or double wrapped when running through masonry or concrete?
It is very corrosive
When should striker plates be used?
When pipe is running through hollow walls
How can piping be protected from vehicular traffic locations?
By posts or guard rails
How should piping be supported that runs vertical out of the ground?
a sleeve to prevent free movement of the soil / covering w/o placing strain on the pipe
How can gas lines be located underground?
by placing a yellow poly coated tracing wire (or something like it) or magnetic tape, buried alongside the pipeline
Where should the tracer wire be placed exactly?
Laid within 6” of the plastic pipe, where its practical but is possible - directly above pipe
Do we have to worry about the ends of the tracer wire?
yes, place them were they can be easily accessible so they can connect to electronic tracing equipment
When do additional corrosion control measures come into play?
When steel gas pipe is buried.
When does electrochemical corrosion occur?
When 2 dissimilar metals contact each other in a moisture - rich environment
How does corrosion occur?
one metal becomes a cathode, the other metal becomes an anode (usually the pipe), which corrodes / develops a leak
What are 3 methods of protecting underground pipe from corrosion
1) protective coatings
2) cathodic protection
3) electrical insulation
How do protective coating protect pipe?
They insulate the pipe from the soil (aka the electrolyte)
- adheres tightly to soil
- can withstand soil stresses, tendency towards cracking
What does high dielectric strength mean?
It’s a good electrical insulator
What are the main coating used?
Yard - applied coal tar
Extruded PE
Can the integrity of the pipe coating be tested?
yes
What is Jeep or Holiday mean?
Areas on a pipe that are not protected?
What is a Jeep meter?
Is an electronic testing unit
It finds imperfections / allows repairs prior to being buried
What happens if 2 metals have a different electrical potential?
A current will flow between them
How does current flow?
From active metals (metals with higher potential) to less active metals (metals w/ lower potential)
What are 4 things necessary for galvanic corrosion to occur?
1) An anode
2) A cathode
3) An electrolyte
4) A conductive path
True or False: It doesn’t matter if metals are close or far, a current will still flow.
True
For galvanic corrosion to occur, there must be a complete electrical circuit, correct?
Yes
True or False: the electrical current travels from cathode to anode.
False: travels from anode to cathode (A before C)
What is the simplest method of protecting against galvanic corrosion?
Connect the protected metal to a sacrificial metal via insulated conductor
(sacrificial metal will act as the anode)
What are 2 basic methods of cathodic protection?
1) Passive Galvanic anode system
2) Impressed Current System
Anodes are made up of what?
Magnesium (Mg) –> Used in BC
Zinc (Zn)
Aluminum (Al)
What does a sacrificial anode here consist of?
A bag containing either magnesium or zinc igot / other chemicals.
Is connected by a wire –> underground metal piping system
How does the sacrificial anode function?
As a battery => induces a direct current on the piping system to slow corrosion
What is the difference bn a Passive galvanic anode system and a impressed current system?
Passive - uses sacrificial anode
Impressed - uses shania twain (that don’t impress me much)
- also uses a DC electrical power source
How is the direct current induced?
by means of a rectifier
Where are Impressed current systems used?
along transmission pipelines
(less interference w/ other pipelines)
In an Impressed Current System, what are the anodes here made of?
corrosion - resistant material used to disperse the electrical current
(graphite, silicone cast iron, lead- silver alloy, platinum, scrap steel)
What kind of output does the DC rectifier have?
10 - 50 amps
50 volts
What is the point of installing a dielectric fitting on the pipeline directly outside the building wall?
Prevents electrical contact bn underground piping (protected piping) + above ground / unprotective piping
What is the common dielectric fitting used?
insulated union
insulated flange
insulated meter spud
What should be added to piping systems to identify contents of any section of piping in a facility?
Pipe markers
What colour are all flammable or oxidizing fluids or gas?
Yellow w/ black text
