formula used for centre to face measurement for 90' long radius butt weld elbow
NPS x 1.5
formula used for centre to face measurement for 45' long radius butt weld elbow
NPS x 5/8
formula used for centre to face measurement for 90' short radius butt weld elbow
NPS x 1
how much carbon in good qulaity cast iron?
3-4%
main characteristics of gray iron
(has graphite flakes in it)
- resistence to wear/corrosion
- low heat expansion
- fractures easily
- cannot bend
Characteristics of Duriron
- silicon is added
- expansion three times greater than gray iron
- very bittle
- VERY high resistence to corrosion
Defn: Annealing
to heat then cool, softening to make flexible
what is the flow capacity of copper pipe?
20% greater than steel or iron, it expands much more though
What is brass?
copper + zinc
What is bronze
copper + tin
Copper Colour Coding
Type K = Green (thickest walls)
Type L = Blue (medium walls)
Type M = Red (cannot bent, hard temper only)
Type H = White (thin wall, for hot water heat systems) no longer available
what is the heat expansion of copper pipe?
1/8" for every 10ft and 100'F temp change
List four reasons for supporting pipes:
- to carry the weight of the pipe and contents
- to grade the pipe system with adequate slope
- to prevent sagging or deflection of piping
- to allow for thermal movement of the system
What is Thermosetting?
resins reacting in plastic pipe to hold a shape or form, cannot be reshaped. Stronger of the plastic pipes.
Disadvantages of plastic pipe:
- high expansion
- low tensile strengtch
- creeps
- low heat resistance
- low ductility
- low fire resistence
advantages of plastic pipe:
- chemical resistance is good
- not affected by electronic corrosion
- smoother bore
- absorbs shocks well
- economical
- easy to join
- low absorbtion rate
what is the greatest disadvantage to ABS piping?
supports combustion. PVC is self-extinguishing.
which plastic pipe is used for underground gas lines?
high density polyethylene
What is the minimum surface temp for solvent cementing plastic pipe an d fittings?
5'C or 40'F
Nesting of pipe refers to:
the storage of pipe with smaller sizes in larger sizes.
List three types of plastics best used for acid waste and vents:
- polyethelene
- polypropylene
- proxylene
Name three ways of joining plastic pipe
butt fusion welding
socket fusion welding
hot air fillet weld
List three type of plastic pipe that can be joined with solvent cement:
- ABS
- PVC
- CPVC
How do you find the Fitting Allowance (F.A.) when cutting pipe?
Thread Engagement (TE) - Throw (T) of the fitting
Subtract FA from the end to centre or centre to centre measurment
What describes cathotic protection?
introducing an outside electrical charge.
T/F
Copper or yellow brass should be used in heating systems where the water may be highly corrosive
False
Which of the following describes a lip union?
has a gasket between two seating faces
Which disc globe valve is ideally suited for very minute throttling?
Plug Valve
Which of the following terms describes the highest temperature at which a metal is completely solid?
Solidus
Standard pressure test hoses are rated for a maximum temperature of _____ Celsius
