Gas Pipe Flashcards
Most common type of material used in gas piping
Black iron
What is schedule
The manufacturers Gauge of metal thickness, lower the number the lighter the gauge
What changes when you change schedule pipe
The inside diameter
The recommended rate for tightening is?
1/4 per revolution
What is the largest diameter pipe you can thread
2”
What is a nipple
A short piece of pipe with a thread on each end comes in the schedules
Are close nipples allowed to be used on gas lines, why or why not
They are not permitted for use on natural gas or propane. No orginal wall thickness.
What makes the seal on gas pipe
A taper thread, then tape or dope
What are tape and dope considered
A lubricant.
What is centerline angle what is included angle
Center line is 30° included is 60°
Recommended # of thread per inch of thread for ½ and ¾ and approx number of threads to cuts to obtain standard thread
14 threads and 10 ½
What happens if you don’t remove the bur from cutting
Can cause pressure loss, turbulence, and the possibility of catching foreign material
Order of cutting threads
Measure, cut, ream, then thread
Hand tight thread engagement and wrench tight
4¾ threads hand tight first than 3 threads wrench
Can power drives use spiral reamers?
No, they dig into aggressively
When should cutting oil be applied to pipe and threading equipment? How much?
It should be applied during the threading process.
How much cutting oil should be used? And why?
A generous amount, it’s the beat safeguard against poor threads, excessive die wear, clearing debris build up and heat
When should you stop threading?
When the outer surface or faces of the dies are flush with the end of the pipe or follow die manufacturers recommendations.
If you continue to thread beyond the stopping point what will happen. Why is it important to stop
You will make a straight or running thread in addition to the taper. Proper thread length is essential in forming leak proof joints
Black iron is referred to as? Why?
Malleable iron, it’s a cast iron that has been heat treated to render it less brittle.
What are elbows used for? What is an elbow that changes from one size to another called
They are used to change directions come in 90° and 45°. A reducing elbow
An elbow with thread on one side is called? Can it be used in gas connections?
Code states that this kind of elbow can not be used in any gas connections you will make.
What are bushings used for
Bushings are sometimes supplied with gas valves to reduce one gas size to another.
Can you use face bushings?
No, same reason you can’t use close nipples
What does nesting bushings mean.
Using multiple bushes to reduce down multiple sizes
Pipe compound must be applied to the… and why
Male end, so any excess dope is forced out the pipe instead of being pushed into it.
How to apply Teflon tape?
Must be applied by wrapping it clockwise, stretching it with a 50% overlap, and leaving the first 2 starter thread bare.
What part of the pipe wrench should and should contract fitting when tightening
Two points of contact the hook jaw shouldn’t touch
What is type k copper
Type K is the thickest wall of copper, available in ¼ to 12”
What is type L copper and it’s color code
Medium wall thickness, availed in the same nps, tempers and lengths as type K. Blue color code
What is type M copper and it’s color code
Type M is lighter walled copper, used for water lines and can’t be bent. Color code red
What is type G copper
Coned in sizes from ⅜ to 1⅛ coil of 25,50 or 100 feet
One of the biggest advantages of copper is?
Easily formed to fit on the job site for tight installation
What is copper pip
Have the same wall thickness as iron pipe and come in the same diameter
What is copper tube
A hard drawn material( braze,flared) that is not flexible
What is copper tubing
Soft draft material, annealed which makes it flexible and comes in coil lengths
What other kind of tubing can be used
Aluminum and CSST( corrugated stainless steel tube)
When copper is cut do you need to remove the bur
Yes
What are the basic designs of flared fittings which is HVAC specific
The SAE 37° autootive
The SAE 45° pipetrades aka hvac
and inverted flare
Two types of benders
Lever and spring tube
