Gas Pipe Flashcards
(40 cards)
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
