In article , dpb wrote:

On 3/1/2013 3:11 PM, Pilgrim wrote:
Can any one tell me what the difference between rigid conduit and iron
pipe? inner finish threads on the pipe and in the fittings and any other
significant differences.

There are three standard weights for electrical conduit -- EMT
("thinwall"), IMC (intermediate metal conduit) and GRC (galvanized rigid
conduit). Partial table of standard dimensions per relevant ANSI spec's...

GRC

MIN. WGT.
/100 FOOT O.D. I.D. THICKNESS
SIZE IN LBS. INCHES INCHES INCHES
1/2" 79 0.840 0.632 0.104
3/4" 105 1.050 0.836 0.107
1" 153 1.315 1.063 0.126
1 1/4" 201 1.660 1.394 0.133
1 1/2" 249 1.900 1.624 0.138
2" 332 2.375 2.083 0.146

EMT

1/2" 29 0.706 0.622 0.042
3/4" 44 0.922 0.824 0.049
1" 65 1.163 1.049 0.057
1 1/4" 96 1.510 1.380 0.065
1 1/2" 111 1.740 1.610 0.065
2" 141 2.197 2.067 0.065

Steel pipe
Sch Sch Sch Sch
OD 5 10 40 80
1/2 0.840 0.065 0.083 0.109 0.147
3/4 1.050 0.065 0.083 0.113 0.154
1 1.315 0.065 0.190 0.133 0.179
1 1/4 1.660 0.065 0.109 0.140 0.140
1 1/2 1.900 0.065 0.109 0.145 0.200
2 2.375 0.065 0.109 0.154 0.218

As can be seen, GRC is roughly same weight as, but still slightly
lighter (thinner wall) than Sch 40 pipe but they have same OD

--

Thanks for your informative reply. What are the thread specs? Std NPT or
something else. The couplings I have seen for GRC seen to be non tapered.
Is GRC meant to be liquid tight to prevent moisture entering?
Thanks

CP