4130 masts

[robert j. walsh]

Has anyone had a failure with 2" x .25" 4130 chrome moly. If so, what 
did you have on your mast and what were the weather condz at the time of 
failure. I would also like to hear from those who are using 2" x .25" or 
bigger who have not had failure. I would like to know what you have on 
your mast (sqft, boom length, how much out of the tower, etc). If there 
have been any failures, what will you use next time?

Also, are there any opinions, pro and con, to using either a larger 
diameter and/or thicker wall? One would think that either one would 
increase the PSI rating. But I am finding that not to be true. In some 
cases the PSI decreases. Can anyone explain the the math on this? Or is 
it a function of the percentage of elements in the alloy? This would 
seem to be the logical explantion. I have found 2" x .25" 4130 with PSI 
ratings from 110,000 up to 168,000.

A number of years ago Stan, W7NI, had an excellent article in NCJ on 
masts. Does anyone remember what year and/or issues?

73
Bob, K6OMB

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