[TowerTalk] Yield strength data for plain steel water pipe

[Mark .]

Greetings gang,

I did some more digging on the strength properties of water pipe, to help us 
select and size it for mast use more effectively. NOTE: I am not referring 
to structural tubing, which is a completely different class of 
higher-quality and stronger steel. Here's what I found out.

Water pipe is no longer made from wrought iron, it is all wrought steel, 
since the 70's. Any 'scheduled' water pipe you buy new should be wrought 
carbon steel.
The 'jackpot' reference table is in the American Society for Metals 
handbook, volume 1, eighth edition, page 149.

The pipes are made to ASTM or API specifications, with corresponding 
sub-grades, which should be marked on your pipe if it is new, so you can 
positively identify the grade and strength.

The most common, and lowest grade of pipe is ASTM grade A120, welded or 
seamless pipe, back or galvanized. It's material composition *is not 
controlled at all* !!!!

****
Specification A120 does not specify or require a minimum yield strength 
(page 146). All that is required is that it pass a hydrostatic pressure 
test! Wow, this is unbelievable. It is used "...for all ordinary purposes 
such as conveying fluids under low pressure..." For this reason alone, I 
would not recommend grade A120 at all. Check the markings. This is crap 
steel! One can only guess that it has close to the lowest strength of the 
other types, *at best*. Now we know where all the recycled steel from those 
AMC Pacers went to! Hee hee hee <*grin*>
****

NOTE: the strengths are *yield* strength (not tensile strength), which is 
the point where the material will first start to bend permanently. Stainless 
steel pipe is different, and I will post that data when I find it.

Match up the mill markings on the pipe itself (best), or if new, refer to 
the vendor's specification/certification.

MINIMUM YIELD STRENGTHS FOR:
COMMON SCHEDULED WATER PIPE TYPES
Carbon (plain) steel, black or galvanized

ASTM TYPES
A120, no sub grade .... ??? pot luck
A53,  grade A ......... 30,000 psi
A53,  grade B ......... 35,000 psi
A106, grade A ......... 30,000 psi
A106, grade B ......... 35,000 psi
A106, grade C ......... 40,000 psi
A135, grade A ......... 30,000 psi
A135, grade B ......... 33,000 psi
A139, grade A ......... 30,000 psi
A139, grade B ......... 35,000 psi
A333, grade C ......... 30,000 psi

API TYPES
5A, grade F-25 ........  25,000 PSI
5A, grade H-40 ........  40,000 PSI
5A, grade J-55 ........  55,000 PSI
5A, grade N-80 ........  80,000 PSI
5A, grade P-105 ....... 105,000 PSI
5A, grade P-110 ....... 110,000 PSI
5A, grade D ...........  55,000 PSI
5A, grade E ...........  75,000 PSI
5L, no grade given ....  25,000 PSI
5L, class I ...........  25,000 PSI
5L, class II ..........  28,000 PSI
5L, class A ...........  30,000 PSI
5L, class B ...........  35,000 PSI


As you can see, the strengths can vary considerably, but if you have 
scheduled water pipe that you cannot positively identify, don't assume a 
yield strength higher than 25,000. And that's with no safety factor.

This material is so commonly available, it can be quite suitable for 
masting, when you select the grade and size it properly. But just remember 
that is the the weakest grade of steel there is, so size your application 
carefully.

Sorry if this seems like too much detail, but this information is crucial to 
being sure that your mast is strong enough.

I frequently get chided  by friends for whipping out the pencil and 
calculator to 'run the numbers'. I admit! My 'nerd watch' has a calculator 
in it. :)

But, when you do it right, you sleep at night (especially during storms).

Hope this has helped someone. From what I have read here, there's little 
worse than trying to replace a bent mast on a tower.

Good luck!

--...MARK_N1LO...--
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