Steel light poles from 1950s or 60s

[bigsam4325]

Trying to verify some old light pole towers for new, larger light fixtures. They are tapered round steel, not polygonal, with slip overlap splices and about 3/16" to 1/2" thick. With no original documentation available, wanted to know what like steel grade might have been used for these if they were built around 1950-1960.

 

[racookpe1978]

I doubt anything stronger than simple, cheap A36. But I am surprised at how little corrosion is present after than long an open-air service near the street (salt and spray and no painting.) If the results for strength assuming simple 36,000 psi fail, you'll need an alloy check. Will need one anyway to determine the weld filler alloy and WPS choice.

 

[bigsam4325]

As a follow-up. I was not looking for reason to use higher than A36. The results check out OK for A36. Rather I was concerned that there may be reason to need to assume lesser than 36 ksi that far back.

In addition the pole not adjacent to any road. It is on the lawn spectator area of a large concert event center. So that has probably helped it condition-wise.

 

[Archie264]

Could that be some type of weathering steel? Looks like a possibility.

 

[bridgebuster]

I looked at NYCDOT light Standards for that time - nothing specific. One drawing called the pole "high-tensile, low alloy or mild steel". Another drawing called out the arm as Schedule 40 pipe. I looked at some bridge plans (NYC circa 1955), the light pole was called "Standard Pipe".

 

[dik]

Can you take a coupon and have it tested? That way, you know what you have...

Dik

 

[racookpe1978]

Tapered (conical) round steel lightposts could not (reasonably) be made or rolled or stretched from standard pipe, but any straight round pole is very likely to be made of some standard round pipe stock.

 

[MotorCity]

Maybe its different in the light pole industry, but I did not think that round shapes were available in A36. That said, A36 would be safe for analysis purposes considering that most hollow shapes are 46 ksi.

 

[PT99]

Could be ASTM A7 in the 1950's. I would use 18 ksi, as an allowable stress, if you have no further information, and it works. This is consistent with AASHTO manual for existing bridge load rating in the 1970's era, (as I recall). I only recently tossed out that book.

 

[bridgebuster]

@racookpe198 - the drawings I was looking at were for round poles.

 

[JStephen]

The most common pipe we see now is A53-B, which is 35,000 psi yield.
If I remember right, Grade A is something like 25,000 psi yield. I don't know if it was ever more popular or not.
This paper shows A36 coming out in 1960:

https://www.aisc.org/globalassets/modern-steel/steelwise/30762_steelwise_reno.pdf

I was thinking the structural tubular standards were all newer than the 1960's.