[TowerTalk] Fwd: Stainless Steel Mast

Tue Nov 3 10:14:02 PST 2009

I beg to differ, Hans, regarding the tall masts.

Irrigation piping, often in 2-6 or bigger inch sizes, is primarily for
the transfer of liquids (usually water) across fields. It is thin-wall
so it can be carried easily and, if examined in the field, it is often
bend and dented. It CAN make a great vertical, but the wall thickness
is a factor that has to be considered and it is not possible to use it
for mast of any kind without substantial guying - it certainly could
never be used as tower rotation masting. It is thin so it is light as
it is carried to where it is needed and really is generally only
strong enough for its intended purpose.

That said, I have looked at the 6" several times as a possible 80
meter vertical if guyed properly, but it would require some planning
because it will collapse.

Michael Goins, k5wmg
Pipe Creek, Texas
Fast cars, slow boats, big dogs, and summers off to write

On Tue, Nov 3, 2009 at 11:56 AM, Roger (K8RI) <K8RI-on-TowerTalk at tm.net> wrote:
> This has been going on for a while, but the first question to ask is:
> HOW is the pipe/tube going to be used?
> IF that 10' section (he did say it was 10' long with 1/4" wall) is going
> to a rotator down in the tower and the antenna is going to be just above
> the top or the tower or bearing, or even if the antenna load is small
> and even a few feet above the top of the tower...It won't matter.
>
> IF OTOH the mast will extend 10, 20, or 30 ft above the top of the tower
> it may and most likely will make a big difference. Water pipe is an
> often used poor choice as it is not only welded, but soft and is easily
> bent although if of sufficient size, it will work safely for a small
> tribander mounted immediately above the top of the tower.
>
> 73
>
> Roger (K8RI)
>
>
> hanslg at aol.com wrote:
>> I was told that tubes are for structure, that is they are made to be
>> strong structurally. Pipes are for transfer of liquids are are built to
>> be able to contain whatever you pass trough them. You can use pipes for
>> construction but have to take necessary precautions not to run into
>> problems. I am, for example, that irrigation pipes are very good for
>> tall masts.
>>
>> 73 de Hans - N2JFS
>>
>>
>> -----Original Message-----
>> From: Pete Smith <n4zr at contesting.com>
>> To: Hank Lonberg <kr7x1 at verizon.net>
>> Cc: TowerTalk at contesting.com
>> Sent: Tue, Nov 3, 2009 6:15 am
>> Subject: Re: [TowerTalk] Stainless Steel Mast
>>
>>
>> Hank, you didn't address the pipe vs tubing issue.  Is pipe with a seam
>> inherently much weaker than seamless tubing of the same material and
>> wall thickness?
>>
>> 73, Pete N4ZR
>> New Articles Daily - the Contesting Compendium at
>> http://wiki.contesting.com
>> The World Contest Station Database, updated daily at
>> www.conteststations.com
>> The Reverse Beacon Network at http://reversebeacon.net
>>
>>
>> On 11/2/2009 8:34 PM, Hank Lonberg wrote:
>>
>>> Dave:
>>>
>>> The important number is the yield stress not the tensile
>>> stress. 6061-T6 and the stainless, most likely 304 or even
>>> 316, have about the same yield of 36,000 psi plus or minus.
>>> This is the threshold stress where the behavior of the
>>> material changes from elastic to plastic. This mean if want
>>> the material to rebound to initial position after loading you
>>> need to keep the max stress below yield. In the case of your
>>> masting material they will both support about the same load
>>> with equal stresses.
>>>
>>> The kicker is the Modulus of Elasticity,E, which for the
>>> stainless, like other steels, is around 29,000,000 psi. The E
>>> for aluminum is around 10,000,000 psi. This means for the same
>>> section dimensions and load the aluminum will deflect 3 time
>>> more than the steel. My money for durability is on the
>>> stainless.
>>>
>>> Regards
>>> Lonberg Design Group, Ltd.
>>> H.S. Lonberg, P.E.,S.E.
>>> President
>>>
>>>
>>> -----Original Message-----
>>> From: towertalk-bounces at contesting.com
>>> [mailto:towertalk-bounces at contesting.com] On Behalf Of Pete
>>> Smith
>>> Sent: Monday, November 02, 2009 1:30 PM
>>> Cc: 'David Jordan'; TowerTalk at contesting.com
>>> Subject: Re: [TowerTalk] Stainless Steel Mast
>>>
>>> BUT, if it's pipe, it may not be seamless
>>>
>>> 73, Pete N4ZR
>>> New Articles Daily - the Contesting Compendium at
>>> http://wiki.contesting.com
>>> The World Contest Station Database, updated daily at
>>> www.conteststations.com
>>> The Reverse Beacon Network at http://reversebeacon.net
>>>
>>>
>>> On 11/2/2009 3:34 PM, Rex Lint wrote:
>>>
>>>
>>>> Dave,
>>>>
>>>> 6061-T6 has Tensile strength of 42K PSI and yeild at 35K PSI
>>>>
>>>>
>>> - See
>>>
>>>
>>>> wikipedia.
>>>> Stainless varies from about 75K to 190K PSI Tensile,
>>>>
>>>>
>>> depending on the
>>>
>>>
>>>> allooy.  See http://www.onlinemetals.com/stainlessguide.cfm
>>>>
>>>>         -Rex-
>>>>
>>>>        K1HI
>>>>          Rex Lint
>>>>          Merrimack, NH
>>>>
>>>> -----Original Message-----
>>>> From: towertalk-bounces at contesting.com
>>>> [mailto:towertalk-bounces at contesting.com] On Behalf Of David
>>>>
>>>>
>>> Jordan
>>>
>>>
>>>> Sent: Monday, November 02, 2009 2:10 PM
>>>> To: TowerTalk at contesting.com
>>>> Subject: [TowerTalk] Stainless Steel Mast
>>>>
>>>> Hi Folks,
>>>>
>>>>
>>>>
>>>> I found a nice length of stainless steel pipe 2" OD (.250"
>>>>
>>>>
>>> wall) by 10ft
>>>
>>>
>>>> that I thought might make a nice mast stub.  How would this
>>>>
>>>>
>>> tubing's
>>>
>>>
>>>> strength compare to 6061 aluminum of similar dimensions?
>>>>
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Dave
>>>>
>>>> Wa3gin
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>>
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