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FW: A 588 STEEL / STACK DESIGN (more details)

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David Handy, P.Eng
The Thompson Rosemount Group
Cornwall, Ontario, CANADA
dhandy(--nospam--at)trg.ca
The preceding was an off the record personal opinion only! (cya)

-----Original Message-----
From:	Horning, Dick/CVO [SMTP:dhorning(--nospam--at)CH2M.com]
Sent:	September 29, 1998 3:08 PM
To:	'seaint(--nospam--at)seaint.org'
Subject:	RE: A 588 STEEL / STACK DESIGN

ASTM A588 steel is referred to as High strength low alloy structural steel with substantially better atmospheric corrosion resistance. Gas up stack is only combustion products of natural gas. There is a barometric damper on stack which reduces gas temperature. There is also 4 / 6" of ceramic fibre insulation on the inside of the stack horizontal and base of vertical section. Temperatures given were calculated by the burner supplier for the stack in still air at 70 deg F (not in Texas obviously). Stack is 70' high and 3' in diameter.

>Couldn't find a listing for SA-588 in the ASME BPV Code, Table UCS.
>Weathering steel sounds like a good choice unless you have something nasty
>going up the stack.  Are you sure about those temperatures?  They don't
>sound very high for a stack.  Joint efficiency of 0.70 is consistent w/ the
>BPV Code, Section UW, for a double-welded butt joint w/o radiographic
>inspection; you could improve it to 0.85 w/ just spot inspection.  On the
>other hand, ASME shows efficiency drops to 0.60 for single-welded butt
>joints and as low as 0.50 for fillet welded lap joints.  Hope this helps a
>little.

	-----Original Message-----
	From:	Dave Handy [SMTP:dhandy(--nospam--at)trg.ca]
	Sent:	Tuesday, September 29, 1998 11:18 AM
	To:	SEAINT SERVER (E-mail)
	Subject:	A 588 STEEL / STACK DESIGN

	I am designing a steel stack and am planning on using A588 steel.
This was recommended by local fabricators as the proper choice. Has anyone
out there used this type of steel before for a stack? I am trying to
determine the allowable stresses / yield stresses for this type of material
at various temperatures. The tensile strength is 70 ksi and the yield point
is 50 ksi. We are operating below 600 deg F and likely the temperature will
have little effect, however, I just want to make sure that all assumptions
made are accurate. Operating temperature is in range of 400 deg F.

	1.	Is yield unaffected?
	2.	What is the effect on E (mod of elast)?
	3.	Does a joint efficiency of 0.7 make sense?

	David Handy, P.Eng
	The Thompson Rosemount Group
	Cornwall, Ontario, CANADA
	dhandy(--nospam--at)trg.ca
	The preceding was an off the record personal opinion only! (cya)