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Strength & Properties of ASTM A36 Steel at -40F
5

Strength & Properties of ASTM A36 Steel at -40F

Strength & Properties of ASTM A36 Steel at -40F

(OP)
Why is it not suitable for -40DegF?

RE: Strength & Properties of ASTM A36 Steel at -40F

Inconsistent notch toughness on thicker plate sections.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
Please elaborate.

The situation is: I have a fabricator who is supposed to U stamp an aqua ammonia tank which is specified at -40F ambient temperature operations. There is no doubt I will reject the design. I understand that ASTM AS36 is OK down to -20F but I don't know how bad it is at -40F with shell thickness 3/8" and heads thickness 5/16"

Thanks for further explanation.

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung,

What is the design MDMT of the tank? What are the rated MDMT of the shell and head?

RE: Strength & Properties of ASTM A36 Steel at -40F

Sam...

Metengr gave you the correct answer....you just do not understand it.

Do you know what these terms mean ?

Where is your tank located ?

Has that area ever experienced -40F ?

API-650 contains a section about the selection of materials based on the geographic area. Materials are grouped base on thier notch-toughness.

Are you aware of the fact that tank shell temperature never mimic the instantaeuos air temperatures ?

Is this the first tank material you have ever evalated ?

-MJC

  

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
Thanks for responding.

Vender: 110F; MDMT: -20F At 25 PSI
Specified: 110F; MDMT: -40F at 30 PSI

My main concern is how bad is it from -20F to -40F if the tank were put into service.  What will be the result and any documentation or real experience to put the tank in prolong period of -40F ambient temperature operation.

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung;
You need to Review ASME B&PV Code, Section VIII, Div 1, Part UCS. There are materials listed, and impact curves, and material that is not permitted.

You need to familiarize your self with Section VIII for pressure retaining items.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
@ MJCronin,

1. You are right I have no idea at all.  Can you explain in real layman terms.

2. The tank will experience -40F.

3. What is the notch toughness at -20F and what is the notch toughness at -40F for SA36? Why notch toughness at -40F is not acceptable?

Thanks for any further elaboration.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
@ metengr,

I have 2 copies of ASME besides me. I read the ASME 2 days ago. I am a bit dum, but that does not address my question how bad it is at -40F or what is bad about the SA36 at -40F.

Will you please elaborate?

Thanks

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
@mentengr,

How thick is thick? > 0.394" on CD curves? That was for impact testing exemption, right?

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung;
A36 is typically not used as pressure retaining material for low temperature service, for the reason I stated above in my first response. ASME Sa 36 is permitted under strict limitations. You are not dumb, you just don't have the experience to understand Code rules. Please review the specific sections below;

ASME Section VIII, Div 1, Part UCS

UCS-6 Steel Plates . Your answer is there for using A 36 plate in a pressure vessel service.

UCS-65 and UCS-66.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
I guess now I understand that SA36 is on curve A and is not even good for -20F tank design temperatures, so impact test is required.

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung,

Quote:

Vender: 110F; MDMT: -20F At 25 PSI
Specified: 110F; MDMT: -40F at 30 PSI
The vendor did not meet the specified design conditions.

I don't know if your specified conditions are correct or not. Correct me if I am wrong, you mentioned the following design conditions:
Design Pressure = 30 psig
Design Temperature = 110 °F
MDMT = -40 °F
Then you mentioned that the ambient (surrounding area) temperature is -40 °F.

You must understand that the MDMT is not always the same as the ambient temperature. Assuming your vessel is operating at 100 °F and insulated (heat conservation), your MDMT would be warmer than the ambient.

So check again if the vessel MDMT is truly -40 °F.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
@doct9960,

Thanks. Our specification calls for freeze protection but the vender proposed tank is bared with only painting, so its ambient - another reason to reject the vender without providing insulation and heat tracing.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
Any quick answer to at what temperature 29% Aqua Ammonia will freeze, thanks.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
OK, I found it, the freezing point of 29% aqua ammonia is about -110F.  So no insulation and heat tracing is required!

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
Please point me to which part of the ASME applicable to pressure tank impact testing, thanks.

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung;
Please see my response above

UCS-65

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
metengr,

I have returned the 2004 version of ASME Section VIII Div 1 to our library, and I have only the 1998 edition with me.  From the 1998 edition, UCS-65 is the scope.  I guess my question was not cleared enough and I should have written:

"which part of the ASME code detailed the impact testing for pressure tanks and for pressure piping if ASTM SA36 were used to construct the tank and carbon steel were used for the pressure piping"

Please point me to the right direction so that I can instruct my vender what should they do to comply with the requirements of impact testing, thanks.

Sam

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung;

Quote:

which part of the ASME code detailed the impact testing for pressure tanks and for pressure piping if ASTM SA36 were used to construct the tank

You will not be permitted to use SA 36 plate based on UCS-6. Please read this section carefully.

Regarding use of carbon steels for piping, this would probably fall under one of the ASME Piping Codes, most likely B31.4 (to convey ammonia to an aqua ammonia tank).

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
metengr,

I cannot find where the code specifically written that ASTM SA-36 is not permitted for constructing pressure tanks.  From Table UCS-23, SA-36 is listed with ... which according to our QA/QC Engineer is OK to construct pressure vessels.  From ASME code UCS-66, SA-36 falls on curve A of FIG. UCS-66 IMPACT TEST EXEMPTION CURVES. Any operating temperature below +20F is not exempted and in our case, our design is -40F.  According to UCS-66, SA-36 is not IMPACT TEST EXEMPTED in our application, therefore my conclusion is an IMPACT TEST is REQUIRED for this material if it were to be used.  Hence my qustion in the above posts is where to find the codes that contain the details on the impact testing of the tank made of SA-36 or is there a section on the detailed testing in the ASME codes at all?

Can some one also chime in on any impact testing details?

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung,

If you browse under CONTENTS of the "2 copies of ASME beside" you, you will find impact testing under UG-84

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
doct9960,

Thanks for the direction.  You help ASME code dummies like me.

RE: Strength & Properties of ASTM A36 Steel at -40F

I have an old code book and in UCS-66 paragraph b:

"Vessels intended for service at temperatures below -20F shall not be constructed of materials complying with Specifications SA-7, SA-36, SA-113, or SA-283."

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
unclesyd,

Thanks for the info.  Which edition you have? Both our editions allow SA-36 for limited pressure vessel use and one of than puzzles me why lethal (gas or liquid but not solids) uses are not permitted. I cannot see any correlation with lethal storages in SA-36 tanks. Is Aqua Ammonia classified as lethal under ASME code?

I invite all, pls feel free to comment if ammonia is lethal, or why lethal uses are not permitted in ASME codes, thanks.

RE: Strength & Properties of ASTM A36 Steel at -40F

SamCheung,

Check the Material SAfety Data Sheet (MSDS) for your aqua ammonia. More than 500 ppm of ammonia is considered dangerous to life. If your tank contains such substance, SA-36 is definitely not permitted by the Code.

For the ASME definition of "lethal substance", refer to the footnote in UW-2

RE: Strength & Properties of ASTM A36 Steel at -40F

I actually copied the info from a 1965 Code book but I found the information first in my notes from a class taken in the mid 70's on low temperature design.

I'm hoping someone can trace this paragraph's lineage to see when the statement was changed or dropped.
One other old timers point is that materials at one time had to comply with ASTM A300, discontinued, and A-36 couldn't meet the criteria of A300 at the time.

I don't think aqua ammonia is classified as a lethal substance as we at one time had over 2 millions gallons of 27% in process. We used 2 different tanks that are still in process service, built 1965. I don't remember any particular precautions  taken for this service. The only thing notable was that both tanks suffered from hydrogen blistering and has to be repaired before a change in service was effected.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
doct9960,

OSHA 29 CFR 1910.1200 classified Aqua Ammonia as hazardous chemical.  TSCA Inventry listed Ammonium Hydroxide as Toxic Substance and SARA TITLE III Section 302 classified it as Extremely Hazardous, but nothing described it as lethal!

I don't see why SS304 or SS316 is OK to store lethal substances while AS-36 cannot be used to store lethal substances, will someone be kind enough to explain to the puzzled mind, thanks.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
unclesyd,

Thanks for sharimg the valuable experiences with SA-36 tanks in use of over 4 decades.

Any clue why  hydrogen blistering occurs to these tanks.  Is it hydrogen ion (dissociated from ammonia?) inside the tank attacking the ferrous materials of the tank?  Could it be oxygen (from air due to tank emptying procedures?) attacking rather hydrogen attacked!

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
unclesyd,

Sorry you must have used other materials than SA-36. Do you know what materials are used to construct your tanks, thanks.

RE: Strength & Properties of ASTM A36 Steel at -40F

I'll try to find the material of construction of the Aqua Ammonia storage tanks.  The storage tanks were equivalent to API 650 designed tanks. All of our Ammonia recovery equipment was CS of some vintage. I'll try to find the material of construction.
We are in Florida so low temperatures aren't a problem for storage tanks. The process equipment was designed to handle the auto refrigeration of the Anhydrous Ammonia.





RE: Strength & Properties of ASTM A36 Steel at -40F

The material for both Aqua Ammonia storage tanks in my previous posts is A-283.

RE: Strength & Properties of ASTM A36 Steel at -40F

Correcting my previous post the material is A 283 Grade C.

RE: Strength & Properties of ASTM A36 Steel at -40F

The toughness of A283-C is about same as A36.  Both have very low toughness at temps below 0 degrees F.

Joe Tank

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
JoeTank,

Thanks for the info.  Where can I find the toughness of A283-C, A36 and other low carbon steel toughness at low temperatures (i.e. at -40F) thanks.

RE: Strength & Properties of ASTM A36 Steel at -40F

Sam,
You won't find a tabulation of impact toughness for these grades.  I've done the impact tests many times on a wide range of thicknesses and find that below about 20F that the impact test results will show ranges of 3 to 5 ft-lbs.  This would be typical for A7, A283 and A36.

Joe Tank

RE: Strength & Properties of ASTM A36 Steel at -40F

Sam;
I have been watching this OP blossom. I would suggest you get your hands on two most important books that I believe will help you in your journey into understanding ASME Boiler and Pressure Vessel Code;

"The ASME Code Simplified Pressure Vessels, 7th Edition, by Robert Chuse and Bryce Carson Jr, Mcgraw Hill

"Pressure Vessel Design Handbook" by Bednar, 2nd Edition, Van Nostrand Reinhold

I have my own personal copy of each and they are tremendous resources.

RE: Strength & Properties of ASTM A36 Steel at -40F

(OP)
metengr,

Thanks for the direction towards the great books.  I will buy them myself if there isn't any available at our library.

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