Has anyone built a Pressure Vessel out of Aluminum ? 4

[HottoJD]

I have heard of gas cylinders built out of Aluminum and of course air plane skins. How about a pressure vessel that also has to transfer heat through the wall? What types of Aluminum would be suitable, 6061 or 2024 ...?

 

[kenvlach]

I am not a mechanical engineer, but I know that Al has been used in many PV applications. Its thermal conductivity is about 10x that of stainless steel. It is commonly used for cryogenic applications due to good ductility at low temperatures, but also often used at moderately elevated temperatures. Heat exchangers and gasoline engine pistons might also be considered PV applications.

For at least 40 years, the ASME Boiler and Unfired Pressure Vessel code has permitted the use of Al 3003 and certain other alloys at metal temperatures not exceeding 400[sup]o[/sup]F.
Aluminum has also been used for steam and condensate lines in the chemical and food industries for at least 60 years.
“In the processing, packing, and storage of foods, aluminum is used for steam-jacketed cookers, tanks and vats…”
Aluminum has also been used at temperatures up to 770[sup]o[/sup]F for molten sulfur.
---Corrosion Resistance of Metals and Alloys, 2nd. Edn. (1963).

Regarding alloys: 2024 & 6061 (& 7075) are heat treatable alloys. I would not expect them to be used in heated applications as overaging (of precipitation-hardening phases) would occur. E.g., the 6061 T6 temper is achieved by aging at 320-350[sup]o[/sup]F.
Also, Al 2024 is a corrosion-prone alloy; for many applications it is clad with a ~pure Al skin to resist corrosion. I believe that the most commonly used Al alloy for heat exchangers is 3003, either with or without the pure Al cladding, depending upon the application. Al 1100 (99% Al) is used for heat exchangers and vessels in more corrosive environments, e.g., hot, concentrated nitric acid.

 

[Mark31]

You should go and talk to Coke. I crack open a little aluminium pressure vessel almost every day!..HAHA

 

[spector]

This reminds me of the Steam kettle that failed after 30 years of use...It was constructed of Alum and rated at 50 PSI MAWP.

The owner had replaced the wooden stir paddle with a pretty stainless one....The hard stainless stir paddle finally thinned the kettle bottom to where it failed while in service. The cook wasn't injured, as he had just cut steam into the cold kettle and turned away. But the kettle full of brown gravy mix sure made a mess of his kitchen.

 

[PPVE]

I have designed several vessels in Aluminium Alloys, static and mobile (road tankers), mostly for cryogenic applications. Some questions come to mind:
How important is the transfer of heat across the wall in comparison to the pressure retention?
What is the service of your intended vessel?
Which code do you intend to use?

I'll offer a view if I can, dependent upon the answers to these questions.

PPVE

 

[HottoJD]

The application requires both heat transfer and contents retention. I was thinking of using Al 6061 and having it designed as a Div II vessel so that the wall could be made thinner. How hard is it to design a pressure vessel to 600 psig for Div I than Div II. The design temperature should be 300 F max.

 

[PPVE]

I must leave the question of thermal conductivity to those who know more than I. As to the code, I have not used ASME VIII Div 2 for a few years - I use PD5500 (was BS5500) and AD-Merkblatter, both of which have similarities to Div. 2, ie., higher allowable stresses than Div. 1.

PD5500 cautions against alloy 6061 unless you can ensure that the welds are not subject to severe weld restraint: In which case, you might want to consider alloy 6082 instead. In the T6 temper, welded it has a design allowable stress of 51 N/mm^2 at 150 deg C according to PD5500 (6061 also 51 N/mm^2 at 150 deg C).

How big is the vessel? For a design pressure of 600 psig (41.38 bar) you would need a wall thickness of about 81 mm for a diameter of 2000 mm (78 in). You might have difficulty obtaining this alloy at that thickness and certainly butt welding would be very costly.

Some aluminium alloys perform better than others in a corrosive environment and you might need specialist advice if your process fluid is corrosive.

Let me know what progress you make.

PPVE

 

[smckennz]

Aluminium works well as a pressure vessel material at low temperatures where it has good strength. It is widely used in the cryogenic industry for liquified and low temp gas storage. Its strength to weight also favours it for medium stress applications in aerospace. Unit strength drops quickly with temperature however. Its a horse for a couple of courses.
For 300F you may be better looking at steel, stainless or exotics like titanium (its cheaper than you think).
For most heat transfer applications such as you describe, the wall thickness is not the bottleneck; its the product side convection coefficient. Unless you are just trying to keep something warm, its normally better to use a heat exchanger. Some of the plate types can run high temperatures now, and are reasonably priced. Plus you have more positive control over heat addition.

Cheers

Steve

 

[Raydel]

CodeCalc / Pvelite software has a complete aluminimum material database and can easily accomplish the design of aluminium pressure vessels. You are cautioned to be aware of any welding problems with certain aluminium alloys. Ensure you weld procedures are qualified in accordance with ASME IX of EN 287/288.