Allowable Stress Value for Cargo Tank Material

What design code are you using? At what temperature, and what thickness material?

I don't imagine you are using ASME VIII because it is a cargo tank, correct?

Actually i am doing re-enginereing work of this vessel. I have to re-design as per ASME VIII with same data

Design Pressure:250 F

Design Tempeature: 150 F

Radography: Full

Shell/Head Material: ASTM A-656 Grade 80 Type 7

I suggest trying ASME Sec II Part D. Good Luck.

But i think allowable stress values for this material is not available in ASME Section 2 Part D.

This material A 656 is a structural steel material in accordance with ASTM and is not specified in accordance with ASME (ASME SA 656). It is hot-Rolled Structural Steel, High-Strength Low-Alloy Plate with Improved Formability.

This specification covers two types and four strength grades of high-strength low-alloy, hot rolled structural steel plate for use in truck frames, brackets, crane booms, rail cars, and similar applications.

As Abdel Halim Galala says this material is "structural grade" and not a "pressure retaining grade". That's the reason why it isn't included in ASME Section II Tables.

Even if you may find or stablish the allowable stresses (obviously any steel has it) you must not use it for a pressure vessel according to ASME (even if ASME stamp wasn't required). You may be responsible for any liability arising from any possible failure.

BTW, I've supposed the design pressure is in "psi", not "F". Or it's design temperature and pressure is missing?

Kind regards

Statement: All material for shell, heads, bulkheads, and baffles must conform to Section II of the ASME Code:

(1) The following steels are also authorized for cargo tanks ''constructed in accordance with the ASME Code'', Section VIII.

ASTM A 569, ASTM A 570, ASTM A 572, ASTM A 622, ASTM A 656, ASTM A 715, ASTM A 1008/ A 1008M, ASTM A 1011/A 1011M.

As per above statement for cargo tank I think I can design a pressure vessel according to ASME (even if ASME stamp wasn't required). Please note that Design Pressure is 250psi

Actually I have taken

Tensile strength=780MPa

Yield Strength=690MPa

(As mentioned in procurement list)

While Allowable Stress is calculated as = Min (.66*690, 780/3.5)

=222Mpa

But I need to confirm this allowable stress value

Any plate material named and specified by "structural" is not allowed to be used in "pressure part" (like as shells and heads) of any vessel designed and fabricated in accordance with the rules of ASME code. Only you have to use that "structural" materials in "non-pressure parts" (like as skirts and saddles).