EUROCODE 3 / EN 1993-1-10 / Low temperature Steel 1

[Fran67]

Hello,

I have a question about the requirement of Eurocode 3 (Steel structure) part 1-10: Material toughness and through-thickness properties.

This part of EC suggest formulas to choose the quality (JR/J0/J2...etc) of a steel part according to some criterias:
- the thickness of the part
- the reference temperature
- the tensile stresses vs. the tensile strength of the material

If I consider the EC requirement, I can choose a S235-JR (Charpy test 27J at +20°C) steel for a mechanical part at -20°C ref temperature if there is never tensile forces and tensile stresses on this part.

BUT the code does not specify if we have to consider shocks for the steel class definition. (Shock -> Screw falling, Hammer falling during a maintenance phase, shock during transportation..etc)
I've already heard some engineers which do not use EC-3 formulas and consider that the Charpy test must be performed at the minimum ref/ambient temperature. (In example above, it would be a S235-J2 for -20°C ambient T°)

An other example: a lifting lug
According to EC-3/1-10 formulas, I can choose a S235-JR lifting lug at -20°C ref temperature for my machine because the traction force during lifting is very low (10% of S235 tensile strength).
But is the case "the slings/shackle knock against the lifting lug (shock) during the lifting" covered by the EC-3/1-10 requirement?

What do you think about these two interpretations?
What are the requirements of american codes about this subject?

Thank you for your responses,
Best regards,
Fran67

 

[HTURKAK]

Yes ...you can select S235-JR for ref temp . -20°C provided that the element is not subject to tension, welding or fatigue . The
evaluation should be done using fracture mechanics . ( see 2.4. Fracture toughness need not be specified for elements only in compression).



Pls look combination at Eurocode 3: Design of steel structures - Part 1-10

Ed = E { A[TEd] "+" ΣGK "+" 1 QK1 "+" Σ 2,i QKi } This effect combination is ‘accidental combination’ . Notice that A[TEd] leading action A for the reference temperature.

 

[Fran67]

Thank you for your response,

I understand that to respect the EC requirement, I can convert a shock energy (Joule) into a stress.

I've already seen a requirement in some Customer specification, and especially in the PED regulation for the pressurized tank material choice requirement: "the material is considered as sufficiently ductile if the impact test has been performed at min ambient design temperature with 27J".

Do you think that this requirement is applicable for every structure, or only for structures with a huge risk in case of breakage (like a pressurized tank)?

Thank you,
F

 

[HTURKAK]

Ed = E { A[TEd] "+" ΣGK "+" 1 QK1 "+" Σ 2,i QKi } The term A[TEd] is leading action that covers stress due to TEd ( the reference temperature )that influences the toughness of material of the member . Consider a member if free to contract at TEd , the effect A[TEd] will be zero. My understanding is, A[TEd] is the stress developing at reference temp. If you mean shock energy due to blast or impact , the stresses for shock and impact should be considered in accompanying variable loads ( Σ 2,i QKi ) which are the quasi-permanent values of the accompanying variable loads.

I have the German version of EN 13445-2. Appendix B ( which is normative ) and Table B. 1-1 — General requirements for prevention of brittle fracture with reference thickness Impact energy KV = 27J defined for Ferritic steel, (1,5 % to 5 % inclusive Ni alloyed steels ). But the temperature is design reference temperature TR .

If the vessel unfired PV and the content is gas ( and moreover flammable, explosive, or toxic ) ,I will feel anxious with Ted and my personnel opinion , the reference temperature SHALL NOT BE AMBIENT . The TR SHALL BE CALCULATED assuming a leakage at min. ambient temperature and the developing material temp. shall be calculated with isentropic cooling process for the scenario leak .

I will suggest , never and never forget Murphy's Law 'If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong' and for vessels ' Things get worse under pressure. '

I agree with statement with a small correction = "the material is considered as sufficiently ductile if the impact test has been performed at min design temperature ( the temperature that the material could experience ) with 27J".

Is this THERMAL SHOCK ? Please let us know your opinion for this picture. I just wrote thermal shock failure of PV and searched ..one of the outcome is ;

Does this respond answer to your question ?. If not, and if the thread subject is PV, please open another thread at forum Boiler and Vessel engineering with more specific vessel data.