UCS-66 (i)

[Paulettea]

Dear All
I am new to the topic of impact testing in ASME BPVC and have come across difficulties regarding interpretation of UCS-66(i).
If I want to use a component which is already impact tested due to its spec. (e.g. SA-350) can I use this component in temperatures colder than the standard impact test temperature as per spec. if the stress ratio is less than one?
I think it is possible as per UCS-66(i) however in PV ELITE 2016 there is a note that says "UCS-66(i) applies to impact tested materials not by specification". I cannot find anything in the text of UCS-66 that limits the use of this to materials that are not impact tested as per their spec.
Can anybody help me understand why PV Elite is excluding these materials from UCS-66(i)

 

[SnTMan]

"(i) For components made of Part UCS materials that
are impact tested, Figure UCS-66.1 provides a basis for
the use of these components at an MDMT colder than
the impact test temperature."

I'd say PVE is in error. I don't particularly trust these kind of decisions to software. After all, UCS-66(b) exists for "impact tested materials not by specification."

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Paulettea]

Hi Mike
Thank you for your reply.
I have come to two conclusions while reading UCS-66 but I am not sure if I am right or not. Would you please help me understand?
1- I think the curves in UCS-66 can not be used for materials that are impact tested as per their Spec. The reason is that these curves are intended for the exemption of materials from impact test which makes them meaningless for impact tested materials.
2-As per UCS-66(b)1 I can use figure UCS-66 in order to obtain an MDMT for a given C.S. and then use figure UCS-66.1 to reduce the MDMT based on the coincident ratio. If the coincident ratio is more than 0.35 then I can achieve MDMT as cold as -48 C but not colder. If the the coincident ratio is less than 0.35 the MDMT could be as low as -105 C. Therefore, it is not possible to obtain an MDMT equal to -60 C or - 90 C. However, if I have an impact tested material say SA-350 LF2 Cl.1 with standard MDMT of -46 C I can use figure UCS-66.1 to reduce the MDMT based on the coincident ratio and for this material the reduced MDMT can be as cold as -105 C. for the impact tested materials there is nothing special about coincident ratio of 0.35 and there is nothing important about temperature -48 C and you can achieve any MDMT warmer than -105 C like -60 C or -90 C.
Am I correct in my interpretation?
Warm Regards,
Paulettea

 

[SnTMan]

Paulettea, your question 1), I'd generally agree, there is no need to apply Fig UCS-66 curves to impact tested materials, whether tested per the material spec or not.

2a) "As per UCS-66(b)1 I can use figure UCS-66 in order to obtain an MDMT for a given C.S. and then use figure UCS-66.1 to reduce the MDMT based on the coincident ratio."

Agree.

2b) "If the coincident ratio is more than 0.35 then I can achieve MDMT as cold as -48 C but not colder."

Agree, for materials that are not impact tested.

2c) "If the the coincident ratio is less than 0.35 the MDMT could be as low as -105 C."

Agree, again for materials that are not impact tested.

2d) "Therefore, it is not possible to obtain an MDMT equal to -60 C or - 90 C."

Agree, unless the coincedent ratio is 0.35 or less.

2e) "However, if I have an impact tested material say SA-350 LF2 Cl.1 with standard MDMT of -46 C I can use figure UCS-66.1 to reduce the MDMT based on the coincident ratio and for this material the reduced MDMT can be as cold as -105 C."

Agree, depending on the coincedent ratio. Note this applies to all impact tested materials, whether by spec or not.

2f) "for the impact tested materials there is nothing special about coincident ratio of 0.35 and there is nothing important about temperature -48 C and you can achieve any MDMT warmer than -105 C like -60 C or -90 C.

I don't completely agree with this, because, by my reading, UCS-66(i) is not limited to materials impact tested by the mateial specification, but applies to any Part UCS material impact tested at any temperature. So, if you had a material tested at 20 C, you could reduce its' MDMT per Fig UCS-66.1. If the component coincedent ratio was 0.35 or less, you could get an 80 C reduction, for an MDMT of -60 C. If the ratio were greater, the reduction woud be less and the resulting MDMT higer.

Gotta tell you I've been reading Part UCS-66 for twenty+ years and I'm still puzzling it all out. This may say more about me than about Part UCS-66

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Paulettea]

Thank you Mike

 

[Jano6924]

Guys:

Interpretation VIII-1-16-62 reads as follows:

Question(s) and Reply(ies): Question 1: May either UCS-66(g) or UCS-66(i) be used to obtain a colder MDMT for a
material required to be impact tested by the material specification and listed in Figure UG-84.1, Note (c)?
Reply 1: Yes

Question 2: For the material in Question 1, may Figure 66.1 be applied to the MDMT determined from UCS-66(g)?
Reply 2: No

My understanding is that if you have an impact tested material per Fig. UG-84.1 note(c), you can use UCS-66(g) or UCS-66(i) at you convenience, however if your choice is for UCS-66(g) then you cannot use Fig. 66.1. For any other impact tested material then you can only use UCS-66(i) for a colder temperature.

What do you think?

Regards.

 

[SnTMan]

Jano6924, I was not aware of that interpretation, thanks. But: The interpretation does not make sense to me. Reply 1 says UCS-66(i) may be applied to materials impact tested per spec, Reply 2 seems to say not. As well, the reference to Fig. UG-84.1 Note (c) is confusing as this addresses energies, not temperatures.

Aside from that, UCS-66(i) reads as applying to all impact tested materials, it does not except UCS-66(g) materials.

But the interpretation is what it is. I guess

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Jano6924]

Some interpretations make things more confusing, and that happened to me with this one in the begining, but now it is clear to me.

Regards.