SA-414 Grade G UCS-66 Curve

[Woodstock31]

Pressure Vessel built to Sect. VIII- Div. 1

There is some disagreement over what curve SA-414 G should be listed on in UCS-66(b). Our calc software automatically selects curve A. The SA-414 G material is in the shape die-formed heads. Impact test is not required for the construction of the vessel.

Can someone shed some light on this?

 

[SnTMan]

Woodstock31, on the face of it, I'd agree w/ your software.

Regards,

Mike

 

[Woodstock31]

SnTMan-

I appreciate the reply.

There are a couple of arguments that have been made:

1) Since the heads are die-formed they should be permitted to go to curve B since UG-11(b) talks about die formed heads.

2) Since SA-414 A is listed as a curve B material and SA-414 G has better strength, then grade G should be allowed on curve B.


I more lean towards accepting the first argument. I don't believe the second argument has much weight since their isn't literature in code that backs it up.

What is your thought process to help you arrive with curve A? Any feedback is very helpful.

Thanks.

 

[Don56]

Your second argument does not hold up. Just because material has a higher tensile strength does not mean it is tougher, refer to SA-516 grades 55 thru 70 on the same chart.

Aren't you exempt by UG-20(f)?

 

[Woodstock31]

We are exempt from UG-20(f). We are under on the thickness requirement, we test pneumatically per UG-100, and apply Code Case 1518-5.

 

[SnTMan]

Though process for Curve A? Not listed for other curves.

If the head is supplied under and meets UG-11(b), then I'd agree it can be classified as Curve B, otherwise not. Notice this Note UG-66 (2)(d) can place material on a higher (lower letter) curve as well as a lower one.

With Don56, I also disagree w/ your point 2). Don't think you can say that.

Exempt by UG-20 or from UG-20? Not familiar w/ 1518-5

Regards,

Mike

 

[Woodstock31]

I do believe we are exempt by UG-20(f). My apologies for the typo. We have a young group that is not very experienced with the code which is why we have a bunch of opinions.

The heads meet requirements UCS-79(d), UG-77(c), UG-79, & UG-81. The heads are not heat treated.

Head thickness: .250"
Max Working Pressure: 495 psi
Max Metal Temp: 650° F
MDMT: -20° F

 

[SnTMan]

Woodstock31, if you're only trying to get to -20F, sounds like you have multiple ways to get there...

Regards,

Mike