Incorrect Hole on the ASME Head 5

[Dave Rath]

Hello Everybody:
I have 5/16" THK Stainless Head. I need to patch a 6" hole in the head? Does ASME Sec VIII Div 1 allows to do this? If yes, what NDE methods should I use after patching.
Please help

Thank You
Dave

 

[Christine74]

Are you fabricating it now, or is this an existing vessel that's already been hydrotested/U-stamped?


-Christine

 

[Dave Rath]

Christine74 Thanks. It is under construction right now. New Vessel

 

[Christine74]

I'm not aware of any restrictions against flush patches in ASME Section VIII Div. 1. If the vessel is RT'ed the flush patch would have to meet the RT requirements for a Category A weld, but it's possible that your client might have additional NDE requirements.

If this is a seamless head you may have to do 100% RT for your E=1.0 head calculations to still be valid (I may be wrong about this, not sure really).

Also depending on the size of the opening your client may prefer you to use a flush patch that has been dished in order to match the head dish radius, otherwise the head would have a flat spot.


-Christine.

 

[SnTMan]

Always keep your drops

Regards,

Mike

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

 

[david339933]

Any weld in a formed head is considered a Cat. A weld, so the efficiency of UW-12(d) (.85) for seamless heads with no RT is no longer valid. If E=1 is required, full RT is necessary. As stated above, your customer may want Full RT anyhow. And tell your customer...this will be obvious with a stainless head.

 

[Dave Rath]

Thank you Everybody
This is a two piece head with 100% RT came with partial data report. The E used in the calcs is 85%
I was thinking it will come under spin hole category where you can plug the hole & perform a PT inspection. But there is a restriction on diameter for doing this. I think the best bet here is Patch with Full Penetration & 100% RT to maintain 85% efficiency.
Please comment your suggestions. thank you

 

[david339933]

Standard Designation: BPV Section VIII Div 1
Edition/Addenda: 2013 Eidtion
Para./Fig./Table No: UW-34
Subject Description: Spin-Holes
Date Issued: 09/16/2015
Record Number: 15-1429
Interpretation Number :
Question(s) and Reply(ies):
Question 1: Does paragraph UW-34 prohibit the use of spin holes that are greater than 2 3/8 inches (60 mm) diameter in formed heads?

Reply 1: No.

Question 2: If a spin hole larger than 2 3/8 inches (60 mm) is closed using a butt welded plug, is it required to apply the applicable joint efficiency of Table UW-12 to this weld for the design of the head or head-to-shell joint?

Reply 2: Yes.

Standard Designation: BPV Section VIII Div 1
Edition/Addenda: 2015 Edition
Para./Fig./Table No: Paragraph UW-34
Subject Description: Section VIII, Division 1; UW-34 - Spin Hole Plug Configuration
Date Issued: 12/08/2017
Record Number: 17-1867
Interpretation Number : BPV VIII-1-17-77
Question(s) and Reply(ies):
Question: May an opening in a head be closed with a welded plug categorized as a Category A weld joint, and the head thickness calculated following the current code rules for weld type and extent of examination?

Reply: Yes.

 

[r6155]

Type of head?..Diameter?.

Regards

 

[Dave Rath]

r6155. Thanks. It is ASME F & D head, Thk 5/16" & Diameter 72" ID

 

[r6155]

An inspection opening can be installed and avoid RT.

Regards