S & T Repair - Texas Jurisdiction

[SnTMan]

Hello All. My question relates to the repair of a fixed tubesheet exchanger in Texas jurisdiction. Repair is to replace tubes and tubesheets. Service and design conditions are unchanged.

1) Is it required to run any mechanical caluculations if replacement parts are identical to originals?

2) Does NBIC still allow repaired or altered equipment to meet only original code of construction, rather than the latest? (I believe NBIC did allow this in the past, but do not have a copy available.)

3) If tube-tubesheet joint configuration is changed, say from seal to strength weld, is this an alteration, are new design calculations required?

Any other input is appreciated.

Thanks in advance,

Mike

 

[metengr]

Question 1;

1) Is it required to run any mechanical caluculations if replacement parts are identical to originals?

Reply; No

Question 2;

2) Does NBIC still allow repaired or altered equipment to meet only original code of construction, rather than the latest? (I believe NBIC did allow this in the past, but do not have a copy available.)

Reply; Original Code of construction relates to the code of construction that the item was designed and fabricated, not the edition or year.

Question 3;

3) If tube-tubesheet joint configuration is changed, say from seal to strength weld, is this an alteration, are new design calculations required?

Reply; Yes

 

[SnTMan]

metengr, thanks for your reply. Re my question #2, my mistake, I meant to say original edition / addenda.

Am I mistaken in thinking that in the past, original edition / addenda was allowed? I was also thinking that was changed recently such that most recent edition / addenda is required. Is this correct?

While the answer should be implied by my above questions, Re My question #3, design calculations would be per current issue / addenda of Code, i.e. Part UHX?

Thanks again,

Mike

 

[metengr]

SnTMan;
The NBIC has never referred to a specific Edition or year of the code of construction for a pressure retaining item (unless you are attempting to alter the component which was built before 1968 using current allowable stress values).

Original is used in the context of the construction code that item was designed and fabricated, for example ASME B&PV Code or other Code.

Regarding Question #3, the NBIC does not prohibit a later edition of the code of construction.

 

[SnTMan]

metenger, thanks again

Mike

 

[jte]

SnTMan-

To back up what metengr said, take a look at NBIC Interpretation 95-19:

Question: When the National Board Inspection Code references "the original code of construction," is it required to use the edition and addenda of that code as used for construction?

Reply: No. The term "original code of construction" refers to the document itself, not the edition/addenda of the document. Repairs and alterations may be performed to the edition/addenda used for the original construction or a later ediiton/addenda most applicable to the work.

jt

 

[SnTMan]

jte, I called the NBIC today (duh) and was told the same thing. I was also told that whatever edition / addenda you choose you have to stick with it. No cherry-picking.

Thanks all,

Mike