New requirements on older boiler - R stamp repair

[rmillercwi]

I am assisting with a grade 91 tube leak on an older HRSG built in the late 90's. T-91 tube, grade 91 header. Failure at the toe of the weld. Failure cause and weld repair process understood.

The repair tube stub is cold bent. A PG-20 strain calc steers us into heat treatment of the bend after bending but no normalizing allhough I have been involved in repairs that both heat treatment and normalizing was required.

The question is do we really have to do this heat treatment/normalizing on boiler repairs when the requirement for doing so did not exist during original fabrication? I was involved with a large amount of fabrication of this type back in the late 90's to mid 2000's and dont ever recall this requirement.

I certainly understand the requirement for new construction. I struggle to understand the requirement when many boiler tubes on either side of the repair did not have this performed.

Same with tube repairs of T-23 material. Back in the day many boiler harps were made of material to earlier code cases (many to 2199-3) and I think now its up to 2199-8 makeing stock of earlier sourced material un-useable.

Perhaps there is an exemption that allows fabrication/use of materials to original code addenda?

 

[davefitz]

I think the preamble to asme sect I and the nat'l board part 4 provides the exemption words, but I could be wrong.
If it is only an issue of reliability and insurance claims then your insuracne inspector should provide guidance. If it is a life safety issue then it would be prudent to meet the latest code requirements. The distinction is usually based on whether the part is within the boiler setting or if it is in the workplace.

The main changes in code requirements occurred in the 2006 asme section I revision for P91, T23, and other creep strength enhanced alloys. There is still a reluctance by fabricators to provide the required N+T and the code still does not demand the cooling rate for the P91 parts be faster than -9F/minute to ensure martensite is formed.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[FormerAIS]

It seems odd, but the NBIC permits a work to be done utilizing any construction Code from the original construction to the most recently published. Whichever construction Code is used to perform the repair/alteration must be adhered to. Therefore, if the original Code is used, heat treatment and normalization would not be required for this repair.

Keep in mind, that Code is a minimum, and it still could be performed. Also keep in mind that if it is performed, that the rest of the weld(s) were not heat treated, therefore potential problems could arise during the stress relieving process.

A similar instance to this occurs with Impact testing of Carbon steel material in pressure vessels certified before 1974. Simply putting a 1" coupling in a pressure vessel from the 1960's could result in a massive re-rate of the vessel if attempted to be performed using the current Code due to MDMT.

Quality is not an act, it is a habit - Aristotle

 

[rmillercwi]

Thanks guys. An exemption of requirements based on current addenda vs original addenda does make sense but for the life of me I cannot locate the actual verbiage that allows it. I have searched NBIC and the closest I find is in " Material requriements for repairs and alterations sect 3.2.1 (a) " the materials used in making repairs and alterations shall conform insofar as possible to the original code of construction....including the material specificaiton requirements used for the work planned...."

Maybe that means you can backtrack to original addenda but hoping theres something more clear.


The understanding of original code of construction is clear. It doesnt really spell it out either way if you can backtrack to original addenda or must use the most current. If it exists, I would like to locate the actual verbiage that allows it.

 

[weldstan]

The original Code of Construction is ASME I. Either the present Edition and Addenda or the original Edition and Addenda may be used under the NBIC. There was an Interpretation for this but I no longer have access to NBIC.