Is code case 2235-9 applicable to B31.1? 3

[metalhoosier]

Can Code Case 2235-9 - Use of Ultrasonic Examination in Lieu of Radiography Section I; Section VIII‚ Divisions 1 and 2; and Section XII be used for B31.1 pressure piping? My first answer is obviously no based on the criteria called out in the title of the code case, however, a contracted NDE firm has claimed they have used this code case for B31.3 and was curious if and where a loophole exists to extend this NDE to other code sections.

Thank you,
MetalHoo

 

[metengr]

MetalHoo
Is this for new construction or a repair?????

 

[metalhoosier]

Metengr,

This is for a repair.

Metalhoo

 

[metengr]

If this is for a repair, you have maximum flexibility. Currently, B31.1 does allow for UT as an examination method in addition to RT. If the original repair weld was RT and you decide to impose UT that is up to you and concurrence from the Inspector. If this is a repair weld and you want to impose UT instead of RT, no problem or conflict with B31.1.

 

[Duwe6]

Concur with metengr on applicability, disagree on categorization of the Code Case as a 'loophole'. ASME is finally recognizing that there are other Volumetric NDT methods other than RT. RT misses much more side-wall Lack-of-Fusion than it finds. That is where 2235 gets the 'acceptable defect' table.

You find a LOT more using manual UT or Phased Array UT. Find even more [many more 'false positives'] using TOFD. On the other hand, good welders like UT because their random, scattered porosity is almost never rejectable using UT [can see the porosity in 3 dimensions, and see the actual separation of the pores]. RT 'compresses' the porosity onto a single 2-D sheet of film, and the interpretor must assume that the pores are really as close togather as the film shows.

Because of the above, I have accepted a weld using RT, and firmly rejected the same weld for multiple, stacked ares of Lack-of-Fusion. I have accepted a weld using UT, and rejected the same weld when I read the RT film due to "exessive porosity". RT is old, customary, and no longer the best choice for evaluating the quality of weld joints. But it is traditional.

 

[stanweld]

Code Case 2235-9 is not mandated by ASME B31.1; it is limited to the specific sections of the Codes defined therein. Because UT is permitted by B31.1, you can mandate its use in B31.1 weld inspections in your engineering specifications; however, the acceptance criteria of B31.1 based on flaw length cannot be waived if it is more stringent than the permitted flaw length in 2235-9.

 

[Duwe6]

Concur

 

[ndeguy]

metalhoosier

I am curious as to why your contracting NDE firm used code case 2235-9 for B31.3 construction which has its own such code case 181-1.

The code cases are similar but 2235-9 has a mimimum wall thickness of 1/2" whereas 181-1 states no minimum.

 

[fakhfakh]

UT is accepted to be used for weld axamination as per B31.1 which make reference to the article 4 of the section 5 (see table 136.4 and § 136.4.6)
Article 4 specifies the technique which includes ToFD and/or PA with data acquisition. Interpretation of indications shall be as per B31.1 § 136.4.6.

You have all things in the B31.1

You do not need to deal with CC2235-9

 

[Duwe6]

TOFD and PA w/data aquisition is fairly expensive due to training experience costs, and very high equipment costs. 2235-9 allows manual UT performed by an ASNT-qualified technician. Much, much cheaper and faster.

 

[ndeguy]

Duwe6

"2235-9 allows manual UT...". Not so, viz:

2235-9 (d) "The ultrasonic examination shall be performed using a device employing automatic computer based data acquisition."

Code cases 2541 and 2557 allow manual Phased Array fixed beam and sectorial raster scans respectively.

 

[Duwe6]

ndeguy, thanks for the save: i misspoke. Should be ASME B31.1 allows UT . . . [not 2235-9]

NOTE: if the weld has been previously rejected using RT, UT is not an option [and the reverse is true]. ASME requires that repairs be reexamined using the original method. There is an 'out' to this clause: if the weld is cut and the weldmetal entirely removed, then it is a "C/1", not an "R/1" and is a new weld as far as NDT is concerned.

 

[SimJack]

I authored CC 2235-3 which added ASME Section I to the already existing ASME Section VIII and also increased the material thickness range.

ANSI B31.1 adopted the code case (don't remember the number) as written. The ASME Code committee turned it into an ASME Section XI style nightmare with all the ridiculous flaw evaluation criteria and is now up to rev. 9. If it is replacing a two dimensional flaw sizing technique (a.k.a., RT) that has worked for decades then why add the through wall criteria to it?

The use of a code case is dependent on the customer or regulatory authority and is not to be applied at will.

Jack Varner
ASNT NDT Level III

 

[Duwe6]

SimJack, you are not alone in the evaluation that it has "ridiculous flaw evaluation criteria". You can't get dial-caliper tolerances out of either a Phased Array or manual UT. Period. Makes as much sense as trying to measure in 1/10,000's of an inch using a caliper. It is past the physical limits of accuracy.

 

[ndeguy]

Roger, Jack - too true regarding the unachievable flaw height measurement demands of the acceptance criteria in Table 2 (Table 1 is OK as there is no need for tenth of a millimetre discrimination in flaw height).

2010 issues of ASME Code were a missed opportunity to get this right to allow logical introduction of advanced UT. Instead of which NDT practitioners are still burdened with cobbling together procedures with the right to perform UT based on half-baked fracture mechanics but utilising workmanship criteria of Appendix 12 for acceptance. I will NOT write in a procedure that which is beyond our current capablility.

T,K,Y joints in the past have been passed off by manual UT with no data record. Why do end users and others make it so difficult to approve the use of encoded PA scans where the completeness of the data and accuracy of interpretation and evaluation can be subsequently reviewed. It makes no sense to me.