API 650 RT repair %

[Kumar]

Dear All,
Kindly share infos about the weld repair percenatge / rejection rate
with respect to API 650 tank construction. sub-con is calculating on
the basis of repair length divided by total weld length. but the
repairs amy be porosity, tungsten inclusion or other rounded
indications as the case may be. in such cases how we could calculate
the length exactly. also please share why it is not possible by
individual welders too (or how their % can be calculated). i beleive
it is not mentioned by 650.
Thanks in advance,
Kumar

[mohd]

Sunil,

No need to worry abour porosity or TI..length of repair how much they excavate for repair.is it clear

take welder wise length of welder welded divided by length of repair of that welder.

Length wise repair is best way to avoid confusion between plates and pipe welding by welders.

Rejection rate/repair allowed is defiantly mentioned in your project spec.

regards,

mohd.

[Perumal Govindan]

Mr. Kumar, refer below the extraction from API 650, section 8.1.6 further after repair you have to take  2 spot radiography (of repair areas segment : adjacent weld length of both the sides) of 3 inch weld length at least. 

For acceptance of rounded indications, refer ASME Section VIII, Division 1, Appendix 4, Section 4.3 Acceptance Criteria for all rounded indications ( porosity, slag inclusion, tungsten inclusion)

P Govindan

8.1.5 Radiographic Standards

Welds examined by radiography shall be judged as acceptable or unacceptable by the standards of Paragraph UW-51(b) in Sec-tion VIII of the ASME Code.

8.1.6 Determination of Limits of Defective Welding

When a section of weld is shown by a radiograph to be unacceptable under the provisions of 8.1.5 or the limits of the deficient

welding are not defined by the radiograph, two spots adjacent to the section shall be examined byradiography; however, if the

original radiograph shows at least 75 mm (3in.) of acceptable weld between the defectand any one edge of the film, an additional

radiograph need not be taken of the weld on that side of the defect. If the weld at either of the adjacent sections fails to comply

with the requirements of 8.1.5,additional spots shall be examined until the limits of unacceptable welding are determined, or the

Plate Thickness

mm (in.)

Maximum Thickness ofReinforcement

mm (in.)

≤13 (

1

/

2

)1.5 (1

/

16

)

> 13 (

1

/

2

) to 25 (1) 2.5 (

3

/

32

)

> 25 (1) 3 (

1

/8)

•

07

8-4 API STANDARD650

erector may replace all of the welding performed by the welder orwelding operator on that joint. If the welding is replaced, the

inspector shall have the option of requiring that one radiograph be taken at any selected location on any other joint on which the

same welder or welding operator has welded. If any of these additional spots fail to comply with the requirements of 8.1.5, the

limits of unacceptable welding shall be determined as specified for the initial section.

8.1.7 Repair of Defective Welds

8.1.7.1 Defects in welds shall be repaired by chipping or melting out the defects from one side or both sides of the joint, as

required, and rewelding. Only the cutting out of defective joints that is necessary to correct the defects is required.

8.1.7.2 All repaired welds in joints shall be checked by repeating the original inspectionprocedure and by repeating one of the

testing methods of 7.3, subject to the approval of the Purchaser.

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[Shashank Vagal]

Dear,

You are lucky that this % is based on length and not joints.

General repair % action criteria is this: 

< 1% Tolerable

Up to 1.5% Caution level

1.5 -2.5% Welder needs to be warned

>2.5% Welder to be withdrawn from job and sent for practice

 

With Best Regards,

Shashank C Vagal