Ref (1) - Hull Plating Inspect Work Item Excerpt.pdf

11100_JLW_0325_154

WORK ITEM 1: Hull Plating, Inspect (Hull Scan Requirements Excerpt)

TABLE 1 – ELEVATED INSPECTION SCANS

INCLUDED SCAN TYPE

Yes Conduct an automated crawler ultrasonic inspection scanning (i.e. SIDESCAN) of underwater hull plating and entire freeboard, up to the main deck edge to detect all metal corrosion and deterioration. See paragraph 3.6.1 for requirements.

3.6.1 Automated ultrasonic inspection (SIDESCAN) standards and specifications. When performing this type of scan, all shell plate thickness discrepancies must be identified and reported, while accomplishing and conforming to the following:

3.6.1.1 All scanning work must be performed in the presence of the Coast Guard Inspector or COR. The KO may request that evidence be submitted proving that, at all times, one or more of the on-site technicians, who are performing or overseeing the scan work, meet all qualifications set forth below:

• have successfully operated the automated plate thickness scanner being used in this contract during at least one similar contract

• are conforming to all ASNT Recommended Practice No. SNT-TC-1A 2006 requirements

• possess ASNT Level III analyst certifications for overseeing the entire scanning process and for evaluating all data obtained during scanning.

• possess ASNT Level III or II analyst certification for operating a handheld meters

3.6.1.2 An “Echo-To-Echo Transducer” is not authorized for use.

3.6.1.3 The automated scanning machine must cover all areas of the hull (below the water line and entire freeboard area) up to a maximum of six inches around obstacles. Acceptable obstacles include sea suctions, discharges, rudderposts, anodes, stern tubes, drydock blocks and areas blocked by immovable scaffolding or shipyard activity.

3.6.1.4 The automated scanner must be capable of scanning all convex areas with a radius of 8 inches and greater and concave areas with a radius of 12 inches and greater.

3.6.1.5 Automated scanning resolution must be set to 0.5” x 0.5”.

3.6.1.6 Handheld scanning must be accomplished in areas not covered by the automated scanning, and in areas where the automated scanner loses data due to sharp dents, surface irregularities, roughness, etc.

Follow these guidelines:

• the handheld meter must be calibrated each time it is powered up for use using an ASNT certified calibration block made of mild steel. Demonstrate that the equipment is calibrated prior to and immediately after scanning.

• the handheld meter must be set to a resolution of 2.0” x 2.0” or better.

• supplemental handheld readings must be provided on any area of the hull identified as thinner than the criteria for repair defined in paragraph titled “Evaluation criteria” below.

• a resolution set to 1.0” x 1.0” or better must be used in areas where the automated scanner loses data.

3.6.1.7 Measure the average paint thickness in order to provide a more accurate metal thickness at all scanned points. The average paint thickness must be clearly defined in the reports.

3.6.1.8 Evaluation Criteria. Use the following evaluation criteria for all scanned plating (underwater body and freeboard):

• Plates where scan data indicates wastage greater than or equal to 25% nominal plate thickness must be highlighted in “RED” and designated “repair areas”.

• Plates where scan data indicates wastage between 10% to 24% of nominal plate thickness must be highlighted in “YELLOW”.

• Plates where scan data indicates wastage less than 10% of nominal plate thickness must be highlighted in DARK GREEN.

3.6.1.9 Label each plate on the hull designated for inspection as per the CG drawings listed in Section 2.

3.6.1.10 Outline areas measured with the handheld meter on the hull.

3.6.1.11 Outline in WHITE or YELLOW all areas on the hull identified with 25% or greater deterioration.

NOTE

The colors used to label repair areas must not be used for any other markings on the hull.

3.6.1.12 Develop an electronic file side scan report comparing the results and the plate drawings (to be submitted with the CIR specified above). The reports must include the following contents (minimum):

• Findings narrative summary

• Plate summary – must be in table format with at minimum a column for plate identification, repair identification, location of repair area, size of repair area, and brief description (i.e.

exterior pitting, hole, interior corrosion, etc.)

• A composite mosaic of the scan images overlaid on the appropriate shell plate expansion drawing as listed in paragraph titled “Evaluation criteria” above.

• A separate page for each plate with a scan image of that plate only. Each page must contain the following:

o Plate nominal thickness(es).

o A legend showing plate thickness for green, yellow and red criteria.

o All repair areas must be outlined in blue in the scan image as they are marked on the hull.

o All unusual areas on the scan such as rough surface, etc. must be called out and noted in blue.

o Plate orientation relative to the cutter must be identified.

• Provide an individual photo for each plate requiring repairs.

• Raw data files.

3.6.1.13 The report must be organized as follows and included in the "Initial inspection/test report submission" described above with two copies of the side scan report on unprotected/editable compact discs (CDs).:

• Table of contents

• Plate summary

• Complete port side mosaic showing colorized results

• Port side scan and digital photos of each plate in sequential order

• Complete starboard side mosaic showing colorized results

• Starboard side scan and digital photos of each plate in sequential order

• Transom scan and digital photos

NOTE

All files must be compatible with USCG standard workstation software (i.e., AutoCAD, MS Office, Adobe PDF, JPEG format).

4. NOTES

4.1 Data rights. All data regardless of form or medium must be the sole property of the US Coast Guard and must not be released without the written consent of the US Coast Guard.