3.05.operatingprocedures.ultrasonic inspection of welds

7/30/2019 3.05.OperatingProcedures.ultrasonic Inspection of Welds

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3.05 WELDING PROCEDURE MANUAL of 5

OPERATINGPROCEDURES

ULTRASONIC INSPECTION OF WELDS 12/28/10

HIS SECTION PROVIDES STANDARD PROCEDURES FOR ULTRASONIC

INSPECTION of field welds performed on the Company’s pipelines and associatedappurtenances. T

GENERAL

Pipelines requiring non-destructive testing in accordance with Section 3.02 (“Non-

Destructive Testing Requirements”) of this manual can utilize Ultrasonic Testing (UT)

provided another type of more reliable non-destructive testing is not required or utilized. If

another type of non-destructive test is used, UT may not substitute for its specific

requirements.

This procedure defines the requirements for conducting ultrasonic testing, and is intendedto comply with API 1104 Welding of Pipelines and Related Facilities Section 11.4.

This process is used to detect discontinuities that extend through the entire weld, UT is

intended to:

Verify weld integrity

Identify the need for correction of improper welding techniques by indicating

recurring defects

Assist in verifying welder quality in the production weld process

All personnel conducting ultrasonic testing will be qualified as required by SNT-TC-1A

(“Level II for Ultrasonic Testing”).

ULTRASONIC TESTING PROCEDURES

These procedures provide the basic steps in performing ultrasonic inspection. They are notintended to cover all details relative to the process and procedures utilized by each non-destructive testing firm.

PREPARING THE EXTERNAL PIPE SURFACE

Surface conditions greatly influence the sensitivity of the inspection process. Thesurface should be clean, dry, and free from oil, water, excessive weld spatter, or otheraccumulations that would interfere with efficient inspection. Wire brushing,sandblasting, or other comparable cleaning methods are usually satisfactory for mostwelds.

The Field Inspector and/or Welder is responsible to:

1. Ensure the pipe is essentially clean, dry, and free of contaminants within no lessthan 1 inch of the test area.

2. Remove any disbonded coating or corrosion products by using power brushing orlight abrasive blasting:

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OPERATINGPROCEDURES


A blasting medium of a 3:1 mixture of 12/20 size crushed walnut shells

with medium coarse sand (20/50 mesh) may be used Commercial grit (Black Beauty) may be substituted for sand

3. Use a method that will clean and polish the pipeline without cutting an anchorpattern in the steel; if requested by the non-destructive testing personnel, apower grinder can be utilized to smooth the weld surface provided the weldreinforcement is not cut away beyond the effective weld metal.

ULTRASONIC TESTING EQUIPMENT

Pulse echo UT equipment shall be used. The ultrasonic instrument shall beequipped with a fine gain or attenuation control having a minimum increment nolarger than two dB. Instruments shall be capable of generating frequencies overa range of 1.0 to 5.0 megahertz (MHz.).

Both amplitude linearity and amplitude control linearity requirements shall beverified each day that an ultrasonic instrument is used to perform anyexaminations. Should any instrument fail to meet these requirements, allmaterials examined with the instrument since the last acceptable linearity checkshall be re-examined.

Transducers for straight beam examinations shall have an active area from 0.20”to 1.00”. The nominal frequency shall be from 2.25 MHz. to 10 MHz. dual orsingle element transducers may be used.

Transducers for angle beam examinations shall provide a nominal frequency of

2.25 MHz. for ferritic materials. The search unit frequency shall be selectedbased on optimum resolution and sensitivity to the ID notch while maintaining atleast a 2 to 1 signal to noise ratio. Dual or single element transducers may beused.

Appropriate wedges or shoes may be fitted to transducers as required to providenecessary beam angles and modes of transmission. Search unit exit points andbeam angles shall be verified for each calibration. Beam angles shall be within ±3° of required nominal angles.

Calibration Blocks shall comply with the requirements of ASTM SE213/ASMESE-273. Calibration blocks shall be of the same material type and nominal pipe

size and schedule as the items to be tested. Couplants shall be used in sufficient quantity to maintain continuous sonic

contact. The couplant information shall be included on the examination datasheet.

ULTRASONIC TESTING EQUIPMENT CALIBRATION

In addition to linearity verification daily, these units shall have calibration checksdone at the start and finish of each examination, at intervals not to exceed 4hours.




OPERATINGPROCEDURES


Calibration shall include the complete ultrasonic system. Any change in search

units, couplants, cables, instruments or any other components of the systemshall be cause for re-calibration.

The temperature of calibration blocks shall be the same as the component underexamination within ±25° F. Calibration shall not be performed on calibrationblocks over 115° F.

The NDE service provider shall have the calibration procedures on file and beable to demonstrate this procedure.

ULTRASONIC EXAMINATION PROCESS

When scanning for reflectors oriented parallel to the weld, the angel beam shallbe directed at approximate right angles to the weld axis from two directions

where possible. The transducer shall be manipulated so that the ultrasonicenergy passes through the required volumes of weld and adjacent base metal. The primary scanning shall be performed at a gain setting at least two times theprimary reference level. Evaluation shall be performed with respect too theprimary reference level (relative to 80% of full screen height).

When scanning for reflectors oriented transverse to the weld the angel beamshall be directed essentially parallel to the weld axis. The transducer shall bemanipulated so that the angle beam passes through the required volume of theweld and base metal. The scanning shall be performed at a gain setting at leasttwo times the primary reference level. The search unit shall be rotated 180° and

the examination repeated. When evaluating the weld and base metal, all indications greater than 20% of the

reference level shall be investigated to the extent that it can be evaluated interms of the acceptance standard for Section 3.02 (“Non-Destructive TestingRequirements”).

Overlap each pass of the transducer by a minimum of 10% of the width of theactive transducer

The scanning rate of a manual scan shall not exceed 6 inches per second.

When determining flaw size, the following procedure shall be used to determine

the lengths of indications which require investigation:o Maximize signal amplitude from the reflector and record its sound path, depth

and location

o Move the transducer to the right of the maximized signal and mark a point attransducer centerline where the amplitude signal drops by 50% (6dB)

o Repeat this step in the opposite direction (to the left of the maximized signal)and mark another point at transducer centerline where the amplitude signaldrops by 50% (6dB)

o Length of the indication shall be determined by measuring the distancebetween these points










OPERATINGPROCEDURES


When performing ultrasonic testing, geometric indications similar to those caused byweld imperfections may be caused by:

Changes in weld geometry due to alignment offset of abutting pipe ends

Changes in reinforcement profile of I.D. (internal diameter) root and O.D. (outsidediameter) capping passes

Internal chamfering

Ultrasonic wave mode conversion due to such conditions

These are not relevant to the weld’s acceptability (based on API 1104 evaluation criteria).

MARKING WELDS FOR REPAIRWelds needing repair as determined by these procedures may be marked in accordancewith the suggested process below. Prior to construction or weld inspections, other markingprocesses may be submitted to the field inspector for review.

SUGGESTED PROCEDURE FOR MARKING WELDS FOR REPAIR

To mark welds for repair, the authorized representative of the NDE (Non-DestructiveExamination) Service Provider will:

1. Paint a 6-inch diameter circle with bright yellow spray paint on the pipe to the leftside of the weld near the twelve o’clock position. If more than one repair is

required, paint an additional circle adjacent to the first.2. Indicate the specific defect, its location, and the defective weld area to be

repaired, in yellow paint stick or marker inside the circle.

3. After repair(s) have been made and found to be acceptable by appropriate non-destructive testing, paint over the defect and location marks with white spraypaint, completely filling in the yellow circle. This signifies the weld is acceptableand ready for protective coating. Only individuals authorized by the NDE (Non-Destructive Examination) Service Provider and approved by the field inspectorwill use the yellow or white spray paint to mark such indications.

4. If a weld is to be cut out from the pipeline, apply red spray paint along the top of the pipe to the weld for at least 3 inches.

AUTHORIZED REPRESENTATIVE

Only those individuals authorized by the field inspector are permitted to mark welds forrepair or acceptance.




OPERATINGPROCEDURES


The Field Inspector is responsible to:

1. Verify the person performing the NDE performs the inspection per therequirements of this procedure.

2. Verify a daily report is completed including each weld non-destructively testedand all weld repairs. This sheet will include the person performing theinterpretation and their ANST certification level.

3. Verify a status log is maintained daily to ensure all repairs are completed andthat only those welds accepted are released for protective coating.

4. Ensure a copy of the report and status logs are turned into the Operating Centerfor filing for the life of the pipeline.

PERSONNEL QUALIFICATIONS FOR INSPECTION

All personnel conducting ultrasonic testing will be qualified as required by the latestedition of SNT-TC-1A (“Level II for Ultrasonic Testing”, latest edition).

The Field Supervisor or Field Inspector are responsible to:

1. Verify personnel or contract personnel performing the ultrasonic inspection meet,at a minimum, ASNT (American Society of Nondestructive Testing) CentralCertification Program Level II.

2. Verify this documentation is on file.

3. Verify that personnel have the appropriate Operator Qualifications on file.

ACCEPTANCE STANDARDS

The API 1104 acceptance standards for welds apply to discontinuities located by visual,radiographic, magnetic particle, liquid penetrant and ultrasonic methods which are stated inSection 3.02 (“Non-Destructive Testing Requirements”).

All non-destructive test methods are limited in the information that can be derived for theindications they produce. The Company may, therefore, reject any weld that appears tomeet API 1104 acceptance standards if, in the inspector’s opinion, the depth of adiscontinuity may be detrimental to the weld.





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