Wednesday, April 08, 2009

Dimensional Test Procedure

1. Scope

i. The Dimensional Test is measurement method of length used to evaluate sizing, shape, and orientation an item by observation of apparatus.

ii. The Dimensional test is made in general form applicable without adaptation to variety of unlisted products or situations.

iii. The Dimensional Test should be done simultaneous visual examination.

iv. The Dimensional Test provides guidelines for performing dimensional inspection of raw shape & plate materials, marking of work piece, weld fit-up and complete welds that will be applied of fabricated part and/or equipment.

2. References

- Project Quality Assurance plan

- Quality Control Procedure

- Inspection and Test Plan

- Visual Examination Procedure

- Non Destructive Examination Personnel Qualification Procedures

- Material acceptance procedure.

3. Responsibility

3.1. QC Manager

i) QC Manager responsible for supervision of Quality Control activities and coordinates Quality Control efforts to ensure the intended results according contract requirements.
ii) QC Manager responsible for all release and/or rejected work/ inspection/ testing under ultimate judgment of the OWNER specification and statutory requirement.
iii) QC Manager shall approve the acceptable result of inspection.

3.2. QC Engineer
QC Engineer shall responsible to monitor implementation of inspection procedure in accordance with Owner specifications; Code and Standard; Scheduling, and monitoring their inspection result and reporting to QC Manager.
QC Engineer ensures that certification and validity of adjustment and calibration, inspection, test and measuring equipment.
QC Engineer has to maintain a current file on non-conforming items.

3.3. Discipline Inspector
Discipline Inspector has responsibility to report the result of each attend the testing and inspection of their each discipline to the Quality Engineer.
Discipline Inspector has right to inspect at any time according their determined schedule and can give notification that the work is release or rejected.

3.4. Quality Control Administration
i) QC Administration shall also sets up and verifying the documentation filling system and controls all documents on inspection and quality control in accordance to the contract requirements.

4. Personnel Requirements

Personnel performing examinations shall have minimum requirements as the following:

- Knowledge of drawings, specifications, and procedures.

- Knowledge of geometry

- Ability to operate the measurements apparatus.

- Knowledge of welding symbols.

- Ability to make and maintain adequate records.

5. Supporting Documents

i. Specifications and/or drawings shall have been approved “issued for construction” status.

ii. Specification and/or drawings of work piece shall have clear references, such as: material; sizing & starting point; orientation, unit size, scale, part no, welding joint preparation, welding symbols, machining symbols, etc.

6. Technique

i. Direct dimensional examination

Direct dimensional examination of work piece may usually be made when access is sufficient to place the eye within 24 in. (600 mm) of the surface to be examined and at an angle not less than 30 deg. to the surface to be examined. Lighting of the measurement point must be sufficient for good visibility. Auxiliary lighting may be needed.

ii. Remote Dimensional Examination.

In some cases, remote dimensional examination may have to be substitute for direct examination. Remote dimensional test shall have a resolution capability at least equivalent to that obtainable by direct measuring observation.

7. Measurement Apparatus

i. All measurement equipments shall be calibrated.

ii. Direct measuring may be used steel roll meter, vernier caliper, micrometer, steel ruler.

iii. Remote dimensional test may be used thickness meter and theodolite.

iv. A measurement system analysis shall considers the following:

- Selecting the correct measurement and approach

- Assessing the measuring device

- Assessing procedures & operators

- Assessing any measurement interactions

- Calculating the measurement uncertainty of individual measurement devices and/or measurement systems

v. Factors affecting measurement systems, may include:

- Equipment : measuring instrument, calibration, fixture, etc.

- People : operators, training, education, skill, care.

- Process : Test method, specification.

- Samples : materials, item to be tested, sampling plan, sample preparation, etc.

- Environment : Temperature, humidity, conditioning, pre-conditioning.

- Management : Training programs, metrology system, support of people, support of quality management system, etc.

vi. Component of measuring system analysis, as below:

- Bias

- Stability

- Linearity

- Repeatability and reproducibility

- Attribute study

- Practical examples for calculating Bias, Stability, Linearity, Repeatability & Reproducibility, Attribute study.

vii. Errors

- Parallax error: take reading of the main scales in a viewing direction perpendicular to the measured point of the scales.

- Positional error: Measurement position of the large size should be consistent. Measurement in vertical position may differ from those in horizontal position.

8. Coordination

8.1. Incoming material

It shall refer to material acceptance procedure.

8.2. Fabrication work

It shall refer to fabrication procedure

9. Evaluation

An examination checklist shall be used to plan and to verify that the required dimensional test was performed. This checklist shall refer to Inspection & Test Plan that it establishes minimum examination requirements and does not indicate the maximum which the Manufacturer may perform in process.

9.1. Materials

Inspection of raw material can detect mistake of sizing, shortage of length, shortage of thickness, and laminations of plate. The detail inspection shall refer to Acceptance material procedure.

9.2. Marking of Work piece

Examination of the work piece prior to cut can detect mistake of sizing, shape & orientation; and material mistake.

Dimensions should be confirmed by measurements, work piece should be identified by part no. of drawing and material heat no. Corrections should be made before work proceeds.

9.3. Fit up of welding part

After the parts are assembled for welding, the examiner should check the dimension, shape, and orientation of assembly part for conformity to the approved construction drawings.

If all of parts have been assembled in accordance with fabrication drawings, the examiner shall put “OK weld” status of welding area; the welding sequence shall refer to fabrication method.

If the dimension of parts assembly does not yet meet drawings, it shall be confirmed to fitter and foreman for repair. Corrections should be made before work proceeds.

9.4. After Welding
Items that are checked after welding include the following:

i. Dimensional accuracy

ii. Amount of distortion

9.5. After Post Weld Heat Treatment
When a post weld heat treatment is specified, Items that are checked after Post Weld Heat Treatment include the following:
i. Dimensional accuracy
ii. Amount of distortion

10. Acceptance Criteria
The acceptance standards of finish weld shall refer to drawings status “issued for construction”. The dimensional tolerances shall refer to owner specification, relevant codes & standards, and/or manufacturer standard.

11. Non conformity product

The non conformance shall refer to Non conformity procedure.

12. Documentation

12.1. Report of Examination

A written report of the examination shall contain the following information:

- The date of examination

- Technique used

- Identification of the part or component examined.

- Heat number

- Result of the dimensional inspection and visual examination.

- Examination personnel identity, and when required by the referencing code section.

The inspection record shall be maintained and documented of Mechanical Acceptance Report, that it will be sent to OWNER of the end of project.

13. Attachments

Attachment – 1 Dimensional Inspection Record Form

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