QATAR ENGINEERING & CONSTRUCTION COMPANY WLL(Qcon)
Gate 69, Street 48, Salwa Industrial Area, Qatar
Mailing Address;PO Box 24491, Doha, QatarTel: (+974) 458 7200,
Fax: (+974) 458 7201e-mail: [email protected] site:
www.qcon.com..qa
Welding CALIBRATION PROCEDUREDocument numberQCON-P&M-08
026-08-2014DraftSudath Sanjeewa
Rev.DateDescriptionORIGINATED BY CHECKED BY APPROVED BY
IMPORTANTHard copy of this document shall be considered
uncontrolled unless signed and stamped as Controlled Copy by DCC
with copy number and issue date. Current revision of this document
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REVISION RECORD
REVDATEDESCRIPTION
026-08-2014Draft
INDEX
SECTIONTITLEPAGE
-REVISION RECORD2
-INDEX3
1.0PURPOSE4
2.0SCOPE4
3.0DEFINITION4
4.0DIVERSION4
5.0RESPONSIBILITIES4
6.0CALIBRATION5
7.0REGISTRATION & CONTROL OF CALIBRATION6
8.0ACCEPTANCE CRITERIA6
9.0DOCUMENTS6
1. PURPOSE
1.1. To established technical guidelines to perform and
calibrate inverter welding machine, rectifier welding machine, A/C
transformer welding machine, an engine driven welding machine. And
to ensure that only those calibrated welding machines will produce
acceptable quality professional weld as per national and
international standards. 1.2. To minimize the current and voltage
deviations between welding machine set parameters and work piece
and certify the welding machine.1.3. Several national and
international standards specify that the welding machine to be used
for welding machine products shall be calibrated. 1.4. Welding
machine current / voltage is an essential variable in all of the
national and International Standards. A change in current / voltage
can change weld joint properties and introduce unacceptable
discontinuities. Hence having correct current / voltage reading on
the welding machine is very vital to produce acceptable quality
welds.
2. SCOPE
This procedure details the requirement that is required to be
implemented for the welding machine calibration.
3. EXPLANATION / DEFINITIONS
Metrological comparison between a measurement device or an
instrument with their respective benchmarks, certificates and their
accuracy, in order to detect, report or eliminate by adjustment any
inaccuracy of the instrument.
4. DIVERSION
It is the difference in magnitude between the current rating of
the welding machine and the actual value measured in amperage volt
ammeter clamp, taking as basis the corresponding nominal value.
5. RESPONSIBILITIES
5.1. Production Supervisor and / or Sr. Foreman responsible for
:5.1.1. Use only calibrated welding machines.5.1.2. Advice the
staff involved and apply the requirements of this procedure5.1.3.
Arrange and meet with the minimum premises and equipment
calibration.5.1.4. Notify the Quality Control prior to the date for
the calibration of welding machine.
5.2. The Section of the Quality / Welding Inspector responsible
for 5.2.1. Notify the Technical Dept. prior to the date for the
calibration of welding machine.5.2.2. Receive the welding machine
calibration certificates from Technical Dept. and inspect, the
welding machine calibration certificate in acceptable criteria,
5.2.3. Calibration certificate to be stamped, sign and authorized
to use the welding machine. 5.2.4. Verify the validity of the
calibration time.(As per Client requirement)5.2.5. Affix labels on
the welding machine indicating the calibration.5.2.6. Maintain
proper inventory and calibration records.
5.3. The Section of the Technical / Electrical responsibility
for:5.3.1. Receive the notification for welding machine
calibration.5.3.2. Test the welding machine prior to calibration
and certification.5.3.3. Assigning competent technician to perform
welding machine calibration. 5.3.4. Perform and calibrate the
welding machine, utilizing calibrated master
instrument.(Calibration standards traceable to Internal
standards)5.3.5. Adjust and minimise the parameter deviation.
5.3.6. Verify the validity of the calibration time.(As per Client
requirement) 5.3.7. Issue welding machine calibration
certificate.5.3.8. Issue labels to stick on the welding machine
indicating the calibration.5.3.9. Maintain proper inventory and
calibration records.
6. CALIBRATION
6.1. Calibration and certification of welding machine.6.2.
Technical staff required for welding machine calibration.6.2.1.
Welding inspector.(Witness)6.2.2. An Electrician.6.2.3. Qualified
Welder6.2.4. Document controller
6.3. Materials required for welding machine Calibration6.3.1.
Welding PPE.6.3.2. Welding Consumable.6.3.3. Steel plate
appropriate.6.3.4. Accessory.6.3.5. Master instrument. (Third party
Calibrated certify and valid ( traceable to internal standards)
(properly protected from damage and deterioration during handling,
maintenance and storage)6.3.6. Suitable and standard welding
cables.6.3.7. Suitable and standard welding cable connectors.6.3.8.
Suitable and standard welding earth clamp.6.3.9. Suitable and
standard welding electrode holder
6.4. Frequency of Calibration.
6.4.1. All welding machine such as inverter welding machine,
rectifier welding machine, A/C transformer welding machine, an
engine driven welding machine should be Calibrated and certify
before use, and thereafter every six months.6.4.2. All Master
instruments should be Calibrated and certify before use, and
thereafter every six months.
Note: This period can be set by the contractor (CLIENT) but not
higher than that specified above.
6.4.3. Welding machine Calibration Technique.
6.4.3.1. Welding Electrode cable clamp connect to the positive
terminal of the welding machine to be test and calibrate.6.4.3.2.
Welding ground cable clamp connector to the negative terminal of
the welding machine to be test and calibrate.6.4.3.3. Energize the
welding machine. ((ON)Electrically or (Start)Engine driven)6.4.3.4.
Test and record welding machine OCV (Open Circuit Voltage) and
verify with the welding machine name plate.6.4.3.5. Set the welding
parameter positioning liver in the desired position.(Set
point)6.4.3.6. Engage with the volt ammeter clamp the cable clamp
electrode.6.4.3.7. Carry out the reading of the clamp volt ampere
ammeter, comparing it with the values shown on the recorder panel
of the welding machine.(Welding machine Dial)
Note; Evidence records calibration results of deviations in
from. Calibrations should happen in bands of every (It should
indicate the calibration bands for gradual measurement are taken
e.g. every 40A, 60A, 80ANumbering is the same numbering allocated
as indicated in the procedure)
7. REGISTRATION AND CONTROL OF CALIBRATION.
7.1. The results of the calibration process must be registered
in the Control of Calibration of welding machine. It should be kept
track of time calibration, so no equipment is used with their
deadlines expired.
7.2. The equipment may only be labelled when they are
approved.
8. ACCEPTANCE CRITERIA
The maximum permissible deviations for calibration are: + / -
20% on the Set point.
Note: The maximum deviation is in accordance with the criteria
established by Client. Porum not exceeding the amount fixed by the
Standard.
9. DOCUMENTS
1. Master instrument Calibration Certificate. (Sample)
2. Electric Welding machine Calibration Certificate.
(Sample]
3. Engine Driven Welding machine Calibration Certificate.
(Sample)
4. Electrode oven Calibration Certificate. (Sample)