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Title / Carry out a Direct Current Voltage Gradient (DCVG) survey on a steel gas pipe
Level / 4 / Credits / 3
Purpose / People credited with this unit standard are, on a steel gas pipe, able to: demonstrate knowledge of DCVG survey equipment; use DCVG survey equipment; locate and use documentation and reporting criteriafor a DCVG survey; and report the results of DCVG survey.
Classification / Gas Industry > Gas Transmission Operations
Available grade / Achieved
Guidance Information
1Evidence presented for assessment against this unit standard must be consistent with safe working practices and be in accordance with applicable manufacturer’s specifications, company procedures and legislative requirements.
2Performance of the outcomes of this unit standard must comply with the following:
Health and Safety at Work Act 2015;
Resource Management Act 1991;
AS 2832.2-2003, Cathodic protection of metals Part 2: – Compact buried structures;
BS EN 13636:2004, Cathodic protection of buried metallic tanks and related piping;
BS EN 15112:2006, External cathodic protection of well casing;
NACE TM 0169:2012Laboratory Immersion Corrosion Testing of Metals.
3References
Australian standards (AS) may be found at
British standards (BS) may be found at
National Association of Corrosion Engineers standards (NACE) may be found at
4Any new, amended or replacement Acts, regulations, standards, codes of practice, guidelines, or authority requirements or conditions affecting this unit standard will take precedence for assessment purposes, pending review of this unit standard.
5Definitions
Company procedures mean the documented methods for performing work activities, and include health and safety, operational, environmental, and quality management requirements. They may refer to legislation, regulations, guidelines, standard operating procedures, manuals, codes of practice, or policy statements.
Outcomes and performance criteria
Outcome 1
Demonstrate knowledge of DCVG survey equipment used on a steel gas pipe.
Performance criteria
1.1DCVG survey equipment is located, and its use and application are explained.
Rangecathodic protection systems interruption device, DCVG meter, pipe locator.
1.2The type of information relayed by the DCVG survey equipment is explained.
Rangecoating breaks, isolation faults.
Outcome 2
Use DCVG survey equipment on a steel gas pipe.
Performance criteria
2.1Safety procedures relating to DCVGtechniques are used.
2.2Pipeline conditions are assessed to determine the need to use DCVG survey equipment.
Rangelow test point readings, failed flange isolation kits, failed coating systems, periodic maintenance.
2.3DCVG survey equipment is operated.
2.4Potential risks of incorrect application and operation are explained.
Outcome 3
Locate and use documentation and reporting criteria when carrying out a DCVG survey on a steel gas pipe.
Performance criteria
3.1Specified documentation related to the operation of DCVG equipment islocated and used.
Rangetest certificates, certification, standards for safety, standards for in service safety inspection and testing of equipment, identification tags, labels.
3.2General site equipment documentation is located and used.
Rangemanufacturer's information, equipment operating manuals, safety procedures, operating procedures, maintenance procedures.
3.3International cathodic protection standards and reporting criteria are used.
Rangemay include –British standards, Australian standards, National Association ofCorrosion Engineer standards.
Outcome 4
Report the results of DCVG survey on a steel gas pipe.
Performance criteria
4.1Corrections to primary data of DCVG survey are made.
4.2Results of DCVG survey are calculated from primary data.
4.3Deviations from the expected range of results are investigated and actions are taken.
4.4The report includes all information gathered in the DCVG survey.
4.5Outcomes of the analysis are reported and conclusions are drawn in accordance with international standards.
Rangemay include –British standards, Australian standards, National Association ofCorrosion Engineer standards.
Planned review date / 31 December 2022Status information and last date for assessment for superseded versions
Process / Version / Date / Last Date for AssessmentRegistration / 1 / 6 February 1997 / 31 December 2018
Revision / 2 / 3 August 2000 / 31 December 2018
Review / 3 / 24 January 2002 / 31 December 2018
Review / 4 / 22 May 2009 / 31 December 2018
Review / 5 / 17 August 2017 / N/A
Consent and Moderation Requirements (CMR) reference / 0014
This CMR can be accessed at
Comments on this unit standard
Please contact MITO New Zealand Incorporated you wish to suggest changes to the content of this unit standard.
MITO New Zealand IncorporatedSSB Code 101542 / New Zealand Qualifications Authority 2018