Circular 08/2021/TT-BLDTBXH procedures for technical safety inspection on metal piping systems transporting compressed air, liquefied gas, and dissolved gas

CIRCULAR

On promulgation of the procedures for technical safety inspection on metal piping systems transporting compressed air, liquefied gas, and dissolved gas

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Pursuant to the Law on Occupational Safety and Health dated June 25, 2016;

Pursuant to Decree No. 14/2017/ND-CP dated February 17, 2017 of the Government defining the functions, tasks, powers and organizational structure of the Ministry of Labor, Invalids and Social Affairs;

Pursuant to Decree No. 44/2016/ND-CP dated May 15, 2016 of the Government detailing a number of articles of the Law on Occupational Safety and Health with regard to technical inspection of occupational safety, safety training, occupational health and working environment monitoring;

At the proposal of the Director of the Department of Work Safety;

The Minister of Labor, Invalids and Social Affairs promulgates the Circular on promulgation of the procedures for technical safety inspection on metal piping systems transporting compressed air, liquefied gas, and dissolved gas.

Article 1. The procedures for technical safety inspection on metal piping systems transporting compressed air, liquefied gas, and dissolved gas - QTKD: 31-2021/BLDTBXH, is promulgated together with this Circular.

Article 2. This Circular takes effect from September 15, 2021.

Article 3. Ministries, ministerial-level agencies, Government-attached agencies, People's Committees of provinces and municipalities, and relevant organizations and individuals shall be responsible for implementing this Circular./.

PROCEDURES FOR TECHNICAL SAFETY INSPECTION ON METAL PIPING SYSTEMS TRANSPORTING COMPRESSED AIR, LIQUEFIED GAS, AND DISSOLVED GAS QTKD: 31-2021/BLDTBXH

(Promulgated together with Circular No. 08/2021/TT-BLDTBXH dated August 30, 2021 of the Minister of Labor, Invalids and Social Affairs)

Article 1. Scope of regulation

1. The procedures for technical safety inspection on metal piping systems transporting compressed air, liquefied gas, and dissolved gas (hereinafter referred to as the procedures) are applicable to the first-time, periodic, extraordinary technical safety inspection on metal piping systems transporting compressed air, liquefied gas, and dissolved gas with the working pressure of 0.7 bar or more (hereinafter referred to as the piping systems) within the ambit of State management of the Ministry of Labor, Invalids and Social Affairs as prescribed Appendix Ib of Decree No. 44/2016/ND-CP dated May 15, 2016 of the Government detailing a number of articles of the Law on Occupational Safety and Health with regard to technical inspection of occupational safety, safety training, occupational health and working environment monitoring.

2. The procedures are not applicable to the following piping systems:

a) Piping systems transporting liquefied petroleum gas, flammable gas and petroleum products.

b) Piping systems transporting steam and hot water.

c) Piping systems transporting gases used in the health sector.

Article 2. Subjects of application

The procedures are applicable to organizations and inspectors conducting technical inspection of occupational safety, and related organizations and individuals.

Article 3. Terms and definitions

In the procedures, some terms and definitions are construed as follows:

1. Metal piping systems transporting compressed air, liquefied gas, dissolved gas (the above-mentioned gases are referred to collectively as working fluids) mean systems consisting of pipes and piping components that transport the working fluids from one point to another point.

Piping components mean compatible mechanical components that are used to connect pipework together or installed in a piping system, including pipe fittings (adaptors, elbows, pipe tees, flanges, gaskets, bolts and some other pipe fittings), valves, hoses, expansion joints, filters, dehumidifiers, oils, gauges and some other compatible mechanical components.

2. First-time technical safety inspection means the technical inspection of occupational safety performed after a piping system is installed and before it is put into use for the first time.

3. Periodic technical safety inspection means the technical inspection of occupational safety upon the expiration of the previous inspection.

4. Extraordinary technical safety inspection means the technical inspection of occupational safety in the following cases:

a) After a piping system is repaired, upgraded or renovated, which may affect the technical and safety status of the piping system.

b) After the installation location is changed.

c) When a piping system has been inactive for 12 months or more.

d) At the request of the establishment or the competent authority.

Article 4. Steps of verification

1. When conducting technical safety inspection on a piping system, the technical inspection organization must follow the following order:

a) Check records and technical documents of the piping system.

b) Conduct external and internal technical inspection on the system.

c) Conduct quality tests.

d) Inspect the operation of the system.

d) Process the inspection results.

2. The next inspection steps shall only be conducted when the test results in the previous step are satisfactory. All inspection results of each step must be fully recorded in the inspection record made using the form specified in the Appendix enclosed herewith and fully archived by the inspection organization.

Article 5. Equipment and instruments for inspection

1. Equipment and instruments for inspection must be inspected and calibrated in accordance with the regulations.

2. Equipment and instruments for inspection are:

a) Hydraulic pressure test pumps.

b) Air compressors, gas pressure calibrators or cylinders containing compressed air or inert gas.

c) Manometers with the appropriate accuracy class and measuring scale.

d) Endoscopic devices for checking defects.

dd) Instruments and means for checking geometrical dimensions.

e) Foam sprayers, soap bubbles or gas leak detectors.

g) Lead pliers.

h) Insulation resistance testers.

i) Ground resistance testers.

k) Thermometers.

l) Light intensity meters.

m) Ultrasonic devices for checking metal thickness (if necessary).

n) Non-destructive devices for checking defects (if necessary).

Article 6. Conditions for inspection

When conducting the inspection of a piping system, the following conditions must be satisfied:

1. The piping system must be ready for inspection.

2. There must be sufficient records and documents about the piping system.

3. Environmental and weather factors do not affect the test results.

4. The occupational safety and health conditions must be satisfied for the inspection of the piping system to be conducted.

Article 7. Preparation for inspection

Before conducting the inspection, the following preparatory jobs must be done:

1. The inspection organization shall work out an inspection plan and preparation jobs, then coordinate with the establishments using the piping system to prepare the following contents:

a) Preparing technical documents about the piping system.

b) Isolating and removing the working fluids, cleaning inside and outside the piping systems.

c) Preparing works to facilitate the inspection of all parts of the piping system.

d) Preparing human resources and materials for the inspection; sending staff to participate and witness the inspection.

2. Technical documents and records about the piping system must be checked

a) First-time technical safety inspection

- Check the design dossiers (if any) with focus on the following main contents:

+ Requirements on fabricated metal and welds.

+ Calculation of durability or standards on specifications related to the durability of pressure-bearing parts.

+ Schematic drawings of the piping system.

+ Basic parameters of the system.

+ Requirements on measuring equipment; grounding, lightning protection, protective equipment (if any).

- Check the installation and completion documents with focus on the following main contents:

+ Name of the establishments that install and use the system; basic parameters of the system.

+ As-built drawings;

+ Properties of materials added during the course of installation;

+ Certificates of quality inspection of fabricated metals.

+ Welding data, such as: weld positions, welding technology, welding rod codes, name of welders and results of welding quality test.

+ Calculation of durability or standards and specifications related to the durability of pressure-bearing parts (when the design documents are not available).

+ Records of overall appraisal and acceptance of the piping system.

+ Reports on calibration results of measuring equipment; inspection records of grounding, lightning protection, and protective equipment (if any).

+ Operation, maintenance and repair manuals.

b) Periodic technical safety inspection

Check the documents and records as required for the first-time inspection as well as the following additional documents and records:

- Historical records of the piping system, its inspection records and the certificate for the results of the previous inspection.

- Records on management, use, operation, and maintenance, and records of examination and inspection (if any).

c) Extraordinary safety technical inspection

Check and review the records as required for the periodic safety technical inspection as well as additional documents and records in the following cases:

- In case of repair, renovation or upgrade: the design dossiers for repair, renovation or upgrade, records of appraisal and acceptance after repair, renovation or upgrade.

- In case of changing the installation location: the installation documents.

d) Appraisal of results of the record and document check

The results are satisfactory when:

- The records and documents of the piping system are sufficient and meet the above requirements.

- Otherwise, the establishment shall take remedial measures or supplement them.

3. All suitable inspection equipment and instruments shall be prepared for the inspection.

4. Measures to ensure safety for the establishment shall be taken before the inspection. People engaged in the inspection shall be fully equipped with tools and personal protective equipment to ensure their safety during the inspection.

Article 8. Conduct of inspection

The inspection shall be conducted in the following order:

1. Conduct the external technical inspection:

a) Check and compare the piping system’s installation site and location with those specified in its technical records and documents.

b) Check and compare the operating lighting and ventilation systems (if any) with those specified in the technical records and documents of the piping system. In cases where the piping system uses hazardous or explosive working fluids, the ventilation system must be checked, especially at the input sources, the areas of working fluids, and the outlets of the safety valves.

c) Check and compare the working floor, stairs, and hangers with those specified in the technical records and documents of the piping systems.

d) Check, compare the electrical safety and lightning protection grounding systems (if any) with those specified in the technical records and documents of the piping system.

dd) Check and compare the technical parameters inscribed on the labels of the piping system and its components with those specified in the technical records and documents of the piping system.

e) Check and compare the conditions of the safety, measurement and auxiliary devices in terms of quantity, types, and technical parameters with those specified in the technical records and documents of the piping system.

g) Check and compare the types of pipes, valves and piping components installed on the piping system in terms of quantity, types and technical parameters with those specified in the technical records and documents of the piping system.

h) Check the conditions of other auxiliary parts that are attached to the piping system to support its operation.

i) Check the conditions of welds and metal surfaces of pressure-bearing parts of the piping system. When in doubt, the establishment shall be asked to conduct appropriate additional measures to check them for more accurate assessment results.

k) Check and ensure that the technical conditions of the coating and thermal insulation layer (if any) are consistent with those specified in the technical records and documents of the piping system; check for signs of stagnant water under the thermal insulation layer.

l) Check the connection details.

m) Appraise the results of the external technical inspection

The results are satisfactory when:

- The results of the external inspection are consistent with the technical records and documents of the piping system.

- There are no cracks, bulges, dents, or leaks of working fluids from the pressure-bearing parts of the piping system.

- The minimum thickness of the pipe wall which is degraded due to scratches, pits, and corrosion must be calculated when testing the durability to suit the maximum working pressure of the piping system or within the corrosion limit specified in the technical documents and records of the piping system.

2. Conduct internal technical inspection

a) Check the conditions of metal surfaces of the pressure-bearing parts of the piping system.

b) Check the status of dirt, rust, and corrosion on the inner metal wall of the piping system.

c) The inspection of technical conditions of the positions where it is not possible to conduct the internal inspection during inspection must comply with the manufacturer's technical documents. The documents must clearly state the items, methods and order of inspection.

d) When it is not possible to conduct the internal inspection due to the structural characteristics of the piping system, the durability inspection as prescribed at Point c, Clause 3 of this Article shall be conducted instead while the checkable components shall be still inspected.

d) Appraise the results of the internal technical inspection

The results are satisfactory when:

- The piping system are in normal conditions with no cracks, bulges, or dents.

- The minimum thickness of the pipe wall which is degraded due to scratches, pits, and corrosion must be calculated when checking the durability so as to suit the maximum working pressure of the piping system or within the corrosion limit specified in the technical documents and records of the piping system.

3. Conduct quality tests

a) If the piping system has multiple parts working at different pressure levels, a separate test for each part at its pressure shall be conducted.

b) In the test, isolation measures must be taken to ensure that automatic protective devices and measuring devices are not destroyed at the testing pressure. In case of failure, such devices must be removed.

c) Test of the durability

The durability test shall be conducted once in no more than 6 years and comply with the following requirements (including abnormal test cases):

- The testing fluid must be a liquid (water or a non-corrosive, non-hazardous, non-flammable liquid), a gas (inert gas or air) and the temperature of the testing fluid must be below 50⁰C and no more 5⁰C lower than the surrounding temperature.

- The testing pressure for the durability test

+ The testing pressure for the pipeline durability test is specified as follows:

Table: Testing pressure for the pipeline durability test

+ If the testing pressure for the pipeline durability test is equal to or lower than the testing pressure for the durability test of the pressure vessel in the system, the pipeline durability test shall be conducted together with the test of the pressure vessel in the system at the testing pressure for the pipeline durability test as specified in the Table at Point c, Clause 3 of this Article.

+ If the testing pressure for the pipeline durability test is higher than the testing pressure for the durability test of the pressure vessel in the system and the pipeline cannot be isolated from the pressure vessel, the pipeline durability test shall be conducted together with the test of the pressure vessel in the system with the approval of the establishment that use the system at the pressure no less than 77% of the testing pressure of the pipeline durability test as specified in the Table at Point c, Clause 3 of this Article.

- Time allowance for maintaining the testing pressure: 10 minutes.

- The order for durability test is specified as follows:

+ Load the testing fluid: Fill the piping system with testing fluid (pay attention to discharging the gas if the testing fluid is a liquid).

+ Increase the pressure up to the testing pressure (increase slowly to avoid sudden expansion causing damages to the devices and strictly forbid hammering them at the testing pressure). Monitor and detect abnormal phenomena during the test.

+ Maintain the testing pressure as specified.

+ Reduce the pressure slowly to the working pressure, keep this pressure throughout the test. Then reduce the pressure to 0 (zero); fix the shortcomings (if any) and re-test the results that have been fixed.

- If it is impossible to test the durability with liquid testing fluid due to the stress on the footing or the attic floor, or the difficulty in draining water, the test with gas pressure (air or inert gas) shall be conducted instead. The durability test with the gas testing fluid shall be only allowed when the external and internal inspection and the calculation of the durability on the basis of direct measurement data on the piping system. When conducting the durability test with the gas testing fluid, the following safety measures must be applied:

+ Valves and pressure gauges installed on the testing gas intake pipeline must be moved away from the pipeline or outside the room where the pipeline is located.

+ When under the pressure for the durability test with the gas testing fluid, irresponsible persons must stay in safe places.

+ It is strictly forbidden to hammer on parts of the piping system during the durability test with the gas testing fluid.

- Appraise the results of the durability test:

Test results are satisfactory when:

+ No cracks appear.

+ No air bubbles, water sprays, or water leaking from the welds and joints are found.

+ No deformation detected.

The allowable pressure drop in the time the testing pressure is being maintained shall not be larger than 3% of the testing pressure.

d) Test of the tightness

The test of tightness of the piping system shall be conducted after the durability test or in the cases where the piping system transports explosive, hazardous, or corrosive substances:

- Testing fluid: Air or inert gas

- Testing pressure: P _lvmax (maximum working pressure).

- Time allowance for maintaining the testing pressure: at least 30 minutes.

- Order of the test:

+ Fill the piping system with the testing fluid, increase the pressure gradually to the testing pressure and then disconnect the fluid supply.

+ Test with soapy water, foam spray or gas leak detectors; Check the welds, flanges, threaded joints, valve connections before and on the primary pipeline.

- Appraise the results of the closed test

Test results are satisfactory when:

+ The pressure does not decrease when the testing pressure are being maintained.

+ No gas leakage detected.

4. Check the operation of the system:

a) Check all conditions for the piping system to be put into operation.

b) Check the working condition of the piping system and its auxiliary parts, and the working of measuring and protective devices.

c) Calibrate and seal the safety valves with lead as follows: the set pressure of the safety valves shall not be more than 1.1 times the maximum working pressure.

d) Appraise the results: The results are satisfactory when the piping system, its auxiliary parts, protective and measuring devices work normally, and the working parameters are stable.

Article 9. Processing of inspection results

1. A record of the inspection including all contents shall be made using the form specified in the Appendix enclosed herewith.

2. Adopt the inspection record:

a) Persons who are competent to adopt the mandatory inspection record:

- The representative of the establishment or the person authorized by the establishment.

- The person assigned to participate in and witness the inspection.

- Inspectors who conduct the inspection.

b) When the record is adopted, the inspectors, the witness of the inspection, the representative of the establishment or the person authorized by the establishment shall sign and stamp their seals (if any) on the record. The inspection record shall be made in two (02) copies, of which each party shall keep one.

3. The inspection results shall be briefly written down in the historical records of the piping system (the full name of the inspectors and the date of the inspection).

4. Affixing the inspection stamps: If the inspection results of the piping system meet the technical safety requirements, the inspector shall affix the safety-qualified stamps. The stamps shall be affixed on eye-catching positions.

5. Certification of the inspection results:

a) When the inspected piping system meets the safety technical requirements, the inspection organization shall issue a certificate of inspection results for the piping system within 05 working days since the record of the inspection at the establishment is adopted.

b) When the inspected piping system fails to meet the requirements, the inspection organization shall only comply with Clauses 1 and 2 of this Article and issue only the inspection report to the establishment, which clearly states the reasons for the piping system’s failure to meet the inspection requirements as well as asks the establishment to take remedial measures within the proposed time limit; at the same, time send the inspection record and a notice to the agency in charge of State management over labor of the locality where the piping system is installed and used.

Article 10. Time limit for inspection

1. The time limit for the periodic technical safety inspection is 03 years. For piping systems using flammable, explosive, hazardous, or corrosive substances or other piping systems that have been used for more than 12 years, the time limit for the periodic technical safety inspection is 02 years.

2. For piping systems using flammable, explosive, hazardous, or corrosive substances that have been used for more than 12 years, or other piping systems that have been used for more than 24 years, the time limit for the periodic technical safety inspection is 01 year.

3. If the manufacturer specifies, or the establishment requires, a shorter time limit for the technical safety inspection, the inspection shall comply with the manufacturer or the establishment.

4. When the time limit for the technical safety inspection is shortened, the inspectors must clearly state the reason in the inspection record.

5. When the time limit for technical safety inspection is specified in the national technical regulations, such regulations shall prevail./.

(The Appendix enclosed herewith is not translated)