CIRCULAR

PROMULGATING PROCEDURES FOR INSPECTION OF TECHNICAL SAFETY OF METAL PIPING SYSTEM CARRYING COMPRESSED GASES, LIQUEFIED GASES AND DISSOLVED GASES

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

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

Pursuant to the Government’s Decree No. 44/2016/ND-CP dated May 15, 2016 elaborating on several Articles of the Law on Occupational Safety and Health on technical inspection of occupational safety, occupational safety and health training and workplace environment monitoring;

At the request of the Director General of the Department of Work Safety;

The Minister of Labor, War Invalids and Social Affairs hereby promulgates a Circular on procedures for inspection of technical safety of metal piping system carrying compressed gases, liquefied gases and dissolved gases.

Article 1. Procedures for inspection of technical safety of metal piping system carrying compressed gases, liquefied gases and dissolved gases, code QTKD: 31-2021/BLDTBXH are promulgated together with this Circular.

Article 2. This Circular comes into force from October 15, 2021.

Article 3. Ministers, ministerial agencies, Governmental agencies, Chairmen/Chairwomen of People’s Committees of provinces and central-affiliated cities, organizations and individuals concerned are responsible for the implementation of this Circular./.

PROCEDURES FOR INSPECTION OF TECHNICAL SAFETY OF METAL PIPING SYSTEM CARRYING COMPRESSED GASES, LIQUEFIED GASES AND DISSOLVED GASES

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

Article 1. Scope

1. Procedures for inspection of technical safety of metal piping systems carrying compressed gases, liquefied gases and dissolved gases (hereinafter referred to as “Procedures”) shall be used for first, periodic and unscheduled of piping systems carrying compressed gases, liquefied gases and dissolved gases (hereinafter referred to as “piping system”) under the state management of the Ministry of Labor, War Invalids and Social Affairs as specified in the Appendix Ib of the Government’s Decree No. 44/2016/ND-CP dated May 15, 2016 elaborating on several Articles of the Law on Occupational Safety and Health on technical inspection of occupational safety, occupational safety and health training and workplace environment monitoring.

2. The procedures do not apply to the following piping systems:

a) Piping systems carrying liquefied petroleum gas, gases and petroleum products.

b) Piping systems carrying steam and hot water.

c) Piping systems carrying medical gases.

Article 2. Regulated entities

The procedures apply to organizations carrying out technical inspections of occupational safety, occupational safety inspectors and relevant organizations and individuals.

Article 3. Terms and definitions

For the purposes of this document, the following terms and definitions shall apply:

1. “metal piping system carrying compressed gases, liquefied gases and dissolved gases (those gases are hereinafter referred to as “working fluids”)” means a system consisting of pipes and pipe fittings used to carry working fluids from one location to another.

Pipe fittings are compatible mechanical components used to serve the connection or to be fitted to a system, including pipe unions (sockets, elbows, bushings, flanges, gaskets, bolts and other pipe unions), valves, flexible hoses, expansion compensators, filters, dehumidifiers, oil, gauges and other compatible mechanical components.

2. “first safety inspection” means a technical inspection of occupational safety of a piping system after its installation and before its first use.

3. “periodic inspection” means a technical inspection of occupational safety of a piping system after expiration of the last inspection result.

4. “unscheduled safety inspection” means a technical inspection of occupational safety which is carried out:

a) after a repair, upgrade or renovation that affects the technical safety of the piping system.

b) after change of the location of installation.

c) when the piping system has not been in operation for at least 12 months.

d) at the request of the user or a competent authority.

Article 4. Inspection steps

1. An inspection of technical safety of a piping system shall be carried out in the following order:

a) Inspect documents and technical documentation of the piping system.

b) Conduct external and internal inspection.

c) Conduct technical testing.

d) Conduct operational inspection.

dd) Process the inspection result.

2. Only take the next step if the piping system passes the test in the previous step. The result of each step shall be documented according to the form in the Appendix enclosed herewith and fully retained by the inspecting organization.

Article 5. Inspection equipment

1. Inspection equipment shall be inspected and calibrated in accordance with regulations.

2. Inspection equipment includes:

a) Hydraulic test pump.

b) Gas compressor, pneumatic pressure generator or compressed gas and inert gas cylinders.

c) Manometer with appropriate accuracy and scale.

d) Endoscope testing equipment for defect detection.

dd) Apparatus for checking geometric dimensions.

e) Foam sprayer, soapy foam or gas leak detector.

g) Lead sealing plier.

h) Insulation resistance meter.

i) Ground resistance meter.

k) Temperature measuring instrument.

l) ) Luminous intensity meter.

m) Ultrasonic thickness gauge (if necessary).

n) Non-destructive testing equipment for defect detection (if necessary).

Article 6. Conditions for inspection

The inspection must not be carried out unless the following conditions are met:

1. The piping system is at the ready for inspection.

2. Documents of the piping system are adequate.

3. The inspection is not affected by environment or weather.

4. Requirements concerning occupational safety and health are met.

Article 7. Preparation for inspection

Before carrying out the inspection, it is required to make the following preparations:

1. Reach an agreement on the inspection plan and preparations and cooperate with the piping system user in:

a) Preparing documents and technical documentation of the piping system.

b) Isolating and removing working fluids, cleaning internal and external surfaces of the piping system.

c) Preparing facilities for examining all components of the piping system.

d) Providing personnel and materials for inspection; assign personnel to participate in and witnessing the inspection.

2. Inspect documents and technical documentation of the piping system

a) First inspection

- Regarding design document (if any), pay attention to the following:

+ Parameters for fabricated metal and welds.

+ Calculation of strength or standards specifying technical specifications related to strength of pressure retaining components.

+ Diagram of the piping system.

+ Basic specifications of the system.

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

- Regarding installation and as-built documents, pay attention to the following:

+ Name of the installer; basic specifications of the system.

+ As-built drawing

+ Characteristics of materials added upon installation;

+ Certificates of inspection of fabricated metal quality.

+ Welding data such as locations of welds, welding technology, welding electrode code, welder's name and weld quality test results.

+ Calculation of strength or standards specifying technical specifications related to strength of pressure retaining components (in the absence of the design document).

+ Entire piping system commissioning record.

+ Measuring equipment calibration reports; records on inspection of grounding, lightning protection and protection equipment (if any).

+ Guidelines for operation, maintenance and repair.

b) Periodic inspection

Documents shall be inspected as if it is the first inspection and the following shall be additionally inspected:

- Previous profile, inspection record and inspection result report.

- Documents on the use, operation and maintenance of the piping system; inspection record (if any).

c) Unscheduled inspection

Documents shall be inspected as if it is the unscheduled inspection and other documents shall be additionally inspected in the following cases:

- In case of repair, renovation or upgrade: documents on repair, renovation or upgrade or and commissioning record.

- In case of relocation: installation documents.

d) Evaluation

The document inspection result is satisfactory if:

- Documents of the piping system are adequate and satisfy the above-mentioned inspection requirements.

- If the result is unsatisfactory, the user shall take remedial actions.

3. Prepare suitable and adequate equipment for inspection.

4. Develop measures for ensuring safety and reach an agreement with the user before inspection. Provide adequate personal protective equipment to ensure safety during the inspection.

Article 8. Inspection process

An inspection shall be carried out in the following order:

1. External inspection:

a) Check installation area and location against those specified in the documents and technical documentation of the piping system.

If the piping system uses a toxic or explosive working fluid, check the ventilation system, especially at the source area, the area where the working fluid is used and outlet of the safety valve.

c) Check work platform, stairs and hangers against those specified in the documents and technical documentation of the piping system.

d) Check electrical safety grounding and lightning protection system (if any) against those specified in the documents and technical documentation of the piping system.

dd) Check the specifications on the piping system's label and particulars in the piping system against those specified in the documents and technical documentation of the piping system.

e) Check the condition of safety, measuring and ancillary equipment in terms of its quantity, type and technical specifications against those specified in the documents and technical documentation of the piping system.

g) Check pipes, valves and pipe fittings installed on the piping system in terms of their quantity, type and technical specifications against those specified in the documents and technical documentation of the piping system.

h) Check the condition of other ancillary equipment accompanied serving operation of the piping system.

i) Check the condition of welds and metal surfaces of pressure retaining components of the piping system. If any suspicion exists, request the user to take appropriate additional inspection measures to provide a more accurate evaluation.

k) Check the technical condition of the paint and thermal insulation coating (if any) against those specified in the documents and technical documentation of the piping system; check for signs of water stagnation under the thermal insulation coating.

l) Check joints.

m) Evaluate the external inspection result

The document inspection result is satisfactory if:

- The external inspection result shows that the documents and technical documentation of the piping system are conformed to.

- No crack, bulge, dent or sign of working fluid leakage in the pressure retaining components of the piping system is found.

- The minimum thickness of the pipe wall deteriorated by scratches, indentations or corrosion must pass the strength test conducted under the corresponding maximum working pressure of the piping system or fall within the corrosion limit specified in the documents and technical documentation of the piping system.

2. Conduct internal inspection

a) Check the condition of metal surfaces of pressure retaining components of the piping system.

b) Check the inner metal of the piping system for dirt, rust or corrosion.

c) For locations where an internal inspection fails to be conducted during inspection, a technical condition check shall be carried out in accordance with the manufacturer's technical documentation. The following shall be documented: inspection items, method and process.

d) If it is not possible to conduct an internal inspection due to the structural characteristics of the piping system, a strength test may be carried out instead as prescribed in Point c Clause 3 of this Article and examinable components shall be inspected.

dd) Evaluate the internal inspection result

The piping system passes the test if:

- The piping system is in normal working condition and no crack, bulge or dent is found.

- The minimum thickness of the pipe wall deteriorated by scratches, indentations or corrosion must pass the strength test conducted under the corresponding maximum working pressure of the piping system or fall within the corrosion limit specified in the documents and technical documentation of the piping system.

3. Conduct technical testing

a) If the piping system has multiple segments working at different pressure levels, a separate test must be performed for each segment under the corresponding different pressure levels.

b) Upon conducting testing, isolation measures must be taken to ensure that automatic protection equipment and measuring equipment are not destroyed at the test pressure. If not, such equipment shall be removed.

c) Strength test

A strength test shall be conducted at least once every 6 years according to the following requirements (including unscheduled tests):

- The test medium is a liquid (water, non-corrosive, non-toxic or non-flammable liquid), gas (inert gas or air), temperature of the test medium must be less than 50°C and must not be more than 5°C below the ambient temperature.

- Strength test pressure

+ Pipe strength test pressure is as follows:

Table: Pipe strength test pressure

+ If the strength test pressure of the pipe is equal to or less than the strength test pressure of the pressure vessel in the system, the pipe strength test is performed together with the pressure vessel in the system at the pipe strength test pressure specified in the Table in Point c Clause 3 of this Article.

+If the strength test pressure of the pipe is greater than the strength test pressure of the pressure vessel in the system and it is not possible to isolate the pipe from the pressure vessel, the pipe strength test is carried out together with the pressure vessel in the system at the strength test pressure of the pressure vessel which must be approved by the user and not be less than 77% of the pipe strength test pressure specified in the Table in Point c Clause 3 of this Article.

- Test pressure holding time: 10 minutes.

- Test process:

+ Fill the test medium: fully fill the piping system with the test medium (paying attention to releasing gases if the test medium is a liquid).

+ Increase the pressure up to the test pressure (paying attention to increasing the pressure gradually to avoid sudden expansion that may damage the equipment and avoiding hammering while applying the test pressure). Monitor and detect unusual events during the test.

+ Maintain the test pressure as prescribed.

+ Reduce pressure slowly to the working pressure, maintain this pressure during the test. Then reduce the pressure to 0 (zero); correct the deficiencies (if any) and check the result.

- If it is impossible to conduct a strength test using a liquid due to stress on the footing or floor or difficulty in draining water, conduct the test using gas pressure (air or inert gas). The strength test with gas is permitted only when the external and internal inspection give a good result and the strength is calculated and tested using the data obtained from direct measurement of the piping system. When conducting a gas test, the following safety measures must be taken:

+ Valves and manometer on the pipe filled with test gas should be moved away from the pipe location or outside the pipe room.

+ During the period of applying gas test pressure, unauthorized persons must move to a safe place.

+ Hammering on any component of the piping system while applying gas pressure is prohibited.

- Evaluate the strength test result:

The piping system passes the test if:

+ No crack is found.

+ No air bubble, water spray or leakage of water through welds or joints is found.

+ No distortion is detected.

+ The allowable pressure drop during the period of maintaining the test pressure does not exceed 3% of the test pressure.

d) Tightness test

The piping system shall undergo a tightness test after the strength test or when the piping system uses a working fluid which is flammable, explosive or toxic or contains a metal corrosion agent:

- Test medium: Air or inert gas

- Test pressure: Plvmax (maximum working pressure).

- Test pressure holding time: at least 30 minutes.

- Test process:

+ Fully fill the test medium, proceed to gradually increase the pressure to the test pressure, disconnect the source.

+ Conduct the test with soapy water, foam sprayer or gas leak detector; check welds, flanges, threaded joints and valve connections at the ends and along the pipe.

- Evaluate the tightness test result

The piping system passes the test if:

+ The pressure is not reduced when maintained at the test pressure.

+ No gas leakage is detected.

4. Conduct operational inspection:

a) Inspect the satisfaction of all conditions for putting the piping system into operation.

b) Inspect the working condition of the piping system and accompanied fittings and operation of measuring and protection equipment.

c) Adjust and seal a safety valve as follows: the set pressure of the safety valve is not greater than 1.1 times the maximum working pressure.

d) Evaluate results: the piping system passes the test if the requirements concerning the piping system, ancillary equipment, measuring and protection equipment and specifications are met.

Article 9. Processing of inspection results

1. Prepare an inspection record which contains sufficient information according to the form in the Appendix enclosed herewith.

2. Approve the inspection record:

a) Mandatory participants in the process of approving the inspection record include:

- The representative of the user or a person authorized by the user.

- The witness.

- The inspectors.

b) When the record is approved, the inspectors, the witness, and the representative of the user or a person authorized by the user shall append their signatures and seals (if any) on the record. The record shall be made into two (02) copies, each party shall keep 01.

3. Write the brief inspection result to the profile of the piping system (including full names of the inspectors and the date of inspection).

4. Put on the inspection stamp: if the piping system passes the test, the inspector shall put an inspection stamp on it at a noticeable position.

5. Certify the inspection result:

a) If the piping system passes the test, the inspecting organization shall issue the certificate of inspection result to the piping system within 05 working days from the date on which the inspection record is approved.

b) If the piping fails the test, only the steps in Clauses 1 and 2 of this Article shall be taken and the inspection record must specify the explanation for failed result, necessary remedial actions and a deadline for taking such actions. The inspection record shall be sent to the employment authority of the area where the piping system is installed and located.

Article 10. Inspection interval

1. A piping system has to be inspected every 03 years. For a piping system that uses a working fluid that is flammable, explosive or toxic or contains a metal corrosion agent or another piping system that has been used for more than 12 years, such piping system has to be inspected every 02 years.

2. For a piping system that uses a working fluid that is flammable, explosive or toxic or contains a metal corrosion agent or another piping system and has been used for more than 12 years or another piping system that has been used for more than 24 years, such piping system has to be inspected every year.

3. In the case where a shorter interval is demanded by the manufacturer or user, such interval shall apply.

4. If the inspection interval is shortened, the inspector shall specify explanation in the inspection record.

5. If the inspection interval is specified in national technical regulations, such regulations shall apply./.

APPENDIX

SPECIMEN OF RECORD ON INSPECTION OF TECHNICAL SAFETY OF METAL PIPING SYSTEM CARRYING COMPRESSED GASES, LIQUEFIED GASES AND DISSOLVED GASES
(Enclosed with the Procedures for inspection of metal piping system carrying compressed gases, liquefied gases and dissolved gases, code: QTKD: 31-2021/BLDTBXH)

RECORD ON INSPECTION OF TECHNICAL SAFETY OF METAL PIPING SYSTEM CARRYING COMPRESSED GASES, LIQUEFIED GASES AND DISSOLVED GASES

No. ..............

We are:

1.…………………………………… Inspector number: ………………………….

2.…………………………………… Inspector number: ………………………….

currently working for: ………………………………………………………………………..……

Registration certificate No. ………………………………………

Have inspected: ………………………………….……………………………….

Of (name of the user): …………………………………………………………………..

Address (head office of the user) : ………………………………………………………..

Address (location) of the piping system: ………………………………………………………..

Inspection procedures applied: …………………………………………………………….

Individuals witnessing the inspection and approving the record: ……………………………

1………………………………                              Position: ……………………………

2………………………………                              Position: ……………………………

I - BASIC SPECIFICATIONS

Code: ………………

Total length: ………………………..…m

Working fluid: ………………..

Manufacturer (installer): …………………….Manufacturing year (installation year): ………

Uses: ……………………………………………………………………..

Date of last inspection………………………….. By: ……………………

Date of last strength test: …………………., by……………………..

Design pressure: …………….bar

Outer diameter of pipe: ………….…mm     Working pressure: ………...bar

Design temperature: ………………………°C           Working temperature: …….… °C

(If the piping system has multiple segments working at different pressure levels, additional specifications of each segment are required: design pressure; working pressure; outer diameter; design temperature; working temperature).

II - FORMS OF INSPECTION

First time □                  Periodic □                 Unscheduled □

Reason for unscheduled inspection: ………………………….

III - INSPECTION CONTENT

1. Document inspection under Clause 2 Article 7 of the Procedures:

- Comments: ………………………………………………………………............

- Result evaluation:                        Passed □                         Failed □

2. External and internal inspection:

- Comments: ………………………………………………………………............

- Result evaluation:                        Passed □                         Failed □

3. Test:

3.1 Measuring instrument for testing:

3.2 Test:

- Comments: ………………………………………………………………............

- Result evaluation:                        Passed □                         Failed □

4. Result evaluation:                        Passed □                         Failed □

IV – CONCLUSIONS AND RECOMMENDATIONS

1. Result:                        Passed □                         Failed □

2. Inspection stamp No. ………………………At: ……………

3. Working pressure: …………………bar         Working temperature: ………….°C.

4. System safety valve’s set pressure:

System valve opening pressure: ………bar       System valve closing pressure: ……bar

If the system consists of multiple pipe segments working at different pressure levels, specify set pressure of safety valve on each pipe segment.

5. Recommendations: …………………………………………………………………

Deadline for implementation of recommendations: ………………………………………….

V - INSPECTION INTERVAL

Date of periodic inspection………. [date]

Reasons for shortened interval……………………………………………………

The record is approved on……………………[date]

At: …………………………………………………………………………...

The record is made into of .... copies, each party holds....  copies./.

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